瘦身蛋白 (Leptin) 為脂肪細胞胖基因 (ob gene) 所製造的賀爾蒙類蛋白質，由於其涉及體內能量調控的層面相當廣泛，故成為目前肥胖問題研究的焦點，有關運動與人類Leptin的研究不多，而減肥運動處方所推薦的適度有氧性運動，是否會對不同肥胖度女性Leptin有所影響，亦有待探討。
本研究旨在探討單次立即性 (acute) 30分鐘有氧性運動，對不同肥胖程度女性Leptin濃度的影響，並分析心肺耐力、皮脂厚、腰臀圍比、耳鼓膜溫度等變項和Leptin之相關，及其預測公式之預測力。以我國72位女性，平均年齡18.3 ±0.7（歲）為研究對象，依身體質量指數 (BMI) 區分為三組：（一）超重組 (BMI≧23)、（二）體重正常組 (19 < BMI < 23)、（三）體重過輕組 (BMI≦19)。受試者於早上8:00用餐，9:00-11:00進行單次30分鐘跑走運動，強度為50～85%最大保留心跳率 (HPRmax)，並於運動前後抽血觀察血中Leptin變化情形，運動後檢驗值並經血漿容積 (plasma volume) 校正，以排除運動後血液濃縮效應的干擾。所得資料經統計t-考驗、Ｘ'考驗，單因子變異數分析 (ANOVA) 及相關與迴歸等分析之後，獲致如下結果：
(1)運動後，超重組Letpin由20.4 ±9.8ng/ml顯著增加為24.2±12.3ng/ml (P <.001); 體重正常組Leptin由5.4 ±4.5ng/ml顯著增加為6.3 ±5.3ng/ml (P<.001); 體重過輕組Leptin由3.9 ±3.0ng/ml增加為4.0 ±3.7ng/ml，未達顯著水準 (p>.05)。
(2)各肥胖度分組間運動前後Leptin濃度差值及變化率，皆達顯著差異水準 (P<.0001)，超重組大於體重正常組，體重正常組大於體重過輕組。各組之間運動後Leptin上升或下降人數比例之差異，以Ｘ'考驗得知亦具顯著差異性 (P＝.0009)。
(3)不同肥胖程度女性30分鐘運動後Letpin變化的分界點位於BMI=18.8處，BMI>18.8者，BMI愈大運動後Leptin上升幅度愈大; BMI<18.8者，BMT愈小運動後Leptin下降的幅度愈大；BMI愈接近18.8者，運動後Leptin變化幅度愈小。
(4)BMI、心肺耐力、皮脂厚、腰臀圍比和耳鼓膜溫度等變項皆和Letpin運動前、後測量值，有顯著相關 (P<.05)，其最佳單一變項預測公式為：運動前Letpin濃度 (ng/ml)＝2.1601XBMI (kg/m2)-37.677，(R2=.7228, P<.0001)：最佳二變項預測公式為：運動前Letpin濃度 (ng/ml)＝1.7294XBMI-0.0066X12'RW-13.571，(R2＝.7980, P<.0001)。
本研究結論如下，單次立即性30分鐘跑走運動，對不同肥胖程度女性瘦身蛋白 (Leptin) 會有不同影響。BMI愈大者運動後Leptin上升幅度愈大；BMI愈小者，運動後Leptin變化幅度愈小，甚至下降，其分界點位於BMI=18.8處。BMI、心肺耐力、皮脂厚、腰臀圍比和耳鼓膜溫度等變項，皆和瘦身蛋白 (Letpin) 濃度有顯著相關，其中肥胖程度 (BMI) 是影響女性運動後Leptin變化的主要因素。

Leptin, the product of ob gene secreted by adipose tissue as a hormone to regulate the deposition of body energy, has become a research focus of obesity problem during recent years. However, little is known concerning exercise and leptin. Therefore it is worth while to further study the effect of exercise on leptin level, especially the recommended aerobic exercise for weight control.
In this study, single acute aerobic stimulus composed by 30 min run-walk was applied to female subjects with different body compositions to examine the changes of leptin before and after the exercise, to analyze how the leptin response related to the cardiopulmonary endurance, total skinfold, waist to hip ratio, and tympanic temperature of the subjects, and to infer the possibility for a prediction formula. Seventy-two females were divided into three groups according to their body mass index (BMI): (1) the overweight (BMI >. 23), (2) the normal weight (19 < BMI < 23), and (3) the underweight (BMI ≦ 19). All the subjects completed breakfast at 8:00, then were undergone a thirty minutes run-walk stimulus during 9:00 to 11:00 in the morning. The intensity of the exercise was maintained at 50 ~ 85% maximal heart rate reserve (HRRmax). Blood samples were taken before and after the exercise from each individual, and analyzed for leptin concentration. The leptin level in the sera taken after the exercise was corrected by plasma volume to eliminate the effect of hemoconcentration caused by loss of water. All data were statistically analyzed by student t- test, Chi-square, one way ANOVA, regression and correlation analysis, and came to results as follows:
1. After exercise, the average leptin level of the overweight group was significantly elevated from 20.4 ±9.8 ng/ml to 24.2 ± 12.3 ng/ml (P < 0.001). For the normal weight group, leptin level also increased from 5.4 ±4.5 ng/ml to 6.3 ±5.3 ng/ml with significance (P < 0.001). There was no significant change in the leptin level for the underweight group (from 3.9 ±3.0 ng/ml to 4.0 ±3.7 ng/ml, P> 0.05).
2. The average leptin levels and the changes in it before and after exercise among three groups were significantly different (P < 0.0001) for showing the order of the overweight > the normal weight > the underweight.
3. The change in leptin levels was related to the BMI of the analyzed subjects. The regression analysis data showed that females with BMI larger than 18.8 tended to have a positive leptin response to the stimulus, and the degree of elevation was positively related to the BMI. On the contrary, subjects with BMI smaller than 18.8 tend to have a decreased leptin level after exercise, and the degree of decreasing was negatively related to the BMI. Using Chi-square analysis to evaluate the proportion of people that tend5 to have an increase or decrease in leptin level after exercise in each group has reached a meaningful result (P＝0.0009).
4. The leptin levels, no matter before or after the exercise, were significantly correlated to the cardiopulmonary endurance, total skinfold, waist to hip ratio, and tympanic temperature of the subjects (P < 0.05). The best one factor and two factors correlation formula for leptin concentration prediction before exercise were leptin conc, (ng/ml)=2.1601 x BMI (kg/m2) - 37.677, R2=0.7228, P < 0.0001, and leptin conc. (ng/ml)=1.7294 x BMI (kg/m2) - 0.0066 x 12'RW-13.571, R2=0.7980, P < 0.0001.
In conclusion, the effect of single acute 30 min run-walk exercise on the leptin level was different for subjects with different body composition. For women with larger BMI, exercise seemed to stimulate leptin level. As for underweight women, exercise caused a decrease in leptin level. Although cardiopulmonary endurance, total skinfold, waist to hip ratio, and tympanic temperature were also correlated to the level of leptin, BMI showed the best correlation.