Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million worldwide. While PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO2) and a higher rise in BP in PAD compared to age-matched healthy subjects, but low-intensity steady state plantar flexion elicits similar responses between groups. In the first experiment, eight PAD patients and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven PAD patients and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO2 from near-infrared spectroscopy (NIRS) were measured continuously. SmO2 is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, PAD patients had a greater increase in mean arterial BP (18 ± 2 versus vs. 10 ± 2 mmHg, P = 0.029) and HR (14 ± 2 versus 6 ± 2 beats/min, P = 0.033) and a greater reduction in SmO2 (-54 ± 10 versus -12 ± 4 %, P = 0.001). However, both groups had similar physiological responses to low-intensity, non-painful plantar flexion exercise. These data suggest that PAD patients have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response.
- blood pressure
- heart rate
- sympathetic nervous system
- Copyright © 2016, Journal of Applied Physiology