Physical Activity in Prepubescent Children: Relationship with Residential Altitude and Socioeconomic Status

Abstract
The main purpose of this study was to measure physical activity of 10- to 12-year-old prepubescent boys and girls living in Bolivia at low altitude (400 m above sea level) and at high altitude (4,000 m) with either a low socioeconomic status (LSES) or a high socioeconomic status (HSES). Habitual physical activity was measured by 24-hour heart rate (HR) monitoring during a normal school day. The mean HR is expressed as a percentage of heart rate reserve (HRR%) and the time spent at 50–85% HRR. Analysis by ANOVA showed no significant effects (p > .05) in HRR%. However, the boys spent significantly (p < .05) more time at 50–85% HRR (M = 51 min) than did girls (M = 34 min), and LSES children significantly (p < .01) more (M = 51 min) than HSES children (M = 32 min). There was also a significant interaction between SES and gender, indicating that the difference between boys and girls was significantly (p < .05) greater in LSES than in HSES, and the difference between LSES and HSES children was significantly (p < .05) greater in boys than in girls.