Assessing differences in cardio-respiratory fitness with respect to maturity status in highly trained youth soccer players

Purpose: Examine differences in measures of cardio-respiratory fitness and determinants of running economy with respect to maturity status, in a group of highly trained youth soccer players.

Methods: Twenty-one highly trained youth soccer players participated. On separate visits, players’ peak oxygen uptake (VO_2peak), running economy at three different speeds [8km·h^-1, 80% gaseous exchange threshold (GET) and 95% GET], and pulmonary oxygen uptake (VO₂) kinetics were determined. Players also performed a Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1). Players were categorised as either ‘pre-PHV’ (peak height velocity) or ‘mid-PHV’ group using the measure of maturity offset. Independent t tests and Cohen’s d effect sizes were then used to assess differences between groups.

Results: The mid-PHV group were significantly taller, heavier and advanced in maturity status. Absolute measures of VO_2peak were greater in the mid-PHV group; however, when expressed relative to body mass, fat-free mass, and theoretically derived exponents, VO_2peak values were similar between groups. Pre-PHV group presented a significantly reduced VO₂ response, during relative submaximal running speeds, when theoretically derived exponents were used, or expressed as %VO_2peak. VO₂ kinetics (tau) were faster during a low (standing) to moderate (95% GET) transition in the pre-PHV group. Yo-Yo IR1 performance was similar between groups.

Conclusion: While measures of VO_2peak and Yo-Yo IR1 performance are shown to be similar between groups, those classed as Pre-PHV display a superior running economy at relative submaximal running speeds and faster taus during a low-moderate exercise transition, than their more mature counterparts.