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

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 V̇O₂ (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 V̇O₂ 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 V̇O₂ 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 V̇O₂ 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.