目的:了解從事健身中心運動者六個月運動行為階段改變情形，並探討自我效能、結果預期及社會支持對階段改變的影響。方法:縱貫式樣本調查，以便利取樣法選取自願參與調查者(共72位，平均年齡40.0± 7.1歲) 進行三次(第一、三、六個月)運動行為階段、自我效能、結果預期及社會支持評量後，先歸類階段改變情形，再以兩階段集群法分析階段改變存在集群數，並以區別分析按驗集群分類適當性，最後利用多變量單因子變異數分析檢定不同集群自我效能、結果預期及社會支持差異。結果:經歸類六個月運動行為階段有19種改變情形及8種改變方式，兩階段集群法分析顯示階段改變存在三個集群，可被自我效能、結果預期及社會支持區別，正確分類率為91.67%'事後比較則發現第一、三、六個月自我效能是集群3>集群1>集群2'第一、三、六個月結果預期及社會支持則是集群2>集群1>集群3。結論:六個月運動行為階段動態改變歷程，可因自我效能、結果預期及社會支持增加與改變之行為控制、意圖及依附性形成不同改變模式。

Purpose: To investigate the stage of change in exercise behaviors for the participants exercising in fitness center during a six-month period. The impacts of the self-efficacy， outcome expectancy and the social support on the stage of change for exercise behaviors were explored. Method: The longitudinal approach was used to sample the data from 72 volunteers， which average age was 40.0 ± 7.1 years old. After three assessments of the first， third， and the sixth months， and then classified the stage of change in exercise behaviors for six months. Two-stage clustering approach and the discriminate analysis were used to analyze the cluster members of the stage of change and the statistical adequacy. Finally， the one-way MANOVA was employed to test the differences among the self-efficacy， outcome expectancy， and social support based on the stage of change in exercise behaviors. Results: There were nineteen conditions and eight types of changes were generated during a six-month period. Three cluster members were captured by the two-stage clustering approach and were correctly classified to each cluster by self-efficacy， outcome expectation， and social support at 91.67% level. Inself-efficacy， the post hoc comparison indicated the cluster 3 was higher than cluster 1 and cluster 2 in the first， the third and the sixth months. Inoutcome expectancy and social support， the cluster 2 was higher than cluster 1 and cluster 3 in the third and the sixth month. Conclusions: The stage for exercise can be a complex and changeable process during a six-month study. This process should be increased by the self-efficacy， outcome expectancy， social support， and the change of the behavioral control， intention， and adherence of the exercise participants.