The Effect of Recovery Training on Lower Extremity Explosive Strength in Tennis Players

Countermovement Jump Height

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.

Time frame: 4 weeks

Squat Jump Height

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.

Time frame: 4 weeks

Reactive Strength Index

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 .

Time frame: 4weeks

Standing Long Jump

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 .

Time frame: 4 weeks

Single-Leg Hop for Distance

SLH test evaluates unilateral lower-limb performance and limb symmetry. The participant stands on one leg, performs a maximal forward hop, and lands on the same leg while maintaining balance for at least two seconds. Distances are recorded for both legs, and comparisons provide valuable insights into side-to-side asymmetries, rehabilitation status, and injury risk.

Time frame: 4 weeks

Single-Leg Vertical Jump Height

The single-leg vertical jump (SLVJ) test was used to assess unilateral lower extremity explosive performance. Participants stood on one leg with hands placed on the hips, while the non-supporting leg was flexed and held stationary. From a stable standing position, participants performed a maximal vertical jump using the supporting leg only. Jump height (cm) was recorded separately for each limb using \[measurement device - e.g., force plate / jump mat / Optojump system\]. This test allows evaluation of unilateral vertical force production and identification of inter-limb asymmetries.is .

Time frame: 4 weeks