The Acute Muscular Response to Passive Movement and Blood Flow Restriction

Purpose: To compare the acute effects of passive movement combined with blood flow restriction (PM+BFR) to passive movement (PM) or blood flow restriction alone (BFR). Methods: 20 healthy participants completed: time control (TC), PM, BFR, and PM+BFR (one per leg, over 2 days; randomized). For PM, a dynamometer moved the leg through 3 sets of 15 knee extensions/flexions (90° at 45°/second). For BFR, a cuff was inflated to 80% arterial occlusion pressure on the upper leg. Measurements consisted of: anterior muscle thickness at 60% and 70% of the upper leg before and after (-0, -5, and -10 minutes) conditions, ratings of perceived effort and discomfort before conditions and after each set, and of the vastus lateralis during conditions. Data, presented as mean (SD), were compared using Bayesian RMANOVA, except for perceived effort and discomfort, which were compared using a Friedman\u27s Test (non-parametric). Results: 60% [∆cm before-after-0: TC=0.04 (0.09), PM=-0.01 (0.15), BFR=0.00 (0.11), PM+BFR=0.01 (0.22)] and 70% [∆cm before-after-0: TC=0.01 (0.09), PM=-0.01 (0.15), BFR=0.02 (0.11), PM+BFR=-0.03 (0.22)] muscle thickness did not change. Perceived effort was greater than TC following PM (p=0.05) and PM+BFR (p=.001). Perceived discomfort was greater following BFR and PM+BFR compared to TC (all p≤0.002) and PM (all p≤0.010). Changes in deoxygenation [e.g. channel 1; ∆μM start set 1-end set 3: TC=0.9 (1.2), PM=-1.2 (1.9), BFR=10.3 (2.7), PM+BFR=10.3 (3.0)] were generally greater with BFR and PM+BFR (BFinclusion =1.210e+13). Conclusion: Acute muscular responses to PM+BFR are not augmented over the effect of BFR alone