To confirm the differences in landing impact between hard and clay court using four tennis movements, lead to injury prevention for tennis players.
The participants were 20 healthy university students with at least one year of tennis experience (10 Male and 10 Female). Task movements was four: dash, retro-running, slide step, and cross step. Dash and retro-running were instructed to run 5.5 m, slide step and cross step were instructed to run 11 m. The participants performed four task movements on two court surfaces, hard court and clay court. Smart shoes can measure gait-related indicators in real time from sensors built into the insole. To evaluate the hardness of court, we also conducted an experiment on the coefficient of restitution at each court. A golf ball was dropped, and the coefficient of restitution was determined by the ratio of the drop and bounce height on the courts. Statistical analysis compared the landing impact between the two court surfaces performing paired t-test. The significance level was set at 5%.
The Landing impact was larger on hard court than on clay court for all movements (Dash; 9.24 ± 1.9 G vs 8.38 ± 2.0 G, retro-running; 8.14 ± 1.9 G vs 7.63 ± 2.0 G, slide step; 7.65 ± 1.9 G vs 6.89 ± 1.4 G, cross step; 7.89 ± 1.7 G vs 7.20 ± 1.5 G, p0.05, respectively). The coefficient of restitution was 0.43 for clay courts and 0.86 for hard courts, with hard courts being 100% larger than clay courts.
Previous study said coefficient of restitution is positively correlated with landing impact, the landing impact was larger on hard court. We also consider difference the result in the coefficient of restitution and landing impact between courts. This result may be related to the difference between the golf ball and feet ground contact direction. The results of this study indicate that movements frequently used in tennis, such as these four task movements, may increase the load on the knee and ankle joints on hard courts compared to clay courts.
When playing on surfaces with high landing impact, such as hard courts, may lead to the lower limb overuse injuries. To prevent the occurrence of overuse injuries, to understand stress on the lower limb from landing impact is important.
Landing impact
Specific movements
