Relationship between biological age, body dimensions and cardiorespiratory performance in young soccer players

Objective: The purpose of our study was to compare cardiorespiratory performance between groups with different biological age in male adolescent soccer players.

Methods: Eighty-eight young soccer players (age = 15.9 ± 0.5 years, body height = 176.1 ± 5.6 cm, body weight = 65.4 ± 7.2 kg) performed a vita-maxima protocol on a treadmill. Starting speed was 6 km/h and inclination 1.4%, which were increased linearly every minute, to 11 km/h and to 3.5% respectively (first 5 minutes). Then we increased inclination by 2% every minute until exhaustion. The effect of the biological age on functional indices was examined based on two grouping methods. First, the participants were classified into sub-groups by their morphological (or developmental) age, which is an expression of biological age and evaluates the developmental state of specific body dimensions (body height, body weight, shoulder width, lower arm girth, and hand circumference). Then, from anthropometric and body composition measures three clusters were created, according to the participants' developmental state. For both grouping methods, the groups were: late-maturing, average-maturing, early-maturing.

Results: Based on the morphological age grouping method, biologically more advanced athletes achieved greater cardiorespiratory performance (late-maturing: 337 ± 33 W, average maturing: 363 ± 48 W, early maturing: 386 ± 43 W) with higher oxygen uptake (late-maturing: 3529 ± 336 ml/min, average-maturing: 3798 ± 436 ml/min, early-maturing: 3983 ± 541 ml/min) and oxygen pulse (late-maturing: 18.1 ± 1.8 ml/beat, average-maturing: 19.6 ± 2.5 ml/beat, early-maturing: 20.8 ± 2.8 ml/beat). There were no differences in time spent on the treadmill, maximal lactic acid levels, relative power, maximal heart rate, respiratory rate, tidal volume, relative maximal oxygen uptake, maximal ventilation. There were significant differences in weight, plastic index and muscle mass between all the three groups. Differences in cardiorespiratory indices between groups of different maturity status were larger when we grouped the athletes based on cluster analysis compared to the morphological age-based grouping method.

Conclusions: During growth and maturation Body dimensions and body (and muscle) mass significantly affect maximal oxygen uptake in young athletes. The inclusion of body composition components in addition to body dimensions increases the explanatory power of biological age on cardiorespiratory performance.