Randomised controlled trial of partitioned aerobic exercise training using one-leg cycling in patients with idiopathic pulmonary fibrosis.

Background: Although many individuals with idiopathic pulmonary fibrosis (IPF) are referred for pulmonary rehabilitation (PR), their breathlessness can be so severe as to prevent their tolerating the most effective aerobic training intensity for adequate time. Ventilation is less with one-leg cycling and a meaningful exposure to intensity can be achieved. This study aimed to determine if one-leg training improved exercise tolerance more than two-leg training in individuals with stable IPF.

Methods: This was a prospective randomised controlled trial comparing one-leg versus two-leg cycle exercise training in the setting of PR. The primary outcome was the time to intolerance of exercise (t limit ). Participants completed conventional constant power endurance tests to t limit before randomisation to one-leg (1Lgrp) or two-leg (2Lgrp) aerobic training on a stationary cycle. Training sessions were 30 min, 3 days/week for 6-8 weeks, with progression guided by tolerance. The 1Lgrp switched legs mid-training session. Tests were also completed midway and after PR.

Results: 40 individuals with IPF (mean±SD: forced vital capacity =61±16 %pred; Gender-Age-Physiology Index=4±1; 37 on pirfenidone or nintedanib) were included in the intent-to-treat analysis. Their t limit at baseline was 6.5±2.2 min. After training, both groups (n=20) increased t limit in accord with slower progression of heart rate during constant power exercise. There was a significant between-group difference in the change in t limit (difference=10.5 (3.4 to 17.6) min) of the 1Lgrp (change=21.8 (16.0 to 27.6) min) versus the 2Lgrp (change=11.3 (5.8 to 16.8) min).

Conclusion: Partitioning training to a smaller muscle volume (one-leg) improved exercise endurance more than two-leg cycle training in patients with stable moderate-to-severe IPF. Trial registration number NCT03752892.