運動抑制肥胖的機轉

運動可增加能源消耗，這個一般性的概念使得早期學者用來推測，運動抑制肥胖的機轉可能與燃燒脂肪組織三酸甘油脂有關。然而，運動過程身體燃燒的主要能源為醣類而非脂肪。高強度運動下，身體脂肪組織所儲存的三酸甘油酯並未增加消耗。雖然運動後24小時身體休息代謝率(RMR)明顯提昇，但三酸甘油酯燃燒總量卻未因此提昇。這些證據顯示「運動燃燒脂肪」這個理論很難解釋運動抑制肥胖的實際結果。事實上，脂肪細胞對能源的吸收能力（包括醣類與脂肪）對於肥胖具有決定性的影響。目前研究發現運動明顯抑制脂肪細胞能源吸收。這個效果主要來自於兩大因素：（一）運動的肌肉組織（身體最主要的組織）對於能源的競爭力提高；（二）運動使脂肪組織對於能源的吸收能力暫時下降。因此，研究常發現規律運動對於身體組成的改變較多，造成體重的下降未必非常明顯－「塑身效果高於減重效果」。運動改變飯後能源分配的效果與「運動強度」及「持續時間」有關，然而其效應的持續力並不長。因此，規律運動的「頻率」對於防止肥胖為運動處方內容的另一個關鍵要素。

關鍵字

肥胖；身體活動；身體組成；脂肪

並列摘要

It is generally known that exercise can increase energy expenditure, and thus this simple concept was used to assume how exercise prevents adiposity is due to its fat-burning effect. However, it was currently known that carbohydrate is the main fuel source during exercise, whereas fat serves as the major fuel under resting condition. In addition, lipolysis in adipose tissue cannot be elevated in a significant extent during exercise. Although exercise can elevate the 24-h energy expenditure, the overall amount of fat utilization is not significantly affected. Therefore, it is difficult to assume that ”energy expenditure” per se accounts for the fact that exercise can prevent obesity. In fact, the amount and rate of fuel uptake, including fat and carbohydrates, by adipose tissue dictate the degree of adiposity. It is now becoming clear that exercise can temporally inhibit postprandial fuel uptake. This effect is attributed by two main factors derived from exercise: (1) exercise makes skeletal muscle more competitive for fuel acquisition, and thus deprives energy delivery to adipose tissue; (2) Exercise reduces TG hydrolysis in adipose tissue. Accordingly, we typically found that exercise can change body composition, but may not necessarily reduced body weight. Effect of exercise on altering postprandial fuel repartitioning is affected by exercise intensity and duration. Since the lasting effect of exercise on preventing adiposity cannot last long, frequency to perform exercise is apparently important for the fat-reducing effect of exercise.

並列關鍵字

Obesity ； Physical activity ； Body composition ； Fat

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