Table 2.
Division of study population according to age (groupage; * classification according to Prader et al. (1989) [23]), performance level (groupPL) and football exposure (groupFE).
| Criterion: | Age/Growth Phase | ||
|---|---|---|---|
| groupage | age [years] | phase * | characteristics |
| I | 7–11 | pre-pubescent | before the main growth phase |
| II | 12–14 | pubescent | onset of puberty, main growth phase of the lower limb in male individuals |
| III | 15–18 | adolescent | beginning of growth plates closing, main longitudinal growth is completed |
| criterion: | performance level | ||
| groupPL | description | training time per week [min] | |
| I | basic training exposure | ≤180 | |
| II | extended training exposure | 180 < x < 360 | |
| III | high training exposure | >360 | |
| criterion: | football exposure | ||
| groupFE | number of seasons [n] | ||
| I | ≤5 seasons | ||
| II | 6 to 10 seasons | ||
| III | >10 seasons | ||