Abstract

Environmental factors, particularly high-altitude conditions, significantly influence physical fitness. While cross-sectional studies provide valuable insights into the effects of altitude on fitness, there is a notable scarcity of longitudinal research investigating both short-term and long-term impacts of high-altitude environments on physical fitness. This study leverages China's robust national physical fitness monitoring system to assess fitness indicators among three distinct groups: high-altitude natives, high-altitude migrants, and sea-level controls. The sample comprised 2,633 university students aged 18–22 from Lhasa, Tibet (3,650 meters), and a low-altitude region (260 meters), including 949 native students, 807 migrants from low-altitude areas, and 877 low-altitude controls. Fitness evaluations were conducted during the students' first and third years of university, adhering to national standards. Measurements included Body Mass Index (BMI), lung capacity, 50-meter sprint, sit-and-reach, sit-ups or pull-ups, and 800-meter or 1,000-meter runs. The results indicated significant differences in fitness performance among female students across the three groups, particularly in lung capacity, 50-meter sprint, standing long jump, sit-and-reach, 800-meter run, and sit-ups. Males also showed significant differences, except for the standing long jump. Both native and migrant groups experienced declines in most performance measures from freshman to junior year, except for the sit-and-reach test. Notably, changes in the 800-meter run for females and the 1,000-meter run for males varied significantly across the three groups (P < 0.001). Curve regression analysis demonstrated an inverse "J" relationship between Physical Fitness Index (PFI) and BMI across all groups (P < 0.001), with BMI having a lesser impact on female PFI than on males. While PFI values increased for both females and males in the control group by their junior year, the migrant group experienced a decline, and the native group showed minimal changes. In conclusion, group status significantly impacts fitness outcomes, with the control group consistently outperforming native and migrant groups. Additionally, both native and migrant groups experienced declines in average fitness scores from freshman to junior year, contrasting with the performance of the low-altitude controls. The differences in the relationship between PFI and BMI underscore the necessity for tailored fitness assessments in high-altitude environments that account for gender variations.