Influence of continuous or intermittent blood flow restriction on muscle activation during low-intensity multiple sets of resistance exercise.

Low-intensity resistance exercise with blood flow restriction (BFR) has been shown to induce a prominent increase in muscle activation in response to muscle fatigue. However, the magnitude of muscle fatigue between continuous (Con-BFR) and intermittent BFR (Int-BFR, BFR only during exercise) is currently unknown. We examined the effect of Con-BFR or Int-BFR on muscle activation during exercise. Unilateral arm curl exercise (20% of one-repetition maximum, four sets, 30 sec rest period between sets) was performed without (CON) or with Con-BFR or Int-BFR. During BFR conditions, the cuff was inflated to 160 mmHg on the proximal region of testing arm. Surface electromyography (EMG) was recorded from the biceps brachii muscle, and integrated EMG (iEMG) was analyzed. During the exercise, iEMG increased progressively in Con-BFR and Int-BFR and both conditions were greater (p < 0.05) than CON at the 3rd and 4th set. However, there were no differences (p > 0.05) in iEMG between Con-BFR and Int-BFR during exercise (∼2.45 and ∼2.40 times, respectively). Thus, the magnitude of increase in muscle activation may be similar between Con-BFR and Int-BFR when BFR exercise was performed at a high level of cuff pressure intensity.