The purpose of this investigation was to evaluate relative age effects (RAEs) in elite youth judo athletes from different chronological age groups, between sexes, and across weight categories. Data from 1542 place winners of the cadet (under 17 y, 2009-2013) and junior judo world championships (under 20/21 y, 1990-2013) were separated by birth month into quarters (Q1, Q2, Q3, and Q4). The observed values were compared with expected annual age distributions using χ2 analyses, and odd ratios (OR) were used to evaluate effect sizes between quarters. The observed frequency of place winners was significantly different from the expected frequency for the age-group and sex comparisons and all body-mass groups (P < .05) with the exception of the extra-light categories (P = .572). When comparing Q1 with Q4 (OR, 95% confidence interval), small effect sizes were observed for cadets (1.72, 1.12-2.66), juniors (1.54, 1.23-1.94), males (1.75, 1.32-2.33), females (1.39, 1.03-1.87), and the light- (1.79, 1.21-2.64) and middle-weight (1.80, 1.20-2.70) categories. RAEs are apparent in cadet and junior judo athletes. Thus, coaches and administrators should consider the potential for physical and/or competitive advantages while adopting strategies that encourage long-term participation in youth judo athletes.
David H. Fukuda
Bianca Miarka, Katarzyna Sterkowicz-Przybycien and David H. Fukuda
The purpose of the present study was to create a probabilistic neural network to clarify the understanding of movement patterns in international judo competitions by gender. Analysis of 773 male and 638 female bouts was utilized to identify movements during the approach, gripping, attack (including biomechanical designations), groundwork, defense, and pause phases. Probabilistic neural network and chi-square (χ2) tests modeled and compared frequencies (p ≤ .05). Women (mean [interquartile range]: 9.9 [4; 14]) attacked more than men (7.0 [3; 10]) while attempting a greater number of arm/leg lever (women: 2.7 [1; 6]; men: 4.0 [0; 4]) and trunk/leg lever (women: 0.8 [0; 1]; men: 2.4 [0; 4]) techniques but fewer maximal length-moment arm techniques (women: 0.7 [0; 1]; men: 1.0 [0; 2]). Male athletes displayed one-handed gripping of the back and sleeve, whereas female athletes executed a greater number of groundwork techniques. An optimized probabilistic neural network model, using patterns from the gripping, attack, groundwork, and pause phases, produced an overall prediction accuracy of 76% for discrimination between men and women.
Lindy M. Rossow, David H. Fukuda, Christopher A. Fahs, Jeremy P. Loenneke and Jeffrey R. Stout
Bodybuilding is a sport in which competitors are judged on muscular appearance. This case study tracked a drug-free male bodybuilder (age 26–27 y) for the 6 mo before and after a competition.
The aim of this study was to provide the most comprehensive physiological profile of bodybuilding competition preparation and recovery ever compiled.
Cardiovascular parameters, body composition, strength, aerobic capacity, critical power, mood state, resting energy expenditure, and hormonal and other blood parameters were evaluated.
Heart rate decreased from 53 to 27 beats/min during preparation and increased to 46 beats/min within 1 mo after competition. Brachial blood pressure dropped from 132/69 to 104/56 mmHg during preparation and returned to 116/64 mmHg at 6 mo after competition. Percent body fat declined from 14.8% to 4.5% during preparation and returned to 14.6% during recovery. Strength decreased during preparation and did not fully recover during 6 months of recovery. Testosterone declined from 9.22 to 2.27 ng/mL during preparation and returned back to the baseline level, 9.91 ng/mL, after competition. Total mood disturbance increased from 6 to 43 units during preparation and recovered to 4 units 6 mo after competition.
This case study provides a thorough documentation of the physiological changes that occurred during natural bodybuilding competition and recovery.
Tyler W.D. Muddle, David H. Fukuda, Ran Wang, Joshua J. Riffe, David D. Church, Kyle S. Beyer, Jay R. Hoffman and Jeffrey R. Stout
This study examined the effect of a 10-week introductory judo course on postural control during a bilateral reactionary gripping task using different stance conditions. A total of 20 volunteers were divided into experimental (JDO) and control (CON) groups. Countermovement jump was measured and center of pressure variables were evaluated while performing a bilateral reactionary gripping task under different stance conditions during pre- and posttesting. No interactions were observed for the center of pressure variables (p > .05), while both countermovement jump power (+165.4 W; p = .036) and height (+3.5 cm; p = .018) significantly improved in the JDO group following the 10-week course. Results indicate that 10 weeks of an introductory judo course has no effect on postural control while performing a bilateral reactionary gripping task using different stance conditions.
Kyle S. Beyer, Jeffrey R. Stout, Michael J. Redd, Kayla M. Baker, Haley C. Bergstrom, Jay R. Hoffman and David H. Fukuda
Purpose: To examine the reliability and the maturity-related differences of fatigue thresholds (FTs) among youth males. Methods: Twenty-nine youth males (11–17 y) completed 2 ramp exercise tests on a cycle ergometer. Systemic FTs were calculated from gas exchange and ventilation variables. Localized FTs were calculated from electromyography and near-infrared spectroscopy of the vastus lateralis. All FTs were determined using the maximal distance method and expressed relative to maximal oxygen consumption. All participants were grouped according to the number of years from peak height velocity into PRE- (< −1.5 y), PERI- (−1.5 to +1.5 y) and POST- (> +1.5 y) peak height velocity. Reliability was assessed with intraclass correlation coefficients, and differences between groups were assessed with analysis of variance and Cohen’s d coefficients. Results: Analysis of variance revealed significant group differences with PRE having significantly greater systemic pulmonary FTs than POST, while localized muscular FTs were significantly greater in PRE when compared with PERI and POST. All FTs exhibited excellent reliability (intraclass correlation coefficient > .75) in all maturity groups. Conclusion: Maturity status appears to influence the onset of FTs among youth male athletes, with FTs occurring later in younger athletes. Furthermore, all FTs were reliable measures regardless of maturity.
William P. McCormack, Jay R. Hoffman, Gabriel J. Pruna, Tyler C. Scanlon, Jonathan D. Bohner, Jeremy R. Townsend, Adam R. Jajtner, Jeffrey R. Stout, Maren S. Fragala and David H. Fukuda
During the competitive soccer season, women’s intercollegiate matches are typically played on Friday evenings and Sunday afternoons. The efficacy of a 42-h recovery period is not well understood. This investigation was conducted to determine performance differences between Friday and Sunday matches during a competitive season.
Ten NCAA Division I female soccer players (20.5 ± 1.0 y, 166.6 ± 5.1 cm, 61.1 ± 5.8 kg) were monitored with 10-Hz GPS devices across 8 weekends with matches played on Friday evenings and Sunday afternoons. The players were outside backs, midfielders, and forwards. All players had to participate in a minimum of 45 min/match to be included in the study. Average minutes played, total distance covered, total distance of high-intensity running (HIR) (defined as running at a velocity equal to or exceeding 3.61 m/s for longer than 1 s), the number of HIR efforts, and the number of sprints were calculated for each match. Data for Friday vs Sunday matches were averaged and then compared using dependent t tests.
No differences were seen in minutes played, distance rate, or number of sprints between Friday and Sunday matches. A significant (P = .017) decrease in rate of HIR between Friday (25.37 ± 7.22 m/min) and Sunday matches (22.90 ± 5.70 m/min) was seen. In addition, there was a trend toward a difference (P = .073) in the number of efforts of HIR between Friday (138.41 ± 36.43) and Sunday (126.92 ± 31.31).
NCAA Division I female soccer players cover less distance of HIR in games played less than 48 h after another game. This could be due to various factors such as dehydration, glycogen depletion, or muscle damage.