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The study aimed to determine the acute effects of subtetanic neuromuscular electrical stimulation (NMES) combined with active recovery between sprint exercises on blood lactate accumulation, sprint performance, and muscle fatigue. Sixteen healthy young individuals [23(4) years, 10 males] underwent a 1-min rest followed by sprint interval training consisting of four 15-sec maximal sprint exercises with three 5-min active cycling sessions. Participants engaged in voluntary cycling at 40% of peak oxygen consumption, with or without NMES (VOLES or VOL; interventions). Blood lactate concentration ([La] b ) was assessed at the end of the rest and each intervention periods. Mean power was assessed during each sprint exercise session. Maximum voluntary contraction (MVC) of the knee extensor was measured before and after sprint interval training to evaluate muscle fatigue. The [La] b was significantly higher in VOLES than in VOL (main effect, P=0.037). Mean power did not differ between conditions (main effect and interaction, P>0.050). MVC after sprint interval exercise was significantly lower in VOLES than in VOL (interaction, P<0.001). Subtetanic NMES combined with voluntary cycling enhanced blood lactate accumulation and induced greater voluntary fatigue but resulted in similar peripheral muscle fatigue and sprint exercise performance compared with voluntary cycling without NMES., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Purpose: Training zones are generally assessed by gas-exchange thresholds (GET). Several mathematical analyses of heart rate variability (HRV) are proposed for indirect GET determination. Our study aimed to investigate the accordance of the detrend fluctuation analysis (DFA α1) for determining GET with first (VT1) and second ventilatory (VT2) thresholds in well-trained subjects., Methods: Eighteen female and 38 male sub-elite cyclists performed a maximal incremental cycling test of 2-min stage duration with continuous gas exchange and HR measurements. Power output (PO), Oxygen uptake ( V ˙ O 2 ) and HR at VT1 and VT2 were compared with DFA α1 0.75 (HRVT1) and 0.50 (HRVT2). Agreements between PO, V ˙ O 2 and HR values were analyzed using Bland-Altman analysis., Results: Large limits of agreement between VT1 and HRVT1 were observed for measures of V ˙ O 2 expressed in mL.min -1 .kg -1 [- 21.3; + 14.1], HR [ 39.2; + 26.9] bpm and PO [- 118; + 83] watts. Indeed, agreements were also low between VT2 and HRVT2 for measures of V ˙ O 2 [- 26.7; + 4.3] mL.min -1 .kg -1 , HR [- 45.5; + 10.6] bpm and PO [- 157; + 35] watts. Our results also showed a sex effect: women obtained worst predictions based on DFA α1 than men for HR (p = 0.014), PO (p = 0.044) at VT1 and V ˙ O 2 (p = 0.045), HR (p = 0.003) and PO (p = 0.004) at VT2., Conclusion: There was unsatisfactory agreement between the GET and DFA α1 methods for VT1 and VT2 determination in both sex well-trained cyclists. Trial registration number 2233534 on 2024/03/05 retrospectively registered., Competing Interests: Declarations. Conflict of interest: Authors declare to have no conflict of interest with results studies or any authors producing previous research not in line whit our findings., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

During an IRONMAN, the pacing strategy in the running segment differs significantly between sexes. However, it is unknown if sex affects the running pace in shorter triathlon events. This study compared the pacing strategy between sexes during a 5-km running test performed following a 20-km cycle (sprint triathlon distances). Participants included 16 men (34.7±7.5 years) and 16 women (39.5±7.7 years). A cardiopulmonary exercise test to measure maximal oxygen uptake (˙VO 2 max) and a functional threshold power (FTP) were performed. Body composition was measured using a dual-emission X-ray absorptiometry system. Participants cycled at 90% FTP for 20 km and ran as fast as possible for 5 km. The total time spent cycling 20 km was shorter (~11%) in male than in female athletes (p<0.001). Similarly, the time spent to run 5 km was shorter in male (~11%) than in female athletes (p=0.006). Male athletes performed the last 600 m of the 5km race significantly faster than the initial meters (p<0.05). Female athletes performed the 5-km race without pace variation (p>0.05). In conclusion, apart from the sex differences associated with performance in short-term triathlon events, the pacing strategy was also different., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Purpose: This study compared the effects of off- and on-bike resistance training (RT) on endurance cycling performance as well as muscle strength, power, and structure., Methods: Well-trained male cyclists were randomly assigned to incorporate two sessions/week of off-bike (full squats, n = 12) or on-bike (all-out efforts performed against very high resistances and thus at very low cadences, n = 12) RT during 10 wk, with all RT-related variables (number of sessions, sets, and repetitions, duration of recovery periods, and relative loads [70% of one-repetition maximum]) matched between the two groups. A third, control group ( n = 13), did not receive any RT stimulus, but all groups completed a cycling training regime of the same volume and intensity. Outcomes included maximum oxygen uptake (V̇O 2max ), off-bike muscle strength (full squat) and on-bike ("pedaling") muscle strength, and peak power capacity (Wingate test), dual-energy X-ray absorptiometry-determined body composition (muscle/fat mass), and muscle structure (cross-sectional area, pennation angle)., Results: No significant within/between-group effect was found for V̇O 2max . Both the off-bike (mean Δ = 2.6%-5.8%) and on-bike (4.5%-7.3%) RT groups increased squat and pedaling-specific strength parameters after the intervention compared with the control group (-5.8% to -3.9%) ( P < 0.05) with no significant differences between them. The two RT groups also increased Wingate performance (4.1% and 4.3%, respectively, vs -4.9% in the control group, P ≤ 0.018), with similar results for muscle cross-sectional area (2.5% and 2.2%, vs -2.3% in the control group, P ≤ 0.008). No significant within/between-group effect was found for body composition., Conclusions: The new proposed on-bike RT could be an effective alternative to conventional off-bike RT training for improving overall and pedaling-specific muscle strength, power, and muscle mass., (Copyright © 2024 by the American College of Sports Medicine.)

Objective: This study compared the effects of two different warm-up protocols (normal vs. priming) on the oxygen plateau ([Formula: see text]) incidence rate during a ramp test. It also compared the cardiopulmonary responses during the ramp test and subsequent verification phase., Methods: Eleven recreational cyclists performed two experimental visits. The first visit required a normal warm-up (cycling at 50 W for 10 min) followed by the ramp test (30 W.min-1) and supramaximal verification phase with 30 min rest between tests. The second visit required a priming warm-up (cycling at 50 W for 4 min increasing to 70% difference between the gas exchange threshold [GET] and maximum work rate [WRmax] for 6 min) followed by the same protocol as in the first visit. Physiological responses were collected during the exercise and compared. Oxygen kinetics ([Formula: see text] Kinetics) and [Formula: see text] incidence rate were determined during the ramp tests for both visits., Results: As planned, following the warm-up the priming visit experienced greater physiological response. However, the incidence rate of [Formula: see text] during the ramp test was the same between visits (73%), and maximal oxygen uptake was not different between visits after the ramp test (normal, 4.0 ± 0.8; primed, 4.0 ± 0.7 L·min-1, p = 0.230) and verification phase (normal, 3.8 ± 0.6; primed, 3.8 ± 0.7 L·min-1, p = 0.924) using a Holm-Bonferroni correction for controlling family-wise error rate. [Formula: see text] Kinetics were not different between visits during the ramp test (normal, 10.8 ± 1.1; primed, 10.8 ± 1.2 mL·min-1·W-1, p = 0.407). The verification phase confirmed [Formula: see text] in 100% for both the normal and priming visits., Conclusion: Our hypothesis that a priming warm-up facilitates the incidence rate of [Formula: see text] during a ramp test is not supported by the results. The verification phase remains a prudent option when determining a 'true' [Formula: see text] is required., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

The purpose of this study was to evaluate the effects of a microcycle of high-intensity interval training (HIT) sessions with multiple short work intervals followed by an active recovery period, compared to a similar duration of regular training, on determinants and indicators of endurance performance in well-trained cyclists. The participants in the BLOCK group performed a 6-day HIT microcycle including five HIT sessions (5 × 8.75-min 30/15 s short intervals) followed by a 6-day active recovery period with reduced training load, while the regular training group (REG) performed 12 days of their regular training, including four HIT sessions. Physiological testing was performed before and after the training periods. From pre- to post- intervention, BLOCK demonstrated significantly larger improvements than REG in mean power output (PO) during the last min of the maximal oxygen uptake (VO 2max ) test (PO VO2max ) (3.7 vs. 0.7%, p = 0.009, and effect size (ES) = 1.00) and mean PO during the 10-s sprint (2.8 vs. 1.9%, p = 0.028, and ES = 0.63). No significant differences between BLOCK and REG were observed for VO 2max , PO at 4 mmol·L -1 [blood lactate] (PO 4mmol ), 15-min maximal mean power output (PO 15-min ), and gross efficiency (p = 0.156-0.919). However, there was a tendency for larger improvements in the performance index (calculated from the main performance indicators PO VO2max , PO 4mmol , and PO 15-min ) in BLOCK compared to REG (2.9% vs. 1.2%, p = 0.079, and ES = 0.71). A 6-day high-intensity short-interval microcycle followed by a 6-day active recovery period induces improvements in endurance performance indicators compared to regular training, demonstrating its potential as an efficient strategy for endurance training in well-trained cyclists., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

The effects of acute hypoxic exposure on mechanical output and internal responses during cycling with heart rate (HR) clamped at lactate thresholds 1 and 2 (LT1 and LT2, respectively) were investigated. On separate days, 12 trained males cycled for 15 min at a clamped HR corresponding to LT1 and LT2 under normoxic or hypoxic conditions (simulated altitude of ∼3500 m and inspired oxygen fraction of 13.6%). Power output (PO), arterial oxygen saturation, ventilatory and perceptual responses were measured every 3 min, with metabolic response assessed pre- and post-exercise. At LT1, PO was consistently lower in hypoxia compared to normoxia (p < 0.01). At LT2, PO was not different between normoxia and hypoxia at 3 and 6 min (both p > 0.42) but was significantly lower in hypoxia at 9, 12 and 15 min (all p < 0.04). Overall, hypoxia induced a greater decrease in PO at LT1 (-33.3% ± 11.3%) than at LT2 (-18.0 ± 14.7%) compared to normoxia. Ventilatory, perceptual and metabolic responses were influenced by exercise intensity (all p < 0.01) but not environmental conditions (all p > 0.17). A simulated altitude of ∼3500 m is more effective in reducing cycling PO at LT1 than LT2 during HR clamped cycling while maintaining other internal loads. Therefore, normobaric hypoxia provides a greater benefit via a larger decrease in the mechanical constraints of exercise at lower exercise intensities., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

Methods: Twenty-eight adults (16 males and 12 females) aged 30 ± 10 yr (peak oxygen uptake (V̇O 2peak ): 59 ± 11 mL·kg -1 ·min -1 ) completed three experimental trials in a randomized, crossover, and double-blinded manner. Participants ingested either 0.3 (KE-LO) or 0.6 (KE-HI) g·kg -1 body mass of KE or a flavor-matched placebo (PLAC) ~30 min before exercise. Exercise involved a 3-min warm-up, three 5-min stages at fixed incremental workloads corresponding to 75%, 100%, and 125% of individual ventilatory threshold, followed by a ramp protocol to volitional exhaustion to determine peak power output (PPO)., Results: Venous blood [ß-hydroxybutyrate], the major circulating ketone body, was higher after KE ingestion compared with PLAC (KE-HI: 3.0 ± 1.1 ≥ KE-LO: 2.3 ± 0.6 ≥ PLAC: 0.2 ± 0.1 mM; all P ≤ 0.001. There were no differences between conditions in the primary outcome exercise economy, nor gross efficiency or delta efficiency, when analyzed over the entire submaximal exercise period or by stage. Heart rate and ventilation were higher in KE-HI and KE-LO compared with PLAC when assessed over the entire submaximal exercise period and by stage (all P ≤ 0.05). PPO after the ramp was lower in KE-HI compared with both KE-LO and PLAC (329 ± 60 vs 339 ± 62 and 341 ± 61 W, respectively; both P < 0.05) despite no difference in V̇O 2peak ., Conclusions: KE ingestion did not change indices of exercise efficiency but increased markers of cardiorespiratory stress during submaximal incremental cycling and reduced PPO., (Copyright © 2024 by the American College of Sports Medicine.)

We investigated whether pedal cadence (60 vs. 100 rpm) affects oxygen uptake (V̇O 2 ) and power output (PO) at two indexes of the heavy-to-severe-intensity domain boundary (i.e., critical power (CP) and respiratory compensation point (RCP)) and their correspondence. Fourteen adults (7 females, 23 ± 2 years) cycled at 60 and 100 rpm during: (i) a "step-ramp-step" protocol to identify V̇O 2 and PO at RCP; (ii) 4-5 exhaustive constant-PO bouts for CP identification; and (iii) a constant-power bout at CP to identify V̇O 2 at CP. Separate two-way repeated measures Analysis of variance assessed whether V̇O 2 and PO were affected by index (CP vs. RCP) and cadence (60 vs. 100 rpm). The V̇O 2 was not affected by index (mean difference (MD) = 73 ± 197 mL·min -1 ; p  = 0.136) but there was an index × cadence interaction ( p  = 0.014), such that V̇O 2 was higher at 100 versus 60 rpm for CP (MD = 142 ± 169 mL·min -1 ; p  = 0.008), but not RCP ( p  = 0526). The PO was affected by cadence (MD = 13 ± 9 W; p  < 0.001) and index (MD = 8 ± 11 W; p  = 0.016), with no cadence × index interaction ( p  = 0.168). The systematic bias in PO confirms cadence-specificity of CP and RCP. The relationship between these indexes and their change in unison in PO suggests a mechanistic link between these two heavy-to-severe domain boundary candidates., Competing Interests: The authors declare there are no competing interests.

Purpose: This study aimed to develop a new method that more closely represents the heavy to severe exercise domain boundary by evaluating the rates of blood lactate accumulation during the constant power output exercise bouts that are used in the assessment of the maximal lactate steady state (MLSS)., Methods: Eight well-trained male cyclists completed five exercise tests of up to 30 min for the determination of the traditional MLSS (MLSS TRAD ) and a further four maximal tests for the determination of critical power (CP). The rates of change of blood [lactate] between 10 min and the end of exercise in the MLSS tests were plotted against the corresponding power outputs, and a two-segment linear regression model was used to identify individualized break points in lactate accumulation versus power output (modified MLSS [MLSS MOD ])., Results: MLSS MOD was significantly higher than MLSS TRAD (297 ± 41 vs 278 ± 41 W, P < 0.001) but was not significantly different from CP (297 ± 41 W, P > 0.05); MLSS MOD and CP were closely aligned ( r = 0.97, bias = -0.52 W, SEE = 10 W, limits of agreement = -20 to 19 W). The rates of change of both blood [lactate] and V̇O 2 were significantly greater, and exercise intolerance occurred before 30 min, at a power output slightly above MLSS MOD ., Conclusions: A novel method for evaluating blood lactate kinetics during MLSS TRAD protocol produces MLSS MOD that is not different from CP and better represents the heavy to severe exercise domain boundary., (Copyright © 2024 by the American College of Sports Medicine.)

Maximal oxygen uptake (V̇O2max) gradually declines across the lifespan. However, little is known about the octogenarians. This is a knowledge gap given that individuals living >80 years old is the fastest expanding age-group world-wide. The increase in the elderly population has generated greater awareness in healthy ageing including psychosocial, physical, and cognitive domains, all of which benefit from engagement in physical activity or sport. In the present article are reported characteristics of an octogenarian man (GM), starting training for triathlon when he was 75 years old. GM performed an incremental Cardiopulmonary Treadmill-Running Exercise Test (CPX). A competitive 5-day consecutive triathlon event (sprint distance on days 1, 3, 4, 5 and Olympic distance on day 2) was monitored using an advanced smartwatch. Between 2021 and 2022, he trained for 10-to-12 hours/week, and participated in 59 and 39 competitions, respectively. The CPX showed a V̇O2max of 39.8 mL·min -1 ·kg -1 , the 3 rd highest value ever described in the literature among octogenarians and corresponding to the ≈60 th percentile of 40-to-49-year-old men. During the 5-day triathlon (overall 12:15 h:min), 88% of time was spent at 77-95% of maximum heart rate (i.e., vigorous exercise intensity). In addition, GM was the 2022 Triathlon Olympic distance World Champion. The remarkably high V̇O2max and performance described herein were associated with exceptionally high exercise volume and intensity during training and competition, up to more than four times the recommended physical activity by current guidelines. These results further support the benefits of endurance exercise among octogenarians.

Compared to the determination of exercise thresholds based on systemic changes in blood lactate concentrations or gas exchange data, the determination of breakpoints based on muscle oxygen saturation offers a valid alternative to provide specific information on muscle-derived thresholds. Our study explored the profiles and timing of the second muscle oxygenation threshold (MOT2) in different muscles. Twenty-six cyclists and triathletes (15 male: age = 23 ± 7 years, height = 178 ± 5 cm, body mass = 70.2 ± 5.3 kg; 11 female: age = 22 ± 4 years, height = 164 ± 4 cm, body mass = 58.3 ± 8.1 kg) performed a graded exercise test (GXT), on a cycle ergometer. Power output, blood lactate concentration, heart rate, rating of perceived exertion, skinfolds and muscle oxygen saturation were registered in five muscles (vastus lateralis, biceps femoris, gastrocnemius medialis, tibialis anterior and triceps brachii) and percentage at which MOT2 occurred for each muscle was determinated using the Exponential Dmax. The results of Statistical Parametric Mapping and ANOVA showed that, although muscle oxygenation displayed different profiles in each muscle during a GXT, MOT2 occurred at a similar percentage of the GXT in each muscle (77% biceps femoris, 75% tibalis anterior, 76% gastrocnemius medialis and 72% vastus lateralis) and it was similar that systemic threshold (73% of the GXT). In conclusion, this study showed different profiles of muscle oxygen saturation in different muscles, but without notable differences in the timing for MOT2 and concordance with systemic threshold. Finally, we suggest the analysis of the whole signal and not to simplify it to a breakpoint., (© 2024. The Author(s).)

Background: A novel sodium bicarbonate (SB) product has come to market named the "Bicarb System" (M-SB; Maurten AB, Gothenburg, Sweden). It claims to minimise gastrointestinal (GI) discomfort whilst still improving exercise performance., Aim: To investigate the effects of M-SB ingestion on repeated 4 km cycling time trials (TT1 and TT2) in well-trained male cyclists., Methods: The study recruited ten well-trained cyclists (maximal oxygen uptake ( V ˙ O 2 max ): 67 ± 4 ml kg -1  min -1 BM; peak power output (PPO) at V ˙ O 2 max : 423 ± 21 W) to take part in this randomised, crossover and double-blinded study. Following one visit to determine V ˙ O 2 max , participants completed a second visit to identify individual time to peak blood bicarbonate (HCO 3 - ) (ITTP) in a rested state. Visit three was a familiarisation trial mimicking the experimental procedures. Visits four to seven consisted of completing 2 × 4 km cycling TTs separated by 45 min passive recovery, following one of either: 0.3 g kg -1 BM M-SB, 0.21 g kg -1 BM sodium chloride (placebo; PLA) in vegetarian capsules (size 00), or a control trial (CON). Supplements (M-SB or placebo) were ingested pre-exercise at their respective ITTP., Results: Performance in TT1 was faster in the M-SB condition compared with TT1 in CON (- 5.1 s; p = 0.004) and PLA (- 3.5 s; p < 0.001). In TT2, performance was also significantly faster in the M-SB condition compared with CON (- 4.4 s; p = 0.018) or PLA (- 4.1 s; p = 0.002). Total aggregated GI symptoms were generally low and not significantly different between PLA and the M-SB conditions for a range of symptoms., Conclusions: The ingestion of M-SB improves repeated 4 km cycling TT performance and the recovery of acid-base balance between bouts, whilst causing minimal GI discomfort., Competing Interests: Declarations. Funding: Partial financial support and the M-SB product was supplied by Maurten AB. Conflict of interest: L.A.G. has previously received research funding from Maurten AB and S.A.S. was employed in the Department of Sport and Physical Activity, at Edge Hill University, UK at the time of the study conception, design, funding award, data collection and data analysis, and is now employed by Maurten AB and has been during the writing and revisions of the manuscript. Ethics approval: The study received university ethical approval (Birmingham City University: #10651 /sub2 /R(B) /2022 /May /HELS FAEC). The study was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki and later amendments. Consent to participate: Participants provided written informed consent to take part. They were provided with the participant information sheet and were permitted to ask questions at least 24 h prior to signing. Consent for publication: Participants provided consent for publication of findings. Availability of data and material: Data are available on request from the corresponding author. Code availability: Not applicable. Author contributions: Both authors contributed to the study conception and design. Material preparation and data collection were performed by L.A.G. and analysis was performed by S.A.S. The first draft of the manuscript was written by L.A.G. and both authors commented and revised the manuscript. Both authors read and approved the final manuscript., (© 2024. The Author(s).)

Background: There is growing interest in the use of nutrition and dietary supplements to optimize training and time-trial (TT) performance in cyclists. Separately, quercetin (QCT) and citrulline (CIT) have been used as ergogenic aids to improve oxygen (VO 2 ) kinetics, perceived effort, and cycling TT performance. However, whether the combination of QCT and CIT can provide additive benefits and further enhance cycling performance production is currently unknown., Methods: We examined 28-days of QCT + CIT supplementation on TT performance and several performance measures (i.e. mean power, VO 2 , respiratory exchange ratio (RER), and rate of perceived exertion (RPE)). Forty-eight highly trained cyclists were assigned to one of four supplementation groups: (1) QCT + CIT (QCT: 500 mg, CIT: 3000 g), (2) QCT (500 mg), (3) CIT (3000 mg), or (4) placebo (3500 mg of a zero-calorie flavored crystal light package). Supplements were consumed two times per day for 28 consecutive days. Participants performed a 20-km cycling time-trial race, pre- and post-supplementation to determine the impact of the combined effects of QCT + CIT., Results: There were no potential benefits of QCT +CIT supplementation on TT performance and several performance measures. However, there was an improvement in VO 2 from pre-to-post-supplementation in QCT ( p  = 0.05) and CIT ( p  = 0.04) groups, but not in the QCT+CIT and PL groups., Conclusions: QCT + CIT does not seem beneficial for 20-km TT performance; further exploration with a focus on an increase in cycling duration or QCT+CIT combined with additional polyphenols may amplify any perceived bioactive or metabolic effects on cycling performance. The efficacy of QCT + CIT supplementation to improve cycling performance remains ambiguous.

Objectives: This study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (V̇O 2max ) are taken into account to normalise relative exercise intensity., Design: Repeated-measures, within-subjects design with mixed-effects modelling., Methods: Eighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O 2max : 51.6 ± 5.3 ml·kg -1 ·min -1 ) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O 2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2-min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability., Results: Greater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively., Conclusions: Due to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method., Competing Interests: Declaration of interest statement The authors declare that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: Vigorous intermittent lifestyle physical activity (VILPA) are bursts of incidental vigorous activity that occur during day-to-day activities outside of the exercise-domain. Vigorous intermittent lifestyle physical activity has shown promise in lowering risk of mortality and chronic disease. However, there is an absence of an empirically derived definition. Using physiological and effort-based metrics commonly used to define vigorous intensity, we investigated the minimum time needed to elicit physiological and perceived exertion responses to standardized activities of daily living., Methods: Seventy adults (age = 58.0 ± 9.6 yr; 35 female) completed 9 VILPA activities of daily living in a randomized order, which included fast walking, fast incline walking, stair climbing, stationary cycling, and carrying external weight equal to 5% and 10% of body weight. Metabolic rate (by continuous indirect calorimetry), heart rate (telemetry) and perceived effort (Borg Scale) were measured during exercise. Time to reach VILPA was assessed using %V̇O 2max , %HRmax, and rating of perceived exertion thresholds., Results: The mean time to elicit VILPA ranged from 65 to 95 s (mean ± sd = 76.7 ± 3.8 s) for %V̇O 2max , 68 to 105 s (mean ± sd = 82.8 ± 6.8 s) for %HRmax, and 20 to 60 s (mean ± sd = 44.6 ± 6.7 s) for rating of perceived exertion. For each of the three indices, there was no difference in the time to elicit VILPA responses by sex or age ( P > 0.08), and times were also consistent between activities of daily living tasks. For example, for females and males, the average time to elicit vigorous responses while walking on a flat surface was 85.8 s (±16.9 s) and 80 s (±13.9 s), respectively, and for stair climbing while carrying 10% of body weight the duration was 78.4 s (±17.6 s) and 76.9 (±17.7 s)., Conclusions: When participants undertook activities of daily living, VILPA elicited a physiological response at an average of 77 to 83 s for %V̇O 2max and %HRmax, and 45 s for perceived exertion. The absence of a difference in the time to reach VILPA between sex and age suggests that a consistent behavioral VILPA translation can be used in interventions and population-based studies designed to assess the health effects of incidental physical activity., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Sports Medicine.)

Running performance is crucial for triathlon performance. However, the prior bout of cycling may affect the running split time. This study compared the triathletes' cycling plus running (C+R) time, when cycling was performed at three different intensities and running was maximal. A total of 38 athletes (21 males and 17 females) were included. Body composition, maximal oxygen uptake, and functional threshold power (FTP) was evaluated. The participants visited the laboratory three times to cycle 20 km at 80%, 85%, or 90% FTP (in randomized order) and run 5 km as fast as possible. Males ran faster after cycling at 80% FTP than after cycling at 90% FTP (mean difference=35.1 s; CI% 2.2, 68.1 s; p=0.035). The C+R time was faster when cycling at 90% FTP than at 80% FTP (mean difference=57.7 s; CI% 26.1, 89.3 s; p<0.001). For females, no significant difference was observed in the running time after cycling at 80%, 85%, or 90% FTP. The C+R time was faster when cycling at 90% FTP than at 80% FTP (mean difference=80.9 s; CI% 29.7, 132.1 s; p=0.002). In conclusion, to optimize triathlon performance, male and female athletes should cycle at a minimum of 90% FTP., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Abstract: Boynton, JR, Peiffer, JJ, and Abbiss, CR. Effects of HIIT in cool and hot on temperate performance and physiological response in trained cyclists. J Strength Cond Res 39(3): e485-e495, 2025-This study investigated cardiopulmonary responses in hot and cool high-intensity interval training (HIIT) and the subsequent effects on time-trial (TT) performance and physiological responses in temperate conditions. Twenty trained cyclists were separated into 2 groups and completed a 4-week HIIT intervention (8 sessions, 5 × 4 minute) at an environmental temperature (TA) of either 13° C (HIIT13) or 35° C (HIIT35). Cardiorespiratory data (e.g., heart rate [HR] and time above 90% V̇o2max [T > 90% V̇o2max]) were assessed for the first and last interval sessions. Subjects completed 20 km TTs in temperate conditions (22° C) before (TT1) and after (TT2) HIIT training, during which power output, HR, and thermoregulatory measures were recorded. T > 90% V̇o2max was greater in HIIT13 (875 ± 295 seconds; p = 0.007), compared with HIIT35 (420 ± 395 seconds). Average power output during the TT increased from TT1 to TT2 in both groups (HIIT13p = 0.023, 3.3 ± 3.4%; HIIT35p = 0.003, 7.3 ± 6.3%) but with no significant interactions or differences between groups (p = 0.115; p = 0.421, respectively). Within-subject increases for HR and core temperature were observed during TT2 for HIIT13 (2.7 ± 2.1%, 0.5 ± 0.6%) but not HIIT35 (1.5 ± 4.9%, 0.0 ± 0.7%). After 4 weeks of HIIT, the improvement in temperate 20-km TT performance was not greater for HIIT13 than HIIT35, despite greater T > 90% V̇o2max during 13° C HIIT vs. 35° C HIIT. Physiological responses (e.g., HR and thermoregulation) during the TT differed between HIIT13 and HIIT35, indicating varying adaptive responses., (Copyright © 2025 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the National Strength and Conditioning Association.)

Previous research examining the ergogenic benefits of blackcurrant supplementation (BC) on exercise performance is contradictory. The BC supplementation period in many studies has typically been chronic (> 6-days), with a final dose taken hours before testing. Whether any observed performance benefits are from the acute dose or chronic supplementation is unclear. This study aimed to examine the effects on cycling performance of a single-acute dose and 7-day supplementation with BC extract. This study was a placebo-controlled, double-blind, randomised, cross-over trial. Sixteen cyclists (mean ± SD: age 37 ± 11 years; height 175.8 ± 7.6 cm; body mass 73.2 ± 12.5 kg; V̇O 2peak 3.8 ± 0.7 L·min -1 ) completed a total of six experimental sessions (2 × 3 treatment blocks). Each treatment block consisted of a no-supplement baseline trial, a single dose (acute) and a 7-day (chronic) supplementation trial. During each trial, subjects completed a maximal incremental test and 4 km time trial, separated by 15 min of recovery. Respiratory data, heart rate, muscle oxygenation and performance power were measured continuously in each trial, and differences between treatments were determined using RM-ANOVA and effect size analysis. There was no significant difference (p > 0.05) in cycling performance between experimental and placebo treatments following acute or chronic supplementation periods. There were no significant effects on measured physiological and metabolic parameters, and any observed differences in performance or physiology were trivial to small. Blackcurrant supplementation delivered either acutely or over a period of 7 days had no significant effect on cycling performance or physiology. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry: ACTRN12622001277730., (© 2025 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

Purpose: To investigate metabolism and exercise economy during prolonged race simulation (>4 h) in a world-class, full-distance triathlete to help guide/adjust strategies for training, nutrition, hydration, and thermoregulation., Methods: Two experimental race-simulation days, designed to mimic the demands of a full-distance triathlon, were executed by a world-class male triathlete (MD; 25 y, body weight 82 kg, V˙O2max 6.2 L·min-1, blood lactate threshold ∼410 W, and 18 km · h-1 in cycling and running) who at the time ranked second in the world. Race simulation was performed 23 and 10 days prior to competing in Challenge Roth 2023, where MD won in a new world record/best time (7:24:40 h:min:s). Both test days lasted ∼4 to 5 hours with physiologic testing every ∼45 to 60 minutes in a "stationary" setting during cycling on a direct-mount trainer (∼320 W) and treadmill running (16 km · h-1), enabling gas exchange measurements (V˙O2 and respiratory exchange ratio) and other physiologic measurements of interest (ie, core temperature and heart rate). This was combined with "real activity" as repeated loops in an open-air field setting at expected race pace in swimming, biking, and running., Results: V˙O2 was maintained at ∼4.2 L·min-1, with carbohydrates being the dominant fuel for oxidation as respiratory exchange ratio values dropped from ∼1 at the start of cycling to ∼0.85 during running. Cycling economy was stable, whereas a slight impairment in running economy occurred over time., Conclusion: High aerobic energy turnover and stable exercise economy can be maintained in a world-class record-breaking triathlete for prolonged period of time (+4 h), showcasing the importance of both for success in competition.

This study compared the impact of two polarized training programs (POL) on aerobic capacity in well-trained (based on maximal oxygen uptake and training experience) female cyclists. Each 8-week POL program consisted of sprint interval training (SIT) consisting of 8-12 repetitions, each lasting 30 seconds at maximal intensity, high-intensity interval training (HIIT) consisting of 4-6 repetitions, each lasting 4 minutes at an intensity of 90-100% maximal aerobic power, and low-intensity endurance training (LIT) lasting 150-180 minutes with intensity at the first ventilatory threshold. Training sessions were organized into 4-day microcycles (1st day-SIT, 2nd day-HIIT, 3rd day-LIT, and 4th day-active rest), that were repeated throughout the experiment. In the first POL program, exercise repetitions during SIT and HIIT training were performed with freely chosen cadence above 80 RPM (POLFC group, n = 12), while in the second POL program with low cadence 50-70 RPM (POLLC group, n = 12). Immediately before and after the 8-week POL intervention, participants performed an incremental test to measure maximal aerobic power (Pmax), power achieved at the second ventilatory threshold (VT2), maximal oxygen uptake (VO2max), maximal pulmonary ventilation (VEmax), and gross efficiency (GE). Moreover, participants performed VO2max verification test. Analysis of variance showed a repeated measures effect for Pmax (F = 21.62; η2 = 0.5; p = 0.00), VO2max (F = 39.39; η2 = 0.64; p = 0.00) and VEmax (F = 5.99; η2 = 0.21; p = 0.02). A repeated measures x group mixed effect was demonstrated for Pmax (F = 4.99; η2 = 0.18; p = 0.03) and VO2max (F = 6.67; η2 = 0.23; p = 0.02). Post-hoc Scheffe analysis showed that increase in Pmax were statistically significant only in POLLC group. The Friedman test showed that VT2 differed between repeated measures only in the POLLC group (χ2 = 11; p = 0.001; W = 0.917). In conclusion, it was found that POL program where SIT and HIIT were performed at low cadence was more effective in improving aerobic capacity in well-trained female cyclists, than POL with SIT and HIIT performed at freely chosen cadence. This finding is a practical application for athletes and coaches in cycling, to consider not only the intensity and duration but also the cadence used during various interval training sessions., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Hebisz, Hebisz. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Introduction: This study aimed to analyze the effect of caffeine (CAF) intake on pulmonary oxygen uptake (V˙O2) kinetics, muscle fatigue, and physiological and perceptual parameters during severe-intensity cycling exercise., Methods: Twelve physically active men (age: 26 ± 5 years; V˙O2peak: 46.7 ± 7.8 ml·kg-1·min-1) participated of this placebo (PLA)-controlled, randomized, double-blinded, and crossover design study. Participants performed on separate days (a) a ramp incremental test to determine V˙O2peak and gas exchange threshold and (b) four 8-min constant work rate tests at 60% of the difference between gas exchange threshold and maximal V˙O2peak (i.e., Δ60%) 1 hr after taking either 6 mg/kg of body mass of CAF or PLA. Before and immediately after constant work rate tests, a 5-s all-out isokinetic sprint was performed to assess the muscle torque. V˙O2 kinetics, blood lactate concentration ([La]), and rating of perceived exertion were analyzed during constant work rate tests., Results: CAF did not alter the primary time constant of V˙O2 kinetics (PLA: 38.3 ± 14; CAF: 36.7 ± 7.5 s), V˙O2 slow component (PLA: 0.5 ± 0.2; CAF: 0.5 ± 0.2 L/min), or peak torque (PLA: 144.6 ± 18.6; CAF: 143.9 ± 18.7 N·m). CAF decreased rating of perceived exertion (15.9 ± 1.8 vs. 17.0 ± 1.5 a.u.) and increased blood lactate concentration (9.0 ± 2.5 vs. 8.3 ± 2.2 mmol/L; p < .05) after constant work rate tests compared with PLA., Conclusion: CAF ingestion does not alter V˙O2 kinetics or muscle torque production during 8 min of severe-intensity cycling exercise.

It has been suggested that time spent at a high fraction of maximal oxygen consumption (% V ˙ $\dot{\mathrm{V}}$ O 2max ) plays a decisive role for adaptations to interval training. However, previous studies examining how interval sessions should be designed to achieve a high % V ˙ $\dot{\mathrm{V}}$ O 2max have exclusively been performed in males. The present study compared the % V ˙ $\dot{\mathrm{V}}$ O 2max attained during three different 6 × 8 min interval protocols, in female (n = 11; V ˙ $\dot{\mathrm{V}}$ O 2max , 62.5 (6.4) mL · min -1 ·kg -1 ) and male (n = 8; V ˙ $\dot{\mathrm{V}}$ O 2max , 81.0 (5.2) mL · min -1 ·kg -1 ) cyclists. Mean power output during work intervals were identical across the three interval protocols, corresponding to the cyclist's 40 min maximal effort (PO 40min ): (1) 30 s intervals at 118% of PO 40min interspersed with 15 s active recovery at 60% (30/15), (2) constant pace at 100% of PO 40min (CON), and (3) altering between 60 s intervals at 110% and 60 s at 90% of PO 40min (60/60). Additionally, the study explored whether the m. vastus lateralis characteristics of the cyclists (fiber type proportion, capillarization, and citrate synthase activity) were associated with the % V ˙ $\dot{\mathrm{V}}$ O 2max attained during the interval sessions. Overall, mean % V ˙ $\dot{\mathrm{V}}$ O 2max and time ≥90% of V ˙ $\dot{\mathrm{V}}$ O 2max were higher during 30/15 compared to CON (86.7 (10.1)% and 1123 (787) s versus 85.0 (10.4)% and 879 (779) s, respectively; both p ≤ 0.01) and 60/60 (85.6 (10.0)% and 917 (745) s, respectively; both p ≤ 0.05), while no difference was observed between 60/60 and CON (both p ≥ 0.36). During interval sessions, % V ˙ $\dot{\mathrm{V}}$ O 2max and time ≥90% of V ˙ $\dot{\mathrm{V}}$ O 2max did not differ between sexes. Skeletal muscle characteristics were not related to % V ˙ $\dot{\mathrm{V}}$ O 2max  during interval sessions. In conclusion, well-trained cyclists demonstrate highest % V ˙ $\dot{\mathrm{V}}$ O 2max during 30/15, irrespective of sex and skeletal muscle characteristics., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

It has been suggested that time at a high fraction (%) of maximal oxygen uptake (VO 2max ) plays a decisive role for adaptations to interval training. Yet, no study has, to date, measured the % of VO 2max during all interval sessions throughout a prolonged training intervention and subsequently related it to the magnitude of training adaptations. Thus, the present study aimed to investigate the relationship between % of VO 2max achieved during an interval training intervention and changes in endurance performance and its physiological determinants in well-trained cyclists. Twenty-two cyclists (VO 2max 67.1 (6.4) mL·min -1  ·kg -1 ; males, n = 19; females, n = 3) underwent a 9-week interval training intervention, consisting 21 sessions of 5 × 8-min intervals conducted at their 40-min highest sustainable mean power output (PO). Oxygen uptake was measured during all interval sessions, and the relationship between % of VO 2max during work intervals and training adaptations were investigated using linear regression. A performance index was calculated from several performance measures. With higher % of VO 2max during work intervals, greater improvements were observed for maximal PO during the VO 2max test (R 2 adjusted  = 0.44, p = 0.009), PO at 4 mmol·L -1 [blood lactate] (R 2 adjusted  = 0.25, p = 0.035), the performance index (R 2 adjusted  = 0.36, p = 0.013), and VO 2max (R 2 adjusted  = 0.54, p = 0.029). Other measures, such as % of maximal heart rate, were related to fewer outcome variables and exhibited poorer session-to-session repeatability compared to % of VO 2max . In conclusion, improvements in endurance measures were positively related to the % of VO 2max achieved during interval training. Percentage of VO 2max was the measure that best reflected the magnitude of training adaptations., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

This study investigated the middle cerebral artery blood velocity (MCAv) response to constant work-rate moderate-intensity cycling exercise in 21 children (9.3 ± 0.8 yr), 17 adolescents (12.3 ± 0.4 yr), and 20 young adults (23.6 ± 2.4 yr). Participants completed an incremental ramp test to exhaustion on a cycle ergometer to determine maximal oxygen uptake and gas exchange threshold (GET) before completing three 6-min transitions at a moderate intensity (90% GET) on separate visits. On each visit, bilateral MCAv was measured by transcranial Doppler ultrasonography and breath-by-breath end-tidal carbon dioxide ([Formula: see text]) via a metabolic cart. Data were ensemble-averaged for each participant and analyzed using a monoexponential model. Absolute MCAv was significantly higher throughout exercise in children and adolescents compared with adults ( P < 0.001). Children had a significantly lower relative increase in MCAv from baseline (∼12%) compared with adolescents (∼20%) and adults (∼18%, P < 0.040). All adolescents and adults had a monoexponential rise in MCAv and [Formula: see text], but this was observed in only eight children. Children and adolescents had a significantly faster MCAv time constant (τ, 12 ± 6 and 14 ± 8 s, respectively) compared with adults (27 ± 9 s, P < 0.001). MCAv τ was positively associated with faster [Formula: see text] τ in adolescents ( r = 0.70, P = 0.002) but not in children ( r = -0.20, P = 0.640). Time- and amplitude-based response parameters of MCAv kinetics were significantly associated with [Formula: see text] kinetics in adults ( r = 0.50-0.74, P ≤ 0.025), but not in children ( r = -0.19 to -0.48, P > 0.227). These findings suggest that the transition from childhood to adulthood impacts the MCAv response to exercise and the relationships between [Formula: see text] and MCAv kinetics during exercise. NEW & NOTEWORTHY This is the first study to find that children have smaller increases in Δ%MCAv (∼12%) during moderate-intensity exercise compared with adolescents and adults (∼18%-20%). Furthermore, MCAv kinetics were significantly faster in children and adolescents, compared with adults. MCAv kinetic responses were significantly and positively associated with [Formula: see text] kinetics in adults, but not in children. These novel data also suggest that the regulatory role of [Formula: see text] on MCAv during exercise begins to strengthen during adolescence.

Purpose:  Peripheral responses might be important in handcycling, given the involvement of small muscles compared to other exercise modalities. Therefore, the goal of this study was to compare changes in muscle oxygen saturation (∆SmO 2 ) and deoxyhemoglobin level (∆[HHb]) between different efforts and muscles., Methods:  Handcyclists participated in a Wingate, a maximal incremental test and a 20-min time-trial (TT). Oxygen uptake (VO 2 ) as well as ∆SmO 2 , ∆[HHb], deoxygenation and reoxygenation rates in the triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD) and extensor carpi radialis brevis (ER) were measured., Results:  ER ∆[HHb]max was 37% greater in the incremental test than in the Wingate (ES = 0.392, P = 0.031). TT mean power (W/kg) was associated with BB ∆SmO 2 min measured in the incremental test (r = -0.998 [-1.190, -0.806], P = 0.002) and in the Wingate (r = -0.994 [-1.327, -0.661], P = 0.006). MAP (W/kg) was associated with Wingate BB ∆SmO 2 min (r = -0.983 [-0.999, -0.839], P = 0.003), and Wingate peak (r = 0.649 [0.379, 0.895], P = 0.008) and mean power (W/kg) (r = 0.925 [0.752, 0.972], P = 0.003) was associated with right handgrip force. The strongest physiological predictor for TT performance was BB ∆SmO 2 min in the incremental test (P = 0.002, r 2  = 0.993, SEE 0.016 W/kg), Wingate BB ∆SmO 2 min for MAP (P = 0.003, r 2  = 0.956, SEE 0.058 W/kg) and right handgrip force for Wingate peak power (P = 0.005, r 2  = 0.856, SEE 0.551 W/kg)., Conclusion:  Peripheral aerobic responses (muscle oxygenation) were predictive of handcycling performance., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Hypoxia and hyperoxia can affect the acute psycho-physiological response to exercise. Recording various perceptual responses to exercise is of particular importance for investigating behavioral changes to physical activity, given that the perception of exercise-induced pain, discomfort or unpleasure, and a low level of exercise enjoyment are commonly associated with a low adherence to physical activity. Therefore, this study aimed to compare the acute perceptual and physiological responses to aerobic exercise under intermittent hypoxia-hyperoxia (IHHT), hypoxia-normoxia (IHT), and sustained normoxia (NOR) in young, recreational active, healthy males., Methods: Using a randomized, single-blinded, crossover design, 15 males (age: 24.5 ± 4.2 yrs) performed 40 min of submaximal constant-load cycling (at 60% peak oxygen uptake, 80 rpm) under IHHT (5 × 4 min hypoxia and hyperoxia), IHT (5 × 4 min hypoxia and normoxia), and NOR. Inspiratory fraction of oxygen during hypoxia and hyperoxia was set to 14% and 30%, respectively. Heart rate (HR), total hemoglobin (tHb) and muscle oxygen saturation (S m O 2 ) of the right vastus lateralis muscle were continuously recorded during cycling. Participants' peripheral oxygen saturation (S p O 2 ) and perceptual responses ( i.e ., perceived motor fatigue, effort perception, perceived physical strain, affective valence, arousal, motivation to exercise, and conflict to continue exercise) were surveyed prior, during (every 4 min), and after cycling. Prior to and after exercise, peripheral blood lactate concentration (BLC) was determined. Exercise enjoyment was ascertained after cycling. For statistical analysis, repeated measures analyses of variance were conducted., Results: No differences in the acute perceptual responses were found between conditions ( p ≥ 0.059, η p 2 ≤ 0.18), while the physiological responses differed. Accordingly, S p O 2 was higher during the hyperoxic periods during the IHHT compared to the normoxic periods during the IHT ( p < 0.001, η p 2 = 0.91). Moreover, HR ( p = 0.005, η p 2 = 0.33) and BLC ( p = 0.033, η p 2 = 0.28) were higher during IHT compared to NOR. No differences between conditions were found for changes in tHb ( p = 0.684, η p 2 = 0.03) and S m O 2 ( p = 0.093, η p 2 = 0.16)., Conclusion: IHT was associated with a higher physiological response and metabolic stress, while IHHT did not lead to an increase in HR and BLC compared to NOR. In addition, compared to IHT, IHHT seems to improve reoxygenation indicated by a higher S p O 2 during the hyperoxic periods. However, there were no differences in perceptual responses and ratings of exercise enjoyment between conditions. These results suggest that replacing normoxic by hyperoxic reoxygenation-periods during submaximal constant-load cycling under intermittent hypoxia reduced the exercise-related physiological stress but had no effect on perceptual responses and perceived exercise enjoyment in young recreational active healthy males., Competing Interests: The authors declare that they have no competing interests., (© 2024 Behrendt et al.)

Muscular efficiency during exercise has been used to interrogate aspects of human muscle energetics, including mitochondrial coupling and biomechanical efficiencies. Typically, assessments of muscular efficiency have involved graded exercises. Results of previous studies have been interpreted to indicate a decline in exercise efficiency with aging owing to decreased mitochondrial function. However, discrepancies in variables such as exercise stage duration, cycling cadence, and treadmill walking mechanics may have affected interpretations of results. Furthermore, recent data from our lab examining the ATP to oxygen ratio (P:O) in mitochondrial preparations isolated from NIA mouse skeletal muscle showed no change with aging. Thus, we hypothesized that delta efficiency (Δ€) during steady-rate cycling exercise would not be altered in older healthy subjects compared with young counterparts regardless of biological sex or training status. Young (21-35 yr) and older (60-80 yr) men ( n = 21) and women ( n = 20) underwent continual, progressive leg cycle ergometer tests pedaling at 60 RPM for three stages (35, 60, 85 W) lasting 4 min. Δ€was calculated as: (Δ work accomplished/Δ energy expended). Overall, cycling efficiencies were not significantly different in older compared with young subjects. Similarly, trained subjects did not exhibit significantly different exercise efficiencies compared to untrained. Moreover, there were no differences between men and women. Hence, our results obtained on healthy young and older subjects are interpreted to mean that previous reports of decreased efficiency in older individuals were attributable to metabolic or biomechanical comorbidities, not aging per se. NEW & NOTEWORTHY Muscular power is reduced, but the efficiency of movement is unaltered in healthy aging.

Purpose: We investigated the effects of low- and high-volume speed endurance training (SET), with a reduced training volume, on sprint ability, short- and long-term exercise capacity, muscle mitochondrial properties, ion transport proteins, and maximal enzyme activity in highly trained athletes., Methods: Highly trained male cyclists (maximal oxygen consumption (V̇O 2max ): 68.3 ± 5.0 mL·min -1 ·kg -1 , n = 24) completed 6 wk of either low (SET-L; 6 × 30-s intervals, n = 8) or high (SET-H; 12 × 30-s intervals, n = 8) volume SET twice per week with a 30% reduction in training volume. A control group (CON; n = 8) maintained their training. Exercise performance was evaluated by i) 6-s sprinting, ii) a 4-min time trial, and iii) a 60-min preload at 60% V̇O 2max followed by a 20-min time trial. A biopsy of m. vastus lateralis was collected before and after the training intervention., Results: In SET-L, 4-min time trial performance was improved ( P < 0.05) by 3.8%, with no change in SET-H and CON. Sprint ability, prolonged endurance exercise capacity, V̇O 2max , muscle mitochondrial respiratory capacity, maximal citrate synthase activity, fiber type-specific mitochondrial proteins (complexes I-V), and phosphofructokinase (PFK) content did not change in any of the groups. In SET-H, maximal activity of muscle PFK and abundance of Na + -K + pump-subunit α 1 , α 2 , β 1 , and phospholemman (FXYD1) were 20%, 50%, 19%, 24%, and 42% higher ( P < 0.05), respectively after compared with before the intervention, with no changes in SET-L or CON., Conclusions: Low SET volume combined with a reduced aerobic low- and moderate-intensity training volume does improve short-duration intense exercise performance and maintain sprinting ability, V̇O 2max , endurance exercise performance, and muscle oxidative capacity, whereas, high volume of SET seems necessary to upregulate muscle ion transporter content and maximal PFK activity in highly trained cyclists., (Copyright © 2024 by the American College of Sports Medicine.)

Exercise training is recommended to improve the quality of life in those living with Parkinson's disease (PD); however, the optimal prescription to improve cardiorespiratory fitness and disease-related motor symptoms remains unknown. Twenty-nine participants with PD were randomly allocated to either 10 wk of high-intensity interval training (HIIT) ( n = 15; 6 female) or moderate-intensity continuous training (MICT) ( n = 14; 5 female). The primary outcome was the change in maximal oxygen consumption (V̇o 2peak ). Secondary outcomes included changes in the Unified Parkinson's Disease Rating Scale (UPDRS) Part III motor score, Parkinson's Fatigue Scale (PFS)-16, resting and exercise cardiovascular measures, gait, balance, and knee extensor strength and fatigability. Exercise training increased V̇o 2peak (main effect of time, P < 0.01), with a clinically meaningful difference in the change following HIIT versus MICT (Δ3.7 ± 3.7 vs. 1.7 ± 3.2 mL·kg -1 ·min -1 , P = 0.099). The UPDRS motor score improved over time ( P < 0.001) but without any differences between HIIT versus MICT (Δ-9.7 ± 1.3 vs. -8.4 ± 1.4, P = 0.51). Self-reported subjective fatigue (PFS-16) decreased over time ( P < 0.01) but was similar between HIIT and MICT groups ( P = 0.6). Gait, balance, blood pressure (BP), and heart rate (HR) were unchanged with training (all P > 0.09). Knee extensor strength increased over time ( P = 0.03) but did not differ between HIIT versus MICT (Δ8.2 ± 5.9 vs. 11.7 ± 6.2 Nm, P = 0.69). HIIT alone increased the muscular endurance of the knee extensors during an isotonic fatigue task to failure ( P = 0.04). In participants with PD, HIIT and MICT both increased V̇o 2peak and led to improvements in motor symptoms and perceived fatigue; HIIT may offer the potential for larger changes in V̇o 2peak and reduced knee extensor fatigability. NEW & NOTEWORTHY The optimal exercise prescription to improve cardiorespiratory fitness and disease-related motor symptoms in adults with Parkinson's disease remains unknown. In a single-center randomized trial consisting of either 10 wk of high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT), we found that both training modes increased V̇o 2peak , with a larger clinically meaningful difference following HIIT. Both exercise modes improved motor symptoms and subjective fatigue, whereas HIIT increased the muscular endurance of the knee extensors.

This study aimed to investigate the effects of caffeine ingestion by chewing gum (GUMCAF) combined with priming exercise on pulmonary oxygen uptake (V˙O2) and near-infrared spectroscopy-derived muscle oxygen extraction (HHb + Mb) kinetics during cycling performed in a severe-intensity domain. Fifteen trained cyclists completed four visits: two under a placebo gum (GUMPLA) and two under GUMCAF ingestion. Each visit consisted of two square-wave cycling bouts at Δ70 intensity (70% of difference between the V˙O2 at first ventilatory threshold and V˙O2max) with duration of 6 min each and 5 min of passive rest between the bouts. The GUMPLA or GUMCAF (400 mg) was chewed for 5 min, 12 min before the first Δ70 bout in a randomized double-blind procedure. The fundamental phase and slow component of HHb + Mb and V˙O2 kinetics were evaluated. For HHb + Mb kinetics, regardless of ingested gum, priming exercise effects occurred on the time constant (GUMCAF 16.0 ± 4.0 vs. 13.9 ± 2.9 s; GUMPLA 15.7 ± 6.1 vs. 13.2 ± 2.5 s), amplitude, slow component, time delay, and mean response time parameters (p ≤ .032). For V˙O2 kinetics, there were significant effects of bouts on the amplitude, slow component, end V˙O2, and the gain kinetics parameters (p < .017). Baseline V˙O2 was higher during GUMCAF than GUMPLA (p = .020). No significant effects occurred for the interaction between gum and bout in any parameter of V˙O2 or HHb + Mb kinetics. Therefore, unlike the priming exercise in severe-intensity exercise, GUMCAF is not an effective strategy for improving V˙O2 or HHb + Mb kinetics acceleration.

Purpose: To compare the training characteristics of an elite team pursuit cycling squad in the 3-month preparation phases prior to 2 successive world-record (WR) performances., Methods: Training data of 5 male track endurance cyclists (mean [SD]; age 23.4 [3.46] y; body mass 80.2 [2.74] kg; 4.5 [0.17] W·kg-1 at LT2; maximal aerobic power 6.2 [0.27] W·kg-1; maximal oxygen uptake 65.9 [2.89] mL·kg-1·min-1) were analyzed with weekly total training volume by training type and heart rate, power output, and torque intensity distributions calculated with reference to the respective WRs' performance requirements., Results: Athletes completed 805 (82.81) and 725 (68.40) min·wk-1 of training, respectively, in each season. In the second season, there was a 32% increase in total track volume, although track sessions were shorter (ie, greater frequency) in the second season. A pyramidal intensity distribution was consistent across both seasons, with 81% of training, on average, performed below LT1 power output each week, whereas 6% of training was performed above LT2. Athletes accumulated greater volume above WR team pursuit lead power (2.4% vs 0.9%) and torque (6.2% vs 3.2%) in 2019. In one athlete, mean single-leg-press peak rate of force development was 71% and 46% higher at mid- and late-phases, respectively, during the preparation period., Conclusions: These findings provide novel insights into the common and contrasting methods contributing to successive WR team pursuit performances. Greater accumulation of volume above race-specific power and torque (eg, team pursuit lead), as well as improved neuromuscular force-generating capacities, may be worthy of investigation for implementation in training programs.

Purpose: To profile the training characteristics of an elite team pursuit cycling squad and assess variations in training intensity and load accumulation across the 36-week period prior to a world-record performance at the 2018 Commonwealth Games., Methods: Training data of 5 male track endurance cyclists (mean [SD]; age 21.9 [3.52] y; 4.4 [0.16] W·kg-1 at anaerobic threshold; 6.2 [0.28] W·kg-1 maximal oxygen uptake 68.7 [2.99] mL kg·min-1) were analyzed with weekly total training volume and heart rate, power output, and torque intensity distributions calculated with reference to their 3:49.804 min:s.ms performance requirements for a 4-km team pursuit., Results: Athletes completed 543 (37) h-1 of training across 436 (16) sessions. On-bike activities accounted for 69.9% of all training sessions, with participants cycling 11,246 (1139) km-1 in the training period of interest, whereas 12.7% of sessions involved gym/strength training. A pyramidal intensity distribution was evident with over 65% and 70% of training, respectively, performed at low-intensity zone heart rate and power output, whereas 5.3% and 7.7% of training was performed above anaerobic threshold. The athletes accumulated 4.4% of total training volume at, or above, their world-record team pursuit lead position torque (55 N·m)., Conclusions: These data provide updated and novel insight to the power and torque demands and load accumulation contributing to world-record team pursuit performance. Although the observed pyramidal intensity distribution is common in endurance sports, the lack of shift toward a polarized intensity distribution during taper and competition peaking differs from previous research.

The purpose of this study was to investigate the potential ergogenic effects of an oral lactate supplement. For this double-blind, randomized, placebo-controlled crossover design, fifteen recreational exercisers (nine males, six females) ingested a placebo or a commercially available lactate supplement prior to cycle ergometer exercise. Primary outcomes included peak oxygen uptake (VO 2peak ; via indirect calorimetry), VO 2 at the ventilatory threshold, and work rate at the lactate threshold (arterialized venous blood from a heated hand) determined during incremental exercise to fatigue, and power output during a 20-min cycling time trial. Compared with placebo, the oral lactate supplement (19 ± 1 mg/kg body mass) did not influence VO 2peak (placebo: 44.3 ± 7.8 vs. oral lactate: 44.3 ± 7.1 mL/kg/min (mean ± SD); p = 0.87), VO 2 at the ventilatory threshold (placebo: 1.63 ± 0.25 vs. oral lactate: 1.65 ± 0.23 L/min; p = 0.82), or work rate at the lactate threshold (placebo: 179 ± 69 vs. oral lactate: 179 ± 59 W; p = 0.41). Throughout the 20-min time trial, the work rate was slightly greater (4%) with oral lactate (204 ± 41 W) compared with placebo (197 ± 41 W; main effect of treatment p = 0.02). Collectively, these data suggest that this commercially available lactate supplement did not acutely influence the physiological responses to incremental cycle ergometer exercise but elicited a modest ergogenic effect during the short-duration time trial.

Purpose: Power output at the moderate-to-heavy-intensity transition decreases during prolonged exercise, and resilience to this has been termed 'durability'. The purpose of this study was to assess the relationship between durability and the effect of prolonged exercise on severe-intensity performance, and explore intramuscular correlates of durability., Methods: On separate days, 13 well-trained cyclists and triathletes (V̇O 2 peak, 57.3 ± 4.8 mL kg -1 min -1 ; training volume, 12 ± 2.1 h week -1 ) undertook an incremental test and 5-min time trial (TT) to determine power output at the first ventilatory threshold (VT 1 ) and severe-intensity performance, with and without 150-min of prior moderate-intensity cycling. A single resting vastus lateralis microbiopsy was obtained., Results: Prolonged exercise reduced power output at VT 1 (211 ± 40 vs. 198 ± 39 W, ∆ -13 ± 16 W, ∆ -6 ± 7%, P = 0.013) and 5-min TT performance (333 ± 75 vs. 302 ± 63 W, ∆ -31 ± 41 W, ∆ -9 ± 10%, P = 0.017). The reduction in 5-min TT performance was significantly associated with durability of VT 1 (r s  = 0.719, P = 0.007). Durability of VT 1 was not related to vastus lateralis carnosine content, citrate synthase activity, or complex I activity (P > 0.05)., Conclusion: These data provide the first direct support that durability of the moderate-to-heavy-intensity transition is an important performance parameter, as more durable athletes exhibited smaller reductions in 5-min TT performance following prolonged exercise. We did not find relationships between durability and vastus lateralis carnosine content, citrate synthase activity, or complex I activity., (© 2024. The Author(s).)

The aim of this study was to determine the effects of subtetanic neuromuscular electrical stimulation combined with voluntary exercise between repeated Wingate tests on sprint exercise performance and blood lactate accumulation during sprint interval training. Fifteen healthy young males volunteered. After 1-min baseline, participants underwent the Wingate test twice. They performed a 4-min intervention between tests: neuromuscular electrical stimulation with free-weight cycling or voluntary cycling alone [43.6 (8.0) watts], which matched oxygen consumption with neuromuscular electrical stimulation with free-weight cycling. The blood lactate concentration was assessed at the end of the baseline, at 3-min intervention, and on recovery at 1, 3, 5, and 10 min after the second Wingate test. Peak and mean blood lactate concentration during recovery were significantly greater with neuromuscular electrical stimulation with free-weight cycling than voluntary cycling alone (P>0.036 and P=0.011, respectively). Peak power, mean power, and rate of decline (fatigue index) were not significantly different between conditions in both Wingate tests (condition/interaction all P>0.300, partial η 2 <0.1). Subtetanic neuromuscular electrical stimulation combined with voluntary exercise indicated similar exercise performance and fatigue levels during Wingate tests, but enhanced blood lactate accumulation compared to oxygen consumption-matched voluntary cycling during sprint interval training., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Purpose: The aims of this study were to: (i) describe the time course of the decrease in power output at the moderate-to-heavy intensity transition during prolonged exercise; (ii) investigate the association between durability of the moderate-to-heavy intensity transition and exercise capacity; and (iii) explore physiological correlates of durability of the moderate-to-heavy intensity transition., Methods: Twelve trained cyclists (age: 40 ± 8 y, V ˙ O 2 peak: 52.3 ± 5.2 mL·min -1 ·kg -1 ) performed an exhaustive cycling protocol involving alternating incremental exercise tests to determine power output at the moderate-to-heavy intensity transition via the first ventilatory threshold (VT 1 ), and 30-min bouts at 90% of the power output at the previously estimated VT 1 in the rested state. The individual time course of VT 1 was modelled using linear and second-order polynomial functions, and time to a 5% decrease in VT 1 (Δ5%VT 1 ) was estimated using the best-fitting model., Results: Power output at VT 1 decreased according to a second-order polynomial function in 11 of 12 participants. Time-to-task failure (234 ± 66 min) was correlated with Δ5%VT 1 (139 ± 78 min, r s  = 0.676, p = 0.016), and these were strongly correlated with absolute and relative rates of fat oxidation at specific exercise intensities measured during the incremental test performed in the rested state., Conclusions: These data: (i) identify a non-linear time course of decreases in the moderate-to-heavy intensity transition during prolonged exercise; (ii) support the importance of durability of the moderate-to-heavy intensity transition in prolonged exercise capacity; and (iii) suggest durability of the moderate-to-heavy intensity transition is related to fat oxidation rates., (© 2024. The Author(s).)

Purpose: This study aimed to ascertain the optimal test duration to elicit the highest maximal lactate formation rate ( V ˙ La max ), whilst exploring the underpinning energetics, and identifying the optimal blood lactate sampling period., Methods: Fifteen trained to well-trained males (age 27 ± 6 years; peak power: 1134 ± 174 W) participated in a randomised cross-over design completing three all-out sprint cycling tests of differing test durations (10, 15, and 30 s). Peak and mean power output (W and W . kg -1 ), oxygen uptake, and blood lactate concentrations were measured. V ˙ La max and energetic contributions (phosphagen, glycolytic, and oxidative) were determined using these parameters., Results: The shortest test duration of 10 s elicited a significantly (p = 0.003; p < 0.001) higher V ˙ La max (0.86 ± 0.17 mmol . L -1. s -1 ; 95% CI 0.802-0.974) compared with both 15 s (0.68 ± 0.18 mmol . L -1. s -1 ; 95% CI 0.596-0.794) and 30 s (0.45 ± 0.07 mmol . L -1. s -1 ; 95% CI 0.410-0.487). Differences in V ˙ La max were associated with large effect sizes (d = 1.07, d = 3.15). We observed 81% of the PCr and 53% of the glycolytic work completed over the 30 s sprint duration was attained after 10 s. BLa maxpost were achieved at 5 ± 2 min (t test 10 s), 6 ± 2 min (t test 15 s), and 7 ± 2 min (t test 30 s), respectively., Conclusion: Our findings demonstrated a 10 s test duration elicited the highest V ˙ La max. Furthermore, the 10 s test duration mitigated the influence of the oxidative metabolism during all-out cycling. The optimal sample time to determine peak blood lactate concentration following 10 s was 5 ± 2 min., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Spiroergometry is important for modern performance diagnostics, and reference values have been evaluated for bicycle and treadmill ergometers. The aim of this study is to assess the comparability of bicycle and hand-crank spiroergometry and its associated parameters, as hand-crank spiroergometry can be used during rehabilitation in patients with definitive or temporally impairment of the lower extremity., Methods: Thirty-seven healthy volunteers completed 2 exhausting performance diagnostics on hand-crank and bicycle spiroergometry. Participants' anthropometric characteristics, maximum power, multiple exertion criteria, maximum aerobic capacity, and maximum heart rate were detected, and ventilatory and metabolic thresholds were determined., Results: The maximum power, maximum heart rate, maximum aerobic capacity, and ventilatory thresholds were significant higher on the bicycle ergometer (P < .001). The metabolic thresholds occurred on higher lactate values on the hand-crank ergometer. Equations for calculating maximum aerobic capacity from the maximum power measured in either hand-crank or bicycle ergometer could be found through regression analysis., Conclusions: Although there are problems in interpreting results of different ergometries due to severe physiology differences, the equations can be used for patients who are temporally unable to complete the established ergometry due to a deficit in the lower extremity. This could improve training recommendations for patients and para-athletes in particular.

Purpose: To assess the effect of 2 work-matched efforts of different intensities on subsequent performance in well-trained cyclists., Methods: The present study followed a randomized controlled crossover design. Twelve competitive junior cyclists volunteered to participate (age, 17 [1] y; maximum oxygen uptake, 71.0 [4.7] mL·kg-1·min-1). The power-duration relationship was assessed through 2-minute, 5-minute, and 12-minute field tests under fresh conditions (control). On subsequent days and following a randomized order, participants repeated the aforementioned tests after 2 training sessions matched for mechanical work (∼15 kJ/kg) of different intensities (ie, a moderate-intensity continuous-training [60%-70% of critical power; CP] session or a session including high-intensity intervals [3-min repetition bouts at 110%-120% of the CP interspersed by 3-min rest periods])., Results: A significantly lower power output was found in the 2-minute test after the high-intensity training session compared not only with the control condition (-8%, P < .001) but also with the moderate-intensity continuous-training session (-7%, P = .003), with no significant differences between the latter conditions. No significant differences between conditions were found for the remaining tests. As a consequence, the high-intensity training session resulted in significantly lower W' values compared to both the control condition (-27%, P = .001) and the moderate-intensity continuous-training session (-26%, P = .012), with no differences between the 2 latter conditions and with no differences for CP., Conclusion: A session including high-intensity intermittent efforts induces a greater fatigue, particularly in short-duration efforts and W', than a work-matched continuous-training session of moderate intensity.

Purpose: This study aimed to determine whether the initial levels of aerobic fitness and hematological variables in young female road cyclists are related to their athletic performance development during their careers., Methods: Results of graded exercise tests on a cycle ergometer and total hemoglobin mass (tHb-mass) measurements were analyzed in 34 female road cyclists (age 18.6 [1.9] y). Among them, 2 groups were distinguished based on their competitive performance (Union Cycliste Internationale world ranking) over the following 8 years. Areas under the curve in receiver-operating-characteristic curves were calculated as indicators of elite-performance prediction., Results: Initial graded exercise test variables (peak power, peak oxygen uptake, and power at 4 mmol/L blood lactate) were not significantly different in elite (n = 13) versus nonelite (n = 21) riders. In contrast, elite riders had higher tHb-mass expressed either in absolute measures (664 [75] vs 596 [59] g, P = .006) or normalized to body mass (11.2 [0.8] vs 10.3 [0.7] g/kg, P = .001) and fat-free mass (14.4 [0.9] vs 13.1 [0.9] g/kg, P < .001). Absolute and relative erythrocyte volumes were significantly higher in elite subjects (P ranged from < .001 to .006). Of all the variables analyzed, the relative tHb-mass had the highest predictive ability to reach the elite level (area under the curve ranged from .82 to .85)., Conclusion: Measurement of tHb-mass can be a helpful tool in talent detection to identify young female road cyclists with the potential to reach the elite level in the future.

The purpose of this study was to test whether a machine learning model can accurately predict VO 2 across different exercise intensities by combining muscle oxygen (MO 2 ) with heart rate (HR). Twenty young highly trained athletes performed the following tests: a ramp incremental exercise, three submaximal constant intensity exercises, and three severe intensity exhaustive exercises. A Machine Learning model was trained to predict VO 2 , with model inputs including heart rate, MO 2 in the left (LM) and right legs (RM). All models demonstrated equivalent results, with the accuracy of predicting VO 2 at different exercise intensities varying among different models. The LM+RM+HR model performed the best across all intensities, with low bias in predicted VO 2 for all intensity exercises (0.08 ml/kg/min, 95% limits of agreement: -5.64 to 5.81), and a very strong correlation ( r  = 0.94, p  < 0.001) with measured VO 2 . Furthermore, the accuracy of predicting VO 2 using LM+HR or RM+HR was higher than using LM+RM, and higher than the accuracy of predicting VO 2 using LM, RM, or HR alone. This study demonstrates the potential of a machine learning model combining MO 2 and HR to predict VO 2 with minimal bias, achieving accurate predictions of VO 2 for different intensity levels of exercise.

Critical power (CP) represents an important threshold for exercise performance and fatiguability. We sought to determine the extent to which sex, hemoglobin mass (Hb mass ), and skeletal muscle characteristics influence CP. Before CP determination (i.e., 3-5 constant work rate trials to task failure), Hb mass and skeletal muscle oxidative capacity (τ) were measured and vastus lateralis (VL) muscle biopsy samples were collected from 12 females and 12 males matched for aerobic fitness relative to fat-free mass (FFM) [means (SD); V̇o 2max : 59.2 (7.7) vs. 59.5 (7.1) mL·kg·FFM -1 ·min -1 , respectively]. Males had a significantly greater CP than females in absolute units [225 (28) vs. 170 (43) W; P = 0.001] but not relative to body mass [3.0 (0.6) vs. 2.7 (0.6) W·kg·BM -1 ; P = 0.267] or FFM [3.6 (0.7) vs. 3.7 (0.8) W·kg·FFM -1 ; P = 0.622]. Males had significantly greater W ' ( P ≤ 0.030) and greater Hb mass ( P ≤ 0.016) than females, regardless of the normalization approach; however, there were no differences in mitochondrial protein content ( P = 0.375), τ ( P = 0.603), or MHC I proportionality ( P = 0.574) between males and females. Whether it was expressed in absolute or relative units, CP was positively correlated with Hb mass (0.444 ≤ r ≤ 0.695; P < 0.05), mitochondrial protein content (0.413 ≤ r ≤ 0.708; P < 0.05), and MHC I proportionality (0.506 ≤ r ≤ 0.585; P < 0.05), and negatively correlated with τ when expressed in relative units only (-0.588 ≤ r ≤ -0.527; P < 0.05). Overall, CP was independent of sex, but variability in CP was related to Hb mass and skeletal muscle characteristics. The extent to which manipulations in these physiological parameters influence CP warrants further investigation to better understand the factors underpinning CP. NEW & NOTEWORTHY In males and females matched for aerobic fitness [maximal oxygen uptake normalized to fat-free mass (FFM)], absolute critical power (CP) was greater in males, but relative CP (per kilogram body mass or FFM) was similar between sexes. CP correlated with hemoglobin mass, mitochondrial protein content, myosin heavy chain type I proportion, and skeletal muscle oxidative capacity. These findings demonstrate the importance of matching sexes for aerobic fitness, but further experiments are needed to determine causality.

Purpose: This study investigated the effects of prolonged intermittent cycling exercise on peak power output (PPO) and 6-min time-trial (6 min-TT) performance in elite and professional road cyclists. Moreover, the study aimed to determine whether changes in performance in the fatigued state could be predicted from substrate utilization during exercise and laboratory measures obtained in a fresh state., Methods: Twelve cyclists (age: 23 years [21;25]; body mass: 71.5 kg [66.7;76.8]; height: 181 cm [178;185]; V ˙ O 2 peak: 73.6 ml kg -1 min -1 [71.2;76.0]) completed a graded submaximal cycling test to determine lactate threshold (LT 1 ), gross efficiency (GE), and maximal fat oxidation (MFO) as well as power output during a maximal 6 min-TT (MPO 6 min ) in a fresh condition. On a separate day, the cyclists completed a 4-h intermittent cycling protocol with a high CHO intake (100 g h -1 ). Substrate utilization and PPO was measured hourly during the protocol, which was followed by another 6 min-TT., Results: MPO 6 min and PPO was reduced by 10% [4;15] and 6% [0;6], respectively, after the cycling protocol. These reductions were accompanied by reductions in the anaerobic energy contribution and V ˙ O 2 peak, whereas the average V ˙ O 2 during the 6 min-TT was unchanged. Correlation analyses showed no strong associations between reductions in MPO 6 min and PPO and laboratory measures (i.e., LT 1 , GE, MFO, V ˙ O 2 peak) obtained in the fresh condition. Additionally, fat oxidation rates during the cycling protocol were not related to changes in neither PPO nor MPO 6 min ., Conclusion: PPO and MPO 6 min were reduced following prolonged intermittent cycling, but the magnitude of these reductions could not be predicted from laboratory measures obtained in the fresh condition., (© 2024. The Author(s).)

Fatigue resistance is vital for success in elite road cycling, as repeated, intense efforts challenge the athletes' ability to sustain peak performance throughout prolonged races. The present study combined recurrent performance testing and physiological measures during 6 h simulated racing with laboratory testing to investigate factors influencing fatigue resistance. Twelve male national elite cyclists (25 ± 3 years; 76 ± 6 kg and VO 2max of 5.2 ± 0.5 L/min) completed incremental power and maximal fat oxidation tests. Subsequently, they underwent field testing with physiological measures and fatigue responses evaluated through peak sprint power and 5 km time trial (TT) testing after 0, 2, 4, and 6 h of exercise. Peak power declined from 1362 ± 176 W in first sprint to 1271 ± 152 W after 2 h (p < 0.01) and then stabilized. In contrast, TT mean power gradually declined from 412 ± 38 W in the first TT to 384 ± 41 W in the final trial, with individual losses ranging from 2% to 14% and moderately correlated (r 2  = 0.45) to accumulated exercise time above lactate threshold. High carbohydrate intake (~90 g/h) maintained blood glucose levels, but post-TT [lactate] decreased from 15.1 ± 2 mM to 7.1 ± 2.3 mM, while fat oxidation increased from 0.7 ± 0.3 g/min at 0 h to 1.1 ± 0.1 g/min after 6 h. The study identifies fatigue patterns in national elite cyclists. Peak sprint power stabilized after an initial impairment from 0 to 2 h, while TT power gradually declined over the 6 h simulated race, with increased differentiation in fatigue responses among athletes., (© 2024 The Author(s). Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Objectives: This study aims to identify the optimal method for determining V̇O 2max in competitive swimmers in terms of validity and test-retest reliability., Design: Controlled experiment., Methods: Twenty competitive swimmers performed four maximal incremental exercise tests: cycling, arm cranking, ergometer swimming, and tethered swimming. Gas analysis was conducted to estimate V̇O 2max . Validity was assessed in terms of the amount of variance of the performance on a 1500-m time trial explained by the estimated V̇O 2max . Test-retest reliability was evaluated using the intraclass correlation coefficient (ICC)., Results: V̇O 2max obtained from tethered swimming, ergometer swimming, and cycling explained a similar amount of variance of the 1500-m performance (R 2  = 0.64, 0.64 and 0.65, respectively). However, ergometer swimming yielded significantly lower V̇O 2max estimates (40.54 ± 6.55 ml/kg/min) than tethered swimming (54.40 ± 6.21 ml/kg/min) and cycling (54.39 ± 5.63 ml/kg/min). Arm cranking resulted in both a lower explained variance (R 2  = 0.41) and a significantly lower V̇O 2max (43.14 ± 7.81 ml/kg/min). Tethered swimming showed good reliability (ICC = 0.81)., Conclusions: Bicycle and tethered swimming tests demonstrated high validity with comparable V̇O 2max estimates, explaining a large proportion of differences in endurance performance. Choosing between these two methods involves a trade-off between a higher practical applicability and reliability of the bicycle test and the more sport-specific nature of the tethered swimming test., Competing Interests: Declaration of interest statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O 2max ) and submaximal thresholds., Methods: Eighty-four young healthy participants (42 females, 42 males) were randomly assigned to six age, sex, and V̇O 2max -matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention., Results: Compared with the change in V̇O 2max (∆V̇O 2max ) in CON (0.1 ± 1.2 mL·kg -1 ·min -1 ), all training groups, except MOD (1.8 ± 2.7 mL·kg -1 ·min -1 ), demonstrated a significant increase ( P < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL·kg -1 ·min -1 ) followed by HVY2 (5.4 ± 2.3 mL·kg -1 ·min -1 ), SIT (4.7 ± 2.3 mL·kg -1 ·min -1 ), and HVY1 (3.3 ± 2.4 mL·kg -1 ·min -1 ), respectively. The ΔPO at the estimated lactate threshold ( θLT ) was similar across HVY1, HVY2, HIIT, and SIT, which were all greater than CON ( P < 0.05). The ΔV̇O 2 and ΔPO at θLT for MOD was not different from CON ( P > 0.05). HIIT produced the highest ΔPO at maximal metabolic steady state, which was greater than CON, MOD, and SIT ( P < 0.05)., Conclusions: This study demonstrated that i) exercise intensity is a key component determining changes in V̇O 2max and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals., (Copyright © 2024 by the American College of Sports Medicine.)

Blood flow restriction (BFR) is increasingly being used to enhance aerobic performance in endurance athletes. This study examined physiological responses to BFR applied in recovery phases within a high-intensity interval training (HIIT) session in trained cyclists. Eleven competitive road cyclists (mean ± SD, age: 28 ± 7 years, body mass: 69 ± 6 kg, peak oxygen uptake: 65 ± 9 mL · kg -1  · min -1 ) completed two randomised crossover conditions: HIIT with (BFR) and without (CON) BFR applied during recovery phases. HIIT consisted of six 30-s cycling bouts at an intensity equivalent to 85% of maximal 30-s power (523 ± 93 W), interspersed with 4.5-min recovery. BFR (200 mmHg, 12 cm cuff width) was applied for 2-min in the early recovery phase between each interval. Pulmonary gas exchange (V̇O 2 , V̇CO 2 , and V̇E), tissue oxygen saturation index (TSI), heart rate (HR), and serum vascular endothelial growth factor concentration (VEGF) were measured. Compared to CON, BFR increased V̇CO 2 and V̇E during work bouts (both p < 0.05, dz < 0.5), but there was no effect on V̇O 2 , TSI, or HR (p > 0.05). In early recovery, BFR decreased TSI, V̇O 2 , V̇CO 2 , and V̇E (all p < 0.05, dz > 0.8) versus CON, with no change in HR (p > 0.05). In late recovery, when BFR was released, V̇O 2 , V̇CO 2 , V̇E, and HR increased, but TSI decreased versus CON (all p < 0.05, dz > 0.8). There was a greater increase in VEGF at 3-h post-exercise in BFR compared to CON (p < 0.05, dz > 0.8). Incorporating BFR into HIIT recovery phases altered physiological responses compared to exercise alone., (© 2024 The Authors. European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

Ground-level ozone (O 3 ) is a potent air pollutant well recognized to acutely induce adverse respiratory symptoms and impairments in pulmonary function. However, it is unclear how the hyperpnea of exercise may modulate these effects, and the subsequent consequences on exercise performance. We tested the hypothesis that pulmonary function and exercise capability would be diminished, and symptom development would be increased during peak real-world levels of O 3 exposure compared with room air. Twenty aerobically trained participants [13 M, 7 F; maximal O 2 uptake (V̇o 2max ), 64.1 ± 7.0 mL·kg -1 ·min -1 ] completed a three-visit double-blinded, randomized crossover trial. Following a screening visit, participants were exposed to 170 ppb O 3 or room air (<10 ppb O 3 ) on separate visits during exercise trials, consisting of a 25-min moderate-intensity warmup, 30-min heavy-intensity bout, and a subsequent time-to-exhaustion (TTE) performance test. No differences in O 2 uptake or ventilation were observed during submaximal exercise between conditions. During the TTE test, we observed significantly lower end-exercise O 2 uptake (-3.2 ± 4.3%, P = 0.004), minute ventilation (-3.2 ± 6.5%, P = 0.043), tidal volume (-3.6 ± 5.1%, P = 0.008), and a trend toward lower exercise duration in O 3 compared with room air (-10.8 ± 26.5%, P = 0.092). As decreases in O 2 uptake and alterations in respiratory pattern were also present at matched time segments between conditions, a limitation of oxygen transport seems likely during maximal exercise. A more comprehensive understanding of the direct mechanisms that limit oxygen transport during exercise in high-pollutant concentrations is key for mitigating performance changes. NEW & NOTEWORTHY We demonstrate that in highly trained endurance athletes, exposure to peak real-world levels of O 3 air pollution (170 ppb) significantly diminishes O 2 uptake along with corresponding changes in ventilation during maximal exercise. As no differences were observed during extended submaximal exercise, a combined effect of effective dose of pollution and exercise intensity on severity of responses seems likely.

Background: Neuromuscular function is considered as a determinant factor of endurance performance during adulthood. However, whether endurance training triggers further neuromuscular adaptations exceeding those of growth and maturation alone over the rapid adolescent growth period is yet to be determined., Objective: The present study investigated the concurrent role of growth, maturation, and endurance training on neuromuscular function through a 9-month training period in adolescent triathletes., Methods: Thirty-eight 13- to 15-year-old males (23 triathletes [~6 h/week endurance training] and 15 untrained [<2 h/week endurance activity]) were evaluated before and after a 9-month triathlon training season. Maximal oxygen uptake (V̇O 2max ) and power at V̇O 2max were assessed during incremental cycling. Knee extensor maximal voluntary isometric contraction torque (MVC ISO ) was measured and the voluntary activation level (VAL) was determined using the twitch interpolation technique. Knee extensor doublet peak torque (T 100Hz ) and normalized vastus lateralis (VL) electromyographic activity (EMG/M-wave) were also determined. VL and rectus femoris (RF) muscle architecture was assessed using ultrasonography., Results: Absolute V̇O 2max increased similarly in both groups but power at V̇O 2max only significantly increased in triathletes (+13.8%). MVC ISO (+14.4%), VL (+4.4%), and RF (+15.8%) muscle thicknesses and RF pennation angle (+22.1%) increased over the 9-month period in both groups similarly (p < 0.01), although no changes were observed in T 100Hz , VAL, or VL EMG/M-wave. No changes were detected in any neuromuscular variables, except for coactivation., Conclusion: Endurance training did not induce detectible, additional neuromuscular adaptations. However, the training-specific cycling power improvement in triathletes may reflect continued skill enhancement over the training period., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)