Table 1. Study group characteristics.
| Whole group | Age categories | |||||
|---|---|---|---|---|---|---|
| 5–6 years |
7–9 years |
10–12 years | 13–15 years | 16–18 years | ||
| Number of subjects | 791 | 20 | 180 | 250 | 230 | 111 |
| Male sex | 464–59% | 12–60% | 105–58% | 126–50% | 135–59% | 86–77% |
| Age [years] | 12 (5) | - | - | - | - | - |
| Height [m] | 156 (30) | 122 (11) | 135 (9) | 151 (13) | 168 (12) | 179 (11) |
| Body mass [kg] | 44.30 (26.05) | 21.8 (6.0) | 29.4 (7.7) | 39.4 (11.4) | 56.0 (14.8) | 68.5 (12.7) |
| BSA [m2]* | 1.39 (0.54) | 0.85 (0.15) | 1.05 (0.17) | 1.27 (0.23) | 1.61 (0.27) | 1.84 (0.20) |
| Training volume [min]** | 270 (180) | 180 (135) | 180 (120) | 180 (180) | 360 (180) | 540 (180) |
| LVD | 4.4 (0.8) | 3.7 (0.3) | 3.9 (0.5) | 4.2 (0.5) | 4.7 (0.4) | 5.0 (0.6) |
| RVOT PLAX | 1.9 (0.6) | 1.5 (0.3) | 1.7 (0.4) | 1.8 (0.5) | 2.0 (0.4) | 2.3 (0.7) |
| IVS | 0.8 (0.2) | 0.6 (0.1) | 0.7 (0.1) | 0.8 (0.1) | 0.8 (0.1) | 0.9 (0.1) |
| PWD | 0.8 (0.2) | 0.6 (0.1) | 0.7 (0.1) | 0.7 (0.1) | 0.8 (0.1) | 0.9 (0.1) |
| LA | 3.0 (0.6) | 2.5 (0.4) | 2.7 (0.3) | 2.9 (0.4) | 3.2 (0.4) | 3.4 (0.4) |
| AO | 2.3 (0.6) | 1.8 (0.3) | 2.0 (0.4) | 2.2 (0.4) | 2.4 (0.5) | 2.6 (0.6) |
All unit-bearing values are represented as “median (interquartile range)”
* BSA was calculated based on the Haycock formula14: BSA (m2) = 0.024265 ∙ Height(cm)0.3964 ∙ Weight(kg)0.5378
** The training volume determines the level of involvement in a sport and was estimated as the product of the average number of training sessions per week and the average duration of a single training session.