Neuromuscular warm-up program and injury risk (IV)

4.2.1.1 Participants and randomization

The fourth study was a cluster randomized controlled study in Finnish female floorball players with six-month follow-up. Twenty-eight teams and 457 female floorball players, mean age 24 years (range 15-53), from Finnish top leagues participated in the study. Final participation was based on the informed consent of each player. A player was included in the study if she was an official member of participating team (licensed player) and did not have major injury at the onset of the study.

Stratified cluster randomization to the intervention teams and control teams was performed at each league level (elite league, first division and second division) using a team as the unit of randomization. Teams allocated to the intervention group (14 teams, n=256) were informed about the upcoming a warm-up program for preventing injuries. Teams in the control group (14 teams, n=201) were asked to do their usual training during the study season.

4.2.1.2 Outcomes and data collection

The main outcome variable in this study was an acute time-loss injury of lower extremities that occurred in non-contact circumstances (no contact with other player, stick or ball). An injury was defined as an acute non-contact injury involving lower extremities occurring during a floorball game or practice and making the player unable to participate in a game or practice session during the following 24 hours.

The secondary outcome variables were other time-loss injuries of lower extremities. Training and game exposure was based on the previous definitions (chapter 4.1.2) with the following exception: training exposure included only structured team-based physical activities, including also the intervention training.

At baseline, players completed a questionnaire about background information including anthropometrics, previous injuries, floorball experience and preseason

training volume. During the six-month study period, each team coach wrote-up players’ structured practice and game hours on an exercise diary and informed about all injured players. All injuries were registered with a structured questionnaire. The study physician contacted a player after each new injury and checked the accuracy and consistency of the filled questionnaire.

In addition, the qualified warm-up instructors kept a diary about the scheduled warm-up sessions in the intervention teams. At the end of the season all players filled in a questionnaire concerning injuries and subjective participation in the study to check the completeness and coverage of data collection.

4.2.1.3 Training program

Teams in the intervention group participated in a structured neuromuscular warm-up program comprising comprehensive exercises. Warm-up sessions were supervised and controlled by a qualified instructor.

The duration of the intervention was 26 weeks, including 42 structured warm-up sessions, which lasted 20-30 minutes each. The intervention program included the following four periods during the season: the first period (3 sessions/week), the second period (>1 session/week), the third period (2-3 sessions/week), and the fourth period (>1 session/week). Intensive training with 2-3 warm-up sessions a week took place at the start of the season and during the break from games in December. Over the competitive season the warm-up exercises were followed through with maintaining principle.

The neuromuscular warm-up program consisted of four different types of exercises: 1) running technique, 2) balance and body control, 3) plyometric and 4) strengthening exercises (Table 4 and Figure 3). Each exercise type had different variations, with diverse difficulty and intensity. The warm-up sessions were carried out just before floorball exercises, with low-to-moderate intensity for each exercise type. These comprehensive warm-up exercises were specifically directed at improving the control of back, knees and ankles during sports specific maneuvers (running, changing direction, stopping, etc.), and by this means to reduce the risk of injuries. Players worked in pairs and they were guided to look each others’

technique and give feedback during warm-up training.

Table 4. Neuromuscular warm-up program

I Running exercises 5-7 minutes

Each training session started with jogging (1), then three to four running technique exercises from eight different variations (2-9), and speed run (10) in the end.

1) Jogging straight forward 2 x 20 metres back and forth

2) Carioca running 1-2 x 20 metres, return by slow jogging

3) Sideways gallop 1-2 x 20 metres, return by slow jogging

4) Zigzag running forward 1-2 x 20 metres, return by slow jogging

5) Zigzag running backwards 1-2 x 20 metres, return by slow jogging

6) Skipping 1-2 x 20 metres, return by slow jogging

7) Walking lunges x 4-8 and slow forward running 1-2 x 20 metres, return by slow jogging

8) Slow alternate bounding 1-2 x 20 metres, return by slow jogging

9) Combination hops (right-right-left-left-right-right..) 1-2 x 20 metres, return by slow jogging

10) Speed running 1-2 x 20 metres, return by slow jogging

II Balance and body control exercises 5-7 minutes

One of the following three exercises during each training session, each of these three exercise types had variations with different degree of difficulty.

1) Squat technique with stick (either double or single leg)

- Double leg 2-3 x 10-15 repetitions

- Single leg (right + left) 2-3 x 8-10 + 8-10 repetitions 2) Balance exercise with medicine ball

- Single leg (right + left) 2-3 x 4-6 + 4-6 throws

3) Balance board exercise (either double or single leg)

- Double leg: with or without stick + ball 2-3 x 20-30 seconds - Single leg (right + left): with or without stick + ball 2-3 x 20-30 + 20-30 seconds

III Plyometric exercises 5-7 minutes

One of the following three exercises during each training session, each of these three exercise types had variations with different degree of difficulty.

1) Forward jumps (either double or single leg)

- Double leg 2-3 x 3-5 repetitions

- Single leg (right + left) 2-3 x 3-5 + 3-5 repetitions

2) Jumps in place

- Three alternative exercises 2-3 x 8-12 repetitions

3) Jumps over stick / sticks (either double or single leg)

- Double leg 2-3 x 8-12 repetitions

- Single leg (right + left) 2-3 x 4-8 + 4-8 repetitions

IV Strengthening exercises 5-7 minutes

One exercise for lower legs (number 1, 2 or 3) and one exercise for core (number 4 or 5) during each training session.

1) Double leg squat with partner on back 2-3 x 8-12 repetitions

2) Single leg split squat 2-3 x 4-8 + 4-8 repetitions

3) Nordic hamstrings 2-3 x 4-8 repetitions

4) Isometric side and front bridge (right + front + left) 2-3 x 10-30 + 10-30 + 10-30 seconds 5) Cross curl-up (right + left) 2-3 x 10-20 + 10-20 repetitions

+ Stretching exercises (5 minutes)

Only for those players who had limits on low back function and flexibility. Stretching exercises were introduced to players during the first two training weeks. After that stretching exercises were performed on players own time.

1) Seated hip and low back neutral zone exercise 2-3 x 20 seconds 2) Hamstring stretch (right + left) 1-2 x 20 + 20 seconds 3) Kneeling hip flexor stretch (right + left) 1-2 x 20 + 20 seconds

Examples of balance and body control exercises:

Examples of plyometric exercises:

Examples of strengthening exercises:

Figure 3. Examples of the warm-up exercises