PURPOSE: To determine the number of trials needed to achieve a RLV measurement on land or submerged in water that compares to recommended criteria value. METHODS: Thirty male subjects (23.8 ± 3.5 yr, 175.7 ± 8.7 cm, 82.0 ± 15.4 kg) had RLV collected five times across two conditions (on land and fully submerged in water). Separate repeated-measures ANOVA were used to compare RLV means across the following criteria: means of the first two trials (FIR), the first two consecutive trials within 100mL (ROW), the first two trials (consecutive or non-consecutive) within 100ml (WIN), the lowest two trials within 100ml (LOW), and the number of trials necessary to satisfy criteria FIR, ROW, WIN and LOW. The alpha level was set at p<0.05. RESULTS: Mean RLV on land showed a significant decrease from trial 1 to 2 of 0.074L, trial 1 to 3 of 0.097L, and trial 1 to 5 of 0.097L (p<0.05). Mean values for LOW (0.99L) were significantly less compared with FIR, ROW, and WIN (1.19L, 1.13L, and 1.05L respectively) on land, and significantly less than FIR (1.11L) submerged. The LOW were obtained in a mean of 4 trials, significantly more trials than FIR, ROW, and WIN in each condition. There was no significant difference between trials to criteria for LOW on land (3.97) compared to submerged (4.07).Table 1: Mean for RLV (L) across trials on land and submerged in water, and of FIR, ROW, WIN, LOW, and trials to criteria in each condition.CONCLUSION: For healthy, young male subjects the number of trials needed to determine RLV depends upon the criteria selected. Based on means and standards deviations, it is recommended that at least 4 trials be used for ROW and WIN, and at least 5 trials for LOW. Additionally, FIR is not an appropriate criterion due to changes in RLV in subsequent trials.
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