Table 1

Operational definitions

Training sessionTeam training that involved physical activity under the supervision of the coaching staff
MatchCompetitive or friendly match against another team.
InjuryAny physical complaint sustained by a player that resulted from a football match or football training and led to the player being unable to take full part in future football training or match play.
Ligament injuryTraumatic distraction injury to a ligament.
Muscle injuryTraumatic distraction or overuse injury to a muscle.
Injury incidenceNumber of injuries per 1000 player hours ((Σ injuries/Σ exposure hours)×1000).
Injury burdenNumber of lay-off days per 1000 player hours ((Σ lay-off days/Σ exposure hours)×1000).
Squad availabilityThe average percentage of players available for training and match selection (eg, not absent due to injury, illness, national team duty or other reasons).
Injury absenceThe average percentage of players who were absent from trainings and match selection due to injury.
ReinjuryInjury of the same type and at the same site as an index injury.