Effects Of Low-load Blood Flow Restriction And High-load Training On Acute Muscle Swelling, Discomfort, And Exercise Preferences

Few studies directly compare acute muscle swelling effects between upper and lower limb training with blood flow restriction (BFR). While BFR is often seen as more uncomfortable, using lower pressures may reduce discomfort. PURPOSE: Determine if there are differences in acute muscle swelling, discomfort, and exercise preference between low-load BFR and high load resistance exercise in both the upper and lower limbs. METHODS: Sixty-one participants (25.7 ± 7.9 years; 32 males, 29 females) completed four exercise conditions in a partially randomized, blocked sequence: first, upper limbs—randomized between 1) low-load BFR upper limbs (BFR-UL) and 2) high-load upper limbs (HL-UL)—and then lower limb—randomized between 3) low-load BFR lower limbs (BFR-LL) and 4) high-load lower limbs (HL-LL). BFR-LL was performed at 30% one-repetition maximum (1RM) with four sets to failure and a set pressure of 50 mmHg whereas exercises with high-loads were performed at 70% 1RM with four sets of 8-12 repetitions. Acute muscle swelling, discomfort (rated on a 0-10 scale), and exercise preference were assessed, and results were presented as mean (95% confidence interval). RESULTS: The probability of an interaction effect between conditions (BFR-UL: 0.501 [0.464, 0.539 cm], HL-UL: 0.455 [0.416, 0.494 cm], BFR-LL: 0.604 [0.534, 0.674 cm], HL-LL: 0.590 [0.526, 0.653 cm]) and limbs for acute muscle swelling was low (BF10 = 0.235). However, there was evidence to show that there was an acute muscle swelling effect from pre- to post-intervention (Pre-intervention: 3.357 [3.240, 3.474 cm] and post-intervention: 3.894 [3.769, 4.019 cm], BF10: 6.681x10+100). For perceived discomfort, there was strong evidence against any interaction between sets, limbs, and conditions (BF10: 0.083). Participants showed no preference between low-load BFR and high-load exercises for the upper limbs (BF10: 0.236), with anecdotal preferences for the lower limbs (BF10: 0.626). CONCLUSION: Acute muscle swelling and perceived discomfort were similar across upper and lower limbs and between blood flow restriction and high-load exercises, suggesting that low-load, low-pressure blood flow restriction could be a viable alternative for those unable or unwilling to perform high-load training while still supporting muscle hypertrophy.