The Effect Of Blood Flow Restriction Resistance Training On Exercise-induced Hypoalgesia

Abstract

PURPOSE: Exercise-induced hypoalgesia (EIH) describes a reduction in pain sensitivity following exercise, characterised by an elevation in pain threshold or decrease pain intensity ratings following exercise. Recent research suggests that performing light-load resistance exercise with blood flow restriction (BFR-RE) may have a pain-modulation effect. Therefore, the aim of this study was to compare the magnitude of EIH with BFR-RE to resistance exercise at both low and high intensities. METHODS: Twelve recreationally active individuals were recruited to participate. In a randomised crossover design, participants completed 4 experimental trials of resistance exercise ((1) light load resistance exercise (LLRE); (2) BFR-RE with low pressure (BFR40); (3) BFR-RE with high pressure (BFR80) and (4) heavy load resistance exercise (HLRE)). Pressure pain threshold (PPT) was then assessed at multiple body sites (dominant and non-dominant quadriceps and non-dominant trapezius muscle) pre, 5 min, 10 min and 24 hr post exercise. RESULTS: There was a two-way interaction effect for the dominant quadriceps site. Post-hoc analysis showed that, compared to LLRE, PPT was higher following BFR40, BFR80 and HLRE. PPT was higher following BFR80 compared to BFR40 and HLRE. At 24h post-exercise, PPTs were 14.5 ± 6.7% and 23.9 ± 8.2% higher than pre-exercise values in the BFR40 and BFR80 trials, respectively, whereas PPTs had returned to baseline in the LLRE and HLRE trials. Compared to LLRE, the increase in PPT was greater following BFR40 (0.28 ± 0.13 AU), BFR80 (0.64 ± 0.42 AU) and HLRE (0.34 ± 0.20 AU) in the non-dominant quadriceps. At 24h PPTs had returned to baseline. Compared to LLRE, the increase in PPT was greater following BFR40 (0.31 ± 0.27 AU), BFR80 (0.30 ± 0.17 AU), and HLRE (0.26 ± 0.13 AU) for the trapezius. At 24h PPTs had returned to baseline. CONCLUSIONS: In conclusion BFR with higher pressure leads to EIH in both dominant and non-dominant limbs suggesting both central and peripheral mechanisms of action.