Cardiorespiratory and metabolic changes in women with obesity undergoing high-intensity tethered deep-water running associated with normoxia or inter-effort hypoxia

Abstract Obesity is characterised by adipocyte hypertrophy, an imbalance of pro- and anti-inflammatory cytokines, and tissue hypoxia. Non-weight-bearing exercise, such as deep-water running (DWR), may be suitable for people with obesity and, when combined with hypoxia exposure, may improve cardiorespiratory fitness and health-related outcomes. This study investigated the effects of tethered DWR combined with intermittent hypoxia on aerobic capacity, body composition, metabolic and inflammation markers and dietary intake in women with obesity. Thirty-one women (36 ± 5·9 years; BMI 32·5 ± 2·3) with grade I obesity were randomised to normoxia (NOR, FiO₂ = 21 %) or inter-effort hypoxia (IEH, FiO₂ = 12 %). Training of four 5 min bouts performed at 100–110 % of the heart rate corresponding to the anaerobic threshold, interspersed with 5 min recovery periods, three times weekly for 8 weeks. Pre- and post-intervention assessments included aerobic capacity, body composition, metabolic and inflammatory markers, and dietary intake. Mixed-effects models followed by Tukey’s multiple-comparisons test were used. IEH reduced SpO₂ ( p < 0·0001) and increased heart-rate-derived internal load ( p < 0·05) without increasing perceived exertion. Significant group × time interactions were observed for glucose ( p = 0·002), total cholesterol ( p = 0·004) and LDL-cholesterol ( p = 0·026), primarily reflecting decreased glucose and increased total and LDL-cholesterol in NOR. Dietary intake and NOVA food categories did not change significantly. Both conditions elicited similar cardiorespiratory and performance-related improvements. IEH did not confer additional benefits for body composition or inflammatory markers.