Physical activity “responders” vs “non-responders” after exercise training with air or oxygen in people with COPD and exercise-induced desaturation
Zoe McKeough, Regina Leung, Anne Holland, Kylie Hill, Norman Morris, Sue Jenkins, Lissa Spencer et al.
Aim: To evaluate changes in physical activity (PA) following exercise training on air or oxygen in people with COPD and EID.
Methods: Secondary analysis of data from the "suppORT" trial was performed. COPD participants who desaturated to SpO2< 90% during a six-minute walk test were randomised to receive oxygen (OG) or air (AG) during thrice weekly exercise training over eight weeks. Outcomes, measured before and after the program, were PA using an activity monitor (SenseWear MF), and peak and endurance exercise capacity using the incremental and endurance shuttle walk tests (ISWT & ESWT). PA responders were defined as increasing their PA by ≥600 steps/day following training. An unpaired t-test was used to compare changes in ISWT distance and ESWT time between responders and non-responders.
Results: 87 participants [mean (SD) age 70 (8) years; FEV1 48 (18)% predicted] completed training (OG n=48; AG n=39). There was no significant difference in the change in PA after training in the OG compared to the AG (mean difference (95% CI) of 333 steps/day (-164 to 831)). Twenty participants (18%) were responders (12 in the OG (25%), 8 in the AG (21%)). The responders had a mean improvement of 1,307 (753) steps/day compared to a 523 (909) steps/day decline in non-responders (p<0.001). There was no difference in the improvement in ESWT time or ISWT distance after training between responders and non-responders (ESWT: 176 (432) s vs 171 (280) s, p=0.6; ISWT: 35 (40) m vs 29 (49) m, p=1.0).
Conclusion: Most people with COPD and EID did not demonstrate an increase in PA following individually-prescribed exercise training on air or oxygen.