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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] more...

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] more...

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. more...

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] more...

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] more...

Purpose: The purpose of the study was to investigate whether carbohydrate utilization is altered during exercise in overreached endurance athletes and examine the utility of continuous glucose monitors (CGM) to detect overreaching status. Methods: Eleven endurance athletes (M:8, F:3) completed a 5‐week training block consisting of 1 week of reduced training (PRE), 3 weeks of high‐intensity overload training (POST), and 1 week of recovery training (REC). Participants completed a Lamberts and Lambert Submaximal Cycling Test (LSCT) and 5 km time‐trial at PRE, POST, and REC time points, 15 min following the ingestion of a 50 g glucose beverage with glucose recorded each minute via CGM. Results: Performance in the 5 km time‐trial was reduced at POST (∆‐7 ± 10 W, p = 0.04, ηp2 = 0.35) and improved at REC (∆12 ± 9 W from PRE, p = 0.01, ηp2 = 0.66), with reductions in peak lactate (∆‐3.0 ± 2.0 mmol/L, p = 0.001, ηp2 = 0.71), peak HR (∆‐6 ± 3 bpm, p < 0.001, ηp2 = 0.86), and Hooper‐Mackinnon well‐being scores (∆10 ± 5 a.u., p < 0.001, ηp2 = 0.79), indicating athletes were functionally overreached. The respiratory exchange ratio was suppressed at POST relative to REC during the 60% (POST: 0.80 ± 0.05, REC: 0.87 ± 0.05, p < 0.001, ηp2 = 0.74), and 80% (POST: 0.93 ± 0.05, REC: 1.00 ± 0.05, p = 0.003, ηp2 = 0.68) of HR‐matched submaximal stages of the LSCT. CGM glucose was reduced during HR‐matched submaximal exercise in the LSCT at POST (p = 0.047, ηp2 = 0.36), but not the 5 km time‐trial (p = 0.07, ηp2 = 0.28) in overreached athletes. Conclusion: This preliminary investigation demonstrates a reduction in CGM‐derived glucose and carbohydrate oxidation during submaximal exercise in overreached athletes. The use of CGM during submaximal exercise following standardized nutrition could be employed as a monitoring tool to detect overreaching in endurance athletes. [ABSTRACT FROM AUTHOR] more...

Relative energy deficiency in sport (RED-S) can result in negative health and performance outcomes in both male and female athletes. The underlying etiology of RED-S is low energy availability (LEA), which occurs when there is insufficient dietary energy intake to meet exercise energy expenditure, corrected for fat-free mass, leaving inadequate energy available to ensure homeostasis and adequate energy turnover (optimize normal bodily functions to positively impact health), but also optimizing recovery, training adaptations, and performance. As such, treatment of RED-S involves increasing energy intake and/or decreasing exercise energy expenditure to address the underlying LEA. Clinically, however, the time burden and methodological errors associated with the quantification of energy intake, exercise energy expenditure, and fat-free mass to assess energy availability in free-living conditions make it difficult for the practitioner to implement in everyday practice. Furthermore, interpretation is complicated by the lack of validated energy availability thresholds, which can result in compromised health and performance outcomes in male and female athletes across various stages of maturation, ethnic races, and different types of sports. This narrative review focuses on pragmatic nonpharmacological strategies in the treatment of RED-S, featuring factors such as low carbohydrate availability, within-day prolonged periods of LEA, insufficient intake of bone-building nutrients, lack of mechanical bone stress, and/or psychogenic stress. This includes the implementation of strategies that address exacerbating factors of LEA, as well as novel treatment methods and underlying mechanisms of action, while highlighting areas of further research. [ABSTRACT FROM AUTHOR] more...

During play, ice hockey goaltenders routinely dehydrate through sweating and lose >2% body mass, which may impair thermoregulation and performance. Purpose: This randomized, crossover study examined the effects of mild dehydration on goaltender on-ice thermoregulation, heart rate, fatigue, and performance. Methods: Eleven goaltenders played a 70-minute scrimmage followed by a shootout and drills to analyze reaction time and movements. On ice, they either consumed no fluid (NF) and lost 2.4% (0.3%) body mass or maintained body mass with water (WAT) or a carbohydrate-electrolyte solution (CES). Save percentage, rating of perceived exertion, heart rate, and core temperature were recorded throughout, and a postskate questionnaire assessed perceived fatigue. Results: Relative to NF, intake of both fluids decreased heart rate (interaction: P = .03), core temperature (peak NF = 39.0°C [0.1°C], WAT = 38.6°C [0.1°C], and CES = 38.5°C [0.1°C]; P= .005), and rating of perceived exertion in the scrimmage (post hoc: R e .04), as well as increasing save percentage in the final 10 minutes of scrimmage (NF = 75.8% [1.9%], WAT = 81.7% [2.3%], and CES = 81.3% [2.3%], post hoc: P < .04). In drills, movement speed (post hoc: P < .05) and reaction time (post hoc: P < .04) were slower in the NF versus both fluid conditions. Intake of either fluid similarly reduced postskate questionnaire scores (condition: F<.0001). Only CES significantly reduced rating of perceived exertion in drills (post hoc: P < .0 5 ) and increased peak movement power versus NF (post hoc: P = .02). Shootout save percentage was similar between conditions (P = .37). Conclusions: Mild dehydration increased physiological strain and fatigue and decreased ice hockey goaltender performance versus maintaining hydration. Also, maintaining hydration with a CES versus WAT may further reduce perceived fatigue and positively affect movements. [ABSTRACT FROM AUTHOR] more...

This study determined the reliability and validity of a Kinexon local positioning system (LPS) for measuring external load in ice hockey players during an on-ice session. Fourteen ice hockey players (25.1 y, 78.6 kg, 176.9 cm) wore two LPS sensors to examine the inter-sensor reliability of the LPS during an on-ice session, and LPS speed and acceleration were measured during 40 m linear on-ice sprints and compared to a previously validated robotic sprint device to examine LPS accuracy. The coefficient of variation (CV), standard error of measurement (SEM), and intra-class correlation coefficient (ICC) were calculated for each LPS measure. Pearson's correlations, simple linear regressions, and Bland–Altman plots were used to test the agreement and relationship between the two systems. Statistical significance was determined at p < 0.05. The majority of LPS measures were reliable (CV < 10% and ICC > 0.9) when comparing the two sensors worn by each player. Peak speed, speed at 5 m, and 0-5 m acceleration were all comparable to those reported by the robotic sprint device, with nearly perfect (peak speed and 0–5 m acceleration) and very large (speed at 5 m) magnitudes of correlation and mean biases <0.5 km/hr for speed measures and <0.01 m/s2 for acceleration. The present results demonstrate that the Kinexon LPS is reliable and accurate for investigating on-ice external load in ice hockey players when sensors are consistently secured on the back of the players' shoulder pads. [ABSTRACT FROM AUTHOR] more...

Ischemic preconditioning (IPC) was initially developed to protect the myocardium from ischemia through altered cardiocyte metabolism. Because of the observed effects on metabolism and oxygen kinetics, IPC gained interest as a potential ergogenic aid in sports. Limited research evaluating the effects of IPC on maximal short-duration activities has been performed, and of the existing literature, mixed outcomes resulting from intrasubject variation may have clouded the efficacy of this technique for enhancing sprint performance. Therefore, the current study employed a randomized repeated-measures crossover design with IPC, placebo (SHAM), and control conditions while using sprint-trained athletes (N = 18) to determine the effect of IPC (3 × 5-min occlusions, with 5-min reperfusion), concluding 15 min prior to maximal 10-s and 20-m sprinting. A visual analog scale was used in conjunction with the sprint trials to evaluate any possible placebo effect on performance. Despite a "significantly beneficial" perception of the IPC treatment compared with the SHAM trials (P <.001), no changes in sprint performance were observed after either the IPC or SHAM condition over 10 m (IPC Δ < 0.01 [0.02] s, SHAM Δ < 0.01 [0.02] s) or 20 m (IPC Δ = −0.01 [0.03] s, SHAM Δ < 0.01 [0.03] s) compared with control. Thus, an IPC protocol does not improve 10- or 20-m sprint performance in sprint-trained athletes. [ABSTRACT FROM AUTHOR] more...

Background: Overreaching is the transient reduction in performance that occurs following training overload and is driven by an imbalance between stress and recovery. Low energy availability (LEA) may drive underperformance by compounding training stress; however, this has yet to be investigated systematically. Objective: The aim of this study was to quantify changes in markers of LEA in athletes who demonstrated underperformance, and exercise performance in athletes with markers of LEA. Methods: Studies using a ≥ 2-week training block with maintained or increased training loads that measured exercise performance and markers of LEA were identified using a systematic search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Changes from pre- to post-training were analyzed for (1) markers of LEA in underperforming athletes and (2) performance in athletes with ≥ 2 markers of LEA. Results: From 56 identified studies, 14 separate groups of athletes demonstrated underperformance, with 50% also displaying ≥ 2 markers of LEA post-training. Eleven groups demonstrated ≥ 2 markers of LEA independent of underperformance and 37 had no performance reduction or ≥ 2 markers of LEA. In underperforming athletes, fat mass (d = − 0.29, 95% confidence interval [CI] − 0.54 to − 0.04; p = 0.02), resting metabolic rate (d = − 0.63, 95% CI − 1.22 to − 0.05; p = 0.03), and leptin (d = − 0.72, 95% CI − 1.08 to − 0.35; p < 0.0001) were decreased, whereas body mass (d = − 0.04, 95% CI − 0.21 to 0.14; p = 0.70), cortisol (d = − 0.06, 95% CI − 0.35 to 0.23; p = 0.68), insulin (d = − 0.12, 95% CI − 0.43 to 0.19; p = 0.46), and testosterone (d = − 0.31, 95% CI − 0.69 to 0.08; p = 0.12) were unaltered. In athletes with ≥ 2 LEA markers, performance was unaffected (d = 0.09, 95% CI − 0.30 to 0.49; p = 0.6), and the high heterogeneity in performance outcomes (I2 = 84.86%) could not be explained by the performance tests used or the length of the training block. Conclusion: Underperforming athletes may present with markers of LEA, but overreaching is also observed in the absence of LEA. The lack of a specific effect and high variability of outcomes with LEA on performance suggests that LEA is not obligatory for underperformance. [ABSTRACT FROM AUTHOR] more...

Thompson, KM, Safadie, A, Ford, J, and Burr, JF. Off-ice resisted sprints best predict all-out skating performance in varsity hockey players. J Strength Cond Res 36(9): 2597–2601, 2022—Off-ice fitness testing is commonly used to predict the physiological abilities of ice-hockey players. Although there is a notable association between certain off-ice tests of jump power and anaerobic capacity with on-ice skating acceleration (r = 0.3–0.7), it is likely that off-ice tests which more closely resemble the demands of skating will have better predictive ability of this skill. The aim of the current study was to compare the suitability of common off-ice fitness tests and off-ice resisted sprints for predicting 15-m on-ice skate time. Male and female varsity-level hockey players performed a battery of common off-ice fitness tests, resisted sprints, and on-ice 15-m sprints over 3 testing days. At least moderate correlations between off-ice tests and on-ice sprints were observed for all common fitness tests (all p ≤ 0.002): Wingate peak power (r = −0.65), Wingate fatigue rate (r = −0.53), vertical jump (r = −0.52), and broad jump (r = −0.61), with resisted sprint tests showing the strongest associations (off-ice 15-kg resisted sprint (r = 0.79) and off-ice 30-kg resisted sprint (r = 0.74)). In multivariate analysis, stepwise regression revealed the 15-kg resisted sprint as the sole meaningful predictor of on-ice sprint time (R = 0.79, R 2 = 0.62; p ≤ 0.001). We conclude that resisted off-ice sprints have better predictive ability of on-ice skate time compared with commonly used off-ice tests. Resisted sprinting can be used by strength and conditioning staff as an indicator of on-ice acceleration ability during periods of limited access to on-ice facilities or as a component of fitness testing. [ABSTRACT FROM AUTHOR] more...

Cannabis is widely used for both recreational and medicinal purposes on a global scale. There is accumulating interest in the use of cannabis and its constituents for athletic recovery, and in some instances, performance. Amidst speculation of potential beneficial applications, the effects of cannabis and its two most abundant constituents, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), remain largely un-investigated. The purpose of this review is to critically evaluate the literature describing the effects of whole cannabis, THC, and CBD, on athletic performance and recovery. While investigations of whole cannabis and THC have generally shown either null or detrimental effects on exercise performance in strength and aerobic-type activities, studies of sufficient rigor and validity to conclusively declare ergogenic or ergolytic potential in athletes are lacking. The ability of cannabis and THC to perturb cardiovascular homeostasis warrants further investigation regarding mechanisms by which performance may be affected across different exercise modalities and energetic demands. In contrast to cannabis and THC, CBD has largely been scrutinized for its potential to aid in recovery. The beneficial effects of CBD on sleep quality, pain, and mild traumatic brain injury may be of particular interest to certain athletes. However, research in each of these respective areas has yet to be thoroughly investigated in athletic populations. Elucidating the effects of whole cannabis, THC, and CBD is pertinent for both researchers and practitioners given the widespread use of these products, and their potential to interact with athletes' performance and recovery. [ABSTRACT FROM AUTHOR] more...

Purpose The purpose of this study was to examine whether an individual's IPC-mediated change in cold pain sensitivity is associated with the same individual's IPC-mediated change in exercise performance. Methods Thirteen individuals (8 males; 5 females, 27 ± 7 years, 55 ± 5 ml.kgs–1.min–1) underwent two separate cold-water immersion tests: with preceding IPC treatment and without. In addition, each participant undertook two separate 5-km cycling time trials: with preceding IPC treatment and without. Pearson correlation coefficients were used to assess the relationship between an individual's change in cold-water pain sensitivity following IPC with their change in 5-km time trial performance following IPC. Results During the cold-water immersion test, pain intensity increased over time (p < 0.001) but did not change with IPC (p = 0.96). However, IPC significantly reduced the total time spent under pain (−9 ± 7 s; p = 0.001) during the cold-water immersion test. No relationship was found between an individual's change in time under pain (r = −0.2, p = 0.6) or pain intensity (r = −0.3, p = 0.3) following IPC and their change in performance following IPC. Conclusion These findings suggest that IPC can modulate sensitivity to a painful stimulus, but this altered sensitivity does not explain the ergogenic efficacy of IPC on 5-km cycling performance. [ABSTRACT FROM AUTHOR] more...

Resisted sprint training (RST) is commonly used for performance enhancement in athletics and team sports to develop acceleration ability. Evidence suggests that RST may be effective as a short-term intervention to improve successive sprints. Although these improvements have been measured in team sport athletes, limited research has considered the acute effects of RST training in sprint-trained athletes. Therefore, the aim of the current study was to determine whether performing RST with varsity-level sprinters using sled-equivalent resistive loads of ~45% body mass results in a potentiation effect, leading to improvements in subsequent maximal sprint performance over 0-5 m and 0-20 m. Competitive sprinters (n = 20) were randomly assigned to perform a pre/post maximal 20-m sprint separated by either 3 resisted (RST group) or unresisted (URS group) sprints. The RST or URS protocol was performed on 4 occasions separated by at least 7 days. No significant differences were observed between the RST and URS groups comparing changes in sprint times over 0-5 m (URS Δ <0.01 ± 0.03 seconds, RST Δ <0.01 ± 0.03 seconds) and 0-20 m (URS Δ 0.013 ± 0.04 seconds, RST Δ <0.01 ± 0.04 seconds). We conclude that resisted sprints using sled-equivalent loads of 45% body mass are ineffective at inducing a potentiating effect on subsequent sprint performance in varsity-level sprinters. In this population of trained athletes, greater loads may be necessary to induce a potentiating effect. [ABSTRACT FROM AUTHOR] more...

Power, as a testing and training metric to quantify effort, is well accepted in cycling, but is not commonly used in running to quantify effort or performance. This study sought to investigate a novel training tool, the Stryd Running Power Meter, and the applicability of running power (and its individually calculated run mechanics) to be a useful surrogate of metabolic demand (V...O2), across different running surfaces, within different caliber runners. Recreational (n = 13) and elite (n = 11) runners completed a test assessing V...O2 at 3 different paces, while wearing a Stryd Power Meter on both an indoor treadmill and an outdoor track, to investigate relationships between estimated running power and metabolic demand. A weak but significant relationship was found between running power and V...O2 considering all participants as a homogenous group (r = 0.29); however, when assessing each population individually, no significant relationship was found. Examination of the individual mechanical components of power revealed that a correlative decrease in V...O2 representing improved efficiency was associated with decreased ground contact time (r = 0.56), vertical oscillation (r = 0.46), and cadence (r = 0.37) on the treadmill in the recreational group only. Although metabolic demand differed significantly between surfaces at most speeds, run power did not accurately reflect differences in metabolic cost between the 2 surfaces. Running power, calculated via the Stryd Power Meter, is not sufficiently accurate as a surrogate of metabolic demand, particularly in the elite population. However, in a recreational population, this training tool could be useful for feedback on several running dynamics known to influence running economy. [ABSTRACT FROM AUTHOR] more...

The use of heart rate variability (HRV) to inform daily training prescription is becoming common in endurance sport. Few studies, however, have investigated the use of pre-training HRV to predict decreased performance or altered exercising autonomic response, typical of functional overreaching (FOR). Further, a new cardiac vagal tone (ProCVT) technology purports to eliminate some of the noise associated with daily HRV, and therefore may be better at predicting same-day performance. The purpose of this investigation was to examine if changes to resting HRV and ProCVT were associated with alterations in performance, maximal heart rate (HRmax), or heart rate recovery (HRrec) in FOR athletes. Twenty-eight recreational cyclists and triathletes were assigned to experimental/control conditions and underwent: 1 week of reduced training, 3 weeks of overload (OL) or regular training (CON), and 1 week of recovery. Testing occurred following the reduced training week (T1), post-3 weeks of training (T2), and following the recovery week (T3). Measures of resting HRV/ProCVT were collected each testing session, followed by maximal incremental exercise tests with HRrec taken 60 s post-exercise. Performance decreased from T1 to T2 in the OL group vs. CON (Δ−9 ± 12 vs. Δ9 ± 11 W, P < .001), as did HRmax (Δ−8 ± 4 vs. Δ−2 ± 4 bpm, P < .001). HRrec increased from T1 to T2 in the OL group vs. CON (Δ10 ± 9 vs. Δ2 ± 5 beats/min, P < .01). HRV and ProCVT did not change in either group. Same-day resting autonomic measures are insufficient in predicting alterations to performance or exercising HR measures following overload training.  [ABSTRACT FROM AUTHOR] more...

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Purpose: The distinct physical and environmental stressors of artistic swimming (previously termed synchronized swimming) result in unique hemodynamic stimuli. Given that the hemodynamic stress associated with participation in an exercise modality drives adaptation of the heart and central vasculature, artistic swimming may produce a distinct cardiovascular phenotype. Presumably, athletes competing at the highest levels also have greater training exposure and thus exhibit more adaptation. The purpose of this study was to characterize cardiovascular form and function across the competitive spectrum of artistic swimmers. Methods: Cardiovascular structure and function were compared in a cross-sectional study of healthy controls, varsity, and elite artistic swimmers, using pulse wave analysis, pulse wave velocity, and echocardiographic images both at rest and during isometric handgrip exercise. Results: Aortic stiffness was similar across all groups, as were characteristics of the decomposed aortic pressure waveform. At rest, both varsity and elite swimmers demonstrated similar systolic function compared with controls. However, peak left ventricular twist was greater in varsity and elites (controls: 8.0 ± 3.9, varsity: 12.8 ± 8.6, elites: 13.4 ± 3.9; both P < 0.02). Furthermore, elites demonstrated greater peak left ventricular radial strain (controls: 29.2 ± 9.9, varsity: 32.5 ± 10.3, elites: 53.9 ± 15.1; both P < 0.001) and longitudinal strain (controls: −16.9 ± 1.6, varsity: −16.5 ± 1.8, elites: −19.5 ± 3.2; both P < 0.04). In contrast to controls, both varsity and elite artistic swimmers demonstrated no change in peak late diastolic transmitral filling velocity (controls: Δ0.2 ± 0.04 m·s−1, varsity: Δ0.06 ± 0.04 m·s−1, elites: Δ0.05 ± 0.04 m·s−1) during isometric handgrip exercise (both P > 0.05), with elites demonstrating lower peak velocity than varsity swimmers (P = 0.048), indicating preservation of diastolic function. Conclusions: Artistic swimmers demonstrate distinct cardiac physiology at rest and during isometric handgrip, with a greater extent of distinguishing features observed in those competing at the highest level of competition. [ABSTRACT FROM AUTHOR] more...

Introduction: This study aimed to explore the potential impact of incorporating blood flow restriction (BFR) training within a training block characterized by minimal high-intensity work on 2000-m rowing ergometer time trial (TT) performance in elite/world-class rowers. Physiological markers often associated with endurance performance (maximal aerobic capacity, ... blood lactate thresholds and hemoglobin mass, Hbmass) were measured to determine whether changes are related to an improvement in performance. Methods: Using a quasi-experimental, observational study design (no control group), 2000-m TT performance, ..., submaximal work rates eliciting blood lactate concentrations of ~2 and ~4mmol⋅L-1, and Hbmass were measured before and after 4 wk of noncompetitive season training, which included BFR rowing. BFR training consisted of 11 sessions of 2 x 10 min of BFR rowing at a workload equating to blood lactate concentrations of ~2 mmol⋅L-1. Paired t-tests were used to compare pre-/postvalues, and Pearson correlation was used to examine whether physiological changes were associated with changes to TT performance. Results: TT performance improved in both female (1.09% ± 1.2%, ~4.6 ± 5.2 s; P < 0.01) and male (1.17% ± 0.48%, ~4.5 ± 1.9 s; P < 0.001) athletes. ... increased in female rowers only (P < 0.01), but both sexes had an increase in work rates eliciting blood lactate concentrations of 2 mmol⋅L-1 (female: 184 ± 16 to 195 ± 15 W, P < 0.01;male: 288 ± 23 to 317 ± 26W, P = 0.04) and 4 mmol⋅L-1 (female: 217 ± 13 to 227 ± 14 W, P = 0.02;male: 339 ± 43 to 364 ± 39W, P < 0.01). No changes in Hbmass (both sexes, P = 0.8) were observed. Improvements in TT performance were not related to physiological changes (all correlations P ≥ 0.2). Conclusions: After 4 wk of training with BFR, the improvement in TT performance was greater than what is typical for this population. Physiological variables improved during this training block but did not explain improved TT performance. [ABSTRACT FROM AUTHOR] more...

Purpose: Overload training is hypothesized to alter autonomic regulation, although interpretations using indirect measures of heart rate variability are conflicting. The aim of the present study was to examine the effects of overload training on muscle sympathetic nerve activity (MSNA), a direct measure of central sympathetic outflow, in recreational endurance athletes. Methods: Measurements of heart rate variability, cardiac baroreflex sensitivity (BRS), MSNA (microneurography), and sympathetic BRS were obtained in 17 healthy triathletes and cyclists after 1 wk of reduced training (baseline) and again after 3 wk of either regular (n = 7) or overload (n = 10) training. Results: After training, the changes (Δ) in peak power output (10 ± 10 vs -12 ± 9 W, P < 0.001), maximal heart rate (-2 ± 4 vs -8 ± 3 bpm, P = 0.006), heart rate variability (SD of normal-to-normal intervals, 27 ± 31 vs -3 ± 25 ms; P = 0.04), and cardiac BRS (7±6 vs -2 ± 8 ms-mm Hg-1, P = 0.02) differed between the control and overload groups. The change in MSNA burst frequency (-2 ± 2vs4 ± 5 bursts per minute, P = 0.02) differed between groups. Across all participants, the changes in resting MSNA and peak power output were correlated negatively (r = -0.51, P = 0.04). No between-group differences in resting heart rate or blood pressure were observed (all P > 0.05). Conclusions: Overload training increased MSNA and attenuated increases in cardiac BRS and heart rate variability observed with regular training. These results support neural adaptations after overload training and suggest that increased central sympathetic outflow may be linked with decreased exercise performance. [ABSTRACT FROM AUTHOR] more...