A change
in the biomechanics of walking may decrease oxygen
cost during constant-load exercise, which would allow
the patient to walk farther before developing a
mismatch between the limited oxygen supply and the
metabolic demands of exercise.An increase in
peripheral blood flow through changes in the collateral
circulation, reduced blood viscosity, or
regression of disease would decrease the amount of
muscle ischemia during exercise, resulting in an increase in peak exercise capacity. Finally, despite
the limited blood flow, improvements in skeletal
muscle metabolism would facilitate the extraction of
oxygen and substrateand, thus, allow for a
greater peak exercise capacity. An example of the
defect in muscle oxidative metabolism is the observation
that patients with PAD generate acylcarnitines
during skeletal muscle ischemia and that
repeated episodes of claudication lead to a chronic
accumulation of acylcarnitines.