Effects of Knee Extension Exercise on Microvascular Function: Implication for Diabetic Foot Ulcer Healing

Diabetic Foot Ulcer (DFU) is one of the leading microvascular complication of diabetes mellitus. It contributes to a greater risk of amputation, and increases the mortality and morbidity rate. Exercise training protocols have been vastly investigated as adjunct treatment strategies over standard care for wounds. The objective of this pilot study is to evaluate the feasibility and effectiveness of an isolated thigh muscle exercise on the blood flow in individuals with diabetes. We hypothesized that the skin blood flow response to localized pressure (RH) and localized heating (HH) will be compromised in patients with diabetes. We also hypothesized that the RH and HH responses would increase post exercise. This study utilized a single-subject design, where all subjects underwent 12 weeks of knee extension exercise using a single-leg ergometer (30 minutes per section, 3 times per week at 60 rpm). RH and HH responses were collected at the great toe and heel. RH was induced with 60mmHg pressure for 3 minutes, and HH was induced with 41°C local heat for 5 minutes. Diabetic characteristics such as diabetic duration, foot sensation, ankle brachial index, medical history, current and previous ulcer/amputation history. Our results demonstrated a greater peak, perfusion and time to peak in diabetic subjects compared to healthy subjects before exercise. Time to peak blood flow decreased in all diabetic subjects with foot complications after 12 weeks of exercise. We found that HH only increases in subjects without foot complications after exercise training. Findings of this study recommended the employment of evaluating skin blood flow responses in studying the microvascular function in diabetic patients with exercise intervention. Studying the same blood flow characteristics on a larger sample size is warranted.