Cardiorespiratory Responses between One-Legged and Two-Legged Cycling in Patients with Idiopathic Pulmonary Fibrosis.

International guidelines recommend exercise training within pulmonary rehabilitation (PR) for adults with idiopathic pulmonary fibrosis (IPF) [1]. However, the magnitude of benefits of PR in IPF may be less than in COPD [2] and are not sustained [3]. Partitioned muscle training has been investigated for other chronic diseases where a central limitation to exercise dominates [4-6]. One-legged cycling partitions the targeted exercising muscle thereby reducing the total ventilatory burden for the same muscle specific power. In ventilatory limited patients with COPD, partitioned training increases cardiorespiratory fitness [4, 7] measured by peak oxygen uptake (V̇ O2pk) greater than that achieved with conventional twolegged cycle training. We hypothesised that patients with IPF would increase their tolerable exercise time of a leg exercising alone (one-legged cycling) compared to two-legged cycling so that the total work would be doubled (the primary outcome). We also aimed to quantify peripheral muscle aerobic capacity relative to the central capacity by determining the ratio of V̇ O2pk achieved during one- versus two-legged cycling.