BLOOD LACTATE AFTER MAXIMAL AND SUPRAMAXIMAL EXERCISE IN 10-YEAR-OLD 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 an d socioeconomic level on blood lactate concentrations obtained after m aximal 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, 3 600 m) and at low altitude (LA) (Santa Cruz de la Sierra, 420 m), 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 leve l ([T]). Blood samples were collected from the earlobe for blood lacta te 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] wa s significantly lower at HA: HA (HSES + LSES): 139.0+/-46.6 vs LA (HSE S + LSES) = 186.2+/-53.7 pmole . 1(-1) (p = 0.0001). There was no sign ificant difference between HAHSES and HALSES but LALSES was significan tly lower than LAHSES. When the four groups were pooled, significant p ositive correlations between [L] and [T] were found; (2) for a same le vel of socioeconomic conditions, [L]v and [L]w were significantly lowe r 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 . 1(-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 mmo le . 1(-1) for [L]w; (3) except for [L]v at HA, the HSES boys exhibite d higher [L]v and [L]w than the LSES children for a same altitude; (4) there were significant linear relationships between the power develop ed during the 30-s Wingate test and [L]w. The slopes were not differen t between HAHSES and HALSES and LAHSES and LALSES. However, the slope for HA (HSES + LSES) was significantly lower than for LA (HSES + LSES) (p = 0.03). In conclusion, the lower [L] in KA vs LA and LSES vs HSES boys may be partly due to their lower gonadal maturation. However, ot her factors in regard to altitude and nutritional aspects are discusse d.