對運動員而言，若運動時水份不足，會影響能量代謝、循環系統、體溫調節及肌肉收縮，進而降低運動表現。運動期間水份平衡與流汗率的相關研究，大多數探討陸上耐力與球類運動，而游泳選手訓練處於水的環境中，和陸上運動情況有很大的差異，但是相關研究卻相當少。本研究目的為探討優秀男女游泳選手在不同水溫環境下的流汗率及體液與電解質平衡狀況。本研究以19名長期接受游泳訓練者為受試者，分別於高水溫(30℃)與低水溫(22℃)環境進行測試。高水溫受試者共14名（10名男性，4名女性），男性身高174.0±5.3公分、體重68.0±11.4公斤、年齡16.0±1.1歲；女性身高162.8±3.0公分、體重57.1±5.3公斤、年齡15.0±1.4歲。低水溫受試者共5名（2名男性，3名女性），男性身高173.5±6.4公分、體重62.4±5.6公斤、年齡17.0±0.0歲；女性身高167±2.6公分、體重59.5±6.4公斤、年齡17.0±0.0歲。記錄訓練期間的飲水量，並在訓練前後，收集受試者體重、尿液與靜脈血液樣本。分析尿液滲透壓和比重值，及血漿中的血紅素、鈉、鉀、葡萄糖、乳酸和氨的濃度。在高水溫環境下流汗率分別為0.57±0.45 L/hr，喝水量分別為0.55±0.32 L/hr體重變化率分別為0.29±1.00%。在低水溫環境下流汗率分別為0.14±0.30 L/hr；喝水量分別為0.11±0.03 L/hr，體重變化率分別為-0.09±1.02%。
　　在高水溫與低水溫的狀況下，喝水量與流汗率均呈現顯著正相關。平均訓練前後血液鈉離子偏高，鉀離子濃度以及尿液滲透壓均在正常值範圍。本研究結果顯示，游泳訓練的流汗率可能低於在相同環境溫度下進行的陸上運動；且流汗率較高的游泳選手，可能有較高的口渴感覺，而於訓練中攝取較多的水分。但仍有5名受試者在訓練後體重流失大於1%，包括3名在高水溫環境，以及2名在低水溫環境。另外，在流汗率、喝水量、血液電解質濃度變化等變數，仍有顯著的個人差異。因此，游泳選手在訓練時，但仍有相當的排汗率，尤其是在高水溫的情況，應注意補充水份。

　　Dehydration has detrimental effect on energy metabolism, circulation, temperature regulation, and muscle contraction, leading to decreased exercise performance. Most studies that investigated fluid balance and sweat rate focus on endurance and ball sports on land. Swimmers are trained in water environment, which is very different from the situations in land. The purpose of this study is to investigate the fluid and electrolyte balance in well-trained male and female swimmers after a single training session in different water temperature. This study included 19 well-trained swimmers in high (30℃) and low (22℃) water temperature. The high water temperature trial included 14 subjects, 10 males and 4 females. The males averaged 174±5.3 cm in height, 68±11.4 kg in weight, and 16±1.1 years. The females averaged 162.8±3.0 cm in height, 57.1±5.3 kg in weight, and 15±1.4 years. The low water temperature trial included 5 subjects, 2 males and 3 females. The males averaged 173.5±6.4 cm in height, 62.4±5.6 kg in weight, and 17.0±0.0 years. The females averaged 167±2.6 cm in height, 59.5±6.4 kg in weight, and 17.0±0.0 years. Urine and venous blood samples were collected before, during, and after the training sessions. Body weight was measured before and after the training. The amount of water consumed during the training was recorded. Plasma concentrations of hemoglobin, sodium, potassium, glucose, lactate, and ammonia, and urine osmolarity and gravity were measured. In high water temperature trial, the sweat rate was 0.57±0.45 L/hr, water consumption rate was 0.55±0.32 L/hr, and body weight change rate was 0.29±1.00%. In low water temperature trial, the sweat rate was 0.14±0.30 L/hr, water consumption rate was 0.11±0.03 L/hr, and body weight change rate was -0.09±1.02%.
　　In both trials, water consumption and sweat rate were positively correlated. Average plasma electrolytes and urine osmolarity were within the normal range. This study revealed that sweat rate in swimming may be lower than that in land exercise under similar temperature. In addition, the swimmers with higher sweat rates may have stronger feeling of thirst, therefore consumed more water during training. However, there were still 5 subjects who lost more than 1% body weight after the training, including 3 in high temperature trial and 2 in low temperature trial. This study also showed significant interpersonal differences in sweat rate, water consumption, and plasma electrolyte concentrations. In conclusion, the well-trained swimmers still have significant sweat rate, while the thirst feeling may not induce sufficient water consumption. Swimmers should be aware of sufficient water consumption during training, especially in high water temperature.