Table 1

Operational definitions used in the study

Elite playerA player who was elected to play in the highest division at the beginning of the season for u-16 and u-18 players, and to the highest and second highest division for senior players.
Reportable injuryAny physical complaint sustained by a player that results from a handball match or handball training causing the player to miss part of or rest of the match or training session.
Time-loss injuryA player being unable to take a full part in future handball15 training or match play. The term ‘future’ refers to any time after the onset of injury, including the day of injury.
Overuse injuryAn injury caused by repeated micro trauma without a single, identifiable event responsible for the injury.
Traumatic injuryAn injury resulting from a specific, identifiable event.
SeverityFull absence: The number of days/weeks from the date of injury the players report having the same injury in the SMS-system (question 1), and report having no exposure time, before the player's return to full participation in team training and availability for match selection. If a player could not participate fully on the day of an injury, but was available on the next day, this was recorded as a time-loss injury with a severity of zero days.15
Partly absence: The number of days/weeks from the date of injury the players report having the same injury in the SMS-system (question 1), but where they still report having exposure time, before the player's return to full participation in team training and availability for match selection.
Recurrent injuryAn injury of the same type and at the same site as an index injury and which occurs after a player's return to full participation from the index injury.15
Previous injuryAn injury before study start that have caused the player a total time-loss from handball activities for a minimum of 4 weeks. Irrespective of when they had had the injury before study start.
Injury prevention trainingInjury prevention training was in the questionnaire defined and described as balance training, specific jump training or training.
National teamPlayers who were selected to the national senior and junior teams at study start. For u-16 players it also included players who were selected to participate in special talent group under the Danish Handball Federation.