The relationship between peak inspiratory flow and hand grip strength measurement in men with mild chronic obstructive pulmonary disease

Background Chronic obstructive pulmonary disease (COPD) decreases quality of life and muscular strength. Inspiratory flow is important for inhalants in the bronchi but is complicated to measure in routine practice. We hypothesized that hand grip strength (HGS) would correlate with inhalation rate in patients with mild COPD. Methods The COPD patients were recruited at the St. Marianna University School of Medicine, Yokohama Seibu Hospital, from 2015 to 2018. We measured peak inspiratory flow (PIF) through an In-Check flow meter attached with Diskus [PIF(D)] and Turbuhaler [PIF(T)] inhalers. The 6-min walking test (6MWT), and the fraction of exhaled nitric oxide (FENO), spirometry, HGS, or forced oscillation technique (FOT) parameters were measured. Results Forty-four subjects were enrolled. All were men, with a mean age (± SD) of 77.8 ± 9.36 years. Thirty-nine patients had mild COPD. PIF(D) was 110 (80, 140) L/min (median, interquartile range), PIF(T) was 80 (70, 90) L/min, and HGS was 28.7 (13.8, 43.6) kgf. PIF(D) and PIF(T) were significantly correlated (r = 0.443, p = 0.003). PIF(D) was significantly correlated with age (r = − 0.327, p = 0.030) and HGS (r = 0.326, p = 0.031). PIF(T) was significantly correlated with age (r = − 0.328, p = 0.030), FVC (r = 0.351, p = 0.019), 6MWT distance (r = 0.392, p = 0.011), and HGS (r = 0.328, p = 0.030). Conclusion HGS might be more useful for predicting PIF than other parameters. Also, elderly COPD patients need to be taught inhaled methods carefully.