High-intensity interval training accelerates oxygen uptake kinetics and improves exercise tolerance for individuals with cystic fibrosis

Ronen Reuveny,Cedric Gunaratnam,Davide Susta,Michael Peled,Fred J Dimenna,Avigdor D Arad,Niall M Moyna,Gerry N Mcelvaney

doi:10.1186/s13102-020-0159-z

Abstract

BackgroundExercise training provides benefits for individuals with cystic fibrosis; however, the optimal program is unclear. High-intensity interval training is safe and effective for improving ‘functional capacity’ in these individuals with peak rate of O2 uptake typically referenced. The ability to adjust submaximal rate of oxygen uptake (V̇O2 kinetics) might be more important for everyday function because maximal efforts are usually not undertaken. Moreover, the ability of high-intensity training to accelerate V̇O2 kinetics for individuals with cystic fibrosis could be enhanced with O2 supplementation during training.MethodsNine individuals with cystic fibrosis completed incremental cycling to limit of tolerance followed by 8 weeks of high-intensity interval cycling (2 sessions per week x ~ 45 min per session) either with (n = 5; O2+) or without (AMB) oxygen supplementation (100%). Each session involved work intervals at 70% of peak work rate followed by 60 s of recovery at 35%. For progression, duration of work intervals was increased according to participant tolerance.ResultsBoth groups experienced a significant increase in work-interval duration over the course of the intervention (O2+, 1736 ± 141 v. 700 ± 154 s; AMB, 1463 ± 598 v. 953 ± 253 s; P = 0.000); however, the increase experienced by O2+ was greater (P = 0.027). During low-intensity constant-work-rate cycling, the V̇O2 mean response time was shortened post compared to pre training (O2+, 34 ± 11 v. 44 ± 9 s; AMB, 39 ± 14 v. 45 ± 17 s; P = 0.000) while during high-intensity constant-work-rate cycling, time to exhaustion was increased (O2+, 1628 ± 163 v. 705 ± 133 s; AMB, 1073 ± 633 v. 690 ± 348 s; P = 0.002) and blood [lactate] response was decreased (O2+, 4.5 ± 0.9 v. 6.3 ± 1.4 mmol. L− 1; AMB, 4.5 ± 0.6 v. 5.2 ± 1.4 mmol. L− 1; P = 0.003). These positive adaptations were similar regardless of gas inspiration during training.ConclusionEight weeks of high-intensity interval training for patients with cystic fibrosis accelerated V̇O2 kinetics and increased time to exhaustion. This provides some evidence that these patients may benefit from this type of exercise.Trial registrationThis study was retrospectively registered in the ISRTCN registry on 22/06/2019 (#ISRCTN13864650).

Highlights

Exercise training provides benefits for individuals with cystic fibrosis; the optimal program is unclear
The main original finding from this investigation is that an eight-week High-intensity interval training (HIIT) training program comprising 16 training sessions for individuals with cystic fibrosis (CF) shortened the V O2 Mean response time (MRT) during constant-work-rate cycling at 30% of the participant’s peak work rate and lengthened the time to limit of tolerance during constant-work-rate cycling at 70%
Previous research suggests that repeat-sprint training (SIT; i.e., HIIT performed with work intervals comprising all-out exercise) accelerates V O2 kinetics and improves high-intensity exercise tolerance in healthy subjects [41]; our findings provide preliminary evidence that this observation might be extended to HIIT for the CF population

Summary

Introduction

Exercise training provides benefits for individuals with cystic fibrosis; the optimal program is unclear. In addition to pulmonary function (e.g., FEV1) and health-related quality-of-life estimates, the peak rate of oxygen (O2) uptake (V O2) achieved on a maximal incremental exercise test (V O2peak) has been routinely used to quantify ‘functional capacity’ [3, 7,8,9,10] for individuals with CF. Not surprising that a strong correlation exists between the V O2 time constant (a parameter that quantifies the rapidity of the V O2 response) and disease severity in subjects with CF [18] With this in mind, it stands to reason that a training program that improves the capacity to rapidly adjust V O2 in response to lower-intensity energetic transitions like those encountered on a daily basis would likely have clinical implications [13]. An improved ability to sustain higher-intensity exercise (i.e., work performed at a work rate that exceeds those that are associated with physical activity performed during daily living) might have implications for pulmonary patients with respect to health-related quality of life and physical-activity levels [19]

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