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Pedro L. Valenzuela, Almudena Montalvo-Perez, Lidia B. Alejo, Mario Castellanos, Jaime Gil-Cabrera, Eduardo Talavera, Alejandro Lucia, and David Barranco-Gil

Purpose : Some power meters are available in both bilateral and unilateral versions. However, despite the popularity of the latter, their validity remains unknown. We aimed to analyze the validity of a unilateral pedal power meter for estimating actual (“bilateral”) power output (PO). Methods: Thirty-three male cyclists were assessed at different POs (steady cycling at 100–500 W, as well as all-out sprints), pedaling cadences (70, 85, and 100 repetitions·min−1), and cycling positions (seated and standing). The PO estimated by a left-only power meter (Favero Assioma Uno) was compared with the actual PO computed by a bilateral power meter (Favero Assioma Duo), and the level of bilateral asymmetry (most- vs least-powerful leg) with the latter system was also computed. Results: Nonsignificant differences, high intraclass correlation coefficients (≥.90), and low coefficients of variation (consistently ≤5% except for low PO levels, ie, 5%–7% at 100 W) were found between Favero Assioma Uno and Favero Assioma Duo. However, although a strong intraclass correlation coefficient (.995) was found between both legs, asymmetry values of 4% to 6% were found for all conditions except when pedaling at the lowest PO (100 W), in which asymmetry increased up to 10% to 13%. Conclusions: Although cyclists tend to present some level of bilateral asymmetry during cycling (particularly at low PO), Favero Assioma Uno provides overall valid estimates of actual PO and is, therefore, an economical alternative to bilateral power meters. Caution is needed, however, when interpreting data at the individual level in cyclists with high levels of asymmetry.

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Felipe Guimarães Teixeira, Paulo Tadeu Cardozo Ribeiro Rosa, Roger Gomes Tavares Mello, and Jurandir Nadal

Purpose: The study aimed to identify the variables that differentiate judo athletes at national and regional levels. Multivariable analysis was applied to biomechanical, anthropometric, and Special Judo Fitness Test (SJFT) data. Method: Forty-two male judo athletes from 2 competitive groups (14 national and 28 state levels) performed the following measurements and tests: (1) skinfold thickness, (2) circumference, (3) bone width, (4) longitudinal length, (5) stabilometric tests, (6) dynamometric tests, and (7) SJFT. The variables with significant differences in the Wilcoxon rank-sum test were used in stepwise logistic regression to select those that better separate the groups. The authors considered models with a maximum of 3 variables to avoid overfitting. They used 7-fold cross validation to calculate optimism-corrected measures of model performance. Results: The 3 variables that best differentiated the groups were the epicondylar humerus width, the total number of throws on the SJFT, and the stabilometric mean velocity of the center of pressure in the mediolateral direction. The area under the receiver-operating-characteristic curve for the model (based on 7-fold cross validation) was 0.95. Conclusion: This study suggests that a reduced set of anthropometric, biomechanical, and SJFT variables can differentiate judo athlete’s levels.

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Alannah K.A. McKay, Trent Stellingwerff, Ella S. Smith, David T. Martin, Iñigo Mujika, Vicky L. Goosey-Tolfrey, Jeremy Sheppard, and Louise M. Burke

Throughout the sport-science and sports-medicine literature, the term “elite” subjects might be one of the most overused and ill-defined terms. Currently, there is no common perspective or terminology to characterize the caliber and training status of an individual or cohort. This paper presents a 6-tiered Participant Classification Framework whereby all individuals across a spectrum of exercise backgrounds and athletic abilities can be classified. The Participant Classification Framework uses training volume and performance metrics to classify a participant to one of the following: Tier 0: Sedentary; Tier 1: Recreationally Active; Tier 2: Trained/Developmental; Tier 3: Highly Trained/National Level; Tier 4: Elite/International Level; or Tier 5: World Class. We suggest the Participant Classification Framework can be used to classify participants both prospectively (as part of study participant recruitment) and retrospectively (during systematic reviews and/or meta-analyses). Discussion around how the Participant Classification Framework can be tailored toward different sports, athletes, and/or events has occurred, and sport-specific examples provided. Additional nuances such as depth of sport participation, nationality differences, and gender parity within a sport are all discussed. Finally, chronological age with reference to the junior and masters athlete, as well as the Paralympic athlete, and their inclusion within the Participant Classification Framework has also been considered. It is our intention that this framework be widely implemented to systematically classify participants in research featuring exercise, sport, performance, health, and/or fitness outcomes going forward, providing the much-needed uniformity to classification practices.

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Fernando Pareja-Blanco, Lucas A. Pereira, Valter P. Reis, Victor Fernandes, Ademir F.S. Arruda, Aristide Guerriero, Pedro E. Alcaraz, Tomás T. Freitas, and Irineu Loturco

Purpose: To examine the changes in resisted sprint performance and kinematics provoked by different sled loads in elite sprinters and rugby players. Methods: Eight elite male sprinters and 10 rugby union players performed 20-m sprints under 3 loading conditions (0%, 20%, and 60% body mass [BM]). Sprint time was measured in 0 to 5, 5 to 10, and 10 to 20 m, while stride length and hip, knee, and ankle angles were measured using an 8-sensor motion analysis system at the same distances. Results: Sprinters were significantly faster than rugby players in unresisted and resisted sprints using 20% BM (effect size, “ES” [90% confidence limit, CL] range: 0.65 [0.03 to 1.27]; 3.95 [3.10 to 4.81]), but these differences were not significant at 60% BM. Compared to rugby players, sprinters showed lower velocity decrement in resisted sprints using 20% BM (ES [90% CL] range: 0.75 [0.06 to 1.44]; 2.43 [0.83 to 4.02], but higher velocity decrement using 60% BM (ES [90% CL] range: 1.13 [0.43 to 1.82]; 1.46 [0.81 to 2.11]). No significant differences were detected in stride length between sprinters and rugby players for any sprint condition (ES [90% CL] range: 0.02 [−0.72 to 0.76]; 0.84 [0.13 to 1.54]). Rugby players showed higher hip flexion in resisted sprints (ES [90% CL] range: 0.30 [−0.54 to 1.14]; 1.17 [0.20 to 2.15]) and lower plantar flexion in both unresisted and resisted sprints (ES [90% CL] range: 0.78 [0.18 to 1.38]; 1.69 [1.00 to 2.38] than sprinters. Conclusions: The alterations induced by resisted sprints in sprint velocity and running technique differed between sprinters and rugby players. Some caution should be taken with general sled loads prescriptions, especially when relative loads are based on distinct percentages of BM, as training responses vary among sports and individuals.

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Emma Brooks, Gilles Lamothe, Taniya S. Nagpal, Pascal Imbeault, Kristi Adamo, Jameel Kara, and Éric Doucet

There has been much consideration over whether exogenous ketone bodies have the capacity to enhance exercise performance through mechanisms such as altered substrate metabolism, accelerated recovery, or neurocognitive improvements. This systematic review aimed to determine the effects of both ketone precursors and monoesters on endurance exercise performance. A systematic search was conducted in PubMed, SPORTDiscus, and CINAHL for randomized controlled trials investigating endurance performance outcomes in response to ingestion of a ketone supplement compared to a nutritive or nonnutritive control in humans. A meta-analysis was performed to determine the standardized mean difference between interventions using a random-effects model. Hedge’s g and 95% confidence intervals (CI) were reported. The search yielded 569 articles, of which eight were included in this review (80 participants; 77 men and three women). When comparing endurance performance among all studies, no significant differences were found between ketone and control trials (Hedges g = 0.136; 95% CI [−0.195, 0.467]; p = .419). Subanalyses based on type of endurance tests showed no significant differences in time to exhaustion (Hedge’s g = −0.002; 95% CI [−0.312, 0.308]; p = .989) or time trial (Hedge’s g = 0.057; 95% CI [−0.282, 0.395]; p = .744) values. Based on these findings, exogenous ketone precursors and monoesters do not exert significant improvements on endurance exercise performance. While all studies reported an increase in blood ketone concentrations after ingestion, ketone monoesters appear to be more effective at raising concentrations than precursors.

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Cate A. Egan, Christopher B. Merica, Grace Goc Karp, Karie Orendorff, and Hayley Beth McKown

Purpose: The purpose of this study was to understand how a service-learning project implementation can help preservice physical education teachers develop physical activity (PA) leadership skills. Methods: A qualitative exploratory single case study was employed, and eight preservice physical education students enrolled in service-learning course were recruited. Data included pre/post self-assessment surveys, reflection journals, individual interviews, and final poster presentations, and were coded using service-learning as a lens. Trustworthiness was established using multiple strategies. Results: Three major themes emerged, each with their own subthemes. Theme 1 was Practical Experience, Theme 2 was Learning to be Leaders, and Theme 3 was Service-Learning. Discussion/Conclusion: The hands-on structure of a service-learning course allowed students to develop PA leadership skills and provided them with the skills and confidence needed to implement expanded PA programs in the future. Service-learning courses are a viable option for PA leadership training in teacher education programs.

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Jaehun Jung, Layne Case, Samuel W. Logan, and Joonkoo Yun

The purposes of this study were (a) to investigate the prevalence of physical educators who report delivering high-quality instructional practices to students with disabilities and (b) to examine the relationships between teachers’ qualifications and the delivery of high-quality instructional practices. A secondary analysis using data from the School Health Policy and Practice Study 2014 data set was employed. The analytic sample included 256 physical educators who taught students with disabilities. Prevalence estimates of physical educators who reported using high-quality instructional practices were calculated. Two separate binary logistic regressions using weighted data were conducted to evaluate the relative contribution of (a) teacher qualifications and (b) educational degrees in accounting for differences in the use of high-quality instructional practices. Less than half of the sample reported using high-quality instructional practices. Considering the increasing prevalence of students with disabilities in general education classrooms, teacher education programs should prioritize providing teacher candidates with coursework that aligns with the expectations of physical educators who teach students with disabilities.

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Karim Saidi, Hassane Zouhal, Daniel Boullosa, Gregory Dupont, Anthony C. Hackney, Benoit Bideau, Urs Granacher, and Abderraouf Ben Abderrahman

Objectives: To analyze biochemical markers, wellness status, and physical fitness in elite soccer players in relation to changes in training and match exposure during a congested period of match play. Methods: Fourteen elite soccer players were evaluated 3 times (T1, T2, and T3) over 12 weeks (T1–T2: 6-wk regular period of match play and T2–T3: 6-wk congested period of match play). Players performed vertical jump tests, repeated shuttle sprint ability test, and the Yo-Yo Intermittent Recovery Test at T1, T2, and T3. Plasma C-reactive protein, creatinine, and creatine kinase were analyzed at T1, T2, and T3. Wellness status was measured daily using the Hopper questionnaire (delayed onset of muscle soreness, stress, fatigue, and sleep quality). Training session rating of perceived exertion was also recorded on a daily basis. Results: A significant increase was found in stress, fatigue, delayed onset of muscle soreness scores, and Hopper index during the congested period (between T2 and T3) compared with the regular period (between T1 and T2) (.001 < P < .008, 0.8 < ES < 2.3). Between T2 and T3, significant relationships were found between the percentage variations (Δ%) of C-reactive protein, and Δ% of creatine kinase with the Hopper Index, and the Δ% of fatigue score. In addition, the Δ% of fatigue score and Δ% of delayed onset of muscle soreness score correlated with Δ% Yo-Yo Intermittent Recovery Test and Δ% best of repeated shuttle sprint ability test (.49 < r < P < .01). Conclusions: An intensive period of congested match play significantly compromised elite soccer players’ physical fitness and wellness status. Elite soccer players’ wellness status reflects declines in physical fitness during this period while biochemical changes do not.

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Jeferson L. Jacinto, João P. Nunes, Stefan H.M. Gorissen, Danila M.G. Capel, Andrea G. Bernardes, Alex S. Ribeiro, Edilson S. Cyrino, Stuart M. Phillips, and Andreo F. Aguiar

The purpose of this study was to investigate the effects of supplementation of whey protein (WP) versus leucine-matched collagen peptides (CP) on muscle thickness MT and performance after a resistance training (RT) program in young adults. Twenty-two healthy untrained participants were randomly assigned to either a WP (n = 11) or leucine-matched CP (n = 11) group and then submitted to a supervised 10-week RT program (3 days/week). The groups were supplemented with an equivalent amount of WP (35 g, containing 3.0 g of leucine) and CP (35 g, containing 1.0 g of leucine and 2.0 g of free leucine) during the intervention period (after each workout and in the evening on nontraining days). MT of the vastus lateralis and biceps brachii, isokinetic peak torque and mean power output of the elbow flexors, and peak power output of the lower body were assessed before and after the RT program. The WP group experienced a greater (interaction, p < .05) increase in the vastus lateralis (effect size, WP = 0.68 vs. CP = 0.38; % Δ, WP = 8.4 ± 2.5 vs. CP = 5.6 ± 2.6%) and biceps brachii muscle thickness (effect size, WP = 0.61 vs. CP = 0.35; % , WP = 10.1 ± 3.8 vs. CP = 6.0 ± 3.2%), with a similar increase in muscle performance (peak torque, mean power output, and peak power output) between groups (time p < .05). Supplementation with WP was superior to leucine content-matched CP supplementation in increasing muscle size, but not strength and power, after a 10-week RT program in young adults.