Author(s): JAKOBSSON, J., DE BRANDT, J., HEDLUND, M., RULLANDER, A.C., SANDSTRÖM, T., NYBERG, A., Institution: UMEA UNIVERSITY, Country: SWEDEN, Abstract-ID: 1766

INTRODUCTION:
High-intensity exercise is essential for optimal development of cardiorespiratory fitness and health. Yet, it is challenging to perform for individuals with chronic obstructive pulmonary disease (COPD) due to ventilatory limitations, resulting in lower exercise intensities with suboptimal stress on the cardiovascular and muscular system. We aimed to compare the feasibility and acute effects of a novel concept of controlled short-duration supramaximal high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT) in people with COPD and matched healthy controls (HC).
METHODS:
Sixteen people with mild to severe COPD (8 males; 75±6 yr; 119±37W max aerobic power [MAP]; 21.8±5.2 ml/kg/min VO2peak; 73±13 FEV1%pred) and 16 HC (8 males; 74±5 yr; 164±38W MAP; 25.4±3.8 ml/kg/min VO2peak; 106±14 FEV1%pred) performed HIIT and MICT on a cycle ergometer in a randomized order. Supramaximal HIIT consisted of 10x6s sprints interspersed with 1-min recovery. Participants performed supramaximal HIIT at two intensities: 60% and 80% of maximal mean power output for 6-sec (HIIT60% and HIIT80%) estimated using the Borg cycle strength test. The MICT session consisted of 20 min at 60% of MAP. Breath-by-breath indirect calorimetry, ratings of perceived exertion, symptoms and exercise modality preference were obtained. Clinical trial registration: NCT05874999.
RESULTS:
The mean exercise intensity was 3.5-fold higher in supramaximal HIIT (HIIT80%) compared to MICT (245±87W vs. 71±22W for COPD, 358±76W vs. 98±23W for HC, p<0.001 for all). In general, the cardiorespiratory demand was similar between the modalities. At the end of exercise, the VO2 demand was not different between modalities for those with COPD (HIIT60%: 16.3±2.9, HIIT80%: 17.6±3.7 , MICT: 18.8±4.0 ml/kg/min, p=0.09). For HC, MICT required a slightly higher VO2 demand (HIIT60: 19.1±2.1, HIIT80: 20.6±3.5, MICT: 2.2±3.1 ml/kg/min, p=0.02). For those with COPD, supramaximal HIIT during HIIT60% but not at HIIT80% resulted in significant and clinically relevant reductions in dyspnea (5.1±2.3 vs 7.1±1.9, p=0.02) and Borg RPE (14.8±2.4 vs. 17.0±2.1, p=0.03) when compared to MICT. All supramaximal HIIT sessions were completed without premature interruption, while 5 out of 16 people with COPD did not complete the MICT due to exhaustion. A general preference for the supramaximal HIIT modality was seen, with 13 out of 16 participants with COPD and 14 out of 16 HC favouring supramaximal HIIT over MICT.
CONCLUSION:
Controlled short-duration supramaximal HIIT appears to be feasible in people with COPD and HC. Compared to MICT, it enabled a 3.5-fold increase in exercise intensity. Despite the higher exercise intensities, the cardiorespiratory demand during HIIT was similar to MICT, and clinically relevant reductions in dyspnea were seen in favor of HIIT in people with COPD. Notably, most participants preferred HIIT over MICT. The long-term feasibility and adaptations to supramaximal HIIT is yet to be investigated in COPD.