Blood Flow Restriction Accelerates the Onset of Neuromuscular Fatigue, Anaerobic Metabolism, and Maximal Oxygen Uptake.

PURPOSE: Prescribing aerobic exercise with blood flow restriction (BFR) relative to physical working capacity at the fatigue threshold (PWCFT), gas exchange threshold (GET), respiratory compensation point (RCP), or maximal oxygen uptake (V̇O2max) derived from an incremental exercise test without BFR may inaccurately estimate exercise intensity. The purpose of this investigation was to examine the acute effects of an incremental cycling test performed with and without BFR on PWCFT, GET, RCP, and V̇O2max.

METHODS

Eighteen aerobically trained females completed an incremental cycling test and a verification bout with and without BFR on separate visits. Each test began with a five-minute warmup at 50 watts (W) and a cadence of 70 revolutions per minute. Following this, the test began at 50 W and increased by 30 W every two minutes until volitional failure. To apply BFR during the incremental protocol, pneumatic cuffs were placed bilaterally to the upper thighs after the warmup. Separate Bayesian paired samples t-tests were performed and are reported as a meaningful difference if the 95% high-density interval (95% HDI) did not include zero.

RESULTS

Applying BFR decreased PWCFT (95% HDI: 28.0 to 46.4 W), decreased V̇O2 at GET (95% HDI: 104.0 to 307.0 mL˙min -1), decreased V̇CO2 at GET (95% HDI: 115.0 to 347.0 mL˙min -1), decreased V̇O2 at RCP (95% HDI: 257.0 to 403.0 mL˙min -1), decreased V̇CO2 at RCP (95% HDI: 329.0 to 525.0 mL˙min -1), and decreased V̇O2max (95% HDI: 374.0 to 470.0 mL˙min -1) relative to the unrestricted incremental cycling test.

CONCLUSIONS

These responses suggest that BFR accelerated the recruitment of higher threshold motor units, induced earlier shifts to the heavy and severe exercise domains, and expedited the plateau in maximal oxygen uptake.