Higher baseline fat oxidation promotes gynoid fat mobilization in response to a 12-week exercise intervention in sedentary, obese black South African women

Abstract

This 12-week exercise intervention study assessed changes in cardiorespiratory fitness (CRF), energy expenditure (EE), and substrate utilisation at rest and during exercise in obese, black South African (SA) women and explored associations with changes in body composition. Black SA women (body mass index: 30–40 kg·m−2, age: 20–35 years) were randomised into control (CTL; n = 15, maintaining usual activity) or exercise (EXE; n = 20; 12 weeks, 4 days·week−1, 40–60 min·day−1 at >70% peak heart rate) groups. Pre- and post-intervention testing included peak oxygen consumption, resting and steady state (50% peak oxygen consumption) EE, respiratory exchange, and body composition (dual-energy X-ray absorptiometry). Dietary intake (4-day) and daily step-count (ActivPAL, activPAL3c; PAL Technologies Ltd, Glasgow, UK) was collected at pre-testing and at 4, 8, and 12 weeks. EXE increased peak oxygen consumption (24.9 ± 2.4 to 27.6 ± 3.4 mL·min−1·kg−1; p < 0.001) and steady state fat oxidation rates (7.5 ± 2.5 to 9.0 ± 2.7 mg·min−1·kg−1 fat-free soft tissue mass; p = 0.003) (same relative exercise intensity). CTL remained unchanged (p > 0.05). EXE reduced proportional gynoid fat mass (percentage total fat mass, p = 0.002). Baseline resting carbohydrate oxidation rates (p = 0.036) and steady state fat oxidation rates (p = 0.021) explained 60.6% of the variability in Δgynoid fat mass (p < 0.001) in EXE. This 12-week exercise intervention improved CRF and steady state fat oxidation rates. Greater reliance on fat oxidation at baseline promoted proportional reductions in gynoid, not visceral, fat mass in response to exercise training. Novelty Combined exercise training in obese black South African women increased cardiorespiratory fitness and rates of fat oxidation during steady state exercise. Exercise training reduced proportional gynoid, not visceral, fat, potentially representing an ethnic/sex-specific response. Baseline substrate utilisation (resting and steady state exercise (50% peak oxygen uptake)) predicted changes in gynoid fat mass.

Changes in systemic and subcutaneous adipose tissue inflammation and oxidative stress in response to exercise training in obese black African women

“…A total of 48 exercise training sessions were conducted, in which participants attended 79 ± 13 (range: 52-100)% at a mean intensity of 79.7 ± 4.0 (range: 71-85)% HRpeak. Participants' dietary intake did not change in either group throughout the intervention, as previously reported (Clamp et al 2019).…”

“…Participants’ dietary intake did not change in either group throughout the intervention, as previously reported (Clamp et al . ).…”

“…Both groups were instructed to maintain their usual dietary intake, which was evaluated every 4 weeks by a food frequency questionnaire as previously described (Clamp et al . ). Before and after the 12‐week intervention, body composition, cardiorespiratory fitness and S I were measured, and blood and fat samples were collected for further analyses.…”

“…The control group was instructed to maintain their normal daily physical activity patterns, and not start any exercise training programme, which was verified through monthly monitoring using accelerometry (ActivPAL3c, PAL Technologies Ltd, Glasgow, UK). Both groups were instructed to maintain their usual dietary intake, which was evaluated every 4 weeks by a food frequency questionnaire as previously described (Clamp et al 2019). Before and after the 12-week intervention, body composition, cardiorespiratory fitness and S I were measured, and blood and fat samples were collected for further analyses.…”

Exercise Training Alters Red Blood Cell Fatty Acid Desaturase Indices and Adipose Tissue Fatty Acid Profile in African Women with Obesity

“…The participants' characteristics are presented in Supporting Information Table S2 and they have been partly published in (28,35). In brief, cardiorespiratory fitness and body composition were not different between the groups at baseline.…”