BACKGROUND: Chest wall mobility is often measured in clinical practice, but the correlations between chest wall mobility and respiratory muscle strength and lung volumes are unknown. We investigate the associations between chest wall mobility, axillary and thoracic cirtometry values, respiratory muscle strength (maximum inspiratory pressure and maximum expiratory pressure), and lung volumes (expiratory reserve volume, FEV 1 , inspiratory capacity, FEV 1 /FVC), and the determinants of chest mobility in healthy subjects. METHODS: In 64 healthy subjects we measured inspiratory capacity, FVC, FEV 1 , expiratory reserve volume, maximum inspiratory pressure, and maximum expiratory pressure, and chest wall mobility via axillary and thoracic cirtometry. We used linear regression to evaluate the influence of the measured variables on chest wall mobility. RESULTS: The subjects' mean ؎ SD values were: age 24 ؎ 3 years, axillary cirtometry 6.3 ؎ 2.0 cm, thoracic cirtometry 7.5 ؎ 2.3 cm; maximum inspiratory pressure 90.4 ؎ 10.6% of predicted, maximum expiratory pressure 92.8 ؎ 13.5% of predicted, inspiratory capacity 99.7 ؎ 8.6% of predicted, FVC 101.9 ؎ 10.6% of predicted, FEV 1 98.2 ؎ 10.3% of predicted, expiratory reserve volume 90.9 ؎ 19.9% of predicted. There were significant correlations between axillary cirtometry and FVC (r ‫؍‬ 0.32), FEV 1 (r ‫؍‬ 0.30), maximum inspiratory pressure (r ‫؍‬ 0.48), maximum expiratory pressure (r ‫؍‬ 0.25), and inspiratory capacity (r ‫؍‬ 0.24), and between thoracic cirtometry and FVC (r ‫؍‬ 0.50), FEV 1 (r ‫؍‬ 0.48), maximum inspiratory pressure (r ‫؍‬ 0.46), maximum expiratory pressure (r ‫؍‬ 0.37), inspiratory capacity (r ‫؍‬ 0.39), and expiratory reserve volume (r ‫؍‬ 0.47). In multiple regression analysis the variable that best explained the axillary cirtometry variation was maximum inspiratory pressure (R 2 0.23), and for thoracic cirtometry it was FVC and maximum inspiratory pressure (R 2 0.32). CONCLUSIONS: Chest mobility in healthy subjects is related to respiratory muscle strength and lung function; the higher the axillary cirtometry and thoracic cirtometry values, the greater the maximum inspiratory pressure, maximum expiratory pressure, and lung volumes in healthy subjects.

This method depends on patient understanding; the operator and measurement variability must also be considered. Several studies have assessed the reliability of chest wall mobility. Malaguti et al. (9) found a substantial intraclass correlation coeffi cient (ICC: 0.89 [95% confi dence interval, CI, 0.75 -0.95]) between two chest wall mobility measurements in chronic obstructive pulmonary disease (COPD) patients. Similar ICC values were reported in other studies of healthy volunteers (10,11).External stimuli can infl uence tests reliant on patient cooperation. AbstractBackground: Visual feedback could optimize the evaluation of chest wall mobility. Objective: To compare chest wall mobility performed with and without visual feedback. Methods: Cross-sectional study, 64 healthy volunteers, average age 24 years old. The thorax circumference was measured at two locations, the axillary and xiphisternum regions, by a tape placed at the anterior axillary line and at the xiphoid process. The evaluations were performed: (i) after verbal explanation (without visual feedback), (ii) after verbal explanation plus visual feedback (with visual feedback); for this evaluation the volunteer remained in front of the computer, which provides visual feedback. Results: There was no difference between axillary measurement with vs. without feedback (7.5 Ϯ 2.4 cm vs. 7.9 Ϯ 3.3 cm, respectively, p ϭ 0.215), but signifi cant difference between xiphisternum measurement 7.1 Ϯ 2.7cm with feedback vs. 6.5 Ϯ 2.3cm without feedback, p ϭ 0.043. Low intraclass correlation coeffi cients were observed for the axillary measurement [0.51 (0.19 -0.72, p ϭ 0.003) and for xiphisternum measurement [0.60 (0.35 -0.76, p Ͻ 0.001) performed with and without feedback, respectively. Conclusion: Thoracic mobility presents great variability when compared with and without feedback, so the visual stimulus must be taken into account in this evaluation.