The association between muscle strength and z scores of pulmonary function

Z scores and percent predicted values of spirometry parameters are widely used for the evaluation of pulmonary function and detection of respiratory diseases. Decreased pulmonary function should correlate with reduction of muscle strength although it is unclear whether z scores of respiratory parameters are associated with muscle strength. In a cohort of 398 adults, pulmonary function assessment and muscle strength measurement by handgrip strength and physical activity level were evaluated. Probable sarcopenia was defined by muscle strength reduction. Univariate and multivariate regression analysis and ROC curve were applied. The AUC for FEV1 and FVC were significantly greater than the z FEV1 and z FVC (p = 0.0004 and p = 0.0008) respectively. Multivariate regression analysis adjusted for confounders also reported a significant and independent relationship between z FEV1; z FVC and HGS measurements. FEV₁ and FVC in absolute values have an important role in the detection of sarcopenia status. Predicted values and z scores also show a significant association suggesting the pathophysiological connection between lung function and muscle strength.