Influence of Physical Activity Patterns and Age on Acute Mountain Sickness Incidence during Mt. Kilimanjaro Trek

Abstract

PURPOSE: Physical activity is often noted as a risk factor for the development of AMS. We sought to explore the interaction between age and physical activity patterns on the development of AMS in a group of 27 individuals during a gradual ascent of Mt. Kilimanjaro (19,341 ft). METHODS: 27 adults (44±15 yrs; 24.45±3.90 BMI; n=11/27 Female) climbed over an 11-day period. Use of acetazolamide and NSAIDs were minimized but remained optionally taken as necessary during the ascent. Physical activity was monitored using BodyMedia activity monitors; heart rate and oxygen saturation were monitored with Biovotion devices; AMS incidence was classified from the Lake Louise Questionnaire; and total symptoms were scored from the questionnaire’s original five symptoms plus an additional five symptoms. Groups were divided based on age (group 1: 28±2 yrs, 2: 44±8 yrs, and 3: 58±10 yrs). Comparisons were made using ANOVA and independent T-tests, and post hoc analyses were made using Tukey’s method. RESULTS: Throughout the trek, 59% (n=16/27) of subjects displayed AMS at least for one day during the climb. Average total symptom scores were 4.2±2.9, 2.2±1.9, 3.3±1.5 for group 1 vs. 2 vs. 3 respectively. Focusing on the summit push (day 10), AMS incidence was highest in group 1 (87.5%; n=7/8) compared to group 2 (33%; n=3/9) and group 3 (25%; n=2/8) with an ANOVA statistical significance of p<0.05. Moreover, percentage of climb spent in moderate to vigorous activity (MVPA), hiking speed (KPH), and steps taken per minute were highest for group 1 (MVPA: 65%±14% vs. 54%±19% vs. 52%±14%; KPH: 1±0.1 vs. 0.91±0.09 vs. 0.85±0.06; Steps/min: 23±5 vs. 22±5 vs. 14±2; ANOVA p<0.05 for KPH, steps/min). Average heart rate and SpO2 was higher for group 1 during the climb to summit (HR: 109±13 bpm vs. 88±14 bpm vs. 87±8 bpm; SPO2: 85.5±5.5% vs. 83.2±9.4% vs. 81.9±8.0%; p<0.05 for HR). Post hoc analyses depicted a significant difference between group 1 and group 3 in AMS incidence, KPH and steps/min, and a significant difference in HR between group 1 and the rest. CONCLUSIONS: In this study, the youngest group averaged a higher total symptom score throughout the trek, and exerted greater physical intensity, hiking speed, and activity on summit day. It was found that AMS was more common in young adults, which may be due to being more active and adventurous than older individuals.