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Estimating Muscle Fiber-Type Composition in Elite Athletes: A Survey on Current Practices and Perceived Merit

Eline Lievens, Freek Van de Casteele, Fien De Block, Kim Van Vossel, Tom Vandenbogaerde, Gareth N. Sandford, Phillip Bellinger, Clare Minahan, Jan G. Bourgois, Trent Stellingwerff, Iñigo Mujika, and Wim Derave

Purpose: To gather information on practices and perceptions of high-performance experts regarding their athletes’ muscle fiber-type composition (MFTC) and its estimation. Methods: A questionnaire on the noninvasive versus invasive estimation of MFTC was completed by 446 experts including coaches and sport-science/sports-medicine staff. Moreover, the perceived importance of MFTC for training and performance optimization was assessed. Differences between sport types (individual and team sports) were analyzed using chi-square tests. Results: Forty percent of the experts implemented MFTC assessment in pursuit of performance optimization, while 50% did not know their athletes’ MFTC but expressed a desire to implement it if they would be able to assess MFTC. Ten percent did not perceive value in MFTC assessment. Only 18% of experts believed that their athletes would undergo a muscle biopsy, leading to the adoption of alternative noninvasive techniques. Experts primarily relied on their experience to estimate MFTC (65%), with experts working in individual sports using their experience more frequently than those working in team sports (68% vs 51%; P = .009). Jump tests emerged as the second-most commonly employed method for estimating MFTC (56%). When only considering experts who are currently using MFTC, 87% use MFTC to individualize training volume and 84% to individualize training intensity. Conclusions: Experts value MFTC assessment primarily to individualize training but mainly rely on noninvasive methods to estimate MFTC. Some of these methods lack scientific validity, suggesting a continuing need for education and further research in this area.

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Optimizing Athletic Performance Through Brain Endurance Training

Bart Roelands and Špela Bogataj

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Socialization Into and Through Doctoral Programs in Adapted Physical Activity

Paul R. Malinowski, Wesley J. Wilson, Paul H. Warner, Alyssa M. Trad, Peter Rifenburg, and Kevin Andrew Richards

This study examined doctoral students’ occupational socialization experiences in U.S. adapted physical activity doctoral programs. Twenty-eight doctoral students were recruited and participated in semistructured, in-depth interviews. Interview transcripts were analyzed through a collaborative qualitative analysis, which resulted in the construction of four themes: (a) early socialization experiences foster a positive, but limited impression of physical education and physical activity; (b) doctoral education is pursued to have a greater impact on the disability community; (c) relationships with socializing agents provide support during doctoral education; and (d) coursework and learning in the community facilitate preparation for faculty roles. The findings indicate that there are several similarities between doctoral students and their peers in other doctoral degree programs. Some of these similarities point to issues that may concern prospective doctoral students and faculty members in adapted physical activity terminal degree programs.

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Change-of-Direction Performance and Its Deficits in Relation to Countermovement-Jump Height and Phase-Specific Performance Among Female Athletes

Naoyuki Yamashita, Daisuke Sato, and Takaaki Mishima

Purpose: Jump and linear sprint performances both correlate with pro-agility performance. However, correlation does not imply causation, and potential confounders may affect the correlation. Therefore, this study aimed to determine the relationship between change-of-direction (COD) performance and COD deficits (COD-D) in linear-sprint and countermovement-jump (CMJ) -related performance using multiple stepwise linear-regression models. Methods: The study included 42 female national-level intercollegiate athletes. The 10- and 20-m linear-sprint and pro-agility times, COD-D, CMJ height, and phase-specific force production and rate of force development during eccentric unloading, eccentric braking, and the concentric phases of CMJ were measured. Stepwise linear-regression analyses were used to predict the factors related to COD and COD-D. Results: CMJ height was the sole predictor in the 10-m pro-agility model (adjusted R 2 = .234, P = .001). Modified Reactive Strength Index (standardized coefficient, −.710) and the lowest center-of-mass depth during the CMJ (standardized coefficient, .323) were predictors in the 20-m pro-agility model (adjusted R 2 = .330, P < .001). For the 10- and 20-m COD-D models, the rate of force development at 30 and 60 milliseconds, respectively, during the concentric phase was the only predictor of performance (adjusted R 2 = .183, P = .003 and .237, P = .001, respectively). Conclusions: These results suggest that athletes should concentrate on improving their CMJ height, increasing their ability to lower their center of mass more deeply, and increasing their instantaneous force-production abilities immediately after the eccentric braking phase of CMJ to improve their COD performance.

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Third-Man-Passing Small-Sided Games Induce Higher Anaerobic Energy Contributions Than Regular-Passing Small-Sided Games in Football Players

Woo-Hwi Yang, So-Young Park, Young-Je Kwak, Zi-Hyun Kim, and Sung-Hwan Choi

Purpose: This study compared the physiological profiles and energy-system contributions of trained football players engaged in regular-passing and third-man-passing small-sided games (SSGs) that included 4 versus 4 and a goalkeeper. Methods: Ten male trained football players participated in this crossover study. All participants were randomly assigned to either regular-passing SSG or third-man-passing SSG (4 vs 4 with a goalkeeper, 35-m × 17-m pitch size, and 6-min match duration). During these SSGs, physiological parameters including peak and mean heart rate, oxygen uptake ( V ˙ O 2 peak and V ˙ O 2 mean ), metabolic equivalents in V ˙ O 2 peak and V ˙ O 2 mean , and blood lactate concentrations (peak La and delta La [Δ La]), were measured. Energy contributions (oxidative [W Oxi], glycolytic [W Gly], and phosphagen [W PCr] systems) and Global Positioning System (GPS) variables (total distance, total acceleration counts, mean speed, and maximum speed) were also analyzed. Results: No significant differences in physiological parameters and GPS variables were found between regular- and third-man-passing SSGs. W Oxi in kilojoules and percentages was significantly higher during both SSGs than W PCr and W Gly (P < .0001, respectively). W PCr and W PCr + W Gly values during third-man-passing SSGs were significantly higher than those during regular-passing SSGs (P < .05). Additionally, low to moderate positive correlations were observed between W Oxi, W Gly in kilojoules, V ˙ O 2 peak , V ˙ O 2 mean , peak La, Δ La, total acceleration counts, and mean speed (r = .39–.64). Conclusions: Third-man-passing SSGs may be useful for increasing anaerobic capacity. More third-man-passing SSG sessions in preparation for football games may support high metabolic power and repeated powerful anaerobic performances in trained football players.

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Time–Motion and Technical–Tactical Aspects of Glory World Series Matches in the Male Middle-Heavy-Weight Category

Jean C. Calabrese, Renata G. Silva, Romulo Bertuzzi, and Adriano E. Lima-Silva

Purpose: To characterize the time structure of K1 kickboxing matches of Glory World Series (Glory) and to determine potential differences between winners and losers. Methods: Seventeen matches of Glory 2019 (17 first rounds, 13 second rounds, and 8 third rounds) were video-analyzed to quantify (1) the time expended in high- and low-intensity activity and pauses, (2) the number and pattern of attacks, and (3) the number of effective attacks. Fighters were professional male athletes (age 27.9 [2.7] y) of the middle-weight category (85 kg). The number and the pattern of attacks and the number of effective attacks were compared between winners and losers. Results: The mean times expended in high- and low-intensity activity and pauses were 234.6 (133.9) seconds, 97.4 (60.1) seconds, and 36.0 (19.9) seconds, respectively, resulting in an effort-to-pause ratio of ∼1.8:1. Compared with losers, winners presented (1) a greater number of attacks in the second round (P = .004) and entire match (P = .009), (2) a greater number of attacks containing 3 attacks in sequence in the second round (P = .001) and attacks containing >3 attacks in the third round (P = .049), and (3) a greater number of effective attacks in the second round (P = .011) and entire match (P = .008). Conclusions: The findings of the present study indicate that K1 kickboxing in Glory matches presents a ∼1.8:1 effort-to-pause ratio and that winners perform more attacks, effective attacks, and attacks in sequence. These data provide useful insights to improve the training specificity of kickboxing athletes.

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Habituation Does Not Change Running Economy in Advanced Footwear Technology

Lars C. Schwalm, Dominik Fohrmann, Marcelle Schaffarczyk, Thomas Gronwald, Steffen Willwacher, and Karsten Hollander

Purpose: This study aimed to compare running economy across habituated and nonhabituated advanced footwear technology (AFT) in trained long-distance runners. Methods: A total of 16 participants completed up to six 5-minute trials in 1 to 3 pairs of their own habituated shoes and 3 different and standardized AFTs at individual marathon pace. We measured oxygen uptake and carbon dioxide production and expressed running economy as oxygen uptake (in milliliters oxygen per kilogram per minute), oxygen cost of transport (oxygen per kilogram per minute), energetic cost (in watts per kilogram), and energetic cost of transport (in joules per kilogram per kilometer). We used linear mixed-effect models to evaluate differences. Relative shoe weight and shoe mileage (distance worn during running) were covariates. Results: Forty-eight standardized and 29 individual AFT conditions were measured (mileage 117.0 [128.8] km, range 0–522 km; 25 habituated 135.7 [129.2] km, range 20–522 km; 4 nonhabituated 0 [0] km, range 0–0 km). Rating of perceived exertion, blood [La], and respiratory exchange ratio ranged from 9 to 15, 1.11 to 4.54 mmol/L, and 0.76 to 1.01. There was no effect for habituation on energetic cost of transport (t habituation = −.232, P = .409, b = −0.006; 95% CI, −0.058 to 0.046) or other running economy metrics. Neither shoe weight nor shoe mileage had an effect. Conclusions: Our results suggest that habituation to AFTs does not result in greater benefits in the use of AFTs. This means that implementation in training may not be needed, even if we cannot rule out any other possible benefits of habituation at this stage, such as adaptation of the musculoskeletal system.

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Making the Invisible, Visible: An Exploration of Track-and-Field Coaches’ Perspectives of Their Planning Processes

Karen L. Johns, Paul Potrac, and Philip R. Hayes

Purpose: The traditional understanding of how coaches plan for sporting performance is rooted in the assumption that coaches create periodized plans underpinned by physiological principles, thereby providing scientific credibility to their work. In contrast, there remains a paucity of literature exploring how coaches understand or think about their planning practices. The purpose of this study was to generate new knowledge regarding what information coaches actually consider within their planning processes and how they actually approach the task of planning. Method: Using rigorous, in-depth interviews, this study examined athletics coaches’ understandings of their everyday planning practices, in an attempt to contribute to narrowing the gap between academic research and real-world application. Twenty-eight highly experienced, high-performance track-and-field coaches based in England (female, n = 1; male, n = 27) were recruited. The coaches were from the throwing disciplines (n = 10) and endurance running (n = 18). Coaches were interviewed about their planning process, using a maximum of 3 semistructured interviews per coach, spaced across a full athletics season. In total, this generated 68 hours of data. Results: The analysis demonstrated that, while the participant coaches utilized the principles of periodization, their planning activities were not limited to this issue. The findings highlighted how the coaches conceptualized successful athletic performance in a holistic way; that is, planning is multifaceted in nature. Conclusion: This study presents a holistic picture of the complexity of coaches’ planning, detailing the considerable time and attention given to planning for athletes’ psychological, personal, and social development, to enhance athlete performance and development.

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The Training and Development Process for a Multiple-Grand-Slam Finalist in Tennis

Thomas A. Haugen, Caroline Ruud, Silvana Bucher Sandbakk, Øyvind Sandbakk, and Espen Tønnessen

Purpose: To investigate the training and development process of a multiple-Grand-Slam finalist. Methods: A mixed-methods case-study design was used to capture the quantitative and qualitative aspects related to the training and successful development process. We used a 3-step data-collection process and pragmatic analyses of (1) training history based on logs, plans, and questionnaires; (2) in-depth semistructured interviews with the player’s head coach/father, physical coach, and team administrator/mother; and (3) systematic quality assurance through negotiation among researchers and all key informants, including the player. Results: The player’s exceptional performance level was achieved by a progressive, nonlinear increase in annual training load during childhood and early youth, stabilizing at 800 sessions and 1250 to 1300 hours per year at the age of 19. The annual tennis-specific training plateaued at ∼750 hours from the age of 15, and 60 to 80 matches were played in most of the analyzed years. Point-play accounted for approximately 50% of the total amount of specific tennis training, clearly ahead of ground strokes (∼30%), serve/return (∼15%), and smash/volley (∼5%). Physical-conditioning hours increased 5-fold from 12 to 19 years, before stabilizing at ∼500 hours at senior age. Key success factors included the athlete’s multidimensional sports talent, discipline, and inner drive; a highly dedicated father and tennis-enthusiastic family; and strong support from a complementary and interdisciplinary performance team. Conclusion: This study provides novel information regarding the training and development process for a world-leading tennis player, providing a point of departure for the development of future talents.

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Chill Without Thrill: A Crossover Study on Whole-Body Cryotherapy and Postmatch Recovery in High-Level Youth Basketball Players

Marco Pernigoni, Andrea Perazzetti, Mattia Digno, Antonio Tessitore, Sigitas Kamandulis, and Daniele Conte

Purpose: To assess the effect of whole-body cryotherapy (WBC) on postmatch recovery in basketball. Methods: Using a crossover design, 17 youth male players (age 16.2 [1.2] y, stature 190.5 [9.4] cm, body mass 79.2 [9.6] kg, experience 9.9 [3.9] y) completed 2 simulated matches, followed by WBC (4 min, −75 to − 85 °C) or a placebo intervention (CON). Countermovement-jump height, change-of-direction performance, 10- and 20-m sprint times, heart-rate variability (log-transformed squared root of the mean sum of the squared differences between R-R intervals [Ln-rMSSD]), muscle soreness, and perceived recovery (Perceived Recovery Status Scale [PRS]) were recorded at prematch, postmatch, postrecovery, and 24 hours postmatch. Additionally, Ln-rMSSD was recorded upon awakening on match day and the following morning. Results: Compared with CON, higher PRS values were reported in WBC at prematch and postrecovery (P ≤ .026), while no significant between-interventions differences were found for any other measure (P > .05). Regarding the effect of time, our findings revealed that 20-m sprint times, Ln-rMSSD, and PRS deteriorated in both interventions from prematch to postmatch (ie, acute changes, P ≤ .045), while muscle soreness worsened in WBC only (P ≤ .003). Conversely, countermovement-jump height, change-of-direction, and 10-m sprint performance were unaffected by match play in the acute phase (P > .05), while none of the investigated measures showed impairments at 24 hours postmatch, compared with prematch (P > .05). Conclusions: Overall, these findings suggest that WBC was mostly ineffective for improving postexercise recovery in the investigated sample, with benefits observed for perceived recovery being potentially influenced by the participants’ status at baseline (ie, higher prematch PRS scores in WBC compared with CON).