Search Results

Purpose: Progressively overloading the body to improve physical performance may lead to detrimental states of overreaching/overtraining syndrome. Blunted cycling-induced cortisol and testosterone concentrations have been suggested to indicate overreaching after intensified training periods. However, a running-based protocol is yet to be developed or demonstrated as reproducible. This study developed two 30-min running protocols, (1) 50/70 (based on individualized physical capacity) and (2) RPE_TP (self-paced), and measured the reproducibility of plasma cortisol and testosterone responses. Methods: Thirteen recreationally active, healthy men completed each protocol (50/70 and RPE_TP) on 3 occasions. Venous blood was drawn preexercise, postexercise, and 30 min postexercise. Results: Cortisol was unaffected (both P > .05; 50/70, ${\eta }_{\mathrm{p}}^2$ = .090; RPE_TP, ${\eta }_{\mathrm{p}}^2$ = .252), while testosterone was elevated (both P < .05; 50/70, 35%, ${\eta }_{\mathrm{p}}^2$ = .714; RPE_TP, 42%, ${\eta }_{\mathrm{p}}^2$ = .892) with low intraindividual coefficients of variation (CV_i) as mean (SD) (50/70, 7% [5%]; RPE_TP, 12% [9%]). Heart rate (50/70, effect size [ES] = 0.39; RPE_TP, ES = −0.03), speed (RPE_TP, ES = −0.09), and rating of perceived exertion (50/70 ES = −0.06) were unchanged across trials (all CV_i < 5%, P < .05). RPE_TP showed greater physiological strain (P < .01). Conclusions: Both tests elicited reproducible physiological and testosterone responses, but RPE_TP induced greater testosterone changes (likely due to increased physiological strain) and could therefore be considered a more sensitive tool to potentially detect overtraining syndrome. Advantageously for the practitioner, RPE_TP does not require a priori exercise-intensity determination, unlike the 50/70, enhancing its integration into practice.

Purpose: Physical overexertion can lead to detrimental overreaching states without sufficient recovery, which may be identifiable by blunted exercise-induced cortisol and testosterone responses. A running test (RPE_TP) elicits reproducible plasma cortisol and testosterone elevations (in a healthy state) and may detect blunted hormonal responses in overreached athletes. This current study determined the salivary cortisol and testosterone responses reproducibility to the RPE_TP, to provide greater practical validity using saliva compared with the previously utilized blood sampling. Second, the relationship between the salivary and plasma responses was assessed. Methods: A total of 23 active, healthy males completed the RPE_TP on 3 occasions. Saliva (N = 23) and plasma (N = 13) were collected preexercise, postexercise, and 30 minutes postexercise. Results: Salivary cortisol did not elevate in any RPE_TP trial, and reduced concentrations occurred 30 minutes postexercise (P = .029, η ² = .287); trial differences were observed (P < .001, η ² = .463). The RPE_TP elevated (P < .001, η ² = .593) salivary testosterone with no effect of trial (P = .789, η ² = .022). Intraindividual variability was 25% in cortisol and 17% in testosterone. “Fair” intraclass coefficients of .46 (cortisol) and .40 (testosterone) were found. Salivary and plasma cortisol positively correlated (R = .581, P = .037) yet did not for testosterone (R = .345, P = .248). Conclusions: The reproducibility of salivary testosterone response to the RPE_TP is evident and supports its use as a potential tool, subject to further confirmatory work, to detect hormonal dysfunction during overreaching. Salivary cortisol responds inconsistently in a somewhat individualized manner to the RPE_TP.

Purpose: To determine how a cooling vest worn during a warm-up could influence selected performance (countermovement jump [CMJ]), physical (global positioning system [GPS] metrics), and psychophysiological (body temperature and perceptual) variables. Methods : In a randomized, crossover design, 12 elite male World Rugby Sevens Series athletes completed an outdoor (wet bulb globe temperature 23–27°C) match-specific externally valid 30-min warm-up wearing a phase-change cooling vest (VEST) and without (CONTROL), on separate occasions 7 d apart. CMJ was assessed before and after the warm-up, with GPS indices and heart rate monitored during the warm-ups, while core temperature (T _c; ingestible telemetric pill; n = 6) was recorded throughout the experimental period. Measures of thermal sensation (TS) and thermal comfort (TC) was obtained pre-warm-up and post-warm-up, with rating of perceived exertion (RPE) taken post-warm-ups. Results: Athletes in VEST had a lower ΔT _c (mean [SD]: VEST = 1.3°C [0.1°C]; CONTROL = 2.0°C [0.2°C]) from pre-warm-up to post-warm-up (effect size; ±90% confidence limit: −1.54; ±0.62) and T _c peak (mean [SD]: VEST = 37.8°C [0.3°C]; CONTROL = 38.5°C [0.3°C]) at the end of the warm-up (−1.59; ±0.64) compared with CONTROL. Athletes in VEST demonstrated a decrease in ΔTS (−1.59; ±0.72) and ΔTC (−1.63; ±0.73) pre-warm-up to post-warm-up, with a lower RPE post-warm-up (−1.01; ±0.46) than CONTROL. Changes in CMJ and GPS indices were trivial between conditions (effect size < 0.2). Conclusions: Wearing the vest prior to and during a warm-up can elicit favorable alterations in physiological (T _c) and perceptual (TS, TC, and RPE) warm-up responses, without compromising the utilized warm-up characteristics or physical-performance measures.

Purpose: To characterize player core temperature (Tc) across a World Rugby Women’s Sevens Series tournament day (WRWSS) and determine the efficacy of commonly employed cold-water-immersion (CWI) protocols. Methods: Tc was measured in 12 elite female rugby sevens athletes across 3 games (G1–3) from day 1 of the Sydney WRWSS tournament. Symptoms of exertional heat illness, perceptual scales, CWI details, playing minutes, external-load data (measured by global positioning systems), and wet-bulb globe temperature (range 18.5°C–20.1°C) were also collected. Linear mixed models and magnitude-based inferences were used to assess differences in Tc between periods (G1–3 and warm-ups [WU]). Results: Average Tc was “very likely” lower (effect size; ±90% confidence limit −0.33; ±0.18) in G1 than in G2. Peak Tc was “very likely” (0.71; ±0.28) associated with increased playing time. CWI did not remove the accumulated Tc due to WU and match-play activity (∼1°C–2°C rise in Tc still present compared with Tc at WU onset for players ≥6-min match play). Conclusions: Elite WRWSS athletes experienced high Tc during WU (Tc peak 37.9–39.0°C) and matches (Tc peak 37.9–39.8°C), a magnitude known to reduce intermittent high-intensity physical performance (≥39°C). The CWI protocol resulted in players (≥6-min match play) with ∼1°C to 2°C raised Tc compared with Tc at WU onset.

The individual pursuit is a 4-km cycling time trial performed on a velodrome. Parathletes with transtibial amputation (TTA) have lost physiological systems, but this may be offset by the reduced aerodynamic drag of the prosthesis. This research was performed to understand the effect of a unilateral TTA on Olympic 4-km pursuit performance. A forward-integration model of pursuit performance explored the interplay between power loss and aerodynamic gains in parathletes with TTA. The model is calibrated to a 4-km pursuit time of 4:10.5 (baseline), then adjusted to account for a TTA. Conditions simulated were based on typical pedal asymmetry in TTA (AMP), if foot stiffness were decreased (FLEX), if pedaling asymmetries were minimized (ASYM), if the prosthesis were aerodynamically optimized (AERO), if the prosthesis had a cosmetic cover (CC), and if all variables were optimized (OPT). A random Monte Carlo analysis was performed to understand model precision. Four-kilometer pursuit performances predicted by the model were 4:10.5, 4:20.4, 4:27.7, 4:09.2, 4:19.4, 4:27.9, and 4:08.2 for the baseline, AMP, FLEX, ASYM, AERO, CC, and OPT models, respectively. Model precision was ±3.7 s. While the modeled time decreased for ASYM and OPT modeled conditions, the time reduction fell within model precision and therefore was not significant. Practical application of these results suggests that parathletes with a TTA could improve performance by minimizing pedaling asymmetry and/or optimizing aerodynamic design, but, at best, they will have performance similar to that of intact cyclists. In conclusion, parathletes with TTA do not have a net advantage in the individual pursuit.

The purpose of this study was to calculate the coefficients of variation in jump performance for individual participants in multiple trials over time to determine the extent to which there are real differences in the error of measurement between participants. The effect of training phase on measurement error was also investigated. Six subjects participated in a resistance-training intervention for 12 wk with mean power from a countermovement jump measured 6 d/wk. Using a mixed-model meta-analysis, differences between subjects, within-subject changes between training phases, and the mean error values during different phases of training were examined. Small, substantial factor differences of 1.11 were observed between subjects; however, the finding was unclear based on the width of the confidence limits. The mean error was clearly higher during overload training than baseline training, by a factor of ×/÷ 1.3 (confidence limits 1.0–1.6). The random factor representing the interaction between subjects and training phases revealed further substantial differences of ×/÷ 1.2 (1.1–1.3), indicating that on average, the error of measurement in some subjects changes more than in others when overload training is introduced. The results from this study provide the first indication that within-subject variability in performance is substantially different between training phases and, possibly, different between individuals. The implications of these findings for monitoring individuals and estimating sample size are discussed.

Background: The effect of the 2020 COVID-19 lockdown on athlete sleep and training behavior is documented, albeit without a worldwide soccer-specific focus. Method: Soccer (football) players (N = 1639; 30 countries; age 22.5 [5.7] y; 81% ≤25 y; 56% male; 30% elite; 66% Muslim) answered a retrospective, cross-sectional questionnaire related to their behavioral habits before and during COVID-19 lockdown (survey period July to September 2020), including (1) Pittsburgh Sleep Quality Index PSQI, (2) Insomnia Severity Index (ISI), (3) bespoke questions about training behaviors, and (4) Muslim player focused sleep and training behavior questions. Results: During lockdown (compared to prelockdown), PSQI (P < .001; moderate effect size [ES]) and ISI (P < .001; moderate ES) scores were higher in the overall sample and in elite versus nonelite (PSQI: P < .05; small ES and ISI: P < .001; small ES), >25 years versus ≤25 years (PSQI: P < .01; small ES and ISI: P < .001; moderate ES), females versus males (PSQI: P < .001; small ES), <1 month versus >1 month lockdown (PSQI: P < .05; small ES and ISI: P < .05; small ES), and players maintaining versus reducing training intensity (PSQI: P < .001; moderate ES and ISI: P < .001; small ES). Muslim players (41%) reported unfavorable sleep and/or training behaviors during Ramadan in lockdown compared to lockdown outside of Ramadan. Conclusions: Specific subgroups appear more vulnerable to lockdown effects, with training-intensity maintenance moderating negative effects relative to sleep. Policy and support (respectful of subgroup nuances) during lockdown-like challenges that facilitate training (including intensity) appear prudent, given their favorable relationship with sleep, mental health, and physical health, in the present data and elsewhere.

Numerous studies in the past 30 years have researched physiological adaptation to stress by wheelchair-bound subjects. Instrumentation necessary to produce this effect had to be designed and tested prior to obtaining valid data. This study had two main purposes: to design a wheelchair ergometer for physiological testing of spinal cord-injured subjects, and to demonstrate the validity of the maximal stress test when using the wheelchair ergometer. To test the validity of the wheelchair ergometer, 10 disabled subjects (9 paraplegic and 1 quadriplegic) participated in both a maximal field test (FT) and a maximal wheelchair ergometer test (WERG), with each subject serving as his or her own control. A randomly assigned counterbalanced design (5 subjects assigned to complete the FT first, with the second group of 5 subjects completing the WERG first) was used to reduce the learning effect in the study. The results of the t-tests indicated there was no significant difference between V̇O₂ and V̇_E, (STPD) averages for the WERG and FT for maximal effort with two-tailed significant levels of t = .9016 and t = .7294, respectively. The Pearson product moment correlation level was statistically significant at p < .0001, when the WERG V̇O₂ was compared to the FT V̇O₂ (r = .94), and was significant at p < .005 when the WERG V̇_E was compared to the FT V̇_E (r = .82).

Purpose: To describe the physiological (resting core temperature, exercising heart rate, and sweat rate) and psychophysical (rating of perceived exertion, thermal sensation, and thermal comfort) responses to a short-term heat acclimatization (HA) training camp in elite female rugby sevens athletes. Methods: Nineteen professional female rugby sevens athletes participated in a 5-day HA camp in Darwin, Australia (training average: 32.2°C and 58% relative humidity). Training involved normal team practice prescribed by appropriate staff. Markers of physiological and psychophysical adaptations to HA were collected at various stages during the camp. Partial eta-squared effect sizes (from linear mixed-effects models), rank-biserial correlations (from Freidman tests), and P values were used to assess changes across the protocol. Results: Resting core temperature did not significantly change. Exercising heart rate showed a large and significant reduction from day 1 to day 5 (175 [13] vs 171 [12] beats·min⁻¹), as did sweat rate (1.1 [0.3] vs 1.0 [0.2] L·h^–1). Thermal sensation showed a large and significant reduction between day 1 and day 5 (median [interquartile range] = 5 [5–5.5] vs 4.5 [4–5]). Changes in rating of perceived exertion and thermal comfort were unclear. Conclusions: Beneficial cardiovascular adaptations were observed simultaneously across a full squad of elite female rugby sevens players (without expensive facilities/equipment or modifying training content). However, beneficial changes in resting core temperature, sweat rate, and thermal/effort perceptions likely require a greater thermal impulse. These data contribute to the development of evidence-informed practice for minimal effective HA doses in female team-sport athletes, who are underrepresented in the current research.