This study aimed to clarify the effect of body position on cough force and respiratory function. Twenty healthy young males were included. Cough force and respiratory function were measured using a spirometer in the sitting, side-lying, 30° head-up, and supine positions. The order of measurement for each body position was randomized. Peak cough flow was used as an index of coughing force. Peak cough flow, vital capacity, % vital capacity, tidal volume, forced expiratory volume1.0%, forced expiratory volume in one second and forced vital capacity showed no significant differences between body positions. However, inspiratory capacity was significantly lower and expiratory reserve volume was significantly higher in the sitting and side-lying positions than in the 30° head-up and supine positions. Peak cough flow was significantly positively correlated with vital capacity and forced expiratory volume1.0%, forced expiratory volume in one second and forced vital capacity. The conflicting relationship between inspiratory and expiratory volumes may have resulted in PCF showed no significant difference between four body positions.

[Purpose] There have been various studies on the evaluation of periprosthetic hip muscles after total hip arthroplasty, and many reports have evaluated them using isometric muscle strength measurement with a hand-held dynamometer. In this study, we evaluated muscle strength from preoperative to 1 year postoperatively using an isokinetic muscle strength measurement device, and examined the correlation with changes in patient stance evaluation. [Methods] BIODEX SYSTEM 4 (Biodex Medical Systems, Inc., USA) was used to measure muscle strength and the Japanese Orthopaedic Association Hip Disease Assessment Questionnaire (JHEQ) was used to evaluate patient stance. The correlation between muscle strength and JHEQ score was investigated. [Results] The periprosthetic muscle strength of both the operative and nonoperative sides of the hip improved in all muscles at six months and one year postoperatively compared to that of preoperatively. Each score of the JHEQ improved significantly in the first six months and one year after surgery, but there was no significant difference between the first six months and one year after surgery. Weak positive correlations were found between the periarticular hip muscles and the movement scores of JHEQ, and significant differences were found in flexion and abduction muscle strength at six months postoperatively and flexion muscle strength at one year postoperatively. [Conclusions] Both the operated and nonoperated sides showed improvement in the periarticular hip muscles from six months to one year postoperatively. Improvement in movement scores on the JHEQ was associated with periprosthetic hip muscle strength, suggesting that improvement in muscle strength may be important in improving patient satisfaction．