A Randomized Controlled Trial Comparing High- and Moderate-Intensity Interval Walking on Hematological and Functional Markers in Postmenopausal Women with Obesity

Postmenopausal women with obesity often show blood abnormalities and low plasma volume, which reduce aerobic capacity and raise health risks. The purpose is to compare the effects of high-intensity (HIIWT) versus moderate-intensity interval walking training (MIIWT) on body composition, plasma volume variations (PVV), hematological parameters, muscle damage, and aerobic capacity in postmenopausal women with overweight/obesity. Thirty-two postmenopausal women with overweight/obesity were randomly assigned to HIIWT (n = 11), MIIWT (n = 11), or control (CON, n = 10) groups. The HIIWT and MIIWT groups performed intermittent walking at 90–110% and 60–80% of their 6-min-walk-test (6MWT) distance, respectively, four times per week for 10 weeks. Body composition, hematological and muscle damage markers, and 6MWT performance were assessed pre- and post-intervention. After ten weeks, PVV was calculated in all three groups. A significant group × time interaction was observed for body composition, erythrocytes, hemoglobin levels, hematocrit, creatine kinase (CK), lactate dehydrogenase (LDH), and 6MWT performance (p < 0.05). Both the HIIWT and MIIWT groups showed significant reductions in body mass, body fat, waist circumference (p < 0.05), and erythrocyte count (p = 0.010 and 0.028, respectively). Only the HIIWT group showed significant reductions in hemoglobin (p < 0.001), hematocrit (p = 0.005), CK (p = 0.002), and LDH (p = 0.009), along with a significant increase in 6MWT-performance (p = 0.002). The HIIWT group demonstrated a significantly greater increase in PVV compared to both MIIWT (p = 0.018) and CON (p < 0.001) groups. HIIWT induced superior improvements in body composition, aerobic capacity, plasma volume, and hematological and muscle-damage markers compared to MIIWT. HIIWT represents a practical strategy for improving health outcomes in postmenopausal women with overweight/obesity.