Water balance in Japanese male kendo college athletes during training: a pilot study assessing seasonal differences with adjusted energy expenditure.

BACKGROUND: Due to various factors, water balance may vary across seasons. These effects may be particularly prominent in athletes and dependent upon energy expenditure during training. METHODS: Japanese male kendo college athletes participated in this study during their training sessions. The participants were observed for three days each season, i.e., in spring, summer, and winter. The energy expenditure of the participants during training was monitored using the heart rate method. Data regarding the total amount of sweating, rate of sweating, amount of water intake, and rate of water intake were collected for each season and the differences were assessed using analysis of covariance, with energy expenditure as the covariate. RESULTS: The water balance parameter values observed during a kendo training session in summer were the highest, whereas these values were significantly reduced in winter. Energy expenditure was the highest in spring. The amount of sweating per energy expenditure varied seasonally, reaching as high as 2.14 g/kcal in summer. After adjusting for the influence of energy expenditure, the amount of sweating, amount of water intake, and water intake rate varied significantly by seasons, with the highest values in summer (P<0.001). The sweating rate was high in all the seasons, but the highest rate was observed in summer, followed by spring and then winter. There was a significant difference in the sweating rate in each season (P<0.001). The rehydration rate was 28% in spring, 39% in summer, and 22% in winter. CONCLUSIONS: After adjusting for the influence of energy expenditure, seasonal differences in water balance were observed in Japanese male kendo college athletes during training. These results suggest that water intake is essential after training in any season to maintain the water balance of the body.

The Validation of the Dai Nippon Medi·Ca SA Method for AOAC Research Institute Performance Tested MethodsSM Certification.

A ready-made dry medium method for Staphylococcus aureus count, the Medi·Ca SA method incubated at 35 or 37°C, was compared with the Baird-Parker method (AOAC Official MethodSM 975.55) for 11 food matrices: raw beef, raw ground beef, raw lamb, cooked ham, raw salmon, frozen prawn, fresh chilled pasta, pasteurized milk, natural cheese, cream puff, and potato salad. The mean difference between the two methods at each contamination level for each matrix was <0.5 log10, and the 95% confidence intervals on the mean differences fell within the range of -0.50 to 0.50. Standard deviation of repeatability and RSDr values of the Medi·Ca SA method were generally the same level as those of the Baird-Parker method, and r2 ranged from 0.98 to 1.00. Product consistency and stability studies showed little variability between productions lots and a shelf-life of 16 months. Incubation time within the range of 22-26 h and variations to the sample volume did not adversely affect the results. These results showed that the Medi·Ca SA method is a reasonable alternative to the reference method for selected food matrices and makes it possible to simultaneously detect and enumerate S. aureus in only 24 h.

Validation of Medi·Ca EC Method for AOAC Research Institute Performance Tested MethodsSM Certification.

A ready-made dry medium method for Escherichia coli and coliform count, the Medi·Ca EC method, was compared with the most probable number (MPN) method using Brilliant Green Lactose Bile broth and E. coli broth (AOAC INTERNATIONAL Official MethodSM 966.24) for seven food matrixes: raw beef, raw pork, raw frozen pork, raw lamb, raw salmon, frankfurter sausage, and cooked ham. The mean difference between the two methods at each contamination level for each matrix was <0.5 log10, and the 95% confidence intervals for the mean differences fell within the range of -0.5 to 0.5, with the exception of a few cases in the independent laboratory study. sr and RSDr values of the Medi·Ca EC method were generally lower than those of the MPN method, and r2 ranged from 0.91 to 0.99. Product consistency and stability studies showed little variability between production lots and the shelf-life of 20 months. An incubation time within the range of 22-26 h did not adversely affect the results; however, variations in sample volume did affect final counts. These results showed that the Medi·Ca EC method is a reasonable alternative to the reference method for the selected food matrixes and makes it possible to simultaneously detect and enumerate E. coli and coliform in only 24 h.