Comparison of EMG activity among Low-intensity Exercise with and without KAATSU and Ischemic Conditions

Abstract

It is established that electromyographic (EMG) activity increases during ischemia with low-intensity exercise compared with normal conditions. Since low-intensity (20% of one repetition maximum, 1 -RM) exercise combined with restricted venous blood flow (KAATSU) produced substantial muscle hypertrophy and strength gain, we hypothesized that EMG activity in working muscle could be increased during low-intensity KAATSU exercise. PURPOSE: To compare the magnitude changes in EMG activity during low-intensity exercise with and without KAATSU and ischemic conditions. METHODS: Seven male volunteers [mean (SD) age: 24.9 (3.3) years] performed two modes (3 sets of 10 reps with 30 sec rest between sets and 30 consecutive reps) of single arm curl exercise (20% of a predetermined 1-RM) during three different conditions (Control, KAATSU and Ischemia). In the KAATSU condition, a specially designed elastic cuff belt (30 mm wide) was placed at the most proximal position of the upper arm and inflated to a pressure of 30% higher than their systolic blood pressure. During the ischemic condition, blood flow was occluded by over 300 mmHg of occlusive pressure via occlusion cuff. Surface EMG was recorded from muscle belly of the biceps brachii muscle, and mean integrated EMG (iEMG) was analyzed. RESULTS: During 3 sets of 10 reps exercise, a gradual increase (P < 0.01) in iEMG was observed in Ischemia but not in both KAATSU and Control. The magnitude increase in iEMG was higher (P < 0.01) in Ischemia (101% higher at end of 3 sets) compared with KAATSU (52%) and Control (23%). On the other hand, there was similar increase in iEMG between Ischemia (92%) and KAATSU (78%) during 30 consecutive reps of exercise, and both conditions were higher (P < 0.05) than that of Control (40%). After 30 consecutive reps of exercise, both KAATSU and Control conditions performed additional sets of exercise (3 sets of 15 reps with 30 sec rest between sets). At the end of 3 sets of 15 reps, the increase in iEMG was 244% for KAATSU and 86% for Control. The increase in iEMG was larger (P < 0.01) in KAATSU compared with Control. CONCLUSION:Increase in iEMG during KAATSU may be an important factor for KAATSU training-induced muscle hypertrophy and strength gain.