There are some differences existing in muscle metabolic profiles of children and adults. In subsequent periods of ontogenesis there is a gradual growth of anaerobic metabolic pathways in kids’ and teenagers’ organisms. These changes explain increasing abilities (during the years) to perform short physical efforts with a high and maximal intensity.
In one of the researches conducted (whose results were published in ‘Journal of Applied Psychology’) scientists decided to examine differences in effort changes of metabolites accumulation during gradual physical effort involving a belly of a calf. To aim this, the nuclear magnetic resonance (31p-NMR) were used to analyze changes in intramuscular pH and the percentage of Pi and PCr (unbounded phosphorane to phosphocreatine) in adults’ and children’s organisms.
Renting quantities of intramuscular pH and the values of percentage were the same in both groups. In initial phase, practicing gradual effort of straightening up and bending the ankle, similar changes in decrease of pH and increase of Pi/ PCr in adults’ and children’s muscles were observed. However, with the growth of intensity, a larger and faster decrease of pH and a bigger increase of Pi / PCr were observed in adults’ muscles than in children’s ones.
The authors then concluded that the observed dynamic course of changes in metabolites described during intensive physical effort differs among children and adults. It is due to the fact that younger children have smaller PCr (phosphocreatine) reserves and, what is connected with this fact, they have limited ability of fast re- synthesis of ATP. It explains limited ability to perform short efforts with high or a maximal intensity. What is more, the drop of intramuscular pH during intensive effort is smaller among children than among adults- that means, a lower level of muscles acidification during physical effort.
From a practical viewpoint, those observations are highly important for sport coaches and P.E. teachers, because they emphasis the necessity of including changes undergoing in children’s bodies connected with teenage years. Knowing these facts would be necessary in planning P.E. lessons or training sessions ( for example, various intensity and the time of physical exercises for younger children or mature young ).
Zanconato S, Buchthal S, Barstow TJ, Cooper DM. 31P-magnetic resonance spectroscopy of leg muscle metabolism during exercise in children and adults. Journal of Applied Physiology. 1993; 74: 2214-8.