When participating in tennis, you will need to execute explosive bursts of speed. This means you will be working at 100% for a short amount of time; while you complete a serve or return or, during the period in which you move to hit the ball. These efforts would only last for less than 5 seconds, and when working at such a high intensity for this amount of time you are using your ATP-PC system.
A whole game of tennis would basically consist of repeating these movements for the duration of the game with rests in between rallies. So your body would be working for the majority of the game in its ATP-PC system as it would have time to replenish.
Adenosine Triphosphate (ATP) stores in the muscle last for approximately 2 seconds and the resynthesis of ATP from Creatine Phosphate (CP) will continue until CP stores in the muscles are depleted, approximately 4 to 6 seconds. This gives us around 5 to 8 seconds of ATP production. (MACKENZIE, B. (1998) Energy Pathways [WWW])
The ATP-PC system is divided into two different sections- the Adenosine Tri-Phosphate (ATP) section, and the PhosphoCreatine (PC) section. A muscle cell contains rough;y enough ATP to last for the duration of 4-6 seconds when working at 100%. This means, that a phosphate will ‘break off’ creating a new nucleotide; Adenosine Di-phosphate.The ‘PC’ part of the energy systems involves trying to replenish the ATP by contributing a phosphate to turn the ATP back into ATP-PC, for further use.
Your ATP-PC system will replenish after about 3-5 times the duration of the activity or until breathing is normal. The average rally would last for no longer than 10 seconds, so there is plenty of time in between for at least some of the phosphocreatine to replenish and therefore it will enable us to continue to use this system.
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