Impact of Complete Intermittent Blood Flow Restriction in Upper Limbs Strength and Neural Function

Purpose: We aimed to investigate the chronic effects of low-load strength training (LT) with complete intermittent blood flow restriction (IBFR) on neural adaptations and strength in biceps brachii. Methods: Nineteen volunteers were randomly assigned into two different 9-week training protocols consisting of three assessment weeks and six training weeks: (a) LT with complete IBFR (LT-IBFR; n = 10) and (b) LT without complete IBFR (LT; n = 9). Strength was evaluated by predicted 1 repetition maximum (1RM) at weeks 1, 5, and 9 and neural function by root mean square (RMS) and median frequency (MDF) at sessions 1, 7, and 12 during the first three and last three repetitions. Both groups performed three sets of Scott curl with 20% of predicted 1RM interspersed with 90s rest twice a week. Results: No changes were found in predicted 1RM throughout the training protocols nor between groups. LT-IBFR group showed lower RMS in the first set than LT for the first three repetitions and higher RMS in all sets for the last three repetitions with decreases in this value across the sets with no longitudinal changes for both groups. MDF in the first three repetitions did not differentiate between groups, however, in the last three repetitions, MDF were lower for LTIBFR group in all sets and it increased across the sets for this condition with no chronical changes for both groups in both repetitions zones. These results suggest that LT-IBFR may be ineffective for increasing Q5 strength and it did not promote chronic neural adaptations.