Force-velocity Characteristics of the Leg Muscles and Anaerobic Performance in African-American and Caucasian College-aged Males

PURPOSE: To compare vertical jump height and power and sprint time in African- American and Caucasian college-aged males, to compare isokinetic knee extension and flexion torques between the two groups, and to examine correlations between these variables. METHODS: The participants were fifty recreationally active, college-aged males (23 African-American and 27 Caucasian). Physical activity was assessed using the Behavioral Risk Factor Surveillance Survey (BRFSS) Physical Activity module, body composition was determined using the Bod Pod, and anthropometric measures (height, weight, and thigh circumference) were taken. Subjects performed a 100-m sprint on an outdoor track and a countermovement vertical jump. Vertical jump power was calculated using both the Lewis and Sayers equations. Isokinetic knee extension and flexion testing were performed on a Biodex System 3 at angular velocities of 60, 120, 210, 300, and 400 degrees per second. Peak torques and relative torques (using torque generated at 60 degrees per second as the reference) were used in data analysis. RESULTS: There were no significant differences between African-Americans and Caucasians in anthropometric variables, physical activity, wind velocity measured during the 100-m dash, or isokinetic extension and flexion peak and relative torques. When controlling for body fat percentage, there were significant differences between the two groups with African- Americans having greater jump heights (p<.001), greater vertical jump power using the Sayers equation (p<.05), and faster 100-m sprint times (p<.05). In the entire sample, vertical jump height significantly correlated with 100-m sprint time (r = -.769, p<.001). Vertical jump power using both equations significantly correlated with isokinetic knee extension peak torque at all angular velocities and with knee flexion at 120, 300 and 400 degrees per second. There were no significant correlations between 100-m sprint times and isokinetic knee extension and flexion variables. CONCLUSION: African- Americans performed better than Caucasians in the vertical jump and 100-m dash but not in isokinetic knee flexion and extension testing. However, African-Americans showed a trend towards greater peak torques at high angular velocities indicative of faster speeds of muscle contraction.