With so many types of exercise out there, how do you know which is right for you? The choice is important because it can mean the difference between a slimmer, healthier you and a muscle injury.

Before beginning any exercise program, you should visit your physician for a physical examination. During the visit, you should ask if there are any types of exercise you should avoid.

About your heart rate

One main reason to exercise is to increase your heart rate and keep it elevated for a certain length of time. Aerobic exercise does this faster than casual stretching or resistance training.

It is important to exercise within 60 to 80 percent of your maximum heart rate, a range called your target heart rate. To calculate your target heart rate, use the following formula:

• Maximum heart rate (MHR) = 220 - your age. For example, the MHR of a 50-year-old would be 170 (220-50).

Your MHR multiplied by 0.7 is the low range of your target heart rate. Continuing the example from above, while exercising a 50-year-old should reach a heart rate of least 119 (170 x 0.7).

Your MHR multiplied by 0.8 is the high range of your target heart rate. The same 50-year-old should not exceed a heart rate of 136 (170 x 0.8) while exercising.

Warming up prior to exercising can prevent a muscle or bone injury and allows the cardiovascular system to gear up to bring oxygen to working muscles. This should be done for at least five to ten minutes, no matter the type of exercise that is to follow.