Objective: To study the level of aerobic capacity using maximal oxygen consumption (VO2max) in the fifthyear medical students at Chiang Mai University.
Material and Method: This was a retrospective study in which data were collected from the database of the fifth-year medical students who attended the rehabilitation medicine course at Department of Rehabilitation Medicine, Faculty of Medicine, Chiang Mai University between January 2003 and December 2004. The level of aerobic capacity was evaluated by maximal oxygen consumption (VO2max), which was calculated using sub-maximal exercise test on a bicycle ergometer (Astrand-Rhyming test).
Results: During two-year period, 226 medical students performed 226 Astrand-Rhyming submaximal cycle ergometer tests. The mean age was 22.3 + 0.7 years (range 21-26 years) and average body weight was 56.8 + 11.9 kg (range 30-125 kg). The number of male and female students was comparable (male 44.7% and female 55.3%). Average VO2max of the students was 38.1 + 8.6 ml/kg/min (range 18.5-76.7 ml/kg/min) and there was no statistical significance between sex (VO2max of male = 38.4 + 7.6 and female = 37.9 + 9.4 ml/kg/min, p = 0.636). When standard VO2max value of Thai people was compared, 39.4% was categorized in low health fitness group, 40.7% was in health fitness group, and only 19.9% was in high health fitness group. However, 65% of the fifth-year medical students exercised 0-1 sessions per week (group 1), 24.3% exercised 2-4 sessions per week (group 2) and only 10.7% exercised > 4 sessions per week or everyday (group 3). Mean VO2max in group 2 (40.3 + 9.1 ml/kg/min) and 3 (43.2 + 8.4 ml/kg/min) are more than group 1 (36.5 + 8.4 ml/kg/min) significantly (p < 0.001 and p < 0.001 respectively) but there was no significant difference between group 2 and 3 (p = 0.16). The two most popular exercises were jogging and aerobic dance, 48.7% and 31.9% respectively. There was no significant difference of VO2max between methods of exercise (p = 0.132) and between the single and combination of exercises (38.9 + 9.3 and 37.9 + 7.4 ml/kg/min respectively, p = 0.4).
Conclusion: VO2max in most of the medical students was in poor to average range when compared to the standard value of Thai population. This information should prompt medical educators to address this problem, consider promoting exercise and corporate physical fitness into the medical school curriculum.

Keywords: Aerobic capacity, Maximal oxygen consumption, VO2max