Acute changes in muscle thickness, edema, and blood flow are not different between low-load blood flow restriction and non-blood flow restriction.

The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean ± SD; 22 ± 2years) volunteered to perform an acute exercise bout that consisted of 75 (1 × 30, 3 × 15) isokinetic, reciprocal, concentric-only, submaximal (30% of peak torque), forearm flexion and extension muscle actions. Pretest, immediately after (posttest), and 5-min after (recovery) completing the 75 repetitions, muscle thickness and echo intensity were assessed from the biceps brachii and triceps brachii muscles and muscle blood flow was assessed from the brachial artery. There were no between group differences for any of the dependent variables, but there were significant simple and main effects for muscle and time. Biceps and triceps brachii muscle thickness increased from pretest (2.13 ± 0.39 cm and 1.88 ± 0.40 cm, respectively) to posttest (2.58 ± 0.49 cm and 2.17 ± 0.43 cm, respectively) for both muscles and remained elevated for the biceps brachii (2.53 ± 0.43 cm), but partially returned to pretest levels for the triceps brachii (2.06 ± 0.41 cm). Echo intensity and muscle blood flow increased from pretest (98.0 ± 13.6 Au and 94.5 ± 31.6 ml min-1 , respectively) to posttest (109.2 ± 16.9 Au and 312.2 ± 106.5 ml min-1 , respectively) and pretest to recovery (110.1 ± 18.3 Au and 206.7 ± 92.9 ml min-1 , respectively) and remained elevated for echo intensity, but partially returned to pretest levels for muscle blood flow. The findings of the present study indicated that LLBFR and LL elicited comparable acute responses as a result of reciprocal, concentric-only, forearm flexion and extension muscle actions.