Human Muscle Energy - Increases or Decreases by doing work? When Human does some work, he gets tired. I will think he looses some energy. If he really loses energy by doing work how does he gain more strength to do more work later. His muscles become strong and body gets more power to do extra work after routine practise. 
How does the energy work with muscles during any physical work or exercise? Does body looses energy or gains energy by doing work and how?
 A: Assuming your question is about the concept of energy in physics:
The muscle actually uses chemical energy. How this works in detail is not a physics but a biology question. The chemical reaction will create heat and cause your muscle to contract. Consequently, your body loses chemical energy, that's why you have to eat, drink and breath, to keep these reactions going. In return you body loses heat energy to it's environment, as well as kinetic energy, which will be the actual movement of your arm. 
If you do exercises, long term speaking, your body will not gain or lose any energy, it will become more efficient and capable of converting chemical energy to kinetic energy, potential energy, etc..
You might have a slight misunderstanding of what energy in a physics actually is. Wikipedia might help you.
http://en.wikipedia.org/wiki/Energy
A: http://www.launc.tased.edu.au/online/sciences/PhysSci/done/kinetics/wep/Work.htm 
The above link talks about WORK, ENERGY and POWER. Does this basic concept of physics applies all only to OBJECT and not to Human doing the work or applying power and using its own energy? Just confused here and I think I was wrong in linking with Human energy.
If I pushed an object and moved it from position A to position B, the work was done on object by me. The object got kinetic energy. But did the object got energy from me as I feel I lost some energy. I think Physics don't deal with my(Human) energy here, I have to look into Biology as suggested by my friend. Am I correct?
