By Cathe Friedrich

Most exercises divide loosely into low-impact or high-impact. Knowing the differences between the two types is critical because each poses its own risks and benefits.

Defining Low-Impact and High-Impact Exercise

Very generally, low-impact exercise is any physical activity in which you keep at least one foot on the ground as you work. moreGood examples are cross-country skiing, rollerblading and Zumba. Many people include activities such as cycling and spinning as low-impact, but technically, they're more properly classified as no-impact, because you are either suspended or have both feet grounded. Usually, low-impact exercises are cardiovascular, as well, so although things like weightlifting or Pilates could meet the one-foot rule, they still don't fall into this category.

High-impact exercise is physical activity in which both feet may leave the ground. Jumping rope, gymnastics and plyometrics are good examples. These exercises typically are harder in terms of intensity. They tend to elevate the heart rate quickly and are excellent for burning calories. They also can improve bone density--the body naturally will strengthen the bones over time as a protective measure against the force put on them.

Pros and Cons

If you are looking to lose weight, high-impact exercises might help you reach your goals more quickly because of their ability to get the heart pumping at a good clip and blast through calories. The downside here is that many people are not at a fitness level that supports the intensity these exercises have. If you're a beginner, you might not be able to do them for very long, or you might need to work up to them over time.

Low-impact exercises generally burn fewer calories, so they aren't always the top choice if you need to slim down. Nevertheless, they are much gentler on the joints. Remember, Newton's Third Law says that every action has to have an opposite and equal reaction. Applied to exercise, it means that the more force you have during an impact, the more force your body has to absorb. If you have any kind of joint-related injury or condition, such as arthritis or disc degeneration, then these are almost always the safer bet. Low-impact exercises also are better choices for beginners because they often are less intense.

The Best of Both Worlds

The general consensus among medical and fitness professionals is that your best route for optimum health is do both low-impact and high-impact exercises if you can. This way, even as you improve your strength, endurance and cardiovascular and bone health, you're not putting constant stress on your body and have a chance to recover, decreasing injury risk. Improving your fitness level over time does not mean you have to abandon low-impact work, even if it's what you started with.

It is very possible to concentrate on either high-impact or low-impact work during an exercise session. An incredibly popular way of combining low- and high-impact exercise is through interval training. For instance, you might do 30 seconds of jumping jacks, 30 seconds doing basic step, another 30 seconds of cannonballs and so forth. You can combine this with circuit training. In this form of training, you put a few (usually no more than three) exercises in a group, repeat the entire set two to four times, and then move on to another group. Still another option is to use high-intensity interval training (HiiT). Your goal with HiiT is to use intervals that get you on the upper end of your target heart rate (80 to 90% of your max heart rate, which is approximately accepted as 220 minus your age.

Conclusion

Low-impact and high-impact exercises differ mainly in their effect on the joints and the degree to which they elevate the heart rate, with high-impact exercises usually being of higher intensity. You typically should opt for low-impact exercises if you have a musculoskeletal condition or injury, are new to exercise, or if you are overweight, pregnant or more elderly. Go for high-impact if you are in good musculoskeletal health, have a good baseline of fitness and would like to burn a higher number of calories. Most professionals recommend that, if you are able, you should try to get a good mix of both low- and high-impact exercises.