Abstract
Volunteers provided data comparing two classes (integrated electromyography, anthropometry) of predictor variables to explain the variance associated with calf press performance done against inertial resistance. Subjects performed three 3-set 10-repetition workouts, each starting with body mass and body surface area determinations. During the first and last repetitions per set, integrated electromyography (IEMG) was collected from the lateral and medial gastrocnemius (LG, MG), and soleus (SOL). Multivariate regression revealed all prediction equations were significant (p < 0.05). For tenth repetition dependent variables, anthropometry explained more variance than did IEMG; perhaps due to greater series elastic element involvement of the musculotendinous unit, less motor unit recruitment may have occurred. IEMG was generally more correlated to first than tenth repetition dependent variables. Among IEMG variables, SOL data explained more variance seen with tenth repetition concentric variables; yet correlations between dependent measures and MG data were usually high for first repetition eccentric, but low for tenth repetition, variables. The diverse levels of variance explained among independent variable classes illustrate pronounced differences in what they contribute to performance, and within IEMG variables suggests considerable anatomical/histochemical differences among the triceps surae.