| 摘要: | 適度規律的運動習慣有益於身體健康，但是運動過程中，體內消耗大量氧氣及能量的情況下，使得代謝率上升，在這同時也伴隨產生釵h活性氧分子（reactive oxygen species; ROS），而過量的自由基會提高體內氧化性壓力（oxidative stress），造成潛在氧化性傷害（oxidative damages）。故本研究目的為探討適度規律的運動習慣，對於體內自由基產生與清除機制之調控。本研究以健康女大學生為對象，分為無運動習慣組（sedentary group；SED）和長期規律運動習慣組（long-term training group；LTT）；SED組經過6週有氧體適能訓練後稱為短期訓練組（short-term training group；STT）。我們分別對SED、STT、LTT進行遞增負荷運動測試，並且在測試前後及休息後採集血液，並分析血液中超氧自由基（superoxide anion radical；O2-•）、抗氧化酵素活性（scavenger enzymes activities）及各項生化指標等。結果顯示，運動表現能力隨運動訓練時間增加而改變，如最大攝氧量、可負荷之最大運動時間和可負荷之最大運動強度，皆隨訓練時間增加而有顯著性提高之趨勢。相關係數分析顯示，超氧自由基與肌肉損傷指標、血球計數分析、脫水指標等因子無正相關性，表示本研究中超氧自由基量的變化並非上述因素所造成。血液中超氧自由基在遞增負荷運動測試後，SED有顯著性增加，STT有增加現象，但統計上並無顯著差異，LTT並無明顯改變。此外，在安靜狀態下（resting state），STT與LTT血液中超氧自由基皆低於SED。短期訓練後（STT），紅血球中抗氧化酵素活性有顯著性提高的現象，但STT卻與SED無顯著性差異。此外，血液脂肪分析中，除高密度脂蛋白隨訓練過程有逐漸上升的現象，其它項目並無明顯改變。
根據我們的研究結果發現，無運動習慣者，在運動過程中產生大量超氧自由基，但於體適能訓練後，自由基產量明顯降低。隨著不同的訓練型態及訓練時間長短，體內自由基產生與清除之平衡機制可能有所差異，短期有氧訓練，會以提高體內抗氧化酵素活性，來維持體內自由基之平衡狀態，而長期訓練可能提升粒線體電子傳遞鏈的效率使體內自由基的產生機率降低。故抗氧化酵素系統活性在長期規律運動習慣組與無運動習慣組間並無顯著性差異。另外，研究結果也顯示，高密度脂蛋白隨訓練期間加長而增加，再加上訓練後自由基產量明顯降低，減少了體內低密度脂蛋白被過氧化的危險性，因此我們認為，規律運動除有益於維持體內自由基的平衡狀態外，亦有利於預防心血管疾病之發生。
Generation of free radical is a part of normal metabolic processes, which can be neutralized by elaborating the antioxidant defense system. Physical activities may elicit an imbalance between the level of reactive oxygen species (ROS) and antioxidants, which is referred to as oxidative stress. On the other hand, one of the benefits of programmed physical training is that the increased modulate antioxidants defense system will enhance the quenching rate of the overproduced ROS during exercise.In order to elucidate the relationship between ROS homeostasis and physical fitness training, the ROS levels of blood were measured before, after and during the recovery from a certain physical challenge by the method of chemiluminescence. The female volunteers were categorized into three groups, one consisted of people who regularly exercised (long-term training group；LTT), another that seldom exercised (sedentary group；SED). The group of seldom exercisers that underwent 6 weeks aerobic training were designated as short-term training group (STT). Other than the ROS levels, several clinical parameters of blood, and activities of antioxidants were also collected and evaluated at the same time.The ROS turnover of these three groups were quite different during physical challenge. The ROS level seems to be consistent in the group of regular exercise, but increasing in the group of seldom exercisers during physical challenge. All volunteers were capable of neutralizing ROS after two hours rest. In spite of no significant change in some clinical parameters of blood, the activities of some scavenger enzymes seem to be down regulated in the group of regular exercisers. By comparing before with after 6-weeks-aerobic training, the group of seldom exercisers showed a decreased but similar patterns of the ROS level during physical challenge. Evan after 6-weeks of training, the ROS level measured after and recovery from the physical challenge were still higher than the group of regular exercisers.
Since the physical training will lead to increase ROS production at the very first stage, the strategy of human body to tolerate increased ROS is to up-regulate the performance of scavenger enzymes. As the training goes on, the efficacies of electron transport increase gradually, and ROS production decreases consequently. Thus, the expression of scavenger enzymes will return to basal or even lower levels in order to compromise with the decreased ROS. Based on the observation that we have made, we speculate that the more efficient energy supply will make people with regular exercise be able to tolerate more ROS during physical stress. The major benefit of regular exercise should be the increasing efficacies of the electron transport rather than the transient up-regulated activities of scavenger enzymes. |
