Johnson, B D

Background Physical activity has been proposed as a risk factor for altitude illness however it is unclear whether the total amount or intensity of activity determines illness. Purpose To examine activity patterns relative to the incidence of acute mountain sickness (AMS) in United States Antarctic Program workers rapidly transported to the South Pole (SP, 9303 ft). Methods 53 medically screened subjects (age=37±10yr, BMI=24±3 kg/m 2 ) were transported by a 3 hour flight from McMurdo Station (sea level, SL) to the SP. Physical activity was monitored at SL and for 3 days after ascent using BodyMedia® activity monitors. Symptoms of AMS were assessed using Lake Louise Questionnaires. Results 53% of subjects displayed AMS between SP days 1–3 (23% day 1, 43% day 2, 15% day 3). Energy expenditure at SP was 3414±944, 3458±781, & 3543±869 Calories/day for days 1–3, respectively. Steps/day at SP was 12593±4926, 13124±4392, & 12966±4482 for days 1–3, respectively. Overall, more activity at higher intensity (>3 METS) on SP day 1 was associated with higher AMS incidence the next morning (p<0.05). Also, calorie expenditure with activity at >3 METS and time of activity at >6 METS in the first 24 hours after ascent independently increased the odds of AMS on SP day 2 (p<0.05). Conclusions With rapid transport to altitude, moderate to intense activity within the first 24 hours of ascent contributes to the incidence of AMS. NSF ANT 0540710