Muscle Damage and Inflammation Marker Responses to Acute and Chronic Blood Flow Restricted Resistance Exercise

Low intensity resistance exercise with blood flow restriction (BFR) has been shown to increase muscle protein synthesis, however, the acute and chronic effects of BFR on muscle damage and muscle inflammatory markers are not as well known. PURPOSE: To compare muscle damage and muscle inflammatory marker responses to acute and chronic resistance exercise with and without blood flow restriction in young men (18-30 yrs). METHODS: Subjects were assigned to either a high intensity group (HI n=10) (70% 1RM, 3 sets, 10 reps), low intensity group (LI n=6) (45% 1RM, 3 sets, 10 reps), a blood flow restriction group (BFR n=7) (20% 1RM, 4 sets, 30-15-15-15 reps), or a control group (CON n=7). The training programs were 3 days/wk for 6 weeks for knee flexion/extension and 4 upper body exercises. Blood samples were obtained pre and post training at pre-exercise (PRE), and immediate post-exercise (IP) to assess serum levels of Creatine Kinase (CK) and Endothelin-1 (ET-1). RESULTS: There were no significant changes in resting ET-1 level in response to training and ET-1 did not significantly change from rest to IP. There were significant (p<0.01) time, time × group (p<0.05), training × group (p<0.05), and training × time × group effects (p<0.05) for CK. HI showed significant (p<0.05) increases in CK levels from PRE to IP both pre and post training, while also showing a significant increase in resting CK level after training. BFR had a significant (p<0.05) increase in CK levels from PRE to IP only after training. The acute CK percent change post training showed a significant (p<0.05) group effect, as HI had significantly (p<0.05) greater increases in CK levels than LI, BFR, and CON (HI 13.6%, LI 3.5%, BFR 3.5%, CON 2.2%). CONCLUSION: Muscle damage marker responses to acute bouts of resistance exercise were similar for traditional high intensity and blood flow restricted groups, and only the high intensity group showed an adaptation to chronic training. The muscle inflammatory marker response was not affected by either acute or chronic resistance exercise.