Leg blood flow and cardiac output are cyclically reduced during low‐intensity exercise with intermittent <scp>KAATSU</scp> cuff inflation in young adults

The present investigation sought to determine the cardiovascular responses to a commercially available KAATSU cuff system with rhythmic cuff inflation-deflation periods during leg exercise. Seventeen participants performed two-legged knee flexion/extension exercise at 25% of peak work rate (WR_Peak) with bilateral KAATSU cuffs applied to the proximal thigh (KAATSU) or work-rate matched control exercise (CTL). During KAATSU trials, the cuffs were set to Cycle Mode (repeated 30-s inflation; 5-s deflation) at progressively increasing cuff pressure (150-220 mmHg). Right leg blood flow (LBF; Doppler and echo ultrasound) and cardiac output (CO; finger photoplethysmography) were measured continuously. The deflated KAATSU cuffs impaired exercising LBF (p < 0.01), with no further impairment during the first cuff inflation (p > 0.99). Following the initial cuff inflation, deflated KAATSU cuffs no longer compromised LBF (p = 0.78). Subsequently, LBF (p < 0.01) and CO (p = 0.04) were compromised during each of the remaining cuff inflations, but the magnitude of compromise was not augmented by progressive increases in cuff pressure (2LBF interaction: p = 0.41; CO interaction: p = 0.40). KAATSU cuff inflation reduces exercising LBF to a similar extent across cuff pressures. Furthermore, reductions in exercising CO during cuff inflation were immediately restored upon deflation, revealing the dependency of CO on exercising leg perfusion and subsequent venous return.