High-Intensity Interval Training Improves COPD Outcomes

Pulmonary function, exercise capacity, and quality of life in patients with chronic obstructive pulmonary disease (COPD) may be improved in those aged 40 and older with high-intensity interval training (HIIT), according to review and meta-analyses findings published in Respiratory Medicine.

HIIT involves high-intensity exercises repeated in a short time period, interspersed with brief recovery intervals between exercises and carried to exhaustion. Some research has suggested that this type of exercise may help patients with COPD overcome intolerance to long-term exercise and improve rehabilitation training compliance. Investigators in China therefore sought to assess the intervention effect and safety of HIIT for COPD patients.

The researchers conducted a review and meta-analyses of 20 randomized controlled trials (RCTs) on the effects and efficacy of HIIT for patients with COPD in the Medline, Embase, Wanfang, Weipu, China National Knowledge Infrastructure, Cochrane Library, Web of Science, and PubMed databases from inception until mid-September 2022. Studies identified included 962 COPD patients, including 514 who underwent HIIT interventions. For inclusion in the meta-analysis, studies needed participants who were at least 40 years of age, had no mental illness, and had a clinical diagnosis of COPD. Those included in the meta-analysis “experimental group” had undergone HIIT and those in the control group had undergone routine nursing care or moderate/low-intensity exercise. Primary endpoints were 6-minute walking distance, peak work rate, peak minute ventilation, peak oxygen consumption, forced expiratory volume in 1 second (FEV₁), and the ratio of FEV₁ to forced vital capacity (FVC). Additional endpoints included the St. George’s Respiratory Questionnaire, dyspnea, and health-related quality of life.

The researchers calculated standardized mean differences (SMDs) to assess outcomes. Use of the Egger test and funnel plots found that meta-analysis results were not affected by publication bias (all P >.05).

The meta-analysis found that patients with COPD who did HIIT increased their 6-minute walking distance (SMD=0.39; 95% CI, 0.23-0.55), peak work rate (SMD=0.34; 95% CI, 0.17-0.51), peak minute ventilation (SMD=0.26; 95% CI, 0.05-0.47), and peak oxygen consumption (SMD=0.30; 95% CI, 0.14-0.46) (all P <.05). Doing HIIT improved these patients’ quality of life (SMD=0.30; 95% CI, 0.06-0.54) and reduced dyspnea (SMD = -0.27; 95% CI, -0.51 to -0.03) (all P <.05).

The investigators found no significant differences between the experimental and the control groups in FEV₁/FVC ratio (SMD=0.28; 95% CI, -0.01 to -0.56) and in St. George’s Respiratory Questionnaire score (SMD = -0.35; 95% CI, -0.73 to 0.03) (all P >.05).

Review and meta-analyses limitations include blinding deficiencies in the studies included for analysis, missing data for FEV₁ in most RCTs, missing data on side effects other than dyspnea, and between-study differences in method of HIIT, training time, intensity, and frequency, which could have caused heterogeneity in the final measurement indicators.

The investigators concluded that “HIIT may be beneficial to improve pulmonary function, exercise capacity, and quality of life compared with other exercise or routine care. HIIT may be recommended as a safe and effective exercise in a pulmonary rehabilitation program.” However, “As the overall results are based on a limited number of studies with potential heterogeneity, conclusions should be drawn with caution,” said the study authors.