Operational definitions
| Training session | Team training that involved physical activity under the supervision of the coaching staff. |
| Match | Competitive or friendly match against another team. |
| Injury | Any 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. |
| Hip and groin injury | Injury located to the hip joint or surrounding soft tissues or at the junction between the anteromedial part of the thigh, including the proximal part of the adductor muscle bellies, and the lower abdomen. |
| Reinjury | Injury of the same type and location as a previous injury that occurred within 2 months of a player’s return to full participation. |
| Slight/minimal injury | Injury causing 0–3 days lay-off. |
| Mild injury | Injury causing 4–7 days lay-off. |
| Moderate injury | Injury causing 8–28 lay-off. |
| Severe injury | Injury causing >28 days lay-off. |
| Acute injury | Injury with sudden onset and known event. |
| Overuse injury | Injury with insidious onset and no identifiable event. |
| Injury rate | Number of injuries per 1000 player hours ((Σ injuries/Σ exposure hours)×1000). |
| Injury burden | Number of lay-off days per 1000 player hours ((Σ lay-off days/Σ exposure hours)×1000) |