Can maximal and rapid isometric torque characteristics predict playing level in division I American collegiate football players?

The purpose of this study was to determine if maximal and rapid isometric torque characteristics could discriminate starters from nonstarters in elite Division I American collegiate football players. Sixteen starters (mean ± SD: age = 20.81 ± 1.28 years; height = 184.53 ± 6.58 cm; and mass = 108.69 ± 22.16 kg) and 15 nonstarters (20.40 ± 1.68 years; 182.27 ± 10.52 cm; and 104.60 ± 22.44 kg) performed isometric maximal voluntary contractions (MVCs) of the leg flexor and extensor muscle groups. Peak torque (PT), rate of torque development (RTD), the time to peak RTD (TTRTDpeak), contractile impulse (IMPULSE), and absolute torque values (TORQUE) at specific time intervals were calculated from a torque-time curve. The results indicated significant and nonsignificant differences between starters and nonstarters for the early rapid leg flexion torque characteristics that included RTD, IMPULSE, and TORQUE at 30 and 50 milliseconds, and TTRTDpeak. These variables also demonstrated the largest effect sizes of all the variables examined (0.71-0.82). None of the leg extensor variables, leg flexion PT, or later leg flexion rapid torque variables (≥ 100 milliseconds) were significant discriminators of playing level. These findings suggest that the early rapid leg flexion torque variables may provide an effective and sensitive muscle performance measurement in the identification of collegiate football talent. Further, coaches and practitioners may use these findings when designing training programs for collegiate football players with the intent to maximize rapid leg flexion characteristics.

Relationships between rapid isometric torque characteristics and vertical jump performance in division I collegiate American football players: influence of body mass normalization.

The purpose of the present study was to examine the relationships between absolute and body mass-normalized rapid isometric torque variables and vertical jump (VJ) performance of the leg extensors and flexors in elite National Collegiate Athletic Association Division I Football Bowl Subdivision collegiate American football players. Thirty-one players performed isometric maximal voluntary contractions of the leg extensor and flexor muscle groups and a countermovement VJ. Rate of torque development (RTD) and the contractile impulse (IMPULSE) were determined from 0 to 30, 0 to 50, 0 to 100, and 0 to 200 milliseconds from the onset of muscular contraction. The relationships between absolute and normalized rapid torque variables and VJ performance were assessed using correlation coefficients (r). There were no significant correlations (p > 0.05) observed between the absolute rapid torque variables and VJ performance, except for leg flexion RTD at 0-200 milliseconds (p = 0.024). All normalized rapid torque variables of the leg extensors and flexors were significantly correlated to VJ performance (p ≤ 0.001-0.026). These findings indicated that normalizing rapid torque variables to body mass improves the relationships between isometric rapid torque variables and VJ performance and normalized leg extension and flexion are both similarly related to VJ performance. Strength and conditioning professionals may use these findings in an attempt to identify and monitor dynamic sport performance. Furthermore, future studies examining the relationship between dynamic on the field performances and laboratory-based isometric strength testing may consider including normalized rapid torque variables.