Table 1.

Characteristics of participants and compliance of clubs. Values are numbers (percentages) of participants unless otherwise indicated

Characteristic	Intervention group (n=958)	Control group (n=879)
Girls	808 (50.9)	778 (49.1)
Boys	150 (59.8)	101 (40.2)
Mean (SD) age in years*	16.3 (0.6)	16.2 (0.6)
Dropouts	68 (7.1)	51 (5.8)
Injury prevention programme:
Clubs	61†	13
Training sessions (SE, range)	27 (12, 1-55)‡	26 (7, 14-35)§
Average time spent per session in minutes (SE)	18 (6)¶	18 (9)**
Average attendance per session in %	73††	81‡‡

^*Range 15-17 years in both groups.

^†Eight (13%) of the clubs did not continue using the programme of warm-up exercises used to prevent injuries after the initial intensive introduction period. They used the programme at 5 (SE 5, range 1-13) sessions during the first part of the season and then discontinued the programme.

^‡14 (SE 7, 1-30) in the first part of the season (September to December) and 13 (SE 7, 0-26) in the second part (January to April).

^§14 (SE 4, 7-20) in the first part and 12 (SE 3, 7-15) in second part.

^¶20 (SE 5) in the first part v 16 (SE 7) in second part.

^**18 (SE 9) minutes in both first and second part.

^‡‡78% in the first part v 69% in second part.

^††85% in the first part v 78% in second part.