De-training effects of physical performance characteristics over a 4-week winter off-season period in highly trained youth soccer players - no need to consider biological maturity

De-training effects of physical performance characteristics over a 4-week winter off-season period in highly trained youth soccer players-no need to consider biological maturity. BLUF Highly trained U14 to U16 youth soccer players were able to maintain explosive power, reactive strength, and maximal strength characteristics while cardiovascular fitness was impaired, yet only to a small magnitude, after a 4-week winter off-season period irrespective of the chronological age and biological maturity. ABSTRACT The aim of the current study was to quantify the changes from a 4-week winter off-season period upon physical qualities in highly trained youth soccer players in relation to chronological age and biological maturity. Data were collected from 39 male U14, U15 and U16 soccer players of a professional club. Players performed a testing battery during the last week prior to and first week after the 4-week winter off-season period consisting of standing height, body mass, Countermovement Jump (CMJ), Repeated Jump Test 5max (RJT5max), Isometric Mid-Thigh Pull (IMTP), and a sub-maximal run assessing exercise heart rate (HRex). Changes between pre-and post were assessed for each age group (U14, U15, and U16), and each maturity group (growth spurt, post-growth spurt, approaching maturity) by calculating standardized mean differences (SMD) and Pearson product-moment correlations (r). ... mehrChanges in standing height and body mass were trivial (SMD: 0.09 to 0.15) across age groups and maturity groups. There were small to large correlations (r:-0.67 to 0.33) between skeletal age and changes in standing height and body mass within maturity groups. Changes in CMJ, RJT5max, and IMTP were trivial across age groups (SMD:-0.19 to 0.19) and maturity groups (SMD:-0.19 to 0.19). Changes for HRex were small across age groups (SMD: 0.51 to 0.58) and maturity groups (SMD: 0.48 to 0.59). Correlations between changes in physical performance characteristics and skeletal age within maturity groups revealed no clear pattern ranging from trivial to moderate (r:-0.42 to 0.30). Highly trained youth soccer players were able to maintain their physical performance characteristics except for cardiovascular fitness irrespective of the chronological age and biological maturity, while standing height and body mass remained largely unchanged.