Prolonged exercise in prepubertal boys

Abstract

The circulatory and metabolic changes during prolonged exercise (60 min) were studied in a group of 10 healthy prepubertal boys. The boys worked on the treadmill and on the bicycle ergometer at two levels of load, namely at oxygen uptakes of 36--39%, and 60% of the respective VO2 max for both types of exercise. The identical relative work loads represent higher metabolic rate at the treadmill exercise. The rectal temperature was higher after exercises on treadmill than on bicycle. The heart rate increase during prolonged exercise was lower in boys than in adults in both types of exercise. Better cardiovascular adjustment is suggested. The blood lactate increase was negligible in the initial phase of exercise with subsequent removal from the blood during extended exercise, which was more pronounced at the treadmill exercises. The increasing blood free glycerol concentration indicates similar fat share on energy release in children as in adults. No biological handicap could be found for prolonged exercise in children. The preference of short-time exercises in children lies probably in the psychological sphere.

Transient Oxygen Uptake and Heart Rate Responses at the Onset of Relative Endurance Exercise in Prepubertal Boys and Adult Men*

“…Table 1 presents the maximal (peak) and relative endurance (average of last 4-mm values) exercise variables for both children and adults. The maximal data are comparable to those of active individuals of the same age in other studies (1, 3,6,[10][11][12]23,27,29,35). As can be seen, all the maximal variables were higher (P < 0.05) than the relative endurance values within each group.…”

“…The faster HR adaptation to relative endurance exercise of children suggests a more rapid cardiovascular adjustment to exercise than adults. Although comparisons of these unique data to those of other studies are not possible, other investigators have suggested that children have a quicker cardiovascular adjustment to exercise than adults (6,12,23). Koch (21) reported, however, that a steady state of muscle blood flow is reached within 30 s after changing from one exercise load to another for both boys and men.…”

“…An estimate of the V02 response in children, however, can be obtained from oxygen deficit (34). Eriksson et al (8) and Má&k et al (23,25) reported lower initial 02 deficits during heavy exercise in children, suggesting faster mobilization of aerobic metabolism at the onset of exercise. Recently, Máëek et al (25,26) estimated the V02 tl/2 for maximal work to be less than 20 s. Earlier, Robinson (29) found that young children attained values of 41%-55% 02 max during the first 30 s of exhausting treadmill work compared to the adults reaching only 20%-35% V02 max during the same time period.…”

Maximal oxygen uptake and concentric isokinetic muscle strength in pubertal football trained and untrained boys of the same biological age

“…The aerobic capacity and the muscle strength in prepubertal and pubertal children have been a matter of long-lasting controversy (Vamvakoudis et al, 2007). Some studies demonstrated an improvement in ® VO 2 (Eriksson & Koch, 1973;Máček et al, 1976;Lussier & Buskirk, 1977;Savage et al, 1986;Baxter-Jones et al, 1993), while other investigations (Kobayashi et al, 1978;Bar-Or, 1983;Mirwald & Bailey, 1984;Williams & Reilly, 2000) have shown little or no improvement. During puberty (13-16 years of age) occur difference in body size, aerobic power, muscle strength and performance between boys of contrasting maturity status, e.g.…”

Exercise Thermoregulation in Prepubertal Children: A Brief Methodological Review

“…In this section, we provide a brief overview of existing child–adult comparisons of exercise thermoregulation to facilitate later discussion of the methodological considerations associated with this work. Several investigators have assessed postpubertal children, adolescents, and/or performed retrospective comparisons of data from children and adults, but often in differing exercise and/or environmental conditions ( 43 – 46 ). Our discussion here, however, focuses on direct comparisons of exercise thermoregulation in prepubertal children and young adults (summarized in Table 1 ).…”