The CG performed the training program using the linear periodization model with possible to daily undulate the resistance as high as tolerated. The training program consisted of 4 different lower body exercises which were back squat, power clean, pistol squat and walking lunge with long step. Back squat and power clean weights were chosen after the pretest session where 1 RM of those lifts were tested. During the first two weeks of the intervention, the players performed back squat and power clean exercises so that the first set was 12 RM, second 10 RM, third 8 RM and fourth 6 RM. The Pistol squat exercise consisted of 4 sets of 8 repetitions with each leg and it was done with 10-15 kg extra weights or as high as tolerated. The walking lunge exercise consisted of 4 sets of 10 repetitions with each leg and was done with long forward steps and added 30-40 kilograms extra weights or as high as tolerated. The above-mentioned program was performed identically twice a week by both EG and CG from 4 weeks before the intervention started. After first 2 weeks of the intervention, the program was modified in the CG as shown in Figure 2.
The EG training program consisted of 4 YoYoTM exercises which were bilateral squat, unilateral squat, leg curl and leg press. All the exercises were carried out with same incremental volume methodology and program was advised to do in this order (1.
Bilateral squat, 2. Unilateral squat, 3. Leg curl and 4. Leg press). The first two weeks of exercises were performed once a week and next 6 weeks two times per week. Volume was increased so that during the first four weeks were 3 times 6 repetitions, fifth and sixth weeks were 4 times 6 repetitions and seventh and eight weeks were 4 times 7 repetitions.
Break between the sets was 3 minutes and 3-5 minutes between the exercises.
Figure 2. Study design – timeline
In the bilateral squat exercise, participants were advised to make the transition phase from ECC to CON between 90-110 knee angle and then perform the CON phase as fast as possible. The strap was adjusted so that it was possible to achieve full extension from knee and hip, so the starting position was fully extended standing position. It was advised to repeat the first couple of controlled repetitions and once good rhythm and position was achieved, applying maximal CON effort for the first counted repetition. This starting instruction was the same for all four exercises.
The unilateral squat (Picture 2.) was advised in a similar manner, pushing knee and hip in almost full extension and breaking the ECC action around 90 degrees of knee flexion.
Movement direction was supero-laterally, pushing leg against the foot stance and the
other leg on the lateral foot platform stabilizing the machine to the floor and allowing maximal effort for unilateral squat. The unilateral exercise was developed to mimic skating push off action during skating. Together with the foot work, mediolateral arm swing was executed to maximize the outer leg ground reaction forces (GRF´s) comparable to each skating stride (Hayward-Ellis et al. 2017).
Picture 2. Start and turning point position of the unilateral skating squat exercise.
With the leg curl machine, participants performed bilateral knee flexion exercise (Picture 3.) where they were advised to emphasize maximal effort through the entire CON action until the turning point. Then, after the strap started to rewind in the ECC phase, it was advised to resist gently first 20-30 degrees and then breaking the action before the mechanical stop at around 170 degrees knee angle and then continuing to the next repetition with maximal effort without pausing the movement. In the ECC phase, the instruction was to keep the ankles in plantar flexion to minimize calf musculature involvement and the strap was adjusted so that maximal knee flexion was possible to achieve.
Picture 3. Start and turning point position of the bilateral knee flexion exercise.
In the leg press machine, seated bilateral ankle, knee and hip extension exercise (Picture 4.) the subjects were advised to execute the motion from around 90 degrees knee angle to almost full knee and ankle extension in the CON phase until the turning point when flywheel strap starts to rewind. Then in the ECC phase, the first 20-30 degrees should be gently resisted and then breaking the action around 90 degrees knee angle before hitting the mechanical stop and then continuing to the next repetition with maximal effort and without pausing the movement.
Picture 4. Start and turning point position of the bilateral leg press exercise.
Both CG and EG performed the same amount of exercise sessions with strength training and both groups were otherwise involved in the normal training regimen with an identical weekly training volume and methodology. Lower limb exercise sessions were separated in both groups by 48-96 hours. Warm-up and supplementary exercises were the same in both groups in the strength training sessions. Warm-up consisted of biking/running/rowing, followed by 8 complementary warm-up exercises before the main exercises. Sessions ended with to 3x15 repetitions of toes to bar exercise and 3x5 repetitions of hurdle jumps followed by short sprints.
3.5 Performance tests