Abstract
There is evidence that skeletal muscle oxidative capacity contributes to differences in walking performance in people with peripheral arterial disease (PAD). To further explore this, walking performance was assessed using an incremental treadmill walking test in 16 people with PAD and 14 healthy controls (C) of similar age and weight. Mitochondrial ATP production rates (MAPR) in the presence of pyruvate + malate (PM), palmitoyl-carnitine +malate (PCM), and pyruvate + palmitoyl-carnitine + alpha-ketoglutarate + malate (PPKM), as well as citrate synthase (CS) activity, were measured on biopsy samples taken from the medial gastrocnemius muscle in the leg with the lowest ankle-brachial index in PAD and the randomised leg in C. Total walking time was significantly lower in PAD when compared with C (9.8±4.6min vs 26.57±24.3 min). In PAD, pain-free walking time was an average 31.8% of the total walking time. MAPR (PM) and MAPR (PPKM) were significantly greater in PAD than C, but MAPR (PCM) was significantly lower in PAD than C. CS activity was not different between PAD and C. The pain-free walking time in PAD was positively correlated (r = 0.583, p less than 0.05) with MAPR (PPKM). The total walking time in PAD and C were not significantly correlated with MAPR. These findings suggest that the muscle mitochondrial capacity to oxidise carbohydrate is increased in PAD, and that it, rather than the mitochondrial oxidation of fat, is an important determinant of differences in pain-free walking performance in PAD.