The Results of the Study
These results show that except for elbow and shoulder, peak joint angles at impact and before impact were greatly affected by ball speed for all the racket side joints. The peak joint angle for the trunk rotation towards the dominant arm was -29.6 when the ball was travelling at high speeds, this decreased proportionately as the speed of the ball decreased to -27 degrees for medium speed and -23.1 for a slow speed.
The peak angular velocity was mostly affected by the speed of the ball, with the exception of the shoulder and knee joints. The results show that when a ball is travelling at high speeds the angular velocity of the wrist flexion is 1337 ^ 493*, this decreases as the speed of the ball decreases. At a medium speed the angular velocity is recorded as 1021 ^ 352* which decreases further to 612 ^ 241* for slow speeds. At impact the angular velocity was not affected by ball speed with the exception of the wrist and trunk which were significantly altered.
Importance of the Lower Extremities
The lower extremities such as the trunk, hips, knees and ankles are very important for sports as this is where most of the movement stems from (Hamill, Knutzen, & Derrick, 2015). During a game of tennis the legs will be used to run forward and backwards to return the ball. They will therefore control momentum and balance which is needed to successfully play the game. In order to serve or return the ball, the player will need to twist at the hips whilst the knees may be slightly bent. These two actions will help the player have more power in their forehand allowing the ball to travel further and at a greater speed.
In conclusion to the above research study, I have noted that it is important for athletes as well as armature sports players and the general public to stretch (dynamic and static) before and after taking part in exercise. As the lower extremities are the base of human movement it is particularly important to stretch the trunk, hips, knees and ankles to strengthen them and avoid injury (Hamill, Knutzen, & Derrick, 2015). Doing warm up and cool down exercises will also help to keep the joint subtle and flexible and will help muscles to repair themselves, especially after a particularly hard work out or game.