Terry L. Dupler

Anthropometric and performance differences among high-school football players.

Dupler, TL, Amonette, WE, Coleman, AE, Hoffman, JR, and Wenzel, T. Anthropometric and performance differences among high-school football players. J Strength Cond Res 24(8): 1975-1982, 2010-The purpose of this study was to examine physical and performance differences between grade levels and playing positions within High-School football players. Two thousand three hundred and twenty-seven athletes were tested for height, weight, 40-yd sprint time, proagility time, and vertical jump height. Mean scores across age groups and playing positions were compared using repeated-measures analysis of variance (ANOVA) and 1-way ANOVAs. The results indicate that defensive players in the 11th and 12th grades were significantly faster in the 40-yd sprint, quicker in the proagility, and generated more power than 9th and 10th grade defensive players across all positions (p < 0.05). Similarly, offensive players in the 11th and 12th grades were significantly faster, quicker, and jumped higher than did football players in lower grades (p < 0.05). Overall, these data suggest that there are distinct differences in the physical and performance characteristics of high-school football players. The greatest difference is observed between the sophomore and junior years. Older, more mature athletes are faster, quicker, and capable of generating more power than younger athletes. Practically, these data lend support to the common 3-tiered approach (i.e., Freshman, Junior Varsity, and Varsity) most high schools use for their football programs. This approach is likely indicated to allow for physical maturation of young players and to allow time for the development of strength, power, speed, and agility necessary to compete with older players.

PEAK VERTICAL JUMP POWER ESTIMATIONS IN YOUTHS AND YOUNG ADULTS

Abstract Amonette, WE, Brown, LE, De Witt, JK, Dupler, TL, Tran, TT, Tufano, JJ, and Spiering, BA. Peak vertical jump power estimations in youths and young adults. J Strength Cond Res 26(7): 1749–1755, 2012—The purpose of this study was to develop and validate a regression equation to estimate peak power (PP) using a large sample of athletic youths and young adults. Anthropometric and vertical jump ground reaction forces were collected from 460 male volunteers (age: 12–24 years). Of these 460 volunteers, a stratified random sample of 45 subjects representing 3 different age groups (12–15 years [n = 15], 16–18 years [n = 15], and 19–24 years [n = 15]) was selected as a validation sample. Data from the remaining 415 subjects were used to develop a new equation (“Novel”) to estimate PP using age, body mass (BM), and vertical jump height (VJH) via backward stepwise regression. Independently, age (r = 0.57), BM (r = 0.83), and VJ (r = 0.65) were significantly (p < 0.05) correlated with PP. However, age did not significantly (p = 0.53) contribute to the final prediction equation (Novel): PP (watts) = 63.6 × VJH (centimeters) + 42.7 × BM (kilograms) − 1,846.5 (r = 0.96; standard error of the estimate= 250.7 W). For each age group, there were no differences between actual PP (overall group mean ± SD: 3,244 ± 991 W) and PP estimated using Novel (3,253 ± 1,037 W). Conversely, other previously published equations produced PP estimates that were significantly different than actual PP. The large sample size used in this study (n = 415) likely explains the greater accuracy of the reported Novel equation compared with previously developed equations (n = 17–161). Although this Novel equation can accurately estimate PP values for a group of subjects, between-subject comparisons estimating PP using Novel or any other previously published equations should be interpreted with caution because of large intersubject error (± >600 W) associated with predictions.

Physical Determinants of Interval Sprint Times in Youth Soccer Players

Abstract Relationships between sprinting speed, body mass, and vertical jump kinetics were assessed in 243 male soccer athletes ranging from 10-19 years. Participants ran a maximal 36.6 meter sprint; times at 9.1 (10 y) and 36.6 m (40 y) were determined using an electronic timing system. Body mass was measured by means of an electronic scale and body composition using a 3-site skinfold measurement completed by a skilled technician. Countermovement vertical jumps were performed on a force platform - from this test peak force was measured and peak power and vertical jump height were calculated. It was determined that age (r=-0.59; p<0.01), body mass (r=-0.52; p<0.01), lean mass (r=-0.61; p<0.01), vertical jump height (r=-0.67; p<0.01), peak power (r=-0.64; p<0.01), and peak force (r=-0.56; p<0.01) were correlated with time at 9.1 meters. Time-to-complete a 36.6 meter sprint was correlated with age (r=-0.71; p<0.01), body mass (r=- 0.67; p<0.01), lean mass (r=-0.76; p<0.01), vertical jump height (r=-0.75; p<0.01), peak power (r=-0.78; p<0.01), and peak force (r=-0.69; p<0.01). These data indicate that soccer coaches desiring to improve speed in their athletes should devote substantive time to fitness programs that increase lean body mass and vertical force as well as power generating capabilities of their athletes. Additionally, vertical jump testing, with or without a force platform, may be a useful tool to screen soccer athletes for speed potential.

Neurocognitive responses to a single session of static squats with whole body vibration

Abstract Amonette, WE, Boyle, M, Psarakis, MB, Barker, J, Dupler, TL, and Ott, SD. Neurocognitive responses to a single session of static squats with whole body vibration. J Strength Cond Res 29(1): 96–100, 2015—The purpose of this study was to determine if the head accelerations using a common whole body vibration (WBV) exercise protocol acutely reduced neurocognition in healthy subjects. Second, we investigated differential responses to WBV plates with 2 different delivery mechanisms: vertical and rotational vibrations. Twelve healthy subjects (N = 12) volunteered and completed a baseline (BASE) neurocognitive assessment: the Immediate Postconcussion Assessment and Cognitive Test (ImPACT). Subjects then participated in 3 randomized exercise sessions separated by no more than 2 weeks. The exercise sessions consisted of five 2-minute sets of static hip-width stance squats, with the knees positioned at a 45° angle of flexion. The squats were performed with no vibration (control [CON]), with a vertically vibrating plate (vertical vibration [VV]), and with a rotational vibrating plate (rotational vibration [RV]) set to 30 Hz with 4 mm of peak-to-peak displacement. The ImPACT assessments were completed immediately after each exercise session and the composite score for 5 cognitive domains was analyzed: verbal memory, visual memory, visual motor speed, reaction time, and impulse control. Verbal memory scores were unaffected by exercise with or without vibration (p = 0.40). Likewise, visual memory was not different (p = 0.14) after CON, VV, or RV. Significant differences were detected for visual motor speed (p = 0.006); VV was elevated compared with BASE (p = 0.01). There were no significant differences (p = 0.26) in reaction time or impulse control (p = 0.16) after exercise with or without vibration. In healthy individuals, 10 minutes of 30 Hz, 4-mm peak-to-peak displacement vibration exposure with a 45° angle of knee flexion did not negatively affect neurocognition.

Physical Determinants of Velocity and Agility in High School Football Players: Differences Between Position Groups

PURPOSE: The purpose of this study was to develop prediction equations for speed and agility within different position groupings of High School football players using age, height, body mass, and vertical jump as predictor variables. METHODS: A total of 987 athletes (14-18y) completed testing at a regional high school football combine. Athletes were divided into three groups according to their playing position: Linemen (LM; n = 354; 16.3 6 0.8y; 179.4 6 5.6cm; 105.1 6 18.3kg), Big Skill Players (BSP; n = 189; 16.2 6 0.9y; 175.5cm 6 5.2cm; 85.7 6 11.6kg), and Skill Players (SP; n = 444; 16.4 6 09y; 175.8 6 5.9cm; 75.5 6 8.9kg). The LM included offensive tackles, offensive guards, centers, defensive tackles, and defensive ends. BSP included linebackers, running backs, and tight ends. SP included wide receivers, corner backs, safeties, and quarterbacks. In sequential order, height (HT), body mass (BM), 40 yard sprint (40Y), 5-10-5 shuttle (SH), and countermovement vertical jump height (VJ) were determined on each player. HT and BM were measured using a stadiometer and an electronic scale, respectively. 40Y and SH were measured using hand-held stop watches; the highest of two trials was used for analysis. Two vertical jumps were completed on an electronic pressure mat; vertical jump height was calculated using flight time. For each position grouping, correlations (Pearson’s r) were calculated between the four predictor variables