Abstract:
Purpose: To determine if proximal limb blood flow restriction (BFR) influences muscular performance and recovery of the distal limb musculature (i.e., gastrocnemius, soleus, and tibialis anterior). Methods: Participants (N = 20; M±SD: 23.0 ± 3.8 years; 174.1 ± 9.0 cm; 77.9 ± 13.0 kg; 23.8 ± 8.6%body fat) completed a baseline visit and two experimental conditions consisting of exercise only (control; CON) and exercise with BFR. CON and BFR were performed in a counter-balanced order. Personal tourniquet pressure (PTP) was determined in each leg using the Delfi PTS II system at the BFR session only. Participants underwent the following assessments before and after each experimental visit: anatomical cross-sectional area (CSA) of the gastrocnemius, toe tap test, average stride length test, and counter-movement jump. The exercise protocol consisted of 3 sets of 15 repetitions of ankle plantarflexion (PF) and dorsiflexion (DF at 60 and 500 degrees per second, respectively, using an isokinetic dynamometer. Average force per repetition and total work performed were measured by the isokinetic dynamometer for both PF and DF during exercise. The only difference between BFR and CON was the application of BFR during the exercise protocol (unilateral occlusion at 80% of PTP, applied 30 s before initiating exercise on each leg). Two-way repeated measures analysis of variance (ANOVA) was performed to determine if changes in CSA, and measures of muscular strength and performance differed by BFR application (condition x time). Significance was set as p<0.05. Results: Average force per repetition and total work performed was lower during BFR compared to CON for both PF and DF (p<0.05 for both). CSA was increased post- versus pre-exercise following BFR compared to CON (p<0.05). Likewise, toe taps and stride length performance was decreased post- versus pre-exercise following BFR compared to CON(both p<0.05). Jump height decreased post- compared to pre-exercise with no difference between conditions (p<0.05). Conclusion: The addition of BFR to exercise elicited higher levels of muscular fatigue and decreased muscular performance compared to CON. These impairments were far greater than expected, producing significant reductions in force production, neuromuscular activation, and recovery rate.
