Changes in fatigability following intense aerobic exercise training in patients with interstitial lung disease

Abstract

Objective: To determine if, in patients with interstitial lung disease (ILD), fatigue might be lessened after vigorous aerobic exercise.

Methods: 13 physically inactive patients (5 men and 8 women; age 57.2 ± 9.1 years, BMI 28.2 ± 4.6 kgm(-2)) with ILD of heterogeneous etiology and able to walk on a motor driven treadmill without physical limitation were enrolled. Subjects underwent cardiopulmonary exercise (CPET) and 6-min walk (6MWT) tests and completed Fatigue Severity Scale and Human Activity Profile questionnaires before and after an aerobic exercise-training regimen. The training regimen required participation in at least 24 of 30 prescribed aerobic exercise training sessions at a target heart rate of 70-80% of the heart rate reserve, 30 min per session, 3 times per week for 10 weeks.

Results: After training, a 55% (p < 0.001) increase in time to anaerobic threshold on the CPET, and an 11% (p = 0.045) reduction in performance fatigability index (PFI), calculated from the performance on the 6MWT were observed. Distance walked on the 6MWT (6MWD) increased by 49.7 ± 46.9 m (p = 0.002). Significant improvements in scores on the Fatigue Severity Scale (p = 0.046) and Human Activity Profile (AAS p = 0.024; MAS p = 0.029) were also observed. No adverse events related to the training regimen were noted.

Conclusion: After training, the decrease in fatigability appeared to result in increased 6MWD and was associated with physical activity. Since significant declines in 6MWD may be a marker for impending mortality in ILD, a better understanding of the etiological state of fatigue in patients with ILD and its reversal might provide fundamental insight into disease progression and even survival. [ClinicalTrials.gov identifier NCT00678821].

Keywords: Aerobic exercise physical activity; Fatigability; Fatigue severity; Interstitial lung disease; Pulmonary rehabilitation.

Copyright © 2015 Elsevier Ltd. All rights reserved.

Figures

Figure 1

Oxygen consumption (VO2) at the anaerobic threshold and at peak exercise during CPET before (white) and after (black) training (Panel A). Gray bar in background represents the range of VO2 requirements for the instrumental activities of daily living. Cardiorespiratory response pattern to CPET, depicting the change in time to anaerobic threshold (AT-time), observed in a representative subject (Panel B). For the group represented by this subject AT-time increased from 307.2 ± 122.9 s at baseline to 450.5 ± 158.2 s following training (p < 0.001).

Figure 2

Correlations among the indices of performance and fatigability before and after aerobic exercise training. In Panel A, 6-min walk distance (6MWD) correlated significantly with the performance fatigability index (PFI) and in Panel B, with time to anaerobic threshold (AT-time), before and after training. In Panel C, PFI correlated with 6MWD only after training.

Figure 3

Pre and post-training relationships among measures of fatigability and patient-reported fatigue severity and physical activity. In Panel A, Fatigue Severity Scale (FSS) was unrelated to either the performance fatigability index (PFI) or time to anaerobic threshold (AT-time). In Panel B, the Human activity Profile (HAP) Maximum Activity Score (MAS) was not related to PFI and was related to AT-time but only after training. In Panel C, HAP Adjusted Activity Score (AAS) was related to both PFI and AT-time but only after training.