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Toshiyuki Ohya, Kenta Kusanagi, Jun Koizumi, Ryosuke Ando, Keisho Katayama, and Yasuhiro Suzuki

Purpose: Inspiratory muscle strength training (IMST) can improve exercise performance. Increased maximal inspiratory mouth pressure (MIP) could be beneficial for swimmers to enhance their performance. This study aimed to clarify the effect of high-intensity IMST for 6 weeks on MIP and swimming performance in highly trained competitive swimmers. Methods: Thirty male highly trained competitive swimmers were assigned to high-intensity IMST (HI; n = 10), moderate-intensity IMST (MOD; n = 10), and control (n = 10) groups. The 6-week IMST intervention comprised twice daily sessions for 6 d/wk at inspiratory pressure threshold loads equivalent to 75% MIP (HI) and 50% MIP (MOD). Before and after the intervention, MIP and swimming performance were assessed. Swimming performance was evaluated in free and controlled frequency breathing 100-m freestyle swimming time trials in a 25-m pool. For controlled frequency breathing, participants took 1 breath every 6 strokes. Results: The MIP values after 2 and 6 weeks of IMST in the HI and MOD groups were significantly higher than those before IMST (P = .0001). The magnitudes of the MIP increases after 6 weeks of IMST did not differ between the HI (13.4% [8.7%]) and MOD (13.1% [10.1%]) groups (P = .44). The 100-m freestyle swimming times under the controlled frequency condition were significantly shorter after IMST than those before IMST in both the HI (P = .046) and MOD (P = .042) groups. Conclusions: Inspiratory pressure threshold load equivalent to 50% MIP could be sufficient to improve MIP and swimming performance under the controlled frequency breathing condition in highly trained competitive swimmers.

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Olivier Girard, Romain Leuenberger, Sarah J. Willis, Fabio Borrani, and Grégoire P. Millet

Purpose: The authors compared the effects of active preconditioning with local and systemic hypoxia during submaximal cycling. Methods: On separate visits, 14 active participants completed 4 trials. Each visit was composed of 1 preconditioning phase followed, after 40 minutes of rest, by 3 × 6-minute cycling bouts (intensity = 85% of critical power; rest = 6 min). The preconditioning phase consisted of 4 × 5-minute cycling bouts at 1.5 W·kg−1 (rest = 5 min) in 4 conditions: control (no occlusion and normoxia), blood flow restriction (60% of total occlusion), HYP (systemic hypoxia; inspired fraction of oxygen = 13.6%), and blood flow restriction + HYP (local and systemic hypoxia combined). Results: During the preconditioning phase, there were main effects of both systemic (all P < .014) and local hypoxia (all P ≤ .001) on heart rate, arterial oxygen saturation, leg discomfort, difficulty of breathing, and blood lactate concentration. Cardiorespiratory variables, gross efficiency, energy cost, and energy expenditure during the last minute of 6-minute cycling bouts did not differ between conditions (all P > .105). Conclusion: Local and systemic hypoxic stimuli, or a combination of both, during active preconditioning did not improve physiological responses such as cycling efficiency during subsequent submaximal cycling.

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Kathleen H. Miles, Brad Clark, Jocelyn K. Mara, Peter M. Fowler, Joanna Miller, and Kate L. Pumpa

Purpose: To compare the habitual sleep of female basketball and soccer athletes to age- and sex-matched controls and to characterize the sleep of basketball and soccer athletes at different competition locations and on the days surrounding competition. Methods: Using an observational case–control design, 41 female participants were recruited to participate, consisting of 11 basketball athletes (mean [SD]: age = 24.1 [4.9] y), 10 soccer athletes (24.8 [6.4] y), and 20 nonathletic controls (24.2 [2.8] y). Sleep was monitored using actigraphy for four 7-day periods throughout the preseason and subsequent competition season. Generalized linear models were used to analyze the effect of group and competition situation (eg, Home or Away) on sleep. Results: During habitual conditions, basketball athletes had longer sleep durations (7.4 [1.5] h) than soccer athletes (7.0 [1.2] h, P < .001) and controls (7.3 [1.2] h, P = .002). During competition, basketball and soccer athletes had longer sleep durations following home (7.7 [1.7] and 7.2 ± 1.3 h) compared with away games (6.8 [1.8] and 7.0 [1.3] h). In addition, basketballers went to bed earlier (23:49 [01:25]) and woke earlier (07:22 [01:59]) following away games compared with soccer athletes (00:10 [01:45] and 08:13 [01:45]). Conclusions: Basketballers had longer habitual sleep durations compared with soccer athletes and nonathletic controls. During competition, basketballers had earlier bed and wake times compared with soccer athletes following away games, highlighting the need for individualized sleep strategies.

Open access

Kobe C. Houtmeyers, Arne Jaspers, and Pedro Figueiredo

Elite sport practitioners increasingly use data to support training process decisions related to athletes’ health and performance. A careful application of data analytics is essential to gain valuable insights and recommendations that can guide decision making. In business organizations, data analytics are developed based on conceptual data analytics frameworks. The translation of such a framework to elite sport may benefit the use of data to support training process decisions. Purpose: The authors aim to present and discuss a conceptual data analytics framework, based on a taxonomy used in business analytics literature to help develop data analytics within elite sport organizations. Conclusions: The presented framework consists of 4 analytical steps structured by value and difficulty/complexity. While descriptive (step 1) and diagnostic analytics (step 2) focus on understanding the past training process, predictive (step 3) and prescriptive analytics (step 4) provide more guidance in planning the future. Although descriptive, diagnostic, and predictive analytics generate insights to inform decisions, prescriptive analytics can be used to drive decisions. However, the application of this type of advanced analytics is still challenging in elite sport. Thus, the current use of data in elite sport is more focused on informing decisions rather than driving them. The presented conceptual framework may help practitioners develop their analytical reasoning by providing new insights and guidance and may stimulate future collaborations between practitioners, researchers, and analytics experts.

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Rafaela Nehme, Flávia M.S. de Branco, Públio F. Vieira, Ana Vitória C. Guimarães, Gederson K. Gomes, Gabriela P. Teixeira, Pedro H. Rodrigues, Leonardo M. de Castro Junior, Guilherme M. Puga, Bryan Saunders, and Erick P. de Oliveira

Carbohydrate (CHO) mouth rinsing seems to improve performance in exercises lasting 30–60 min. However, its effects on intermittent exercise are unclear. It is also unknown whether serial CHO mouth rinses can promote additional ergogenic effects when compared with a single mouth rinse. The aim of this study was to evaluate the effect of single and serial CHO mouth rinses on Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance in soccer players. In a randomized, crossover, double-blind, placebo-controlled design, 12 male (18.9 ± 0.5 years) soccer players performed eight serial mouth rinses under three different conditions: placebo solution only (noncaloric juice), seven placebo mouth rinses plus a single CHO mouth rinse (8% maltodextrin), or eight CHO mouth rinses (8-CHO). Following the final mouth rinse, individuals performed the Yo-Yo IR1 test to evaluate the maximal aerobic endurance performance measured via total distance covered. There were no differences in Yo-Yo IR1 performance between sessions (p = .32; single CHO mouth rinse (8% maltodextrin): 1,198 ± 289 m, eight CHO mouth rinses: 1,256 ± 253 m, placebo: 1,086 ± 284 m). In conclusion, single and serial CHO mouth rinsing did not improve performance during the Yo-Yo IR1 for soccer players. These data suggest that CHO mouth rinsing is not an effective ergogenic strategy for intermittent exercise performance irrespective of the number of rinses.

Open access

Philip Friere Skiba and David C. Clarke

Since its publication in 2012, the W′ balance model has become an important tool in the scientific armamentarium for understanding and predicting human physiology and performance during high-intensity intermittent exercise. Indeed, publications featuring the model are accumulating, and it has been adapted for popular use both in desktop computer software and on wrist-worn devices. Despite the model’s intuitive appeal, it has achieved mixed results thus far, in part due to a lack of clarity in its basis and calculation. Purpose: This review examines the theoretical basis, assumptions, calculation methods, and the strengths and limitations of the integral and differential forms of the W′ balance model. In particular, the authors emphasize that the formulations are based on distinct assumptions about the depletion and reconstitution of W′ during intermittent exercise; understanding the distinctions between the 2 forms will enable practitioners to correctly implement the models and interpret their results. The authors then discuss foundational issues affecting the validity and utility of the model, followed by evaluating potential modifications and suggesting avenues for further research. Conclusions: The W′ balance model has served as a valuable conceptual and computational tool. Improved versions may better predict performance and further advance the physiology of high-intensity intermittent exercise.

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Paulius Kamarauskas, Inga Lukonaitienė, Aaron T. Scanlan, Davide Ferioli, Henrikas Paulauskas, and Daniele Conte

Purpose: To assess weekly fluctuations in hormonal responses and their relationships with load and well-being during a congested in-season phase in basketball players. Methods: Ten semiprofessional, male basketball players were monitored during 4 congested in-season phase weeks consisting of 3 weekly matches. Salivary hormone variables (testosterone [T], cortisol [C], and T:C ratio) were measured weekly, and external load (PlayerLoad™ and PlayerLoad per minute), internal load session rating of perceived exertion, percentage of maximum heart rate (HR), summated HR zones, and well-being were assessed for each training session and match. Results: Significant (P < .05) moderate to large decreases in T were found in the third and fourth weeks compared with the first week. Nonsignificant moderate to large decreases in C were apparent in the last 2 weeks compared with previous weeks. Summated HR zones and perceived sleep significantly (P < .05) decreased in the fourth week compared with the first week; whereas, percentage of maximum HR significantly (P < .05) decreased in the fourth week compared with the second week. No significant relationships were found between weekly changes in hormonal responses and weekly changes in load and overall wellness. Conclusions: A congested schedule during the in-season negatively impacted the hormonal responses of players, suggesting that T and C measurements may be useful to detect fluctuations in hormone balance in such scenarios. The nonsignificant relationships between weekly changes in hormonal responses and changes in load and well-being indicate that other factors might induce hormonal changes across congested periods in basketball players.

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Arilene M.S. Santos, Alberto J. Maldonado, Antônio V.M. de Sousa Junior, Susi O.S. Brito, Rayane C. de Moura, Caique Figueiredo, Paula A. Monteiro, Lucas M. Neves, Ismael F. Freitas Junior, Marcos A.P. dos Santos, Sergio L.G. Ribeiro, and Fabrício E. Rossi

Purpose: To analyze peripheral brain-derived neurotrophic factor (BDNF) levels and psychophysiological parameters in youth badminton athletes during the season and to determine the relationship between variables. Methods: Fourteen young badminton athletes were assessed over the season (preseason, middle season, and final season). Serum BDNF (sBDNF) was determined during the preseason and final season. Sleep time, total physical activity, and time in vigorous activity were measured using an accelerometer. The fat-free mass, skeletal muscle mass, fat mass, handgrip strength, cardiorespiratory fitness (VO2max), and dietary intake were evaluated during the season. The Stroop Color and Word Test was employed to assess cognitive tasks. To evaluate the mood, the Brunel Mood Scale was used. Results: There  were lower sBDNF levels (−16.3% [46.8%]; P = .007) and sleep time (final season = 5.7 [1.1] vs preseason = 6.6 [1.1] h·night−1, P = .043) during the end of the season. The total calories and carbohydrate intake decreased across the season (P < .05). Conversely, better cognitive function was found in the final season with respect to the preseason (P < .05). There were significant correlations between BDNF and VO2max only in the preseason (r = .61, P = .027), but no significant relationship was found among sBDNF and cognitive performance, sleep time, and percentage of won games. Conclusions: Youth badminton athletes decreased their sBDNF levels, sleep time, carbohydrate, and calorie intake across the season. The athletes improved in cognitive function; however, only the females improved in body composition, and the males improved their VO2max in the middle season. The sBDNF levels were positively correlated with the VO2max in the preseason, and no correlations were observed among the sBDNF and psychological parameters, sleep time, and sport performance during the season.

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Jacob N. Kisiolek, Kyle A. Smith, Daniel A. Baur, Brandon D. Willingham, Margaret C. Morrissey, Samantha M. Leyh, Patrick G. Saracino, Cheri D. Mah, and Michael J. Ormsbee

The relationship between sleep duration, sleep quality, and race completion time during each stage of a 3-day ultra-endurance triathlon (stage 1: 10-km swim, 146-km cycle; stage 2: 276-km cycle; and stage 3: 84.4-km run) was investigated. Seventeen triathletes partook in sleep analysis throughout the ultra-endurance multiday triathlon using an actigraphy wristband. The participants wore the band to record objective sleep outcomes for approximately 4 days (1–2 d prerace, 3 race days, and 1 d postrace), except while racing. The total sleep time (TST; prerace: 414.1 [95.3] min, prestage 1: 392.2 [138.3] min, prestage 2: 355.6 [62.5] min, and prestage 3: 299.7 [107.0] min) significantly decreased over time (P < .05). Significant Pearson moment–product correlations were found between TST and subsequent race–day performance for race stage 1 (r = −.577; P = .019) and stage 3 (r = −.546; P = .035), with further analysis revealing that TST explained 33% and 30% of the variation in performance for stages 1 and 3, respectively. During a 3-day ultra-endurance triathlon, the TST was reduced and had a significant negative correlation to exercise performance, indicating that sleep loss was associated with slower performances. Sleep onset latency, wake episodes, and sleep efficiency did not significantly change over the course of this investigation, which may stem from the close proximity of exercise to sleep.