Table 1.
Participant characteristics and physical parameters
(Mean values and standard deviations)
| Autumn | Spring | |||||||
|---|---|---|---|---|---|---|---|---|
| Outdoor (n 22) | Indoor (n 25) | Outdoor (n 22) | Indoor (n 25) | |||||
| Mean | sd | Mean | sd | Mean | sd | Mean | sd | |
| Age (years)‡ | 21·0 | 1·8 | 20·0 | 1·4 | – | – | – | – |
| BMI (kg/m2) | 25·4 | 3·4 | 23·3* | 2·7 | 25·7 | 3·8 | 23·5† | 2·9 |
| Body fat (%) | 19·7 | 6·9 | 19·5 | 6·4 | 20·6 | 6·5 | 20·1* | 6·5 |
| FFM (kg) | 64·8 | 9·5 | 58·4* | 12·2 | 63·5 | 10·6 | 57·5* | 10·9 |
| Training (h)‡§ | 5·8 | 3·3 | 7·3* | 2·9 | 5·2 | 2·4 | 7·14 | 4·2 |
| Vitamin D intake (μg/d)‡§ | 3·3 | 2·5 | 2·2 | 2·0 | 4·4 | 5·0 | 2·4 | 1·6 |
| Ca intake (mg/d)‡ | 1022·4 | 370·6 | 932·9 | 493·7 | 814·2 | 198·0 | 678·3* | 233·5 |
| 25(OH)D status (nmol/l) | 54·3 | 25·3 | 57·7 | 22·0 | 31·0 | 17·5 | 31·0 | 16·1 |
| PTH (pmol/l)‡§ | 6·6 | 3·2 | 6·5 | 4·3 | 5·5 | 2·2 | 7·0 | 5·1 |
| Knee extensor strength (Nm) | 259·5 | 51·8 | 245·1* | 99·0 | 276·4 | 71·2 | 234·8† | 61·8 |
| Handgrip (kg) | 42·0 | 10·3 | 37·0 | 10·6 | 41·2 | 11·6 | 36·9 | 10·2 |
| CMJ (cm)‡ | 31·8 | 8·4 | 29·5 | 9·4 | 33·7 | 7·3 | 32·2 | 7·6 |
| VO2max (ml/kg per min)‡ | 42·9 | 3·2 | 43·1 | 2·8 | 43·7 | 2·2 | 42·5 | 3·2 |
FFM, fat-free mass; Ca intake, Ca intake from self-reported 5-d food diary; 25(OH)D, 25-hydroxyvitamin D; PTH, parathyroid hormone; CMJ, counter movement jump; VO2max, aerobic fitness.
*
Mean value is significantly different from that for outdoor athletes in the same season (P < 0·05; independent t test/Mann–Whitney U test between indoor and outdoor athletes).
†
Mean value is significantly different from that for the same type of athlete in autumn (P < 0·05; paired t test/Wilcoxon rank test).
‡
Not normally distributed in autumn.
§
Not normally distributed in spring.