Handgrip strength is associated with improved spirometry in adolescents.

Introduction: Pulmonary rehabilitation, including aerobic exercise and strength training, improves function, such as spirometric indices, in lung disease. However, we found spirometry did not correlate with physical activity (PA) in healthy adolescents (Smith ERJ: 42(4), 2016). To address whether muscle strength did, we measured these adolescents' handgrip strength and correlated it with spirometry.

Methods: In 1846 non-smoking, non-asthmatic Germans (age 15.2 years, 47% male), we modeled spirometric indices as functions of handgrip strength by linear regression in each sex, corrected for factors including age, height, and lean body mass.

Results: Handgrip averaged 35.4 (SD 7.3) kg in boys, 26.6 (4.2) in girls. Spirometric volumes and flows increased linearly with handgrip. In boys each kg handgrip was associated with about 28 mL greater FEV1 and FVC; 60 mL/sec faster PEF; and 38 mL/sec faster FEF2575. Effects were 10-30% smaller in girls (all p<0.0001) and stable when Z-scores for spirometry and grip were modeled, after further correction for environment and/or other exposures, and consistent across stages of puberty.

Conclusions: Grip strength was associated with spirometry in a cohort of healthy adolescents whose PA was not. Thus, research into PA's relationship with lung function should consider strength as well as total PA. Strength training may benefit healthy lungs; interventions are needed to prove causality.