Hi everyone~ I'm new.. but not new.
Haha, i've joined for a few months but a little posts.
Anyway, I'm going to be 18 this year, and slightly overweight. I've visited the gym since Aug 2005. Everything goes really slowly. Through the months, i built up my stamina, muscles and lose only 4lbs or so, probably gaining too much muscle. Everything went fine, i can do anything that i like in the gym...

until..

a week ago.
As usual, i proceed to the gym for my workout. I did stretching for 3 minutes before i start the cardio. I went to cycling for 20 minutes as warm up, then to the elliptical machine. This is where the problem starts. Usually, i am able to do the elliptical machine for 1 hour, however, this time round, 5 minutes is enough for me to die. It's not that i'm panting, it's my legs. It's not pain or what, i just feel that its tired, but i've just started the exercise only. The feeling is like you've hung something over your shoulder(same side) for 2 hours without moving. It feels "Sour". Nevermind, i continue with it but there're like 2 minutes of temporary rest in between. I completed 35 minutes and give up.
I rest for a while, and go to the treadmill. This is another machine that i used to be good at. A few months ago, i can jog non-stop for 7km at a constant speed. However, now, just 5-10 minutes, i feel the same "sour" feeling on my legs. I wonder what's wrong with me.

Q: Is it the bones?
Q: Is it the muscles?
Q: What should i do?
Q: Should i eat more kind of calcium or something?
Q: Or should i just visit the doctor.

Thanks people!~

Its the muscles. NEVER stretch cold muscles. The ideal situation is a light and easy cardio warm up for about 10 minutes. THEN stretch. Then continue with your workout. Do final stretches after your workout is complete, and while your muscles are still warm. I've run track competitively when I was younger and in better shape. The majority of injuries to atheletes is due to incorrect or inadequate stretching. You have to do stretches with progressive intensity and while muscles are warm. The human body's limitations on things like running, cycling etc, is limited by cardiovascular capacity, not muscular capacity. So basically you should run out of breath before you run out of muscle. You may experience some muscle pain and soreness in the meantime of course. But if you run out of muscle before you run out of breath in a cardio workout, theres a problem with what you're doing.

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