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Mental Fatigue Impairs Tackling Technique in Amateur Rugby Union Players

Demi Davidow, Mitchell Smith, Tayla Ross, Gwyneth Laura James, Lara Paul, Michael Lambert, Ben Jones, and Sharief Hendricks

Purpose: To test the effects of mental fatigue (MF) on tackling technique on the dominant and nondominant shoulders in rugby union. Methods: Twenty male amateur rugby union players and a total of 953 tackles were analyzed. A randomized crossover counterbalanced design was used across a non-MF (control) and an MF condition. During each condition, each player performed 24 tackles, divided into 4 sets of 6 tackles (3 tackles on each shoulder). In the MF condition, players performed the Stroop Task between each set of tackles. A video recording of each tackle was used to evaluate each player’s technical proficiency. A score of 1 point was awarded if a specific technique was performed correctly, and 0 point was given if not. The total score, measured in arbitrary units (AU) out of 11, represents the player’s overall tackling proficiency. Results: Overall, players displayed a significantly lower technical proficiency score in the MF condition compared to control (set 2: control 7.30 [7.04–7.57] AU vs MF 6.91 [6.70–7.12] AU, P = .009, effect size (ES) = 0.30 small and set 3: control 7.34 [7.11–7.57] AU vs MF 6.88 [6.66–7.11] AU, P = .002, ES = 0.37 small). For the nondominant shoulder, players had a significantly lower technical proficiency score during the MF condition at set 2 (control 7.05 [6.68–7.41] AU vs MF 6.69 [6.42–6.96] AU, P = .047, ES = 0.29 small) and set 3 (control 7.14 [6.83–7.45] AU vs MF 6.61 [6.35–6.87] AU, P = .007, ES = 0.49 small). Conclusions: MF can diminish a player’s overall tackling proficiency, especially when tackling on the nondominant shoulder. The physiological mechanism for this finding may be impaired executive function and suboptimal functioning of neural signals and pathways, which result in less skillful coordination of movement. To further understand and explain MF-induced physiological changes in tackling, the feasibility of monitoring brain activity (such as electroencephalogram) and neuromuscular function (such as electromyogram) needs to be investigated. The findings from this study may also contribute to the development of more effective tackle training programs for injury prevention and performance.

Open access

Synthetic Data as a Strategy to Resolve Data Privacy and Confidentiality Concerns in the Sport Sciences: Practical Examples and an R Shiny Application

Mitchell Naughton, Dan Weaving, Tannath Scott, and Heidi Compton

Purpose: There has been a proliferation in technologies in the sport performance environment that collect increasingly larger quantities of athlete data. These data have the potential to be personal, sensitive, and revealing and raise privacy and confidentiality concerns. A solution may be the use of synthetic data, which mimic the properties of the original data. The aim of this study was to provide examples of synthetic data generation to demonstrate its practical use and to deploy a freely available web-based R Shiny application to generate synthetic data. Methods: Openly available data from 2 previously published studies were obtained, representing typical data sets of (1) field- and gym-based team-sport external and internal load during a preseason period (n = 28) and (2) performance and subjective changes from before to after the posttraining intervention (n = 22). Synthetic data were generated using the synthpop package in R Studio software, and comparisons between the original and synthetic data sets were made through Welch t tests and the distributional similarity standardized propensity mean squared error statistic. Results: There were no significant differences between the original and more synthetic data sets across all variables examined in both data sets (P > .05). Further, there was distributional similarity (ie, low standardized propensity mean squared error) between the original observed and synthetic data sets. Conclusions: These findings highlight the potential use of synthetic data as a practical solution to privacy and confidentiality issues. Synthetic data can unlock previously inaccessible data sets for exploratory analysis and facilitate multiteam or multicenter collaborations. Interested sport scientists, practitioners, and researchers should consider utilizing the shiny web application (SYNTHETIC DATA—available at

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Monitoring Changes in Lower-Limb Strength and Power in Elite Athletes With the Countermovement-Jump and Keiser Leg-Press Tests

Sondre Nysether, Will G. Hopkins, Fredrik Mentzoni, Gøran Paulsen, Thomas A. Haugen, and Paul A. Solberg

Purpose: To determine the utility of countermovement-jump and Keiser leg-press tests for tracking changes in elite athletes of different sports. Methods: Elite athletes of the Norwegian Olympic Federation (126 individuals from 18 sports) performed countermovement-jump and Keiser tests on 2 to 11 occasions between 2014 and 2021. Separate analyses were performed for male and female alpine skiing, male and female handball, male ice hockey, and males and females of other sports. Means and standard deviations of consecutive change scores were combined with short-term error of measurement (3.7%–7.0%) and smallest important changes (2.0%–3.6%, defined by standardization) to determine the proportions of athletes who experienced decisive changes in 2 senses: first, the athlete did not get substantially worse or better (>90% chance of either), and second, the athlete did get substantially worse or better (>90% chance of either). Results: Averaged over sports, Keiser peak power and relative peak power had the highest proportions of decisive changes in the first (60% and 55%) and second senses (25% and 28%). The velocity intercept of the force–velocity relationship had the lowest proportions in the first and second senses (29% and 11%), while jump height, Keiser mean power, relative mean power, the force intercept, and the slope of the force–velocity relationship had similar proportions (40%–53% and 15%–21%). Conclusions: With the possible exception of the Keiser test velocity intercept, the proportions of observed decisive changes in elite athletes using Keiser measures and countermovement-jump height between tests appear adequate for the measures to be useful for routine monitoring.

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Adapting Training to the Menstrual Cycle

Xanne A.K. Janse de Jonge and Belinda M. Thompson

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Volume 18 (2023): Issue 7 (Jul 2023)

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Between-Seasons Variability of Cyclists’ Peak Performance: A Longitudinal Analysis of “Real-World” Power Output Data in Male Professional Cyclists

Pedro L. Valenzuela, Manuel Mateo-March, Xabier Muriel, Mikel Zabala, Alejandro Lucia, David Barranco-Gil, and Jesús G. Pallares

Purpose: The record power profile (RPP) has gained popularity as a method of monitoring endurance cycling performance. However, the expected variation of cyclists’ performance between seasons remains unknown. We aimed to assess the between-seasons variability of peak performance (assessed through the RPP) in male professional cyclists. Methods: The study followed a longitudinal observational design. Sixty-one male professional cyclists (age 26 [5] y) with power output data from both training sessions and competitions were analyzed for a median of 4 consecutive seasons (range 2–12). The highest mean maximum power values attained for different durations (from 10 s to 30 min), as well as the resulting critical power, were determined for each season. Within-cyclist variability between seasons was assessed, and the upper threshold of expected changes (ie, twice the normal coefficient of variation) was determined. Results: All mean maximum power values showed an overall high agreement and low variability between seasons (intraclass correlation coefficient [ICC] = .76–.88 and coefficient of variation [CV] = 3.2%–5.9%), with the lowest variability observed for long efforts (>1 min). Critical power showed an ICC and CV of .79 (95% CI, .70–.85) and 3.3% (95% CI, 3.0%–3.7%), respectively. Upper thresholds of expected variation were <12% for short efforts (≤1 min) and <8% for long efforts. Conclusions: “Real-world” peak performance assessed through the RPP shows a low variability between seasons in male professional cyclists—especially for long efforts—with expected variation being around 6% and 3% for short (≤1 min) and long efforts, respectively, and with changes >12% and >8%, respectively, being infrequent for these effort durations.

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Effects of a Sleep Hygiene Strategy on Parameters of Sleep Quality and Quantity in Youth Elite Rugby Union Players

Adrien Vachon, Fabien Sauvet, Florane Pasquier, Jean-Baptiste Paquet, and Laurent Bosquet

Purpose: To assess the effects of a sleep hygiene strategy on parameters of sleep quality and quantity in youth elite rugby union players. Method: Eleven male players (age: 19.0 [1.4] y) undertook a sleep hygiene strategy composed of 2 theoretical sessions and 3 practical sessions over a 4-week period. Sleeping time, time in bed, total sleep time, sleep latency (SL), sleep efficiency (SE), wake after sleep onset, and wake bouts were recorded with an actigraphic device during the 4-week sleep hygiene strategy (baseline) and during 4 weeks after the last intervention (postintervention). Results: At baseline, the overall group reported poor sleep quantity (total sleep time = 6:27 [0:30] min), but sleep quality was considered acceptable (SL = 0:18 [0:08] min and SE = 77.8% [5.8%]). Postintervention, the overall group showed a small improvement in SL (d = −0.23 [−0.42 to −0.04], P = .003) and SE (d = 0.30 [0.03 to 0.57], P = .0004). For individual responses, sleeping time, time in bed, and total sleep time were positively influenced in only 4, 3, and 5 players, respectively. For parameters of sleep quality, SL and SE were positively influenced in a majority of players (n = 7 and 8, respectively). The magnitude of difference between baseline and postintervention was strongly associated with baseline values in SE (r = −.86; P = .0005) and wake after sleep onset (r = −.87; P = .0007). Conclusion: A sleep hygiene strategy is efficient to improve sleep quality but not sleep quantity in young rugby union players. The strategy was more efficient in players with lower initial sleep quality and should be implemented prior to a high cumulative fatigue period.

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The Evolution of World-Class Endurance Training: The Scientist’s View on Current and Future Trends

Øyvind Sandbakk, David B. Pyne, Kerry McGawley, Carl Foster, Rune Kjøsen Talsnes, Guro Strøm Solli, Grégoire P. Millet, Stephen Seiler, Paul B. Laursen, Thomas Haugen, Espen Tønnessen, Randy Wilber, Teun van Erp, Trent Stellingwerff, Hans-Christer Holmberg, and Silvana Bucher Sandbakk

Background: Elite sport is continuously evolving. World records keep falling and athletes from a longer list of countries are involved. Purpose: This commentary was designed to provide insights into present and future trends associated with world-class endurance training based on the perspectives, experience, and knowledge of an expert panel of 25 applied sport scientists. Results: The key drivers of development observed in the past 10–15 years were related to (1) more accessible scientific knowledge for coaches and athletes combined with (2) better integration of practical and scientific exchange across multidisciplinary perspectives within professionalized elite athlete support structures, as well as (3) utilization of new technological advances. Based on these perspectives, we discerned and exemplified the main trends in the practice of endurance sports into the following categories: better understanding of sport-specific demands; improved competition execution; larger, more specific, and more precise training loads; improved training quality; and a more professional and healthier lifestyle. The main areas expected to drive future improvements were associated with more extensive use of advanced technology for monitoring and prescribing training and recovery, more precise use of environmental and nutritional interventions, better understanding of athlete–equipment interactions, and greater emphasis on preventing injuries and illnesses. Conclusions: These expert insights can serve as a platform and inspiration to develop new hypotheses and ideas, encourage future collaboration between researchers and sport practitioners, and, perhaps most important, stimulate curiosity and further collaborative studies about the training, physiology, and performance of endurance athletes.

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Flight Path and Scheduling Effects on Perceived Jet Lag, Fatigue, and Sleep in Footballers Traveling to and From National Teams

Ewan Clements, Fabian Ehrmann, Andrew Clark, Mark Jones, Alan McCall, and Rob Duffield

Purpose: This study examined posttravel perceptual responses of national-team footballers (soccer) following different flight paths, arrival/departure times, and trip contexts. Methods: Details of 396 flights from national-team players (N = 68) were obtained and verified via an online flight database. Each player provided ratings of perceptual fatigue, sleep, soreness, stress, and jet lag for 2 days before and after each trip. The flight path (continents of departure and arrival), travel context (into vs out of national team), and arrival and departure times were obtained for each trip. Linear mixed models compared the pretravel with posttravel change in perceptual responses based on flight path, context, and schedule. Results: Perceived jet-lag ratings were more responsive to travel variables (R 2 = .48) than other perceptual ratings (R 2 < .26). Travel from Asia to Europe (P < .05) and Europe to Australia (P < .001) had significantly higher jet-lag ratings than all other paths. Fatigue scores were worst following Asia to Europe (P < .05) and Europe to Australia (P < .05) travel, while sleep scores were worst following Europe to Australia travel (P < .01). Perceptual responses were poorer following travel from national team to club compared with all other travel contexts (P < .05). Arrival during the daytime (11 AM to 5 PM) resulted in better perceptual responses than early-morning or late-night arrivals (P < .05). Conclusions: Perceived jet-lag ratings are more responsive to travel demands than perceptual wellness scales in national-team football athletes. Poorer perceptual responses may be expected when travel is longer in nature, ends later in the day, or involves travel out of the national team back to club.

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Training Characteristics and Competitive Demands in Women Road Cyclists: A Systematic Review

Alba Herrero-Molleda, María José Álvarez-Álvarez, Pablo Floría, and Juan García-López

Purpose: To identify the main training characteristics and competitive demands in women’s road cycling. Methods: A systematic search was conducted on 5 databases according to PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. The articles had to be primary studies, written after 1990 with a sample of competitive women between the ages of 15 and 50. The Quality Assessment Tool for Quantitative Studies and the Oxford Levels of Evidence scales were used. Results: The search yielded 1713 articles, of which 20 were included. Studies on training and competitive demands (n = 5) found that both external and internal loads are higher in women than in men. Studies on strength and endurance training (n = 5) showed that both velocity-based and heavy-load strength training programs performed at least 2 days per week and including 3 to 4 lower-body exercises improved performance. Altitude-training studies (n = 3) found that “Live High–Train Low” was effective to increase performance during the first 9 days after the training camp. The 7 remaining studies focused on a range of topics. The methodological quality was strong for 12 studies and moderate for 8. In contrast, the level of evidence was high in 7 and low in the other 13. Conclusions: Endurance training and competitive demands in women’s road cycling are higher than those of men. Strength training is effective in women when the frequency, intensity, and number of exercises are appropriate, while altitude training should be completed a few days before competing. Further studies are warranted to better define the participants’ competitive level, using a methodological design with a higher level of evidence.