Association between knee extensor strength and pulmonary function in the female elderly

[Purpose] The purpose of this study is to study the impact of knee extensor strength, which is an index of the degree of physical activity on lung capacity in older women. [Subjects and Methods] Thirty-three older women who participated in the exercise program hosted by a senior citizen center and S University located in Busan. Force vital capacity (FVC) was measured with digital spirometry (Pony FX, COSMED Inc., Italy). Three rounds of measurements were taken for each participant, with one-minute rests between the tests. The means were computed for analysis. Knee extensor strength was measured with a hand-held dynamometer (HHD, MicroFET2^®, Hogan Health Industries, Inc., UT, USA). Three rounds of measurements were taken for each knee extensor muscle, after which the mean of the measurements was taken for each side. The higher knee extensor muscle strength value was used for the analysis. [Results] Knee extensor muscle strength had significant positive correlations with Forced vital capacity (FVC), Forced expiratory volume in 1 second (FEV₁), Peak expiratory flow (PEF), and Forced expiratory flow (FEF 25-75%). Association between knee extensor muscle strength and pulmonary function suggested that weakening of the elderly's knee extensor muscle strength has an adverse effect on pulmonary function, although the explanatory power was weak. [Conclusion] Knee extensor muscle weakness in elderly females restricts their physical activity and mobility, thereby serving as a key factor in decreasing their lung capacity.