緒論：運動對於老人認知功能的影響在這三十年間廣泛地被學術界探討，但運動時間、身體質量指數與認知功能間的關係，仍有待進一步探究。本研究之目的在探討老人運動時間、身體質量指數與認知功能障礙間的關聯。方法：本研究採橫斷式次級資料分析法，資料來源為2009年國家衛生研究院聯合行政院衛生署國民健康局所舉辦的「國民健康訪問調查」(NHIS)資料庫，以65歲以上的受訪者為研究樣本，計2557人，扣除非本人作答及變項有遺漏者，共計2146人。在變項測量方面，依變項以簡易知能量表(MMSE)做為認知功能測量工具，MMSE得分再依不同教育程度之切點來決定樣本是否具認知障礙。統計分析中，先進行雙變項分析，了解各自變項與認知功能間的統計顯著性，再進行邏輯斯迴歸分析。結果：研究顯示2009年國民健康訪問調查之老人樣本的認知障礙盛行率為26.37%。邏輯斯迴歸分析顯示，年齡越大、曾經中風、有憂鬱傾向者，有較高的認知功能障礙；而身體質量指數較高、過去兩週運動在60至120分鐘者，有較低的認知功能障礙風險。進一步將身體質量指數分成高(BMI ≧ 23)與低(BMI ＜ 23)兩組，並控制其他變項後，檢視運動時間與認知功能障礙的關係，發現在BMI較低的一組每兩週運動時間要達120分鐘以上才有較佳認知功能，而BMI較高的一組，則是每兩週運動時間在60至120分鐘就有較佳的認知功能表現。結論：本研究發現，每週運動時間的長短與降低認知功能障礙有相關，而運動時間長短對於降低認知功能障礙的效果又依老人的身體質量指數不同而不同。

Introduction: The effects of physical exercises on cognitive functions for elderly people have been discussed extensively in the last three decades while the relationship between exercise time, body mass index and cognitive function has received less attention. The purpose of this study was to explore the relationship in-between. Methods: Based on the ＂National Health Interview Survey＂ (NHIS) of 2009 conducted by the National Health Research Institutes jointly with the Health Promotion Administration and the Ministry of Health Welfare, we gathered data from 2,557 respondents over age of 65 (65 included) while abandoned of them for not being qualified as the first-hand data which resulted in a total sample size of 2,146. The Mini-mental state examination (MMSE) score was dependent variable, according to the different levels of education corresponding to the cut point to determine whether the sample has cognitive impairment or not. The X2 test and logistic regression analysis were used to evaluate the association between cognitive impairment and variables of independent variable. Results: The prevalence of cognitive impairment was 26.37%. Results of logistic regression analysis indicated that older age, with a history of stroke and with a tendency to depression were associated with a higher risk of cognitive impairment. Older with a higher BMI, 60 to 120 minutes exercise time in the past two weeks were associated with a lower risk of cognitive impairment. Further, we divided the samples into two groups according to BMI for analysis. After controlling the confounding variables, we found that the lower BMI group (BMI ＜ 23) is associated with a better cognitive function if exercise time is 120 minutes or more every two weeks. And the higher BMI group (BMI ≧ 23), just spending 60 to 120 minutes for exercise every two weeks, is associated with a better cognitive function. Conclusion: Cognitive impairment risk reduction is associated with exercise time in older adults, and the effect of exercise time on the reduction cognitive impairment is depend on the different BMI level of older adults.