How do I not get so tired in cardio?

Tennis player, tired all the time, cant breathe on court, no energy, whats rong with me?

• im a full time tennis player that does about 3 hours a day tennis atm and up to 2hours fitness. hoever recently iv been going away to tournaments and not doing much fitness or cardio. iv come back and just practicing. but i seem to be so tired all the time, i go to bed at 8.30/9pm so i get enough sleep. iv got dizzy on court few times and i think thats down to dehydration, but im constantly tired. im not playing as much as i did before (4hours a day, 2 fitness) but im still tired. i cough alot on court and find it hard to breathe like mucus on my throat, because it hurts my throat alot when i work hard that could be cos its cold although its indoor hard courts. ill do one hour session and be tired in it and then the rest of the day wanna sleep although i cant becos im studying for my alevels. i cough alot on court and find it hard to breathe like mucus on my throat, because it hurts my throat alot when i work hard that could be cos its cold although its indoor hard courts. im 17 year old girl. iv been training full time for 3 years this heavy schedule so its not new. is it down to lack of cardio. I DONT KNOW IF ITS JUS DOWN TO LACK OF FITNESS OR SOMETHING WORSE? help please.

• Answer:

  You could have Asthma, this is actually very common and easily treated The usual symptoms of asthma are. coughing; wheezing; shortness of breath and tightness in the chest Go and see your doctor :)