The effects of regional quadriceps architecture on angle-specific rapid torque expression

Abstract

Abstract Evaluating anatomical contribution to performance can build an understanding of muscle mechanics and guide physical preparation. While the impact of anatomy on muscular performance is well studied, the effects of regional quadriceps architecture on rapid torque expression are less clear. Regional (proximal, middle, distal) quadriceps (vastus lateralis, rectus femoris, lateral and anterior vastus intermedius) thickness (MT), pennation angle (PA), and fascicle length (FL) of 24 males (48 limbs) were assessed via ultrasonography. Participants performed isometric contractions at 40º, 70º, and 100º of knee flexion to evaluate rate of torque development from 0-200 ms (RTD0 − 200). Measurements were repeated on three separate occasions with the greatest RTD0 − 200 and average muscle architecture measures used for analysis. Linear regression models predicting angle-specific RTD0 − 200 from regional anatomy provided adjusted simple and multiple correlations (√adjR2) with bootstrapped compatibility limits to assess magnitude. Mid-rectus femoris MT (√adjR2 = 0.41–0.51) and mid-vastus lateralis FL (√adjR2 = 0.41–0.45) were the best single predictors of RTD0 − 200, and the only measures to reach acceptable precision with 99%CL. Small simple correlations were found across all regions and joint angles between RTD0 − 200 and vastus lateralis MT (√adjR2 = 0.28 ± 0.13; mean ± SD), vastus lateralis FL (√adjR2 = 0.33 ± 0.10), rectus femoris MT (√adjR2 = 0.38 ± 0.10), and lateral vastus intermedius MT (√adjR2 = 0.24 ± 0.10). Multiple correlations are reported within the article. Researchers should measure mid-region rectus femoris MT and vastus lateralis FL to efficiently and robustly evaluate potential anatomical contributions to changes in rapid knee extension torque expression.