Running economy and metabolic responses following exercise- induced muscle damage at two different velocities

Abstract

Eccentric contractions predispose muscles to damage. Type II muscle fibers are more susceptible than type I, so it seems that contraction velocity interferes in mechanical stress and thus muscle damage. The purpose of this study was to investigate the effect of contraction velocity of acute dominant knee extensor eccentric exercise-induced muscle damage (EIMD) on running economy and metabolic responses in trained young females. Twenty-one trained young females were randomly assigned into two groups: high-velocity contraction eccentric exercise (240°s-1) and low-velocity (60°s-1). To induce muscle damage subjects, in high and low-velocity groups performed 20 and 5 sets of 15 repetitions, respectively, with a load equal to 150٪ of the maximal voluntary isometric contraction (MVIC) torque of knee extensors with a dominant limb. Then; MVIC of knee extensors was recorded before, one and 48 h after EIMD, and running economy (submaximal Steady-state vo2), and metabolic responses were recorded at 60, 70, and 80% of pre-determined vVO2max, 24 h before and 48 h after EIMD. Both exercise bouts resulted in significant changes in MVIC of knee extensor (p<0.05) with no significant difference between the two groups. No significant difference was found in running economy and metabolic responses in three different intensities following both exercise conditions between the two groups. Results of the analysis showed that a four-fold difference in contraction velocity of eccentric exercise-induced muscle damage was not sufficient to induce a difference in muscle damage, running economy, and metabolic responses when the knee extensor muscle tension duration was equalized.

Keywords

• eimd
• contraction velocity
• running economy
• metabolic responses
• trained female