Limb-specific and cross-transfer effects of arm-crank exercise training in patients with symptomatic peripheral arterial disease

Abstract

Arm cranking is a useful alternative exercise modality for improving walking performance in patients with intermittent claudication; however, the mechanisms of such an improvement are poorly understood. The main aim of the present study was to investigate the effects of arm-crank exercise training on lower-limb O2 delivery in patients with intermittent claudication. A total of 57 patients with intermittent claudication (age, 70+/-8 years; mean+/-S.D.) were randomized to an arm-crank exercise group or a non-exercise control group. The exercise group trained twice weekly for 12 weeks. At baseline and 12 weeks, patients completed incremental tests to maximum exercise tolerance on both an arm-crank ergometer and a treadmill. Respiratory variables were measured breath-by-breath to determine peak VO2 (O2 uptake) and ventilatory threshold. Near-IR spectroscopy was used in the treadmill test to determine changes in calf muscle StO2 (tissue O2 saturation). Patients also completed a square-wave treadmill-walking protocol to determine VO2 kinetics. A total of 51 patients completed the study. In the exercise group, higher maximum walking distances (from 496+/-250 to 661+/-324 m) and peak VO2 values (from 17.2+/-2.7 to 18.2+/-3.4 ml.kg-1 of body mass.min-1) were recorded in the incremental treadmill test (P<0.05). After training, there was also an increase in time to minimum StO2 (from 268+/-305 s to 410+/-366 s), a speeding of VO2 kinetics (from 44.7+/-10.4 to 41.3+/-14.4 s) and an increase in submaximal StO2 during treadmill walking (P<0.05). There were no significant changes in the control group. The results suggest that the improvement in walking performance after arm-crank exercise training in patients with intermittent claudication is attributable, at least in part, to improved lower-limb O2 delivery.