It is well known that acute hypoxia has negative effects on balance performance. An attempt to compensate for the influence of hypoxia on competition performance was made by the application of hyperoxic gases (inspiratory fraction of oxygen > 0.2095) prior to exercise. Purpose: To investigate whether hyperoxic preconditioning (pure-oxygen supplementation prior to exercise) improves balance ability and postural stability during normobaric hypoxia (3500 m) in highly skilled skiers. Methods: In this single-blind randomized, crossover study, 19 subjects performed a 60-s balance test (MFT S3-Check) in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 min prior to a balance test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times. Results: Balance performance, indexed by sensory (P = .097), stability (P = .937), and symmetry (P = .202) scores, was not significantly different after the hyperoxic preconditioning phase. Balance performance decreased over time (no group difference). After hyperoxic preconditioning, arterial partial pressure of oxygen increased from 52.7 (4.5) mm Hg to 212.5 (75.8) mm Hg, and oxygen saturation of hemoglobin increased from 85.8% (3.5%) to 98.9% (0.7%) and remained significantly elevated to 90.1% (2.0%) after the balance test. Conclusion: A hyperoxic preconditioning phase does not affect balance performance under hypoxic environmental conditions. A performance-enhancing effect, at least in terms of coordinative functions, was not supported by this study.
David Morawetz, Tobias Dünnwald, Martin Faulhaber, Hannes Gatterer and Wolfgang Schobersberger
Tiago Turnes, Rogério S.O. Cruz, Fabrizio Caputo and Rafael A. De Aguiar
Purpose: The 2000-m rowing-ergometer test is the most common measure of rowing performance. Because athletes use different intervention strategies for enhancing performance, investigating the effect of preconditioning strategies on the 2000-m test is of great relevance. This study evaluated the effects of different preconditioning strategies on 2000-m rowing-ergometer performance in trained rowers. Methods: A search of electronic databases (PubMed, Google Scholar, and Web of Science) identified 27 effects of different preconditioning strategies from 17 studies. Outcomes were calculated as percentage differences between control and experimental interventions, and data were presented as mean ± 90% confidence interval. Performance data were converted to the same metrics, that is, mean power. Meta-regression analyses were conducted to assess whether performance level or caffeine dose could affect the percentage change. Results: The overall beneficial effect on 2000-m mean power was 2.1% (90% confidence limit [CL] ±0.6%). Training status affected the percentage change with interventions, with a −1.1% (90% CL ±1.2%) possible small decrease for 1.0-W·kg−1 increment in performance baseline. Caffeine consumption most likely improves performance, with superior effect in higher doses (≥6 mg·kg−1). Sodium bicarbonate and beta-alanine consumption resulted in likely (2.6% [90% CL ±1.5%]) and very likely (1.4% [90% CL ±1.2%]) performance improvements, respectively. However, some preconditioning strategies such as heat acclimation, rehydration, and creatine resulted in small to moderate enhancements in 2000-m performance. Conclusions: Supplementation of caffeine and beta-alanine is a popular and effective strategy to improve 2000-m ergometer performance in trained rowers. Additional research is warranted to confirm the benefit of other strategies to 2000-m rowing-ergometer performance.
Sarah J. Willis, Jules Gellaerts, Benoît Mariani, Patrick Basset, Fabio Borrani and Grégoire P. Millet
Purpose: To examine the net oxygen cost, oxygen kinetics, and kinematics of level and uphill running in elite ultratrail runners. Methods: Twelve top-level ultradistance trail runners performed two 5-min stages of treadmill running (level, 0%, men 15 km·h−1, women 13 km·h−1; uphill, 12%, men 10 km·h−1, women 9 km·h−1). Gas exchanges were measured to obtain the net oxygen cost and assess oxygen kinetics. In addition, running kinematics were recorded with inertial measurement unit motion sensors on the wrist, head, belt, and foot. Results: Relationships resulted between level and uphill running regarding oxygen uptake (
Jorge Arede, António Paulo Ferreira, Oliver Gonzalo-Skok and Nuno Leite
Purpose: To determine the discriminators as variables to select the under-16 national-team players and to examine the influence of biological age on physical/technical parameters among young basketball players. Methods: Thirty-four under-15 male basketball players performed several anthropometrical (height, wingspan, body mass, and fingers length) and physical (jumping, sprinting, throwing, flexibility, change-of-direction speed, and aerobic fitness) tests during the under-15 male national-team training camp. Maturity offset, lower-limb asymmetry index, and power outputs for jumping and sprinting were also computed. In addition, game performance was taken into consideration using game-related statistics (assists, turnovers, steals, rebounds, blocks, and points) of 5 games of during the previous regional tournament (April 2016). Cluster analysis was used to analyze the between-maturation status (prepubertal, pubertal, and postpubertal) differences in physical parameters. Results: The postpubertals showed a significantly better performance in power outputs (jumping and sprinting), throwing abilities, and blocks, whereas prepubertal performed significantly better in aerobic fitness and assists. Receiver-operating-characteristic curve confirmed maturational status (area under the curve [AUC] = 0.804; P < .05) and training experience (AUC = 0.789; P < .05) as the most important attributes in predicting under-16 national-team selection. Players with more than 5.5 years of training experience and less than 1.4 y to the age at peak height velocity were most likely to be selected. Conclusion: Maturational status seems to be a key variable that increases the probability of selection for the Portuguese under-16 national team.
Henrikas Paulauskas, Rasa Kreivyte, Aaron T. Scanlan, Alexandre Moreira, Laimonas Siupsinskas and Daniele Conte
Purpose: To assess the weekly fluctuations in workload and differences in workload according to playing time in elite female basketball players. Methods: A total of 29 female basketball players (mean [SD] age 21  y, stature 181  cm, body mass 71  kg, playing experience 12  y) belonging to the 7 women’s basketball teams competing in the first-division Lithuanian Women’s Basketball League were recruited. Individualized training loads (TLs) and game loads (GLs) were assessed using the session rating of perceived exertion after each training session and game during the entire in-season phase (24 wk). Percentage changes in total weekly TL (weekly TL + GL), weekly TL, weekly GL, chronic workload, acute:chronic workload ratio, training monotony, and training strain were calculated. Mixed linear models were used to assess differences for each dependent variable, with playing time (low vs high) used as fixed factor and subject, week, and team as random factors. Results: The highest changes in total weekly TL, weekly TL, and acute:chronic workload ratio were evident in week 13 (47%, 120%, and 49%, respectively). Chronic workload showed weekly changes ≤10%, whereas monotony and training strain registered highest fluctuations in weeks 17 (34%) and 15 (59%), respectively. A statistically significant difference in GL was evident between players completing low and high playing times (P = .026, moderate), whereas no significant differences (P > .05) were found for all other dependent variables. Conclusions: Coaches of elite women’s basketball teams should monitor weekly changes in workload during the in-season phase to identify weeks that may predispose players to unwanted spikes and adjust player workload according to playing time.
Ben T. Stephenson, Christof A. Leicht, Keith Tolfrey and Victoria L. Goosey-Tolfrey
Purpose: In able-bodied athletes, several hormonal, immunological, and psychological parameters are commonly assessed in response to intensified training due to their potential relationship to acute fatigue and training/nontraining stress. This has yet to be studied in Paralympic athletes. Methods: A total of 10 elite paratriathletes were studied for 5 wk around a 14-d overseas training camp whereby training load was 137% of precamp levels. Athletes provided 6 saliva samples (1 precamp, 4 during camp, and 1 postcamp) for cortisol, testosterone, and secretory immunoglobulin A; weekly psychological questionnaires (Profile of Mood State [POMS] and Recovery-Stress Questionnaire for Athletes [RESTQ-Sport]); and daily resting heart rate and subjective wellness measures including sleep quality and quantity. Results: There was no significant change in salivary cortisol, testosterone, cortisol:testosterone ratio, or secretory immunoglobulin A during intensified training (P ≥ .090). Likewise, there was no meaningful change in resting heart rate or subjective wellness measures (P ≥ .079). Subjective sleep quality and quantity increased during intensified training (P ≤ .003). There was no significant effect on any POMS subscale other than lower anger (P = .049), whereas there was greater general recovery and lower sport and general stress from RESTQ-Sport (P ≤ .015). Conclusions: There was little to no change in parameters commonly associated with the fatigued state, which may relate to the training-camp setting minimizing external life stresses and the careful management of training loads from coaches. This is the first evidence of such responses in Paralympic athletes.
Aaron T. Scanlan, Vincent J. Dalbo, Daniele Conte, Emilija Stojanović, Nenad Stojiljković, Ratko Stanković, Vladimir Antić and Zoran Milanović
Purpose: To examine the effect of caffeine supplementation on dribbling speed in elite female and male basketball players. Methods: A double-blind, counterbalanced, randomized, crossover design was used. Elite basketball players (N = 21; 10 female, 11 male; age 18.3 [3.3] y) completed placebo (3 mg·kg−1 of body mass of dextrose) and caffeine (3 mg·kg−1 of body mass) trials 1 wk apart during the in-season phase. During each trial, players completed 20-m linear sprints with and without dribbling a basketball. Performance times were recorded at 5-, 10-, and 20-m splits. Dribbling speed was measured using traditional (total performance time) and novel (dribble deficit) methods. Dribble deficit isolates the added time taken to complete a task when dribbling compared with a nondribbling version of the same task. Comparisons between placebo and caffeine conditions were conducted at group and individual levels. Results: Nonsignificant (P > .05), trivial to small (effect size = 0.04–0.42) differences in dribbling speed were observed between conditions. The majority (20 out of 21) of players were classified as nonresponders to caffeine, with 1 player identified as a negative responder using dribble-deficit measures. Conclusions: Results indicate that caffeine offers no ergogenic benefit to dribbling speed in elite basketball players. The negative response to caffeine in 1 player indicates that caffeine supplementation may be detrimental to dribbling speed in specific cases and emphasizes the need for individualized analyses in nutrition-based sport-science research.
Michael J. Davies, Bradley Clark, Laura A. Garvican-Lewis, Marijke Welvaert, Christopher J. Gore and Kevin G. Thompson
Purpose: To determine if a series of trials with fraction of inspired oxygen (FiO2) content deception could improve 4000-m cycling time-trial (TT) performance. Methods: A total of 15 trained male cyclists (mean [SD] body mass 74.2 [8.0] kg, peak oxygen uptake 62  mL·kg−1·min−1) completed six 4000-m cycling TTs in a semirandomized order. After a familiarization TT, cyclists were informed in 2 initial trials they were inspiring normoxic air (NORM, FiO2 0.21); however, in 1 trial (deception condition), they inspired hyperoxic air (NORM-DEC, FiO2 0.36). During 2 subsequent TTs, cyclists were informed they were inspiring hyperoxic air (HYPER, FiO2 0.36), but in 1 trial, normoxic air was inspired (HYPER-DEC). In the final TT (NORM-INFORM), the deception was revealed and cyclists were asked to reproduce their best TT performance while inspiring normoxic air. Results: Greater power output and faster performances occurred when cyclists inspired hyperoxic air in both truthful (HYPER) and deceptive (NORM-DEC) trials than NORM (P < .001). However, performance only improved in NORM-INFORM (377 W; 95% confidence interval [CI] 325–429) vs NORM (352 W; 95% CI 299–404; P < .001) when participants (n = 4) completed the trials in the following order: NORM-DEC, NORM, HYPER-DEC, HYPER. Conclusions: Cycling performance improved with acute exposure to hyperoxia. Mechanisms for the improvement were likely physiological; however, improvement in a deception trial suggests an additional placebo effect. Finally, a particular sequence of oxygen deception trials may have built psychophysiological belief in cyclists such that performance improved in a subsequent normoxic trial.
Bruno Marrier, Alexandre Durguerian, Julien Robineau, Mounir Chennaoui, Fabien Sauvet, Aurélie Servonnet, Julien Piscione, Bertrand Mathieu, Alexis Peeters, Mathieu Lacome, Jean-Benoit Morin and Yann Le Meur
Purpose: Preconditioning strategies are considered opportunities to optimize performance on competition day. Although investigations conducted in rugby players on the effects of a morning preconditioning session have been done, additional work is warranted. The aim of this study was to monitor changes in physical and psychophysiological indicators among international Rugby-7s players after a priming exercise. Methods: In a randomized crossover design, 14 under-18 international Rugby-7s players completed, at 8:00 AM, a preconditioning session consisting of a warm-up followed by small-sided games, accelerations, and 2 × 50-m maximal sprints (Experimental), or no preloading session (Control). After a 2-h break, the players performed a set of six 30-m sprints and a Rugby-7s match. Recovery–stress state and salivary stress-marker levels were assessed before the preloading session (Pre), immediately after the preloading session (Post 1), before the testing session (Post 2), and after the testing session (Post 3). Results: Experimental–Control differences in performance across a repeated-sprint test consisting of six 30-m sprints were very likely trivial (+0.2, ±0.7%, 3/97/1%). During the match, the total distance covered and the frequency of decelerations were possibly lower (small) in Experimental compared with Control. Differences observed in the other parameters were unclear or possibly trivial. At Post 2, the perceived recovery–stress state was improved (small difference) in Experimental compared with Control. No difference in salivary cortisol response was observed, while the preconditioning session induced a higher stimulation of salivary testosterone and α-amylase. Conclusions: The players’ ability to repeat sprints and physical activity in match play did not improve, but their psychophysiological state was positively affected after the present preconditioning session.
Lachlan J.G. Mitchell, Ben Rattray, Paul Wu, Philo U. Saunders and David B. Pyne
Purpose: Critical speed (CS) and supra-CS distance capacity (D′) are useful metrics for monitoring changes in swimmers’ physiological and performance capacities. However, the utility of these metrics across a season has not been systematically evaluated in high-level swimmers. Methods: A total of 27 swimmers (mean [SD]: 18 females, age = 19.1 [2.9] y, and 9 males, age = 19.5 [1.9] y) completed the 12 × 25-m swimming test multiple times (4  tests/swimmer) across a 2-y period. Season-best times in all distances for the test stroke were sourced from publicly available databases. Swimmers’ distance speciality was determined as the event with the time closest to world record. Four metrics were calculated from the 12 × 25-m test: CS, D′, peak speed, and drop-off %. Results: Guyatt responsiveness index values were calculated to ascertain the practically relevant sensitivity of each 12 × 25-m metric: CS = 1.5, peak speed = 2.3, D′ = 2.1, and drop-off % = 2.6. These values are modified effect sizes; all are large effects. Bayesian mixed modeling showed substantial between-subjects differences between genders and strokes for each variable but minimal within-subject changes across the season. Drop-off % was lower in 200-m swimmers (14.0% [3.3%]) than in 100-m swimmers (18.1% [4.1%], P = .003, effect size = 1.10). Conclusions: The 12 × 25-m test is best suited to differentiating between swimmers of different strokes and events. Further development is needed to improve its utility in quantifying meaningful changes over a season for individual swimmers.