Participants in this group will continue their regular tennis training

Participants in this group will continue their regular tennis training and additionally perform recovery training twice a week for four weeks. The recovery sessions include stretching, foam rolling, and relaxation exercises designed to enhance recovery and improve lower extremity explosive strength.

Participants in this group will continue their regular tennis training and additionally perform recovery training twice a week for four weeks. The recovery sessions include stretching, foam rolling, and relaxation exercises designed to enhance recovery and improve lower extremity explosive strength.

The countermovement jump (CMJ) test was used to assess lower extremity explosive performance. Participants started from an upright standing position with hands placed on the hips. Following a rapid downward movement involving hip and knee flexion, participants immediately performed a maximal vertical jump. Jump height (cm) was recorded using [measurement device - e.g., force plate / jump mat / Optojump system]. The CMJ reflects the efficiency of the stretch-shortening cycle and is considered a reliable indicator of explosive lower limb performance.

The squat jump (SJ) test was used to assess concentric lower extremity explosive performance. Participants started from a semi-squat position with approximately 90° of hip and knee flexion, with hands placed on the hips. After holding this position briefly to eliminate the contribution of elastic energy, participants performed a maximal vertical jump without a preparatory countermovement. Jump height (cm) was recorded using [measurement device - e.g., force plate / jump mat / Optojump system]. The SJ test allows direct evaluation of concentric muscle power of the lower limbs.

RSI is a performance measure that reflects reactive strength and neuromuscular efficiency. It is typically assessed through a drop jump in which the participant steps off a platform, lands, and performs a quick rebound jump with minimal ground contact time. RSI is sensitive to the athlete's ability to rapidly switch from eccentric to concentric action, a capacity highly relevant to sports requiring explosive changes in direction, such as tennis .

SLJ, also known as the broad jump, is a field-based test for assessing horizontal explosive strength of the lower extremities. The participant stands with feet shoulder-width apart, swings the arms, and jumps forward as far as possible. The landing distance, measured from the starting line to the heel mark, reflects the ability of the lower-limb muscles to generate forward propulsion .