Aquatic Exercise Training in Warm versus Cold Water in Elderly Patients with Type 2 Diabetes

Introduction: Older adults with type 2 diabetes face increased risks of macrovascular and microvascular complications. Aquatic exercise offers a joint-friendly alternative in this population. However, the influence of water temperature on exercise outcomes remains unclear. Purpose: This study compared the effects of warm-water versus cold-water aerobic exercise on physical fitness, glycemic control, and vascular function in elderly patients with type 2 diabetes. Methods: Thirty-two sedentary older adults (60–75 yr old) with type 2 diabetes were randomized into warm-water (36°C; n = 16) or cold-water (20°C; n = 16) cycling exercise groups, training three times per week for 12 wk. Results: Fifteen participants in the warm-water group and 12 in the cold-water group completed the study. Both groups demonstrated improvements in peak aerobic fitness, glycosylated hemoglobin, lipid profiles, pulse wave velocity, flow-mediated dilation, and skin microvascular function ( P < 0.05). Warm-water exercise produced greater improvements in all indices of foot microvascular reactivity than the cold-water group. Warm-water training additionally improved isometric leg strength, trunk flexibility, plasma nitric oxide, and reduced oxidative stress ( P < 0.05), while cold-water exercise led to reductions in blood pressure ( P < 0.05). Conclusions: Both warm- and cold-water aerobic exercise effectively improved both macro- and microvascular functions and metabolic health in older adults with type 2 diabetes. However, warm-water exercise conferred extra benefits in muscle strength, flexibility, and oxidative stress, while cold-water exercise reduced blood pressure.