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Purpose: To characterize and compare female ice hockey players' peak skating speed and acceleration ability during linear sprints and gameplay. We also sought to quantify the time spent at various speeds and the frequency of accelerations at different thresholds during games. Methods: Seventeen varsity-level female ice hockey players (20 [1.4] y, 68.9 [4.9] kg, 167.6 [4.7] cm) participated in an on-ice practice session (performing 3 × 40-m linear sprints) and 4 regular-season games while being monitored using a local positioning system. Speed and acceleration were recorded from the sprint and within-game monitoring. Time on ice spent in relative skating speed zones and the frequency of accelerations at different intensities were recorded. Results: Players' greatest peak speeds (29.5 [1.3] vs 28.3 [1.1] km/h) and accelerations (4.39 [0.48] vs 3.34 [0.36] m/s2) reached during gameplay were higher than those reached in linear sprinting (both P <.01). Peak in-game values were moderately predicted by linear sprint values for speed (r =.69, P <.01) but not for acceleration (r <.01, P =.95). Players spent little time at near-peak linear sprint speeds (≥80% [22.7 km/h], ∼3% time on ice; ≥90% [25.5 km/h], <1% of time on ice) during gameplay. However, 26% to 35% of accelerations recorded during the 4 games were ≥90% of linear sprint acceleration. Conclusions: Although skating speed may be advantageous in specific game situations, our results suggest that players spend little time at near-maximal speeds while accelerating frequently during games. This warrants further investigation of direction changes, skating transitions, repeated sprints, and other determinant variables potentially related to on-ice success and the implementation of training strategies to improve repeated acceleration or qualities beyond maximal skating speed. [ABSTRACT FROM AUTHOR]

Intense exercise training with insufficient recovery time is associated with reductions in neuromuscular performance. However, it is unclear how single muscle fibre mechanical function and myofibrillar Ca2+ sensitivity contribute to these impairments. We investigated the effects of overload training on joint-level neuromuscular performance and cellular-level mechanical function. Fourteen athletes (4 female and 10 male) underwent a 3-week intensified training protocol consisting of up to 150% of their regular training hours with three additional high-intensity training sessions per week. Neuromuscular performance of the knee extensors was assessed via maximal voluntary contraction (MVC) force, electrically evoked twitch contractions, and a force-frequency relationship. Muscle biopsies were taken from the vastus lateralis to assess single fibre mechanical function. Neither MVC force nor twitch parameters were altered following training (all p > 0.05), but a rightward shift in the force–frequency curve was observed with average reduction in force of 6%–27% across frequencies 5–20 Hz (all p < 0.05). In single fibres, maximal force output was not reduced following training, but there was a rightward shift in the force–pCa curve driven by a 6% reduction in Ca2+ sensitivity (p < 0.05). These data indicate intensified training leads to impaired Ca2+ sensitivity at the single fibre level, which in part explains impaired neuromuscular function at the joint level during lower frequencies of activation. This is an important consideration for athletes, as performance is often assessed at maximal levels of activation, and these underlying impairments in force generation may be less obvious. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that the incidence and magnitude of diaphragm fatigue following high-intensity exercise would be lower in females with a high aerobic capacity (Hi-Fit) compared with healthy females with an average aerobic fitness (Avg-Fit). Participants were assigned to groups based on their peak O2 uptake (V̇ o 2peak) obtained during cycle exercise: Hi-Fit n = 9, V̇ o 2peak ≥ 56.1 ± 3.4 mL·kg−1·min−1 versus Avg-Fit n = 9, V̇ o 2peak ≤ 35.7 ± 4.9 mL·kg−1·min−1. On the second day, diaphragm fatigue was assessed before and after constant load exercise test to exhaustion. Magnetic stimulation of the phrenic nerve roots was used to nonvolitionally assess diaphragm fatigue by measurement of transdiaphragmatic twitch pressure (Pdi,tw). Both groups exercised at >90% of V̇ o 2peak for a similar duration (Hi-Fit: 546.1 ± 177.8 vs. Avg-Fit: 559.3 ± 175.0 s, P = 0.9). Diaphragm fatigue was defined as a ≥15% reduction in Pdi,tw, approximately two times greater than the coefficient of variation. The mean group average reduction in Pdi,tw following exercise in the Hi-Fit (17.5%) and Avg-Fit groups (12.2%) was not different between groups (P = 0.2). The Hi-Fit group performed exercise at a higher absolute work rate that elicited significantly greater ventilatory work and inspiratory muscle force output. The Hi-Fit group did not experience greater fatigue compared with the Avg-Fit group, which we attribute to a greater reliance on accessory respiratory muscle recruitment, to training-induced increases in the aerobic capacity of the diaphragm, or a combination of the two. In summary, aerobic fitness is not predictive of exercise-induced diaphragm fatigue in healthy females. NEW & NOTEWORTHY: We hypothesized that females with a high aerobic capacity would be resistant to exercise-induced diaphragm fatigue relative to healthy but untrained females. We assessed the pressure generated by the diaphragm following exhaustive exercise by stimulating the phrenic nerves. The magnitude and incidence of fatigue were similar between groups. Despite having higher ventilatory demands during exercise highly trained females were resistant to greater diaphragm fatigue. Aerobic fitness is not predictive of exercise-induced diaphragm fatigue in females. [ABSTRACT FROM AUTHOR]

Exaggerated blood pressure (BP) responses during exercise are independently associated with future development of hypertension. Partial sleep deprivation (PSD) can increase 24-h ambulatory BP, but the effects on exercise BP are unclear. We hypothesized that acute PSD would augment the BP response to constant load cycling exercise and a 20-min time trial. Twenty-two healthy adults (22 ± 3 yr old; 13 males; V̇ o 2peak, 43.6 ± 8.2 mL·kg−1·min−1) completed a randomized crossover trial in which they either slept normally (normal sleep-wake schedule for each participant) or sleep was partially deprived (early awakening, 40% of normal sleep duration). Each participant completed a 12-min warm-up consisting of two 6-min steps (step 1, 62 ± 25 W; step 2, 137 ± 60 W) followed by a 20-min time trial on a cycle ergometer. PSD did not alter power output during the 20-min time trial [(control vs. PSD) 170 ± 68 vs. 168 ± 68 W, P = 0.65]. Systolic BP did not differ during step 1 of the warm-up (141 ± 15 vs. 137 ± 12 mmHg, P = 0.39) but was lower following PSD during step 2 (165 ± 21 vs. 159 ± 22 mmHg, P = 0.004) and the 20-min time trial (171 ± 20 vs. 164 ± 23 mmHg, P < 0.001). These results were maintained when peak oxygen uptake (V̇ o 2peak) was included as a covariate. Systolic BP responses were modulated by sex (time × visit × sex interaction P = 0.03), with attenuated systolic BP during the warm-up and the 20-min time trial in males but not in females. In contrast to our hypothesis, acute PSD attenuates systolic BP responses during constant load and 20-min time trial cycling exercise; however, these observations appear to be primarily driven by changes in males. NEW & NOTEWORTHY: A single night of partial sleep deprivation (PSD) can increase ambulatory blood pressure (BP) the following day. Despite this phenomenon, the present study found that acute PSD attenuates systolic BP responses to both constant load cycling and a 20-min cycling time trial in young healthy adults. Interestingly, the attenuated systolic BP responses following PSD appeared to be modulated by sex such that attenuations were observed in males but not in females. [ABSTRACT FROM AUTHOR]

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 (V̇ o 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 V̇ o 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 V̇ o 2peak and led to improvements in motor symptoms and perceived fatigue; HIIT may offer the potential for larger changes in V̇ o 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 V̇ o 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. [ABSTRACT FROM AUTHOR]

Cardiac output (Q̇C) and leg blood flow (Q̇LEG) can be measured simultaneously with high accuracy using transpulmonary and femoral vein thermodilution with a single‐bolus injection. The invasive measure has offered important insight into leg hemodynamics and blood flow distribution during exercise. Despite being the natural modality of exercise in humans, there has been no direct measure of Q̇LEG while running in humans. We sought to determine the feasibility of the thermodilution technique for measuring Q̇LEG and conductance during high‐intensity running, in an exploratory case study. A trained runner (30 years male) completed two maximal incremental tests on a cycle ergometer and motorized treadmill. Q̇LEG and Q̇C were determined using the single‐bolus thermodilution technique. Arterial and venous blood were sampled throughout exercise, with continuous monitoring of metabolism, intra‐arterial and venous pressure, and temperature. The participant reached a greater peak oxygen uptake (V̇O2peak) during running relative to cycling (74 vs. 68 mL/kg/min) with comparable Q̇LEG (19.0 vs. 19.5 L/min) and Q̇C (27.4 vs. 26.2 L/min). Leg vascular conductance was greater during high‐intensity running relative to cycling (82 vs. 70 mL/min/mmHg @ ~80% V̇O2peak). The "beat phenomenon" was apparent in femoral flow while running, producing large gradients in conductance (62–90 mL/min/mmHg @ 70% V̇O2peak). In summary, we present the first direct measure of Q̇LEG and conductance in a running human. Our findings corroborate several assumptions about Q̇LEG during running compared with cycling. Importantly, we demonstrate that using thermodilution in running exercise can be completed effectively and safely. [ABSTRACT FROM AUTHOR]

The article focuses on the potential risks and benefits of repeated carbon monoxide inhalation in sports performance. Topics include the physiological effects of carbon monoxide on the body, its controversial use as a performance-enhancing strategy, and the potential long-term health hazards associated with repeated exposure.

Purpose: Along with past performance, professional teams consider physical fitness and physiological potential in determining the value of prospective draft picks. The National Hockey League (NHL) Combine fitness results have been examined for their ability to predict draft order, but not bona fide hockey performance. Therefore, we sought to identify the relationships of combine fitness test results to short- and long-term NHL performance. Methods: During NHL Combine fitness testing (1994–2007), a standardized battery of tests was conducted. Player performance (1995–2020) was quantified using career cumulative points, time on ice, transitional period to playing in the NHL, and NHL career length. Forward and defensive positions were considered separately. Goalies were not considered. Stepwise linear regression analysis was used to identify fitness variables that predict NHL success. Results: Overall models ranged in their predictive ability from 2% to 16%. The transitional period was predicted by peak leg power and aerobic capacity ( V ˙ O 2 max ; forwards, R2 =.03, and defense, R2 =.06, both P <.01). Points and time on ice within seasons 1 to 3 were predicted by peak leg power and V ˙ O 2 max for forwards and defense (R2 =.02–.09, P <.01). Among players accumulating 10 NHL seasons, cumulative points were inversely related to upper-body push-strength-related variables in forwards (R2 =.11) and defense (R2 =.16; both P <.01). Conclusions: The NHL Combine fitness testing offers meaningful data that can inform the likelihood of future success. Peak leg power and V ˙ O 2 max predict league entry and early career success. Counterintuitively, upper-body strength is inversely related to long-term performance, which may offer insight into recruitment strategies, player development, or differential team roles. [ABSTRACT FROM AUTHOR]

Context: The physiological determinants of ultramarathon success have rarely been assessed and likely differ in their contributions to performance as race distance increases. Purpose: To examine predictors of performance in athletes who completed either a 50-, 80-, or 160-km trail race over a 20-km loop course on the same day. Methods: Measures of running history, aerobic fitness, running economy, body mass loss, hematocrit alterations, age, and cardiovascular health were examined in relation to race-day performance. Performance was defined as the percentage difference from the winning time at a given race distance, with 0% representing the fastest possible time. Results: In the 50-km race, training volumes, cardiovascular health, aerobic fitness, and a greater loss of body mass during the race were all related to better performance (all P <.05). Using multiple linear regression, peak velocity achieved in the maximal oxygen uptake test (β = −11.7, P =.002) and baseline blood pressure (β = 3.1, P =.007) were the best performance predictors for the men's 50-km race (r =.98, r2 =.96, P <.001), while peak velocity achieved in the maximal oxygen uptake test (β = −13.6, P =.001) and loss of body mass (β = 12.8, P =.03) were the best predictors for women (r =.94, r2 =.87, P =.001). In the 80-km race, only peak velocity achieved in the maximal oxygen uptake test predicted performance (β = −20.3, r =.88, r2 =.78, P <.001). In the 160-km race, there were no significant performance determinants. Conclusions: While classic determinants of running performance, including cardiovascular health and running fitness, predict 50-km trail-running success, performance in longer-distance races appears to be less influenced by such physiological parameters. [ABSTRACT FROM AUTHOR]

Herein, we examine the human exercise response following cannabis inhalation, taking into consideration varied cannabinoid concentrations and different inhalation methods. A semirandomized crossover study design was used, with measures of perceived exertion and physiological responses to submaximal and maximal exercise. Participants (n = 14, 9 males 5 females) completed exercise after 1) smoking D-9-tetrahydrocannabinol (THC)-predominant cannabis (S-THC), 2) inhaling aerosol (vaporizing) from THC-predominant cannabis (V-THC), 3) inhaling aerosol from cannabidiol (CBD)-predominant cannabis (V-CBD), or 4) under control conditions. All exercise was performed on a cycle ergometer, with submaximal testing performed at 100 W followed by an evaluation of maximal exercise performance using an all-out 20-min time trial. Metabolism was characterized via the analysis of expired gases while subjective ratings of perceived exertion (RPE) were reported. During submaximal cycling, heart rate was higher during S-THC and V-THC compared with both control and V-CBD (all P < 0.02). During maximal exercise, V_ E was lower in V-THC compared with control, S-THC, and V-CBD (all P < 0.03), as was S-THC compared with control (P < 0.05). Both V O2 and RPE were similar between conditions during maximal exercise (both P > 0.1). Mean power output during the 20-min time trial was significantly lower in the S-THC and V-THC conditions compared with both control and V-CBD (all P < 0.04). Cannabis containing THC alters the physiological response to maximal and submaximal exercise, largely independent of the inhalation method. THC-containing cannabis negatively impacts vigorous exercise performance during a sustained 20-min effort, likely due to physiological and psychotropic effects. Inhalation of cannabis devoid of THC and primarily containing CBD has little physiological effect on the exercise response or performance. [ABSTRACT FROM AUTHOR]

Endothelium-dependent vasodilation can be tested using a variety of shear stress paradigms, some of which may involve the production of reactive oxygen species. The purpose of this study was to compare different methods for assessing endothelial function and their specific involvement of reactive oxygen species and influence of aerobic training status. Twenty-nine (10 F) young and healthy participants (VO2max: 34–74 mL·kg−1·min−1) consumed either an antioxidant cocktail (AOC; vitamin C, vitamin E, α-lipoic acid) or placebo (PLA) on each of two randomized visits. Endothelial function was measured via three different brachial artery flow-mediated dilation (FMD) tests: reactive hyperemia (RH-FMD: 5 min cuff occlusion and release), sustained shear (SS-FMD: 6 min rhythmic handgrip), and progressive sustained shear (P-SS-FMD: three intensities of 3 min of rhythmic handgrip). Baseline artery diameter decreased (all tests: 3.8 ± 0.5 to 3.7 ± 0.6 mm, p = 0.004), and shear rate stimulus increased (during RH-FMD test, p = 0.021; during SS-FMD test, p = 0.36; during P-SS-FMD test, p = 0.046) following antioxidant consumption. However, there was no difference in FMD following AOC consumption (RH-FMD, PLA: 8.1 ± 2.6%, AOC: 8.2 ± 3.5%, p = 0.92; SS-FMD, PLA: 6.9 ± 3.9%, AOC: 7.8 ± 5.2%, p = 0.15) or FMD per shear rate slope (P-SS-FMD: PLA: 0.0039 ± 0.0035 mm·s−1, AOC: 0.0032 ± 0.0017 mm·s−1, p = 0.28) and this was not influenced by training status/fitness (all p > 0.60). Allometric scaling did not alter these outcomes (all p > 0.40). Reactive oxygen species may not be integral to endothelium-dependent vasodilation tested using reactive, sustained, or progressive shear protocols in young males and females, regardless of fitness level. [ABSTRACT FROM AUTHOR]