In the old days, we believed that it was inappropriate for women to have muscles. We also thought that if they did the same exercises as men, they would begin to look like men. So they were naturally afraid to do any type of training exercise.

Women can build but it is not as easy to pack on the muscle. So they don't usually develop the same size muscles. There are exceptions, but it takes years for anyone to look like Swartzenegger and some will never, no matter how much they train. Pushups, traditionally done on the knees by women, do practically nothing to strengthen the muscle structure. It is rare for anyone to actually bulk up using body weight alone. Additional weights would be required.

The muscles that are targeted in pushups are the triceps, pectorals, shoulders and back muscles. Pectorals are important for a number of reasons. They provide protection for the thoracic cavity due to impact (seat belt in a car accident, etc). They provide support for the chest for both men and women to avoid sagging. They also assist in breathing to lift and expand the thoracic cavity.

In fitness classes, women are genuinely surprised when requested to do full pushups. The visual results are very little building, some good toning, increased definition and greater strength. The added benefit of denser muscle is that it is smaller and heavier unlike training with external weights which build larger denser muscles. Actually the reduction in size comes from an increase in the metabolic rate which burns fat. The metabolic rate increases by 50 calories per day for each pound of lean muscle added. So flabby muscles get pulled in tighter and denser and fat burns away. So, this is a good reason to not use a bathroom scale. It can be very misleading. Many people have cancelled workout programs thinking they were useless because their scale indicated that they were heavier than before they started training. To put it in perspective. Go to the supermarket and compare a 2 pound lean steak with a 2 pound tub of fat/lard. There's a big difference in volume.

Some people build faster than others, but we all level off well below what would occur if we were actually pumping iron. So, don't be afraid of the burn, and besides, it's only lactic acid buildup in the muscles.