SummaryCaffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise per formance in rats and athletes. Rats were administered the caffeine (6mg/kg) 1h prior to the exercise then were run on a treadmill at a speed of 20m/min. They were decapitated at 0min, 30min, 60min of exercise, and exhausted time point. Human subjects ingested the caffeine (5mg/kg) 1h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45min, and then the exercise intensity was increased to 80% of their VO 2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10min during exercise. Respiratory exchange ratio of the caffeine trial was signifi cantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and ath letes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance per formance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.

PURPOSE: Red ginseng (RG) has been reported to improve the blood and organ lipid profile when combined with exercise. However, the effect of RG on energy metabolism during exercise is poorly understood. Therefore, this study was designed to investigate whether RG treatment alters fat utilization during exercise; METHODS: We used seven-week-old ICR mice (n = 42). RG (1 g/kg) was administered orally daily during two weeks of endurance training. All mice were randomized into two groups: training only group (CON group) and training with RG group (RG group). Endurance training consisted of 20~25 m/min on a slope of 8° for one hour five times a week. After a two-week experimental period, we measured substrate utilization during exercise at the same intensity and duration of training using a respiratory calorimetry chamber. Mice were dissected for glycogen measurement of muscles and liver before, immediately after, and one hour after the exercise; RESULT: Fat oxidation during the initial 20 min of the one-hour exercise significantly increased in the RG group compared to the CON group. In addition, the liver glycogen stores significantly decreased immediately after the one-hour exercise compared to at rest in the RG group, but did not differ between immediately after the one-hour exercise and at rest in the RG group. The glycogen concentration in white and red gastrocnemius muscle did not differ between the groups immediately after the one-hour exercise; CONCLUSIONS: These results suggest that RG treatment for two weeks promotes fat oxidation and a glycogen-sparing effect during exercise. This might lead to a delay in peripheral fatigue during endurance exercise performance.

250Obesity is associated with lifestyle habits such as inactivity, bad eating practices, stress and excessive net intake of calories (1). Among these, energy imbalance and inactivity are becoming serious problems. Total energy cost can be divided into three parts, including resting metabolic rate (RMR), diet-induced thermogenesis (DIT), and the amount of energy used for physical activity energy expenditure (AEE) (2). The greatest component of daily energy expenditure is RMR, constituting about 70% of the total energy expenditure (3, 4).Silk peptides (SP) have been ingested for a long time in Asian countries (5). In recent years, additional applications have been developed for silk, mainly in the field of biotechnology and biomedicine. The versatility of these new implementations arises from the singularity of the molecular structure of silk (6). Proteins such as fibroin and sericin are the main constituents of silk, with fibroin constituting 70 to 80% and sericin 20 to 30% of the total cocoon weight (6, 7).Many studies regarding the health benefits of SP intake have been reported (8-11). SP not only regulate blood glucose level and hyperlipidemia and but also decrease blood triglycerides and LDL cholesterol (12,13). In addition, a high dose (800 mg/kg) of SP was shown to exert stamina-enhancing activity in forced swimming mice by preventing tissue injuries and increasing anti-fatigue (14). Moreover, it is well known that increasing the concentration of leptin leads to an exothermic reaction and an increase in the amount of activity. Therefore, SP promotes fat oxidation and increases energy expenditure (15,16). Additionally, in several rat and mouse model studies, food intake and body weight were decreased in rodents fed ad libitum (5,14,16).However, measurements in those studies have been conducted for analysis of blood profiles and hormones in mice. Accordingly, we investigated the effects of SP administration using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for 24 h. Materials and MethodsAnimals. Seven-week-old male ICR-mouse (n518) were used. Mice were purchased from Orient Bio Inc. (Seongnam, Korea). All mice were housed in standard plastic cages under controlled conditions of humidity (50%) and temperature (2361˚C) with alternating 12 h cycles of light and dark. Mice were adapted to the laboratory housing conditions for 3 d. They were given free access to water and a non-purified commercial diet (5L79, Orient Bio Inc.) containing (g/kg diet): crude protein, 180; crude fat, 52; crude fiber, 52; minerals, 57; and carbohydrate, 368. The protein, fat, and carbohydrate ratio (%) based on calories was 21 : 14 : 65, and (Received January 11, 2013) Summary Silk peptides (SP) have been reported to decrease body weight and accumulate fat. We investigated the effects of SP administration by using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for the duration of 24 h. Seven-week-old male ICR-...

Summary(-)-Hydroxycitrate (HCA) is known to inhibit increasing malonyl CoA con centration during endurance exercise. Furthermore, a short-term administration of HCA enhances endurance exercise performance in mice. Therefore we investigated the short term administration of HCA on the exercise performance of athletes. Subjects were adminis tered 250mg of HCA or placebo as a control (CON) for 5 d, after each time performing cycle ergometer exercise at 60% VO2max for 60min followed by 80% VO2max until exhaustion. Blood was collected and expired gas samples analyzed at rest and every 15min. The respira tory exchange ratio was significantly lower in the HCA trial than in the CON trial (p<0.05). Fat oxidation was significantly increased by short-term administration of HCA, and carbo hydrate oxidation was significantly decreased (p<0.05) during exercise, presumably result ing in increasing the cycle ergometer exercise time to exhaustion after 1h of 60% VO2max exercise (p<0.05). These results suggest that a short-term administration of HCA enhances endurance performance with increasing fat oxidation, which spares glycogen utilization during moderate intensity exercise in athletes.

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