Faster intrinsic rate of torque development in elbow flexors than knee extensors: Effect of muscle architecture?

Abstract We studied the effect of pennate vs. fusiform muscle architecture on the rate of torque development (RTD) by examining the predominately fusiform elbow flexors (EF) and highly-pennate knee extensors (KE). Seventeen male volunteers (28.4 ± 6.2 years) performed explosive isometric EF and KE contractions (MVCs). Biceps brachii and vastus lateralis fascicle angles were measured to confirm their architecture, and both the rate of voluntary muscle activation (root-mean-square EMG in the 50 ms before contraction onset; EMG-50) and electromechanical delay (EMD; depicting muscle-tendon series elasticity) were assessed as control variables to account for their influence on RTD. MVC torque, early (RTD50) and late (RTD200) RTDs were calculated and expressed as absolute and normalized values. Absolute MVC torque (+412%), RTD50 (+215%), and RTD200 (+427%) were significantly (p