Objective     To evaluate high altitude acclimatization of motorized infantry who entering an area of 4 300 m high altitude for 1 week to 6 months in order to provide reference of health service for highland troo

ps.     Methods     A total of 358 motorized infantries who entered an altitude of 4 300 m from 1 400 m for about 1 week (n=109

19.71±1.46 years old)

1 month (n=122

19.63±1.29 years old)

and half a year (n=127

20.45±1.60 years old) were selected by cluster sampling. Another 358 age-matched men (19.66±1.55 years old) was randomly selected from a plain troop to serve as control. Heart rate (HR)

systolic blood pressure (SBP)

diastolic blood pressure (DBP)

maximal oxygen uptake (VO

2max

)

hemoglobin content (Hb)

and acute mountain sickness symptoms were measured or questioned. The national military standard (GJB4301-2002) was adopted in the evaluation of acclimatization status.     Results     Among the 109 soldiers entering for 1 week

the primary acclimatization (PA) rate was 84.40%. The basic acclimatization (BA) rate was 90.16% for 1 month group. The fully acclimatization (FA) rate was 88.98% for half a year group. The main factors causing non-acclimatization in those having not in PA (15.6%) and BA (9.84%) after entering for 1 week and 1 month were abnormal HR and SBP

while the main factor for having not in  FA (11.02%) after half a year entering was erythrocytosis. There were 2 cases (1.57%) in the FA diagnosed as high altitude polycythemia (Hb ≥210 g/L). For HR

those of PA and BA were significantly higher than that of control (P0.05)

and that of FA was significantly lower than those of PA and BA (P0.05). For SBP

those of PA and BA were significantly higher than that of control (P0.05)

and that of FA was significantly lower than those of control

PA and BA (P0.05). For DBP

those of all acclimatization phases were significantly higher than that of control (P0.05). For Hb

those of all acclimatization phases were significantly higher than control (P0.05)

and that of FA was significantly higher than those of PA and BA (P0.05). For VO

2max

those of BA and FA was significant lower than that of control (P0.05).     Conclusion     Most soldiers entering an altitude of 4 300 m can a

cclimate the environment well. In early phase of entering

the acclimatization measures should be emphasized on enhancing cardiovascular function. While for the long term (half a year)

erythrocytosis should be prevented

and systematic health promotion should be emphasized.