Changes in body composition during acute exposure to high altitude is related to acute mountain sickness.

Background: Acute hypoxia exposure leads to a high incidence of acute mountain sickness (AMS) and changes in body composition, while the relationship between body composition and AMS remains unclear. We designed this study to detect the body composition and discern its relationship with AMS.

Methods: Eighty-one subjects were transported from the plain (300 m) to the plateau (3680 m). The body weight and body composition were measured in the plain and at the plateau. The occurrence of AMS was investigated by using the Lake Louise Scoring (LLS) system for six consecutive days. Then, the relationship between body composition and AMS was further analyzed.

Results: The body weight, fat-free mass (FFM), total body water (TBW), intracellular water (ICW), extracellular water (ECW) and segmental lean mass decreased significantly with the prolonged stay at the plateau. Compared with those in the plain, FM increased significantly at the plateau, and the mineral increased significantly on the third day while decreasing significantly on the sixth day. The daily incidence of AMS during the first 6 days at the plateau was 23.46 %, 7.41 %, 2.47 %, 2.47 %, 1.23 %, and 2.47 %, respectively. Correlation analysis showed that the decline of FFM, TBW, and ECW was positively correlated with the LLS score. Among the AMS relevant symptoms, only fatigue was positively correlated with the decline of FFM, TBW, ICW, and ECW.

Conclusions: Significant changes of body composition were observed in the early stage after ascent to plateau. The decline of FFM, TBW, and ECW might be related to the severity of AMS, and fatigue was positively correlated with the decline of FFM, TBW, ICW and ECW.