Overall, the intervention players completed 0.8 injury prevention
sessions each week on average, less than the recommendation
of at least two sessions per week. However, they
still experienced a 30–50% reduction in the risk of various
injuries compared with the controls. This indicates that the
injury prevention programme achieved the desired injury preventive
effect.
In contrast to the fi ndings among players, we found no
signifi cant differences in the overall or acute risk of injuries
between teams with different levels of compliance. This is
explained by the large variations in compliance among the
players within each team; the players with high compliance
had a sixfold higher use of the programme compared with the
players with low compliance. These fi ndings emphasise the
inadequacy of recording compliance on a team basis only. The
overall compliance is a product of the compliance among the
teams and the player participation rate (fi gure 1). Although the
compliance among teams and attending players was good, certain
players in each team rarely took part in the team activities,
despite being registered on the roster at the start of the season.
Therefore, the whole group of enrolled players completed the
injury prevention programme in 47% of the maximum number
of sessions the teams possibly could have conducted.
It should be noted that the teams with low compliance
reported three times lower exposure to football than the teams
with high compliance, and four of 10 teams with low compliance
did not report any injuries at all. Even though calculations
of injury incidence take exposure into account, a minimum
exposure is necessary to be at risk of injury. Moreover, coaches
less thorough in conducting the injury prevention programme
and recording compliance may also have been less likely to
record injuries. If so, the injury incidence in the low compliance
group may have been underestimated somewhat.
The programme was designed to prevent injuries. However,
to make it attractive for coaches and players, The 11+ was
specifi cally tailored to football players and we included elements
of variation and progression in the exercise prescription.
We also focused on organising streamlined and effi cient 3 h
educational meetings at baseline, at which the coaches were
provided with a selection of material detailing the exercises.
Although we gave a set of footballs to the teams that completed
the collection of injuries and exposure, no incentives
were provided to ensure high compliance by coaches and players
other than telephone and e-mail contacts related to data
collection. Indeed, the compliance rates among teams in the
current study was higher than previously reported among
teams,18 21 24 27 28 31 as well as among players.23 29 30 In addition,
our intervention period lasted longer than comparable
interventions in other studies. Although compliance decreased
from the fi rst to the second half of the season, these fi ndings
may imply that a long-term intervention period is not synonymous
with low motivation and compliance among the participants.
Other factors, such as the content, the relevance, the
availability and the perceived diffi culty of the intervention
may also play an important role.