Chest wall mobility is related to respiratory muscle strength and lung volumes in healthy subjects

Background: chest wall mobility is often used in clinical practice, but is not determined it's correlation with respiratory muscle strength and lung volumes.

Objective: to investigate the association between chest wall mobility, axilary (Cax) and thoracic cirtometry (Cthor), respiratory muscle strength (maximal inspiratory pressure – PImax, maximal expiratory pressure - PEmax) and lung volumes (expiratory reserve volume - ERV, forced expiratory volume in the first second - FEV1, inspiratory capacity - IC, forced vital capacity - FVC), and secondarily to investigate the determinants of chest mobility in healthy subjects.

Methods: 64 healthy volunteers; spirometry was performed to determine: IC, FVC, FEV₁ and ERV. PImax and PEmax were evaluated using a manometer to measure pressure at the mouth. Chest wall mobility was performed at axillary and thoracic levels using a measuring tape. Linear regression analysis was used to evaluate the influence of some variables on chest wall mobility.

Result: the volunteers were 24 ± 3 years old, Cax was 6.3 ± 2.0 cm, Cthor was 7.5 ± 2.3 cm. Respiratory pressures were PImax: −90.4±10.6% pred; PEmax: +92.8±13.5% pred. Lung function IC: 99.7 ± 8.6% pred, FVC: 101.9 ± 10.6% pred, FEV1: 98.2 ± 10.3% pred; ERV: 90.9 ± 19.9% pred. There was significant correlation between Cax and FVC, FEV₁, PImax, PEmax, IC (r: 0.32, r: 0.30, r: 0.48, r: 0.25, r: 0.24, respectively) and between Cthor and FVC, FEV₁, PImax, PEmax, IC, ERV (r: 0.50, r: 0.48, r: 0.46, r: 0.37, r: 0.39, r: 0.47, respectively). In multiple regression analysis the variable that best explained the Cax variation was PImax (R2: 0.23), and for Cthor was FVC and PImax (R2: 0.32).

Conclusions: chest mobility in healthy subjects is related to respiratory muscle strength and lung function, thus the higher the Cax and Cthor greater PImax, PEmax, and lung volumes in healthy subjects.