Anaerobic threshold and maximal steady-state blood lactate in prepubertal boys

Abstract

To elucidate further the special nature of anaerobic threshold in children, 11 boys, mean age 12.1 years (range 11.4-12.5 years), were investigated during treadmill running. Oxygen uptake, including maximal oxygen uptake (VO2max), ventilation and the "ventilatory anaerobic threshold" were determined during incremental exercise, with determination of maximal blood lactate following exercise. Within 2 weeks following this test four runs of 16-min duration were performed at a constant speed, starting with a speed corresponding to about 75% of VO2max and increasing it during the next run by 0.5 or 1.0 km.h-1 according to the blood lactate concentrations in the previous run, in order to determine maximal steady-state blood lactate concentration. Blood lactate was determined at the end of every 4-min period. "Anaerobic threshold" was calculated from the increase in concentration of blood lactate obtained at the end of the runs at constant speed. The mean maximal steady-state blood lactate concentration was 5.0 mmol.l-1 corresponding to 88% of the aerobic power, whereas the mean value of the conventional "anaerobic threshold" was only 2.6 mmol.l-1, which corresponded to 78% of the VO2max. The correlations between the parameters of "anaerobic threshold", "ventilatory anaerobic threshold" and maximal steady-state blood lactate were only poor. Our results demonstrated that, in the children tested, the point at which a steeper increase in lactate concentrations during progressive work occurred did not correspond to the true anaerobic threshold, i.e. the exercise intensity above which a continuous increase in lactate concentration occurs at a constant exercise intensity.

Physical Training of 9- to 10-Year-Old Children With Obesity to Lactate Threshold Intensity

“…The HR at LT of this study (165beat/min) should be used as the exercise intensity only for obese children at 9-10 years old. The current results cannot be used to determine the LT of other age groups, though the lactate concentration at LT (2.8mmol/L) in this study was similar to those reported in the literature for boys of 11-12 years old (14). It may be difficult to apply the HR at LT in a large-scale prevention study because of the time and personnel needed to perform the testings; however this protocol should be recommended in the individualized treatment of childhood obesity.…”

Velocity of Oxygen Uptake Response at the Onset of Exercise: A Comparison Between Children After Cardiac Surgery and Healthy Boys

“…O 2 during high-intensity exercise [1,5,9] and an anaerobic threshold corresponding to a higher percentage of V . O 2max [10,11] are the reason why healthy children are generally less dependent on anaerobic energy yield than adults. The lesser need for anaerobic glycolysis in children explains their relatively low anaerobic power [4].…”

Oxygen deficit and blood lactate in prepubertal boys during exercise above the anaerobic threshold

“…A reduction in the duration of the steps is assumed to reduce the threshold value [19]. In order to overcome the potential influence of a relatively rapid increase of exercise intensity anaerobic threshold in our study has been estimated from the increase of blood lactate concentrations observed after 7.5min of constant treadmill exercises performed on different days.…”

“…The percentage of "QO2m~ corresponding to the anaerobic threshold differs in children depending on whether ventilatory criteria [2,3,24,27,29] or lactate criteria [8,19,28] are employed, the latter resulting in distinctly higher percentages than ventilatory criteria. Whether or not anaerobic threshold can be substituted by ventilatory anaerobic threshold or whether agreement between the two is purely coincidental is still controversial [22].…”

“…This assumption implies that the duration of work at a constant load in this range is limited due to accumulation of blood lactate. Recent studies [18,19], however, have shown that in 10-to 12-year-old boys, a steady-state of blood lactate is maintained at exericse levels distinctly above the anaerobic threshold. Thus, the dysequilibrium between lactate production and its elimination seen beyond the anaerobic threshold but below the maximal steady-state blood lactate is only transient.…”