Background
Methods
Study design and definitions
Term | Definition |
---|---|
Activity | Scheduled training session or match carried out with the player's own or another team. |
Training session | Team training that involved physical activity under the supervision of the team coach. |
Match | Friendly or competitive match against another team. |
Acute knee injury | Injury to the knee joint with sudden onset and known cause, excluding contusions, leading to a player being unable to fully participate in future training or match play (i.e. time loss injury). |
Sprain | Acute injury to ligament or joint capsule. |
Meniscus lesion | Acute injury to the medial or lateral meniscus (verified by MRI or surgery). |
Cartilage lesion | Acute injury to the articular cartilage (verified by MRI or surgery). |
Bone marrow lesion | Acute injury to the bone marrow including occult fractures (verified by MRI). |
Fracture | Acute injury to the bone (verified by plain X-ray). |
Dislocation | Acute partial or complete dislocation of the patellofemoral joint or the knee joint. |
Re-injury | Injury of the same type and to the same site as a previous injury the player had sustained in her career. |
Early recurrent injury | Re-injury within two months of return to full participation after the index injury. |
Late recurrent injury | Re-injury more than two months after return to full participation from the index injury. |
Injury severity | Time elapsed from injury to full participation (days). |
Minimal injury | Injury causing 1–3 days absence from training and match play. |
Mild injury | Injury causing 4–7 days absence from training and match play. |
Moderate injury | Injury causing 8–28 days absence from training and match play. |
Severe injury | Injury causing >28 days absence from training and match play. |
Injury mechanism | |
Contact injury | Injury resulting from contact with another player or object, but not the surface. |
Non-contact injury | Injury not resulting from contact with another player or object. |
Injury incidence | Number of injuries per 1000 player-hours. |
Club recruitment
Randomization
Study therapist education
Coach education
Intervention
Exercise | Instructions | Repetitions or duration* |
---|---|---|
1. One-legged knee squat | Slow movement with a smooth turn. Keep the pelvis in a horizontal position. Non-supporting foot held in front of the body with slightly flexed hip and knee. | |
Level A | Hands on the hips. | 3 × 8–15 |
Level B | Hold a ball over the head with straight arms. | 3 × 8–15 |
Level C | Hands on the hips. Mark with the non-supporting foot just above the ground at the 12-02-04-06 o'clock positions. | 3 × 5 |
Level D | Bend down while holding a ball and let the ball touch the ground outside the supporting foot. Make a diagonal movement upwards and raise the ball over the head with straight arms on the contralateral side. | 3 × 8–15 |
Pair-exercise | Teammate stands slightly oblique in front of you. Hands on the hips and press a ball between the lateral sides of the feet of the non-supporting legs. | 3 × 5–10 |
2. Pelvic lift | Supine position. Lift the pelvis from the ground while keeping the back straight. | |
Level A | Both feet on the ground and hands across the chest. | 3 × 8–15 |
Level B | One foot on the ground and the contralateral leg flexed in the hip and knee approximately 90 degrees with both hands on the knee. | 3 × 8–15 |
Level C | One foot on a football and the contralateral leg flexed in the hip and knee approximately 90 degrees with the arms on the ground alongside the body for support. | 3 × 8–15 |
Level D | One foot on the ground and the other in the air. Keep the upper arms on the ground for support with the elbows flexed 90 degrees. Push away the supporting foot and land on the contralateral foot. | 3 × 8–15 |
Pair-exercise | Teammate stands with flexed knees and supports the heel of one of your feet in her hands. Hands across the chest and lift the pelvis. | 3 × 8–15 |
3. Two-legged knee squat | Slow movement with a smooth turn. Keep the back in a straight position. Feet shoulder-wide apart with the soles in contact with the ground at all times during the squat. | |
Level A | Hold a ball in front of the body with straight arms. | 3 × 8–15 |
Level B | Hands on the hips. | 3 × 8–15 |
Level C | Hold a ball over the head with straight arms. | 3 × 8–15 |
Level D | Same as Level C, but continue the movement and rise up on the toes after returning to the starting position. Stay briefly in that position with good control. | 3 × 8–15 |
Pair-exercise | Teammate stands next to you approximately 1 meter away, face opposite directions. Hold a ball between you with one hand and the other hand on the hip. Apply slight pressure on the ball while performing the knee squat. | 3 × 8–15 |
4. The bench | Lift the body and keep it in a straight line. | |
Level A | Prone position. Support on the knees and on the lower arms with the elbows kept under the shoulders. | 15–30 seconds |
Level B | Same as Level A but with support on the tip of the feet. | 15–30 seconds |
Level C | Same as Level B, but move the foot to the side and back to the starting position. Alternate sides. | 15–30 seconds |
Level D | Lie sideways with support on the foot and the lower arm with the elbow kept under the shoulder and the other hand on the hip. Lift the hip off the ground and stay briefly in that position with good control before slowly returning to the starting position. | 3 × 5–10 |
Pair-exercise | Teammate stands behind you and holds your feet or lower legs. Lift the body and walk forward by using the hands on the ground. | 15–30 seconds |
5. The lunge | Take a step with a marked knee lift and a soft landing. | |
Level A | Hands on the hips. Move forward with each step. | 3 × 8–15 |
Level B | Hold a ball in front of the body with straight arms. Rotate the upper body while stepping forward and position the ball laterally of the front leg. Move forward with each step and alternate sides. | 3 × 8–15 |
Level C | Hold a ball over the head with straight arms. Perform a forward lunge and push back with the front leg and return to the starting position. | 3 × 8–15 |
Level D | Hold a ball in front of the body with straight arms. Perform a sideway lunge and return to the starting position. | 3 × 8–15 |
Pair-exercise | Teammate stands in front of you 5–10 meters away. Perform a forward lunge while making a throw-in with a ball. | 3 × 8–15 |
6. Jump/landing | Make a jump with a soft landing. Stay briefly in the landing position. | |
Level A | Stand on one leg with the knee slightly bent and hands on the hips. Make a short forward jump and land on the same foot. Jump backwards to the starting position. | 3 × 8–15 |
Level B | Stand on two legs shoulder-wide apart with the hands on the back. Make a sideways jump and land on one foot. Alternate sides. | 3 × 8–15 |
Level C | Take a few quick steps on the same spot and make a short jump straight forward landing on one foot. | 3 × 5 |
Level D | Same as level C, but change direction and jump to one side (90 degrees turn). Alternate sides. | 3 × 5 |
Pair-exercise | Teammate stands in front of you approximately 5 meters away. Make a two-legged jump while heading a football and land on two legs. | 3 × 8–15 |
Data collection
Compliance
Ethics
Sample size
Study | Population | Study design | Number of players in the control group | Number of players with ACL injury (%) |
---|---|---|---|---|
Hewett et al., 1999 [15] | High school | Controlled trial | 193 | 2 (1.04%) |
Heidt et al., 2000 [14] | Age 14–18 years | Randomized controlled trial | 258 | 8 (3.10%) |
Powell & Barber-Foss, 2000 [24] | High school | Prospective cohort study | 6 642 | 33 (0.50%) |
Mandelbaum et al., 2005 [16] | Age 14–18 years | Controlled trial | 3 818 | 67 (1.76%) |
Pfeiffer et al. 2006 [17] | High school | Controlled trial | 189 | 0 |
Steffen et al., 2008 [19] | Age 13–17 years | Randomized controlled trial | 947 | 5 (0.53%) |