It consists on only a regular training performance

It consists on performing the protocol which includes 6 strength, agility and balance exercises together with the regular training. The exercise program has to be performed twice a week during 6 weeks

The multi-intervention exercise protocol consists in a performance of agility, strength and balance exercises. It has to be fulfilled during 6 weeks (twice a week) before the regular training performance. The exercises should be done for almost 15 minutes approx. There will be 6 exercises in total: squat with toe raise, one-leg squats, single-leg balance (throwing a ball with a partner), vertical jumps, hamstring exercise, quick forwards and backwards sprints.

Joint Position Sense: Pictures of the knee joint repositioning of the participant are taken. The camera is placed perpendicularly 2 m from the knee joint and 65 cm from the ground. As references, 4 markers are placed in the lower extremity. The participant is seated with his feet dangling and his eyes closed. The dominant leg of the participant is passively carried by the examiner to 45 ° knee flexion. The participant is asked to maintain that position for 10 seconds. After that examiner returns the leg of the player to initial position in a passive way. The participant is then asked to change the position of the leg in an active way to the target position and maintain it for 4 seconds. After that he should return to the initial position. This exercise should be done 3 times. In each position a photograph is taken and then all of them are measured by Autocad which specifies the angles. The absolute angular error, the relative angular error and the variable angular error are measured.

Vertical jump height: for this, computer software "HSC-Kinovea" must be used. To perform the jump, hands should be placed on hips and the maximum impulse should be taken with both legs in order to take off from the ground. Each participant performs 5 preparatory jumps and then another 5 jumps (as high as possible). These 5 last jumps are the ones that will be analyzed. The height of the best jump is obtained through the formula mentioned above.

The flight time of these 5 jumps will be recorded with a camera that films 240 frames per second (Canon PowerShot SX700 HS). The analysis of the data is done with the software "Kinovea 0.8.15 for Windows" that measures the time difference between the first frame in which both feet are taking off the floor and the frame in which only one or both feet land. This measurement allows us to relate the height of each jump with muscle fatigue