I've read a couple of books on body building - I'm nowhere near a body builder - I don't like to reinvent the wheel, so I read.
Weight lifting and gaining muscle mass or strength is hard work. It is a factor of genetics, food eaten and how you exercise. Let's leave out genetics for the time being.
The short answers:
Eating is about 70% of the equation - you must increase protein intake and reduce other calorie sources so that the exercising you do can be turned into muscle.
How you train is the other 30% - You must stress out the muscle when you exercise to send the message for it to grow. Then the rest comes in so that the muscle can repair itself and grow. Too much rest - more than 1 day usually - and the benefits of the exercise begin to be lost. Too little rest and you over train - no improvement.
If you are going to the gym and using weight but not watching your protein you are really not being effective in your workout. I use the powder protein to increase my intake. You should be aiming for about .75 grams of protein for every pound of bodyweight - per day. This is why you must decrease other sources of calories or you will put on weight.
Other suppliments to consider:
Multiminerals
Multivitamins
Creatine - for muscle repair and growth
L- Glutamine - for recovery
You can tell the people in the gym who know what they are doing if they are carrying a work out plan with a pen to track their routines and some water - I hope you are one of them. Also, they work out with weights first and then do some aerobic exercise. You should move slowly when using weights which will reduce the amount of streeching needed.
There are many work out routines and concepts - - go tp the library and read
Arnold Schwarzenegger - The new encyclopedia of Modern Bodybuilding
Darden - High Intensity body building.
Read Arnold for the routines and Darden for how to do the exercises properly and his thoughts.
My general routine while at home is:
Day 1 - Chest,back,stomach
Day 2 - Shoulders, Arms, stomach
Day 3 - Legs, lower back, stomach
Day 4 - Rest
If traveling - walking, push ups etc - really light stuff. This is why I really don't get big - the benefits of the at home work out are lost by about 30% when I travel.
Weight training is one of the best ways to keep your body young - if done properly.
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Quiz time:
What should the calorie intake be under these circumstances:
Office Worker
Man
Woman
Exercising - as in above
Man
Woman