Training Distribution And The Acquisition Of Maximal Isometric Elbow Flexion Strength

Abstract

PURPOSE This study compared massed versus distributed muscle contractions in the acquisition of maximal isometric elbow flexion strength, to understand the role of motor learning in resistive exercise. METHODS Twenty-six sedentary, collegeaged females were matched and randomly assigned to one of two groups. The massed group (n=13) completed 15 maximal isometric elbow flexion strength trials in one session, while the distributed group (n=13) performed five such contractions on three successive days. After a 2-week and 3 month rest interval, both groups returned to perform another five maximal isometric elbow flexion strength trials to assess retention of any potential strength gains. Elbow flexion torque and surface electromyography (SEMG) of the biceps and triceps were monitored concurrently. RESULTS There was a significant (P <0.05) increase in strength in both groups from Block 1 (first 5 contractions) to Block 2 (first retest) and from Block 1 to Block 3 (second retest). Both groups exhibited a an increase (P <0.05) in biceps root-mean-square (RMS) SEMG amplitude. A significant (P <0.05) decrease in triceps RMS SEMG amplitude was found between Block 1 and Block 2 for both groups. However, a significant (P <0.05) increase was found between Block 2 and 3. CONCLUSIONS These results suggest that there is flexibility in resistive exercise schedules. There was a continued increase in neural drive to the agonist muscle throughout testing. This was accompanied by a reduction in antagonist coactivation that was a short-term (2-weeks) training effect, dissipated over the longer rest interval (3-months).