Abstract
Background: To optimize outcomes in people with cystic fibrosis (CF), guidelines recommend 30 to 60 min of moderate-intensity aerobic exercise on most days. Accumulating this volume of exercise contributes importantly to the substantial treatment burden associated with CF. Therefore, the main aim of this study was to investigate the effects of low-volume high-intensity interval training (HIIT) on exercise capacity in people with CF. Methods: This randomized controlled trial included people with CF aged ≥15 years, who were allocated to either eight weeks of thrice-weekly 10-min sessions of HIIT (experimental group) or eight weeks of weekly contact (control group). Before and after the intervention period, participants completed measurements of time to symptom limitation (Tlim) during a constant work rate cycle ergometry test (primary outcome), and maximal work rate (Wmax) during a ramp-based cycle ergometry test and health-related quality of life (HRQoL). Results: Fourteen participants (median (IQR) age 31 (28, 35) years, forced expiratory volume in 1 second (FEV1) 61 (45, 80) % predicted) were included (seven in each group). Compared to the control group, participants in the experimental group demonstrated a greater magnitude of change in Tlim, Wmax (p = 0.017 for both) and in the physical function domain of HRQoL (p = 0.03). No other between-group differences were demonstrated. Mild post-exercise muscle soreness was reported on a single occasion by four participants. Overall, participants attended 93% of all HIIT sessions. Discussion: Eight weeks of low-volume (i.e., 30-min/week) HIIT produced gains in exercise capacity and self-reported physical function and was well tolerated by people with CF.
Highlights
To optimize outcomes in people with cystic fibrosis (CF), guidelines recommend 30 to 60 min of moderate-intensity aerobic exercise on most days
“It was tough during the time when I wasn’t well, but I was still able to do it” (P2) “If I was having a bad day with my lungs, that was more effort, but I know that when I felt that way we just adjusted the intensity that day so I didn’t ever feel like I was going to ‘over-do’ it” (P8) “I guess if you are feeling sick it is obviously harder to exercise” (P9) “The better I am feeling, the more likely I am to go” (P14) “When you feel unwell, and you have all your medication and you have to try and schedule exercise in, it’s just hard” (P14). This randomized controlled trial (RCT) demonstrated that eight weeks of low-volume high-intensity interval training (HIIT) produced a greater magnitude of change in to symptom limitation (Tlim), Maximal work rate (Wmax), and self-reported physical function over and above the magnitude of change observed by continuing usual care in people with CF
The current study has demonstrated that Tlim, which is traditionally used as a measure of submaximal endurance exercise capacity, is highly responsive in people with CF, and more responsive than measures obtained during a ramp-based cycle ergometry test
Summary
To optimize outcomes in people with cystic fibrosis (CF), guidelines recommend 30 to 60 min of moderate-intensity aerobic exercise on most days. Accumulating this volume of exercise contributes importantly to the substantial treatment burden associated with CF. People with cystic fibrosis (CF) have reduced exercise capacity [1] The cause of such reduction is multifactorial and includes impairments in lung function as well as peripheral and respiratory muscle deconditioning, the latter of which contributes to breathlessness and muscle fatigue during exercise [2,3]. An alternative training approach, such as low-volume high intensity interval training (HIIT), may be a more achievable and efficient method to optimize exercise capacity
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