Biomechanics is the study of the effect of forces on the body. Just two examples of such forces include the Earth’s gravity and the muscles’ own elasticity. By obtaining an understanding of the biomechanics involved in each tennis stroke, coaches are able to direct athletes to use their muscles in the most efficient and injury-free ways.
Traditionally, all tennis players were taught to execute their strokes in a certain way. This was meant to reduce injury. A tennis player would stand in a way that would allow him or her to “step into the ball”. This is done by placing the foot opposite to the dominant hand slightly in front. As the tennis player hits the ball and steps forward, energy is transferred from the back foot forward to the ball. Although traditional technique appears to be energy efficient, contemporary coaches criticize that this motion is too mechanical. In fact, a close observation of top ranked international tennis players reveals that their technique does not follow traditional technique. Instead of turning to traditional technique, tennis players rely more upon their intuitivism. Tennis players’ techniques are usually based upon past experience, world trends and fluency. (Hughes et al., 1995)
Segmental interaction is the transfer of energy from large to smaller joints of the body. This is how tennis players efficiently transfer energy through different parts of their body to the ball, without disrupting the fluency of their technique. For example, the energy may originate from deeply bent knees of a tennis player. In preparation of hitting the ball, the tennis player also rotates their body. This creates a build-up of elastic energy in the torso. As the racquet is swung forward, the energy from the large leg and torso joints is transferred to the smaller upper arm muscles, elbow joint and wrist joint, and to the ball as kinetic energy.
Competitive league tennis players require an immense amount of energy to counter the balls hit by their elite opponents. In order to complete this, the tennis players need to efficiently transfer their energy. This efficient transfer of energy is possible through the use of elastic energy. When tennis players prepare to hit a ball, they will point their entire arm almost perpendicular to the back of the court. This is known as their backswing. In doing so, the arm muscles of a tennis player will stretch similar to a stretched elastic band. At this phase in the player’s technique, there is much elastic energy stored in the arm muscles. As the tennis player swings their racquet to contact the ball at a point close to their body, the arm muscles rebound to their original form (figure 5). During this rebound, an immense amount of energy is released to assist the tennis player in returning the ball over the net. However, if a tennis player initiates their backswing too soon, the effect of the elastic energy will lack efficiency. The stored elastic energy will quickly disappear as the muscles strive to return to their original form. In fact, there is already a 55% loss of the energy in 1 second. By the time that 4 seconds have passed, 100% of the energy will be lost. Therefore, in order to maximize efficiency, a tennis player needs to maintain a high level of fluency in their technique in the transfer of energy. There would need to be minimum time between the phases. This is especially crucial to the performance of junior tennis players, as they have little muscle strength to overcome the inertia of the racquet. (Hughes et al., 1995)
Figure 5; Muscular Elastic Energy
During the backswing of a stroke, a tennis player will stretch their muscles. The resulting effect is much similar to stretching an elastic. There is much elastic energy stored in the muscles. As the arm muscles rebound to their original form, they relase an immense amount of energy that contributes to the power that the tennis players exerts onto the ball.
Leg muscles also use elastic energy to assist the player. An excellent exemplar is in the technique that Andy Roddick exhibits. During Roddick’s follow-through, his muscles are elongated to a point where they are slightly stretched. This stretch is, again, similar to the stretching of the elastic band. The stretched muscles, then, possess stored elastic energy. The elastic energy increases the muscles’ tendency to rebound quicker. This is comparable to a slingshot. The more the elastic is stretched back, the higher the tendency that the elastic has to rebound to its original shape. Therefore, Roddick’s leg muscles’ contraction, due to their high tendency to rebound, allows him to return to his ready position of a deep knee-bend quicker. Furthermore, the immense energy from the rebound of the muscles will naturally make Roddick have his centre-of-gravity lower to the ground. This is very efficient technique, as his low centre-of-gravity allows him to possess greater balance. In addition, the low centre-of-gravity allows him more time to store energy to transfer to the ball, when he will explosively extend his legs from his deep knee bend.
The following includes a dissection of the four most commonly used strokes in tennis: the forehand, the backhand, the serve and the volley.
Forehand- hitting the ball with the palm of your dominant hand facing the court at about hip to shoulder level
Backhand- hitting the ball with the palm of your hand facing yourself usually at hip to shoulder level
Service- hitting the ball at a point over your head in a diagonal direction
Volley- blocking the ball from the air before it bounces on your court
As children just begin to play tennis, coaches need to ensure that the tennis racquet is not too big for pupils. Numerous studies have done by scientists in regards to the impact of the size of racquet on young junior tennis players. It was concluded in these studies that a junior tennis player would definitely benefit from the utilization of a smaller racquet. With smaller tennis racquets, subject junior tennis players were able to hit the ball at a greater velocity and keep the racquet more vertical during impact of the ball. With the usage of smaller racquets, there was an evident increase of consistency in service, forehands and backhands. The only stroke that increased in consistency amongst players with a larger racquet was the volley. Combining two of Newton’s laws of motion, we know that a greater mass at rest will possess more inertia because it will resist movement at a greater extent than a smaller mass. The reason why the larger racquets were not as useful to the junior players was because its greater mass increased the amount of inertia that a player would have to overcome when swinging the racquet forward from a period of no movement. At such a young age when children typically have not developed large muscular capacity, this excessive inertia would unquestionably impede their performance. However, the effectiveness of the larger racquets in executing volleys can be explained by the lesser swing of the racquet.
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