Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease that manifests in hypoxemia, inactivity, and poor prognosis. This study aimed to assess the prognostic role of physical activity (PA) and exertional desaturation (ED) with mortality in IPF. At baseline, 34 IPF patients (68 (50–81) years) were interviewed using the International Physical Activity Questionnaire (IPAQ), and SpO₂ was assessed pre to post 6-min walking test (∆SpO₂). Patients were prospectively followed up for 40 months. Receiver operating characteristics curve analysis determined cut-off points associated with mortality, and Cox proportional hazard ratio (HR) were conducted. Thresholds for increased mortality risk in IPF patients were determined as IPAQ ≤ 417 metabolic equivalent task (METS)-min/week, p = 0.004 (HR; 9.7, CI 95% (1.3–71.9), p = 0.027), and ∆SpO₂ ≥ 10%, p = 0.002, (HR; 23.3, CI 95% (1.5–365), p = 0.025). This study demonstrated a significant association of PA and ED with mortality in IPF patients. The findings emphasize the clinical importance of PA and ED assessments to aid in IPF risk stratification, prognosis prediction, and in providing early appropriate treatments, such as pulmonary rehabilitation, PA consultation, oxygen supplementation, and lung transplantation referral. These results underscore that even low levels of PA corresponding to 100–105 min/week were associated with a reduced mortality risk and better survival in IPF.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal interstitial lung disease associated with poor prognosis and limited effective treatment options. Reliable predictors of outcome in daily clinical practice are needed to determine high-risk patients for urgent lung transplantation referral. This study aimed to identify practical prognostic predictors of mortality using cardiopulmonary exercise testing (CPET) in IPF subjects. METHODS: Thirty-four subjects with IPF (22 men and 12 women), median age 68 (range 50–81) y were prospectively studied. At baseline, all subjects were assessed with CPET and were followed up for 40 months from baseline. Receiver operating characteristic curve analysis was conducted to determine cut-off points of CPET variables for mortality, Cox regression analysis for survival using a log-rank test, and hazard ratio for death using a Wald test. RESULTS: Peak work rate <62 watts ( P = .005), peak V̇ O ₂ ≤13.8 mL/kg/min ( P = .031), tidal volume reserve ≤0.48 L/breath ( P = .010), minute ventilation to carbon dioxide (V̇ _E )/V̇ CO ₂ ) ratio at the anaerobic threshold >34 ( P = .02), and V̇ _E )/V̇ O ₂ nadir >34 ( P = .002) were detected as cut-off points associated with mortality. Non-survivor subjects were characterized by higher dyspnea levels, the presence of pulmonary hypertension assessed by echocardiography, pronounced inefficient ventilatory pattern, lower exercise capacity, and more severe desaturation during physical exertion. By the end of the study, 11 subjects (7 women and 4 men) died. Overall mean survival was 60%, 33.7 months (95% CI 30.2–37.2). CONCLUSIONS: This study provides simple, practical, and novel cut-off points for CPET as predictors of prognosis to identify high-risk IPF subjects. Impairment in exercise capacity and abnormal ventilatory responses during CPET were associated with poorer survival in IPF subjects. The findings suggest considering the use of CPET for IPF risk stratification and prediction of prognosis. (ClinicalTrials.gov registration NCT01499745.)

Key points: Exercise training has been proven to be a safe and effective behavioural intervention for prevention and rehabilitation of chronic conditions. Despite the complexity of the signs and symptoms presented in IPF, supervised exercise training is a feasible and effective treatment for clinical improvement. Emerging data show significant enhancements in exercise capacity, dyspnoea and quality of life among IPF patients after exercise training interventions. Understanding of the principles of exercise training and the pathophysiology of IPF are essential for effective exercise programme delivery. Educational aims: To describe the current evidence supporting exercise training for IPF. To highlight the importance of exercise physiology principles in rehabilitation treatment of patients with IPF. To introduce an effective practical exercise programme for IPF. To discuss the possible underlying physiological mechanisms of training effects in IPF. Exercise is a well-documented safe and effective intervention for prevention and rehabilitation of chronic diseases. Idiopathic pulmonary fibrosis (IPF) is a chronic deadly lung disease associated with severe signs and symptoms, exercise intolerance, diminished quality of life and poor prognosis. In the short term, supervised exercise training programmes have demonstrated clinical benefits in improving exercise capacity, dyspnoea and quality of life in patients with IPF. The underlying mechanisms of chronic adaption to a regular exercise regimen in IPF have yet to be well described and require further investigation. The available data underscore the importance of implementing training principles to target the pathophysiological impairments of IPF in order to optimise training adaption and enhance the outcomes. The current exercise training data in IPF provide sufficient evidence of clinical benefit for consideration to be given to recommending exercise-based pulmonary rehabilitation as standard of care for IPF.