Changes in physical behaviour patterns in response to a 12-week combined exercise intervention in Black South African women from a low-resourced setting

Background This study assessed the effects of a 12-week aerobic and resistance exercise training intervention on changes in habitual physical behaviour patterns in Black South African (SA) women from a low-resourced setting living with overweight or obesity. Methods Forty-five apparently healthy women (18–35 years) were randomized into an exercise (EXE; n = 23) or control group (CON; n = 22). Cardiorespiratory fitness (CRF) was measured pre- and post-intervention. Percentage time spent in light intensity physical activity (LIPA), moderate-to-vigorous-intensity physical activity (MVPA), sedentary behaviour (SB) and total physical activity (TPA) were measured using accelerometery (ActivPAL and ActiGraph GT3X+) at baseline, week 4, 8 and 12. Results CRF increased by ~ 2.7 ml. kg ^− 1 . min ⁻¹ in EXE with no change in CON (p = 0.001 group x time interaction). Considering all valid days (exercise and non-exercise days), MVPA and daily steps increased in the EXE group from baseline to weeks 4, 8 and 12, and sedentary behaviour decreased in EXE from baseline to weeks 8 and 12, while no changes in CON were observed (all p < 0.001 group x time interaction). During non-exercise days only, there was an increase in sedentary time accumulated in > 60 min bouts in EXE in week 8 with no change in CON (p = 0.011 group x time interaction). Conclusions The significant increases in CRF and MVPA with a compensatory reduction in SB were observed in response to the 12-weeks of exercise training. The improvements in CRF highlights exercise as a potential strategy for improving health outcomes in this population.