Fast twitch fibers are powerful but fatigue quickly. If you do a strong, explosive movement like the bench press, you're using fast twitch fibers.

The shoulder joint has the largest range of motion of any of your joints, which makes it the most vulnerable to injury. The joint has the ability to move into 1,600 positions throughout a three-dimensional space.

Weightlifting increases muscle density. Underlying your breasts are your pectoral major and minor muscles. Breast tissue, in front of your pecs, contains no muscle at all, but rather is composed of connective tissue and mammary glands -- called fibroglandular tissue -- and fat.

Although building an impressive set of pectorals -- the muscles of your upper chest -- requires dedication to an effective workout plan, you also need to make good nutritional choices.

Pectus excavatum, or sunken chest, is a condition that is usually present at birth, but it can become more pronounced in adolescence, causing a decreased exercise tolerance, respiratory infections, chest pain and heart murmurs.

No exercise targets chest flab, as spot-reducing body fat is impossible. However, doing brisk cardiovascular exercise shrinks excess body fat wherever you have it, including your chest area.

To build the strength necessary to do regular push-ups, do wall push-ups. Use proper form, activate your core and train regularly.

If your upper chest is lagging in its development, incorporate decline push-up variations to help it grow.

Lowering your body fat and tightening up your chest requires cardiovascular exercise and weight training.

Bad shoulders shouldn't stop you from strengthening and toning your pectorals. However, you should focus on doing effective exercises with proper technique. Use a weight that doesn't place excessive stress on your shoulder joints, and a range of motion that doesn't cause shoulder pain or increase risk of injury.

Uneven push-ups have you put one hand on an elevated surface as you press up and down. This increases muscle activation to make the push-up harder.

Decline dumbbell flyes are a move to add to your chest workouts. They target the lower chest, which is sometimes left out.