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Cesar Gallo-Salazar, Juan Del Coso, David Sanz-Rivas and Jaime Fernandez-Fernandez

Purpose: To determine whether the game activity and physiological responses of young tennis players differed depending on the session of play (eg, morning [MOR] vs afternoon [AFT]) and the final match outcome (eg, winners vs losers) during a simulated competition with 2 matches on the same day. Methods: A total of 12 well-trained male tennis players (age 14.5 [0.8] y) took part in a simulated competition of two 3-set matches separated by 3 h. All the matches were video recorded, and the participants were monitored using 10-Hz global positioning system units including a heart-rate monitor. Effect-size (ES) statistics were used to investigate the magnitudes of the differences. Results: During the AFT matches, in absolute terms, players covered longer total distance (ES = moderate) and ran more distance between 0 and ≤4 m·s−1 (ES = small to large) than in MOR matches. Total duration was also longer (ES = large) in the AFT, where the rest time between rallies was also longer (ES = very large). Heart rate was similar during AFT and MOR matches, but higher rates of perceived exertion (ES = moderate) were reported in the AFT. Only peak running velocity was observed to be likely higher for losers than for winners (ES = small). Conclusions: Game activity and physiological responses of young tennis players differ when 2 consecutive matches are played on the same day. These data might help elucidate the need for specific precompetition training loads and/or between-matches/sessions recovery strategies when facing overloaded competitions.

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Ralph Beneke and Renate M. Leithäuser

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Maureen R. Weiss, Lindsay E. Kipp, Alison Phillips Reichter, Sarah M. Espinoza and Nicole D. Bolter

Purpose: Girls on the Run is an after-school physical activity-based positive youth development program designed to enhance girls’ social, psychological, and physical development. We evaluated the effectiveness of the program by employing a longitudinal design and mixed methods. Methods: Girls (N = 203; aged 8–11 y) completed survey measures of positive youth development constructs (competence, confidence, connection, character, and caring), physical activity, and sedentary behavior prior to, at the end of, and 3 months after the season. Subsamples of girls, coaches, caregivers, and school personnel participated in focus groups. Coaches completed information about their team’s community impact project and number of girls who completed the season-ending 5k. Results: The full sample improved in confidence and connection, whereas girls who started below the preseason average showed the greatest gains from preseason to postseason on all measures, and scores were maintained or continued to improve at follow-up. All stakeholders in focus groups corroborated evidence of season-long improvement in social and emotional behaviors and health outcomes. Involvement in the community impact project contributed to girls’ growth in character and empathy skills. Conclusion: Findings provide empirical evidence that Girls on the Run is effective in promoting positive youth development, including season-long and lasting change in competence, confidence, connection, character, caring, and physical activity, especially among girls who exhibited lower preseason scores than their peers.

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David R. Howell, Thomas A. Buckley, Brant Berkstresser, Francis Wang and William P. Meehan III

The purpose of this study was to identify the rate of abnormal single-task and dual-task gait performance following concussion compared to uninjured controls using previously established normative reference values. The authors examined athletes with a concussion (n = 54; mean age = 20.3 [1.1] y, 46% female, tested 2.9 [1.5] d postinjury), and healthy controls were tested during their preseason baseline examination (n = 60; mean age = 18.9 [0.7] y, 37% female). Participants completed an instrumented single-/dual-task gait evaluation. Outcome variables included average walking speed, cadence, and step length. A significantly greater number of those with concussion walked with abnormal dual-task gait speed compared with the control group (56% vs 30%, P = .01). After adjusting for potential confounding variables (age, concussion history, symptom severity, and sleep), concussion was associated with lower dual-task gait speed (β = −0.150; 95% confidence interval [CI] = −0.252 to −0.047), cadence (β = −8.179; 95% CI = −14.49 to −1.871), and stride length (β = −0.109; 95% CI = −0.204 to −0.014). Although group analyses indicated that those with a concussion performed worse on single-task and dual-task gait compared with controls, a higher rate of abnormal gait was detected for the concussion group compared with the control group for dual-task gait speed only. Dual-task gait speed, therefore, may be considered as a measure to compare against normative values to detect postconcussion impairments.

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Amy Rauer and Lyndsey M. Hornbuckle

The current study explored concordance in spouses’ perceptions about exercise and how these perceptions predicted observed and self-reported marital functioning using a sample of 64 older married couples. Although couples were similarly motivated to exercise, their views on their physical fitness and potential barriers to exercise were uncorrelated. Dyadic analyses suggested that spouses’ exercise perceptions, particularly husbands’, were associated with how spouses treated each other during a marital problem-solving task and with their concurrent and future marital satisfaction. Exploring how spouses’ views of exercise are related to their marital functioning and for whom these links are most salient may highlight potential opportunities and challenges for those wishing to strengthen couples’ individual and relational well-being through exercise.

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Stephen P. Bailey, Julie Hibbard, Darrin La Forge, Madison Mitchell, Bart Roelands, G. Keith Harris and Stephen Folger

Background: Carbohydrate (CHO) mouth rinse (MR) before exercise has been shown to improve physical performance and corticospinal motor excitability. Purpose: To determine the effects of different forms of CHO MR on quadriceps muscle performance and corticospinal motor excitability. Methods: 10 subjects (5 female and 5 male; 25 [1] y, 1.71 [0.03] m, 73 [5] kg) completed 4 conditions (placebo [PLA], 6.4% glucose [GLU], 6.4% maltose [MAL], 6.4% maltodextrin [MDX]). Maximal voluntary contraction (MVIC) of the right quadriceps and motor-evoked potential (MEP) of the right rectus femoris was determined pre (10 min), immediately after, and post (10 min) 20-s MR. MEP was precipitated by transcranial magnetic stimulation during muscle contraction (50% MVIC). Results: The relative change in MEP from pre-measures was different across treatments (P = .025) but was not different across time (P = .357). MEP was greater for all CHO conditions immediately after (GLU = 2.58% [5.33%], MAL = 3.92% [3.90%], MDX = 18.28% [5.57%]) and 10 min after (GLU = 14.09% [13.96%], MAL = 8.64% [8.67%], MDX = 31.54% [12.77%]) MR than PLA (immediately after = −2.19% [4.25%], 10 min = −13.41% [7.46%]). MVC was greater for CHO conditions immediately (GLU = 3.98% [2.49%], MAL = 5.89% [2.29%], MDX = 7.66% [1.93%]) and 10 min after (GLU = 7.22% [2.77%], MAL = 10.26% [4.22%], MDX = 10.18% [1.50%]) MR than PLA (immediately after = −3.24% [1.50%], 10 min = −6.46% [2.22%]). Conclusions: CHO MR increased corticospinal motor excitability and quadriceps muscle after application. The form of CHO used did not influence this response.

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Ali M. McManus, Nathan R. Sletten and Daniel J. Green

Purpose: The effect of exercise intensity on vasodilator function is poorly understood in children. The authors compared the acute effect of high-intensity interval exercise (HIIE) with moderate-intensity steady-state exercise (MISS) on postexercise vasodilation and shear patterns in 7- to 12- year-old children. Methods: Superficial femoral artery diameter, shear rates, and flow-mediated dilation were measured pre, immediately following (post), and 1 hour after (post60) HIIE (six 1-min sprints at 90% peak power [Wmax], with 1-min recovery) and MISS (15 min at 44% Wmax). Results: Baseline superficial femoral artery diameter increased similarly following both HIIE (pre 4.23 [0.41] mm, post 4.73 [0.56] mm) and MISS (pre 4.28 [0.56] mm, post 4.59 [0.64] mm), returning to preexercise values post60. Blood flow and antegrade shear rate were increased post HIIE and MISS, but to a greater extent, post HIIE (P < .05). Retrograde shear rate was attenuated post both exercise conditions and remained post60 (P < .001). There was a decline in flow-mediated dilation postexercise (HIIE Δ −2.9%; MISS Δ −2.4%), which was no longer apparent when corrected for baseline diameter. Conclusion: Acute bouts of external work-matched HIIE or MISS exert a similar impact on shear-mediated conduit artery vasodilation and flow-mediated dilation in children, and this is reversed 1 hour after exercise.

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David Morawetz, Tobias Dünnwald, Martin Faulhaber, Hannes Gatterer and Wolfgang Schobersberger

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.

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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.

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João Pedro Nunes, Alex S. Ribeiro, Analiza M. Silva, Brad J. Schoenfeld, Leandro dos Santos, Paolo M. Cunha, Matheus A. Nascimento, Crisieli M. Tomeleri, Hellen C.G. Nabuco, Melissa Antunes, Letícia T. Cyrino and Edilson S. Cyrino

The aim of this study was to analyze the association between muscle quality index (MQI) and phase angle (PhA) after a program of progressive resistance training (RT) in older women. Sixty-six older women with previous RT experience (68.8 ± 4.6 years, 156.6 ± 5.3 cm, 66.0 ± 13.0 kg, and 26.7 ± 4.6 kg/m2) underwent 12 weeks of RT (3 ×/week, eight exercises, and 10–15 repetition maximum). Anthropometry, muscular strength (one-repetition maximum tests), and body composition (dual-energy X-ray absorptiometry and spectral bioimpedance) were measured pre- and posttraining. There were observed significant increases for PhA, MQI, muscular strength, muscle mass, and reactance, whereas no significant changes in body fat and resistance were found. A significant correlation was observed between the RT-induced relative changes in PhA and MQI (r = .620). We conclude that improvements in MQI induced by RT are associated with increases in PhA. Therefore, PhA may be a valid tool to track changes in MQI after 12 weeks of RT in older women.