SPRINT PERFORMANCE IS RELATED TO THIGH MUSCLE SHAPE IN MALE 100-M SPRINTERS

Abstract

Sprinters possess greater muscle thickness in the upper but not lower portion of the thigh than distance runners. However, the reasons for this phenomenon are unclear. PURPOSE To investigate 1) the relationships between sprint performance and thigh muscle thickness (MTH) distributions, and 2) the relationships between MTH and MRI-measured muscle cross-sectional area (CSA) and volume in the thigh muscles. METHODS Forty-five male 100-m sprinters were recruited for the study. MTH was measured by B-mode ultrasound at 5 sites [anterior (at 30, 50, and 70% thigh length) and posterior (at 50 and 70%) thigh]. The fat-muscle interface and the muscle-bone interface were identified from recording of the ultrasound image, and the distance from the fat-muscle interface and muscle-bone interface was accepted as MTH. In the second study, the quadriceps, hamstrings and adductors muscle CSAs and volumes were measured using MRI (1-cm slice thickness) in 20 subjects. MTH of the anterior and posterior thigh was measured by ultrasound, at the same sites as CSA measurements. RESULTS Anterior thigh MTH (absolute and relative to limb length) was correlated with seasonal-best 100-m sprint time at 30% (r= −0.46 and r= −0.41, respectively, both p < 0.01), but not at 50% or 70%. Absolute and relative MTH at 50%(r= −0.49 and r= −0.42, respectively, both p < 0.01) and 70% posterior thigh (r= −0.43, p < 0.01 and r= −0.36, p < 0.05) were correlated with 100-m sprint time. Difference in anterior thigh MTH between 30% and 70% (r= −0.54, p < 0.01) was correlated with 100-m performance. MTH at 30% anterior thigh was correlated (P < 0.01) to 30% adductors muscle CSA (r=0.92) and adductors muscle volume (r=0.84). MTH at 50% and 70% posterior thigh was correlated (p < 0.01) to the corresponding MRI measured hamstrings muscle CSA (r=0.64 and r=0.59, respectively). CONCLUSION Greater muscle size at the upper portion of the thigh is associated with larger adductors muscle size, which is related to sprint performance.