Body compostion:
Without physical activity muscle mass decreases at a rate of a half a pound per year, which results in an increase in body fat. For example: By the age of 65, an inactive person may have lost half of their lean muscle mass and doubled the amount of body fat.

Muscle imbalances:
Muscular imbalance is due to weak muscles, joints and connective tissue, which will increase your risk of injury, joint pain and poor posture. To improve muscular balance, strengthen opposing muscle groups and include a well balanced stretch program.

Target Training Zone:
Your heart rate can tell much about your body - how fit you are, how much you've improved, if you're burning fat and carbohydrates, and whether you've recovered from yesterday's workout. But how do you know what heart rate to aim for? There is no magic number. Rather, there's a whole range of acceptable numbers called you 'target heart rate zone.' This range is the middle ground between slacking off and knocking yourself out. Typically, your body 'target heart rate zone' is between 50% and 85% of your maximum heat rate; the maximum number of time your heart can beat in one minute.

If you are ready to turn your body into the ultimate fat burning machine, its time you know your target heart rate zone and understand how to effectively work within the zone, not above or below it. Knowing how hard you are working during a workout is far more helpful than knowing how fast you are going. Becoming fatigued instead of energized from exercise is the primary cause of burnout and the same reason why many exercisers see results.

If you keep track of your heart rate over a long period of time, you'll discover some interesting things about your progress. When you are a beginner, your heart works a lot harder to keep up with your body's demands for blood and oxygen. If you work out on a regular basis, your aerobic system gradually becomes more efficient. To find out how much your fitness level is improving, watch how fast your heart rate drops after a workout. The better shape you are in the faster your heart rate drops.

The heart responds to exercise like any other muscle in the body. Working your heart on a regular basis will make it stronger. As your fitness level increases, your heart will pump more oxygenated blood with each beat. When this happens the heart does not have to beat as often to get needed oxygen and nutrients to the muscles. Therefore a fit individual will have a lower heart rate at rest and during exercise.

A number of ways to measure target heart rate:

• Heart rate moniter
• Predicted Maximum Heart Rate Method: Training HR=(training %)X(220-Age)
• Karvonen Method (Max HRR): Training HR=(training %)X[(220-Age)-RHR]+RHR (resting heart rate)