Metabolic cost of locomotion during treadmill walking with blood flow restriction

We explored whether interval walking with blood flow restriction (BFR) increases net metabolic cost of locomotion in healthy young men at their optimal walking speed. We also determined whether decreased walking economy resulting from BFR might be accompanied by an increase in ventilation relative to VO₂ and VCO₂. Finally, we examined possible relationships between the changes in ratings of perceived exertion (RPE) and those obtained in minute ventilation (V_E) during walking with BFR. Eighteen healthy men (age: 22·5 ± 3·4 years) performed graded treadmill exercise to assess VO_2max. In a randomized fashion, participants also performed five bouts of 3-min treadmill exercise with and without BFR at their optimal walking speed. Walking with BFR elicited an overall increase in net VO₂ (10·4%) compared with that seen in the non-BFR condition (P<0·05). The participants also demonstrated greater V_E and V_E/VO₂ values while walking with BFR (P<0·05). Conversely, V_E/VCO₂ was similar between conditions at each walking bout. We found no significant correlation between the changes in V_E and RPE induced by walking with BFR (r = 0·38, P>0·05). Our results indicate that (i) BFR decreases net walking economy in healthy young men, even at their optimal walking speed; (ii) heightened ventilatory drive may explain a small proportion of BFR effects on walking economy; and (iii) the ventilatory responses to BFR walking may be largely independent of changes in perceived exertion and are likely matched to the flux of CO₂ between muscles and respiratory centres.