## 4 Discussion  
This study demonstrates that fatigue and muscle damage are induced by a shuttle run test, and following the DSWTT program, the DSWEG showed a significant decrease in lactate, ammonia, LDH, CK, and AST compared to WEG and CG. WEG showed a significant decrease in lactate, ammonia, CK, and AST compared to CG, but CG did not show any difference compared to other groups. Recently, DSW treatment was used to demonstrate recovery from fatigue and muscle damage using hot spring water [28]. DSW is a resource that maintains a cold temperature at seabeds below a depth of 200 m. DSW is clean seawater that is not contaminated by Escherichia coli or common bacteria. When DSW is applied as an underwater motion, DSW shows buoyancy and water pressure higher than normal water due to eutrophication and salt concentration, and it acts on the human body in a more favorable environment than the general water in the floating posture. Therefore, in this study, DSWTT was applied to the exercise environment in the floating posture and the recovery of fatigue and muscle damage was verified. Fatigue, a physiological phenomenon that is induced by high-intensity training and long-term exercise, significantly reduces muscle glycogen and blood glucose, which reduces the function of organs and tissues in the human body [29]. In general, the blood-glucose concentration is 80-110 mL/dL when the adult is stabilized. During the exercise, the muscle glycogen is rapidly depleted, resulting in fatigue. If exercise reduces blood sugar, insulin secretion is reduced and blood-glucose level is maintained [30]. In order to determine the changes in the secretion of glucose concentration, this study compared the glucose concentration before, immediately after exercise, and 30 min of exercise. Based on the results of group comparison, the effects were significantly higher in DWEG than in CG. These results attributed to a decrease in blood sugar level due to the increased demand for energy sources during the one-time exercise. The muscle glycogen levels depleted immediately after exercise reduced the blood-glucose level, as the glucose entered the muscle to supplement the glycogen reserves [31]. [PERSON] and [PERSON] [32] reported an increase in the use of blood sugar immediately after exercise, and this study was consistent. Another study [33] showed that the underwater environment strongly facilitated blood flow, human body metabolism, and fatigue parameters by inducing changes in the physiology of the human body depending on the differences between water temperature, water viscosity, density, depth, body parts, and individual. This study also showed that the effect of DSW on fatigue recovery was highly favorable. These results suggest that DSWTT can prevent glycogen depletion in the body and lower the blood lactate acid and ammonia concentration, which are private fatigue substances when recovering and have a positive effect on the improvement of recovery ability after high-intensity fatigue induction training. Recovery from muscle fatigue to improve physical activity quickly eliminates lactate accumulated by energy metabolism and enzyme action in muscles and plays a very important role in improving activities of daily life and control conditions [34]. The accumulation and elimination of blood lactate determines the limitations of muscle movement directly linked to muscle fatigue [35]. Among them, the weight load is reduced due to buoyancy and water pressure. During the underwater exercise, the movement of the joints is larger than on the land, and the effect of stability and stretching is increased [19]. Based on this principle, this study, which verified the effectiveness of DSW, showed that the DSWTT program was effective in eliminating lactate. DSWTT may have increased blood flow to the muscle and improved muscle function. Especially, in the recovery process, it was found that DSWTT was very effective in the recovery of muscle tension and the removal of byproducts of metabolic processes through improvement of varicose reflux rate.