Blood lactate after maximal and supramaximal exercise in 10- to 12-year-old Bolivian boys. Effects of altitude and socioeconomic status.

The aim of this paper was to analyze the effects of chronic hypoxia and socioeconomic level on blood lactate concentrations obtained after maximal exercise and a 30-s Wingate test in 145 Bolivian boys (mean age: 10.8 years). Among the boys studied at high altitude (HA) (La Paz, 3600m) and at low altitude (LA) (Santa Cruz de la Sierra, 420m), 23 (HAHSES) and 48 (LAHSES) were from a high socioeconomic status (HSES), and 44 (HALSES) and 30 (LALSES) from a low socioeconomic status (LSES). The pubertal development was evaluated by salivary testosterone level ([T]). Blood samples were collected from the earlobe for blood lactate determination 2 min after cessation of maximal exercise ([L]v) and of a 30-s Wingate test ([L]w). Results (means +/- SD) showed: (1) [T] was significantly lower at HA: HA (HSES + LSES): 139.0 +/- 46.6 vs LA (HSES + LSES) = 186.2 +/- 53.7 pmole.1-1 (p = 0.0001). There was no significant difference between HAHSES and HALSES but LALSES was significantly lower than LAHSES. When the four groups were pooled, significant positive correlations between [L] and [T] were found; (2) for a same level of socioeconomic conditions, [L]v and [L]w were significantly lower at HA: HAHSES = 4.9 +/- 1.5 vs LAHSES = 7.4 +/- 2.1 and HALSES = 4.8 +/- 1.4 vs LALSES = 6.3 +/- 1.5 mmole.l-1 for [L]v; HAHSES = 5.1 +/- 1.0 vs LAHSES = 6.2 +/- 1.4 and HALSES = 4.6 +/- 1.0 vs LALSES = 5.3 +/- 1.4 mmole.l-1 for [L]w; (3) except for [L]v at HA, the HSES boys exhibited higher [L]v and [L]w than the LSES children for a same altitude; (4) there were significant linear relationships between the power developed during the 30-s Wingate test and [L]w.(ABSTRACT TRUNCATED AT 250 WORDS)