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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 lt; .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. [ABSTRACT FROM AUTHOR]

This study describes habitual physical activity (HPA) of Bolivian boys living at different altitudes and from different socioeconomic status. The boys were living at high altitude (HA) in La Paz (4000 m) and at low altitude (LA) in Santa Cruz (400 m). At both altitudes samples of 10- to 12-year-old boys were chosen from a relatively low socioeconomic status (LSES) and a relatively high socioeconomic status (HSES). At HA 19 boys from LSES and 10 boys from HSES were measured and at LA 14 boys from LSES and 13 boys from HSES. HPA was measured by 24-h heart rate (HR) monitoring. Also an interview was completed to recall the HPA. By comparing the registered HR data with the time they were asleep the mean HR during sleep was calculated (HRsleep). The maximal HR (HRmax) was measured from a maximal exercise test on a bicycle ergometer. Heart rate reserve (HRR = HRmax-HRsleep) was used to measure the mean level of physical activity of the subjects. The results show that HRsleep (= HRrest) in HA boys with 70 (+/- 6) beats/min was significantly lower (p < 0.05) than in LA boys with 77 (+/- 10) beats/min. HRmax was also significantly lower (p < 0.05) in HA boys (187 +/- 12 beats/min) compared to LA boys (195 +/- 8 beats/min). Because HA influences HRsleep and HRmax in the same way, HRR is not significantly different between boys of HA and LA. The mean heart rate over 24 h (HRmean) in HA boys (87 +/- 7 beats/min) was significantly lower than in LA boys (93 +/- 8 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

The nutrition of 57 native Bolivian boys living at high altitude (HA) in La Paz (+/- 4000 m) and of 63 boys living at low altitude (LA) in St. Cruz (+/- 400 m) is described. The dietary information was obtained with a 24-h recall method, by interviewing the child and mother. The food items are listed in household measures and weight if possible. All food items were converted into grams, and nutrients were calculated by using food composition tables of Latin America. The results show that the energy and nutrient intake of the HSES boys was significantly higher (p < 0.05) than the intake of the LSES boys, at both altitudes. At HA the mean energy intake of the HSES boys was about 9.8 MJ per day (+/- 0.7); for the LSES boys an intake was found of 8.4 MJ per day (+/- 0.4). At LA the HSES boys had an energy intake of 10.7 MJ per day (+/- 0.6) and the LSES boys 7.7 MJ per day (+/- 0.3). The daily protein intake was in HAHSES boys 85 g (+/- 8), LAHSES 100 g (+/- 8), HALSES 60 g (+/- 4), and LALSES 52 g (+/- 3). In comparison with the recommended daily requirements the dietary intakes of the HSES boys seem too "rich," and of the LSES boys to some extent too "poor." These results are reflected in smaller body height and body weight of LSES boys and a higher fat mass in HSES boys irrespective of altitude.