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 O-2 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 (V) over dotO(2) (O-2 uptake) and ventilatory threshold. Near-IR spectroscopy was used in the treadmill test to determine changes in calf muscle StO(2) (tissue O-2 saturation). Patients also completed a square-wave treadmill-walking protocol to determine (V) over dotO(2) 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 (V)over dotO(2) 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 StO(2) (from 268 +/- 305 s to 410 +/- 366 s), a speeding of (V) over dotO(2) kinetics (from 44.7 +/- 10.4 to 41.3 +/- 14.4 s) and an increase in submaximal StO(2) 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 O-2 delivery.