Effects of blood flow restriction on muscle size and gene expression in muscle during immobilization: A pilot study

PURPOSE: Muscle mass is known to rapidly decrease with muscle disuse. Previous reports suggest that repetitive blood flow restriction (BFR) mitigates the reduction of muscle mass with disuse. However, the effects of BFR on muscle atrophy and gene expression levels in muscle during cast immobilization have not been clarified. METHODS: To investigate the effect of BFR on muscle atrophy and gene expression levels during cast immobilization in humans, we recruited 10 healthy males who were randomly divided into the control and BFR treatment groups. All subjects were immobilized with a cast for 14 days. BFR treatment was conducted only in the BFR group. We evaluated cross sectional area (CSA) of thigh muscles by magnetic resonance imaging before and 14 days after cast immobilization. A percutaneous biopsy of the vastus lateralis muscle (VL) was performed before and 1, 7, and 14 days after cast immobilization. Expression of genes related to muscle atrophy and synthesis were evaluated using real‐time PCR. RESULTS: The CSA of the VL and the thigh flexor muscles were significantly decreased in both groups; however, percent decrease in CSA was significantly smaller in the BFR group compared with the control group. In two‐way repeated ANOVA analysis, the time × treatment interaction in gene expression of the muscle‐specific ubiquitin ligases muscle ring finger 1 (MuRF1) was significant, and elevated MURF1 expression level by cast immobilization was seemed to be suppressed by the BFR treatment. CONCLUSION: BFR treatment may prevent reduced VL and thigh flexor muscles and increased MuRF1 expression level during cast immobilization. Further study is required to confirm these results.