Calf muscle oxygen hemoglobin saturation characteristics in healthy and clinical populations.

Peripheral artery disease (PAD), a manifestation of systemic atherosclerosis, is characterized by atherosclerotic blockages of the arteries supplying blood to the legs. The occlusion results in decreased blood flow during exercise which alters calf muscle hemoglobin oxygen saturation (StO2) limiting functional capacity. Sarcopenia is the natural age-associated loss of muscle mass and function. This study examined changes in calf muscle StO2 across the lifespan in younger and older healthy individuals. The goal was to differentiate between changes seen from ageing and PAD and associate common sarcopenia tests, 4-meter walk speed and handgrip strength, with StO2 kinetics. Subjects completed the same tests, Gardner Treadmill test and 6-minute walk test, commonly performed with PAD patients. The results show that ageing, regardless of health, lowers and slows StO2 kinetics during and after exercise. They also support findings from previous studies that PAD further negatively affects StO2 kinetics beyond that of ageing.