Low-load resistance training with blood flow restriction produced similar increases in muscle cross-sectional area (10.0%) compared to high-load resistance training (10.0%) after 10 weeks, with metabolic stress associated with hypertrophy only in the low-load group.
RCT (n=30)
Randomized and balanced way according to quartiles of baseline CSA and 1-RM values
No
Does blood flow restriction during high or low load resistance training improve muscle hypertrophy and strength compared to high load resistance training alone in young men?
The addition of blood flow restriction to resistance training contributes to neuromuscular adaptations primarily when performed with low loads, where metabolic stress is associated with muscle hypertrophy.
Absolute Event Rate: 10% vs 10%
The metabolic stress induced by blood flow restriction (BFR) during resistance training (RT) might maximize muscle growth. However, it is currently unknown whether metabolic stress are associated with muscle hypertrophy after RT protocols with high-or low load. Therefore, the aim of the study was to compare the effect of high load RT (HL-RT), high load BFR (HL-BFR), and low load BFR (LL-BFR) on deoxyhemoglobin concentration HHb (proxy marker of metabolic stress), muscle cross-sectional area (CSA), activation, strength, architecture and edema before (T1), after 5 (T2), and 10 weeks (T3) of training with these protocols. Additionally, we analyzed the occurrence of association between muscle deoxygenation and muscle hypertrophy. Thirty young men were selected and each of participants' legs was allocated to one of the three experimental protocols in a randomized and balanced way according to quartiles of the baseline CSA and leg extension 1-RM values of the dominant leg. The dynamic maximum strength was measured by 1-RM test and vastus lateralis (VL) muscle cross-sectional area CSA echo intensity (CSA echo ) and pennation angle (PA) were performed through ultrasound images. The measurement of muscle activation by surface electromyography (EMG) and HHb through near-infrared spectroscopy (NIRS) of VL were performed during the training session with relative load obtained after the 1-RM, before (T1), after 5 (T2), and 10 weeks (T3) training. The training total volume (TTV) was greater for HL-RT and HL-BFR compared to LL-BFR. There was no difference in 1-RM, CSA, CSA echo, CSA echo /CSA, and PA increases between protocols. Regarding the magnitude of the EMG, the HL-RT and HL-BFR groups showed higher values than and LL-BFR. On the other hand, HHb was higher for HL-BFR and LL-BFR. In conclusion, our results suggest that the addition of BFR to exercise contributes to neuromuscular adaptations only when RT is performed with low-load. Furthermore, we found a significant association between the changes in HHb (i.e., metabolic stress) and increases in muscle CSA from T2 to T3 only for the LL-BFR, when muscle edema was attenuated.
Biazon et al. (Wed,) conducted a rct in Healthy young men (n=30). Low-load and high-load blood flow restriction training vs. High-load resistance training (80% 1-RM) was evaluated on Increase in muscle cross-sectional area (CSA) at 10 weeks. Low-load resistance training with blood flow restriction produced similar increases in muscle cross-sectional area (10.0%) compared to high-load resistance training (10.0%) after 10 weeks, with metabolic stress associated with hypertrophy only in the low-load group.