Physiological Responses To Acute Arm Cranking With Blood Flow Restriction

Abstract

Aerobic exercise with blood flow restriction (BFR) is emerging as an effective method to improve both aerobic capacity and muscular function. Using an inflatable cuff, blood flow is usually restricted during walking and cycling. The extent to which BFR can be applied during upper-body aerobic exercise such as arm cranking is not well documented. Arm cranking with BFR might offer an exercise option for clinical populations that need to exercise upper-body muscles (e.g., wheelchair users, individuals with shoulder injuries). PURPOSE: To evaluate physiological and perceptual responses to acute submaximal arm cranking with BFR. METHODS: Five active adults (age: 23±3yrs, arm cranking VO2peak: 33±8ml/kg/min) performed 4 intermittent arm cranking protocols (6x2 min, 1min recovery): 1) low-load arm cranking (LL, 40% VO2peak), 2) low-load arm cranking with BFR (BFR, 40% VO2peak), and 3) high-load arm cranking (HL, 80% VO2peak). For BFR, blood flow was restricted using 5cm cuffs inflated to 70% of limb occlusion pressure as identified using Doppler ultrasound. Cardiorespiratory and perceptual responses (VO2, HR, perceived effort) and tissue perfusion (tissue saturation, deoxyhemoglobin concentrations) were measured using a metabolic cart and near-infrared spectroscopy, respectively. RESULTS: Oxygen consumption during BFR (1.15±0.32ml/kg/min) did not differ from LL (1.04±0.26ml/kg/min, P=0.31) and was less than HL (2.28±0.60ml/kg/min, P<0.01). Compared to LL (104±6b/min), heart rate during BFR increased (115±13b/min, P=0.04) but was less than HL (166±19b/min, P<0.01). BFR required greater perceived effort in the arms (12±3) compared to LL (9±2, P=0.03) but less effort than HL (16±2, P=0.01). In general, BFR decreased tissue saturation and increased deoxyhemoglobin concentrations compared to arm cranking without BFR (all P<0.05). CONCLUSION: These results suggest that arm cranking with BFR has potential to increase metabolic stress without excessive cardiorespiratory strain. This exercise mode may provide a useful alternative to HL for populations that need to exercise upper-body muscles for rehabilitation. These findings provide guidance for future acute and chronic studies examining the feasibility and efficacy of arm cranking with BFR.