目的：許多研究體適能相關論文，都以體重過重為研究重點，但近年來社會的審美觀，都以纖細苗條為美的標準，造成現今青少年以及青年，錯誤的飲食及減重的方式，來達成現今完美體態的目標，肥胖已經不是造成影響身體機能的唯一狀況，其中以青年健康體適能的決定因素，不僅只有體重過重或肥胖而已，體重過輕也是影響因素之一。青春後期到成年早期，也就是大學階段，是年輕學生開始形成自己的生活型態，也是影響健康的重要時期，同時也是執行健康促進的重要機會，故想藉由本研究來探討體重過輕之大一男生體適能表現情形，並將檢測結果給予建議及提供學校學生健康管理之參考。方法：本研究針對某科技大學93-98學年度大一男生進行體適能檢測。以SPSS12統計軟體進行資料處理與分析，測得數值以平均數±標準差（mean ± SD）表示，以Pearson積差相關檢驗體適能檢測值之關聯度，顯著水準訂在 P＜.05。結果與結論：本研究收集93-98學年度大一男生體適能檢測資料，樣本數共計1,999人，整體平均年齡為18.98 ± 0.94歲，BMI指數平均為22.40 ± 4.31 kg/m^2。體適能檢測方面，一分鐘仰臥起坐平均值為209.28 ± 30.35下，坐姿體前彎平均值為38.67 ± 8.30公分，立定跳遠平均值為209.28 ± 30.35公分，心肺耐力1600m跑走為577.08 ± 104.20秒。正常組之BMI與立定跳遠呈顯著負相關，與仰臥起坐呈顯著正相關；過重以上組之BMI與立定跳遠、仰臥起坐呈顯著負相關，與心肺耐力呈顯著正相關；過輕組、正常組與過重以上組之耐力跑與立定跳遠呈顯著負相關，顯示立定跳遠成績愈差，則耐力跑成績相對愈差。在坐姿體前彎與耐力跑相關方面，體重過輕組、正常組與過重以上組亦呈顯著負相關，表示柔軟度愈好，則耐力跑愈好。另體重過輕組、正常組及過重以上組之耐力跑與一分鐘仰臥起坐呈顯著負相關，表示一分鐘仰臥起坐成績愈差，則耐力跑成績愈差。由本研究發現造成耐力跑成績不理想原因，可能與肌肉量及肌力有關，導致耐力跑無法有好的表現，值得進一步探討分析。

Introduction: The past research papers on fitness mostly discuss overweight, but in recent years the concept of social has changed, the standard of beauty is slender. The teenagers and young people use the wrong methods to diet and lose weight to reach the ideal shape. So obesity is not the only impact on the performance of the body, when it comes to young people's physical fitness factors, not only overweight or obesity, underweight is one of the factors. From the late adolescence to early adulthood, the university stage is the period of the formation of life style, which is an important period of health, but also an important opportunity to improve health. Therefore, we want to use this study to explore the differences in the physical fitness performance of underweight men in their first year at university. The results can be provided as a reference for student health management. Methods: This study will test the physical fitness of freshman boys at a University of Technology. Statistical methods with SPSS12 statistical software in the data processing and the analysis conducted, the measured values with the standard error of the mean number of ±（mean ± SD）and pearson difference the difference related to verify the parameters associated with the study of significant standards set at P＜.05. Results & Conclusion: In this study, we collected the physical fitness test of College Freshmen in 93-98 year. The total number of samples was 1999, an average age of 18.98 ± 0.94 years old. The BMI index averaged 22.40 ± 4.31 kg/m2, the average waist circumference was 71 ± 0.25 cm. Physical fitness test, one minute sit up an average of 209.28 ± 30.35, sit and reach an average of 38.67 ± 8.30 cm, standing long jump with an average of 209.28 ± 30.35 cm, cardiopulmonary endurance run 1600m was 577.08 ±104.20 seconds. BMI and normal group of standing long jump showed a significant negative correlation and sit ups showed a significant positive correlation. overweight group BMI and above the standing long jump and sit ups showed a significant negative correlation and endurance run to showed significant positive correlation. In the study of physical fitness, the results showed that there was a negative correlation between endurance run and standing long jump. It also showed that the men who have the poor performance of standing long jump have the worse the performance of endurance running. There was a negative correlation between the underweight group and the normal group and overweight group in the front body bending and endurance running. The men with better softness have the better endurance. The endurance run of underweight group and normal weight group was negatively correlated with one minute sit up. It means the men who have worse scores of one-minute sit-ups sit perform the worse endurance running performance. The reason for the poor performance of endurance running is likely to result in a loss of muscle mass and muscular strength.