Here are some important physiological laws to understand the physiological processes involved in serving the ball.
I. The speed of contraction of a muscle fibre decreases as the load increases. The maximum speed is achieved under zero load. Consequently, the racket weight is very important for serving. The heavier the racket, the lower the speed of contraction of a muscle fibre and vice versa. On the other hand, the heavier the racket, the more powerful the shot. An optimal balance is necessary! By gradually increasing the racket weight when training on ServeUp, you will adapt the contraction speed of muscle fibre to the racket weight. Long training with a heavier racket builds stable muscle memory of the racket weight, but once the weight is reduced, the speed of muscle fibre contraction will increase. This, ultimately, helps you achieve the desired result - increase the speed of the racket when striking the ball.
II. There are three fibre types identified in skeletal muscles based on the maximum rate of shortening and predominant mode of ATP (adenosine triphosphate is a universal source of energy for all biochemical processes) formation: slow oxidative, fast oxidative and fast glycolytic. Fast glycolytic fibres are larger in diameter than oxidative fibres and therefore produce higher tension, but fatigue more easily. At the beginning of contraction, slow oxidative motor units are recruited first, then fast oxidative units, and eventually with a very strong contraction, fast glycolytic units are engaged. The involvement of all motor units in contraction increases the speed at which the muscle moves the load. Therefore, in order to achieve maximum speed and power of muscle contraction, you need to do exercises so that to get all the groups of muscle fibres contracted, especially fast glycolytic fibres! ServeUp helps you train all these three muscle fibre groups of the hitting arm.
III. The muscular strength and fatigue can vary throughout the training process
Long low-intensity exercises increase the ability of muscle fibres to generate ATP (universal source of energy for muscle work) using oxidative (aerobic) metabolism. This happens by increasing the number of mitochondria and blood vessels in the muscle. The result is improved muscle endurance. ServeUp allows you to train for better muscular endurance of the hitting arm. And short-term high-intensity exercises increase a fibre diameter due to the actin and myosin synthesis. The result is a higher muscular strength. This is especially important for the muscle groups that perform a very specific function and are rarely used in normal life. These are the pronators and flexors of the wrist (Figure 4). These muscles are crucially important for a strong serve and a targeted methodical training of them with ServeUp is one of the keys to a strong serve.
The relationship between the load and speed of shortening. The speed of muscle fibre shortening declines with increasing load and is determined by repetition of each working cross-bridge cycle and resulting rate of ATP molecule cleavage, as one ATP molecule is cleaved in each cross-bridge cycle. Consequently, with ServeUp you can train exactly the groups of muscle fibres that are used to increase the racket speed to hit the ball.
Muscle length-tension. Muscle stretching not only leads to passive tension of the muscle fibre, but also to a change in its active tension during contraction. Therefore, the force generated by contraction depends on the initial length of the muscle fibre (the more the muscle is stretched before contraction, the greater the contraction force).
Conclusion. Here are few rules to follow for a strong and effective serve in tennis:
1. Adhere fully to the rule of levers. The more levers you use (body, shoulder, forearm, hand and racket) the higher the racket acceleration rate.
2. Improve the endurance and speed of muscle fibre contraction by gradually increasing the weight of the racket during your training and by improving your muscle memory.
3. Adhere fully to the rule of sequential and coordinated biomechanical processes: racket acceleration - long lever; division of the long lever into 3-4 short ones creates an inertial loop to increase the racket acceleration; long lever at the moment the racket makes contact with the ball to increase a stroke power; hand rotation (pronators) to improve a stroke power.
ServeUp design meets all the above challenges.