Responses to Moderate and Low Sodium Diets During Exercise-Heat Acclimation
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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This investigation examined whether lo sodium Na LNA 68 mEq Na. d-1 or moderate Na MNA 137 mEq Na.d-1 intake allowed humans to maintain health, exercise, and physiologic function during 10 days of prolonged exercise- heat acclimation HA. Seventeen volunteers, ages 19 to 21, consumed either LNA n8 or MNA n9 during HA 41 deg C, 21 RH treadmill walking for 30 min.h- 1, 8 h.d-1 at 5.6 km.h-1, 5 grade, which resulted in significantly reduced heart rate, rectal temperature, and urine Na for both groups. There were few between-diet differences in any variables measured. Mean plasma volume in LNA expanded significantly less than in MNA by Days 11 and 15, but reached the MNA level on Day 17 12.3 vs. 12.4 . The absence of heat illness, the presence of normal physiologic responses, and the total distance walked indicated successful and similar HA with both levels of dietary Na.
- Stress Physiology
- Metallurgy and Metallography