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FIGURE 14-1 Mean index of subjective heat illness (SHI) for each test day, where n = 17 male soldiers (4-g salt group, n = 8; 8-g group, n = 9).

On the fifth day of heat acclimation (day 12), there appears to be an increase in subjective heat illness, as measured by the SHI, for the 8-g salt group (see Figure 14-1). Although this ''blip'' in the curve is statistically nonsignificant, it begs an explanation because it disrupts an otherwise fairly smooth curve to asymptote. To address this issue, an inspection of the daily log notes was conducted. The log notes showed that one of the subjects in the 8-g group (subject 21) reported feeling the "possible onset" of flu-like symptoms on that day. When this subject's entire data set for all days is removed from the analysis, the "blip" on day 12 disappears without changing the rest of the curve. Consequently, this "blip" is likely due to one subject experiencing symptoms unrelated to the treatment procedures on day 12.


Whether measured by the mean number of heat illness symptoms reported or by an overall index of subjective heat illness (the SHI), subjective reports of heat illness are significantly higher during the first 2 days of heat acclimation than during subsequent days. A diet that includes the daily consumption of 8 g of salt (as compared to 4 g of salt) during heat acclima-

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