Effects of high intensity interval training on exercise capacity in people with chronic pulmonary conditions: A narrative review

Background: Exercise training is important in the management of adults with chronic pulmonary conditions. However, achieving high intensity exercise may be challenging for this clinical population. There has been clinical interest in applying interval-based training as a strategy to optimise the load that can be tolerated during exercise training. Evidence for such an approach is limited in most chronic pulmonary populations. Main body: In this narrative review, we provide an appraisal of studies investigating whole-body high intensity interval training (HIIT) in adults with chronic obstructive pulmonary disease (COPD). This is the first review to also include studies investigating HIIT in people with conditions other than COPD. Studies undertaken in adults with a chronic pulmonary condition were reviewed when participants were randomised to receive; (i) HIIT or no exercise or, (ii) HIIT or moderate intensity continuous exercise. Data were extracted on peak rate of oxygen uptake (VO; 'cardiorespiratory fitness') and maximal work rate (W; 'exercise capacity'). In people with COPD, two studies demonstrated between-group differences favouring HIIT compared with no exercise. There appears to be no advantage for HIIT compared to continuous exercise on these outcomes. In people with cystic fibrosis (CF), no studies have compared HIIT to no exercise and the two studies that compared HIIT to continuous exercise reported similar benefits. In people prior to resection for non-small cell lung cancer, one study demonstrated a between-group difference in favour of HIIT compared with no exercise on VO. In people with asthma, one study demonstrated a between-group difference in favour of HIIT compared with no exercise on VO and one that compared HIIT to continuous exercise reported similar benefits. No studies were identified non-CF bronchiectasis or interstitial lung diseases. Conclusions: High intensity interval training increases cardiorespiratory fitness and exercise capacity when compared with no exercise and produces a similar magnitude of change as continuous exercise in people with COPD. There is a paucity of studies exploring the effects of HIIT in other chronic pulmonary conditions.