Low-impact exercise is defined in terms of the forces on the body, particularly the bones and joints. In general, low-impact exercises minimize sudden, forceful jarring or twisting of the joints. A broad array of exercise options fall into the low-impact category. In some cases, a high-impact exercise can be made low impact by performing the same or similar body movements less strenuously, for a shorter duration or in a context that reduces the risk for injury.
In low-impact exercise, movements are smooth and at least one foot is on the ground at all times. Movements that are low impact include stepping movements such as walking, elliptical machine workouts or dancing; flexibility moves such as upper body twists and bends; supported exercises such as leg lifts and abdominal curls; arm circles or rowing action; and standing balance exercises.
Heart Healthy Activity
Low-impact exercise can provide aerobic conditioning in addition to building muscle and bone strength, depending on the intensity level. Intensity refers to an increase in metabolism during the exercise. The frequency and duration of workouts and the number of repetitions also influence the overall benefit of an exercise regimen. It is possible to get a medium- or high-intensity workout doing low-impact exercise. The American Heart Association noted in its November 1996 "Statement on Exercise" that medium-intensity activity benefits the heart and circulation. The Centers for Disease Control and Prevention explains that low-impact activities such as walking, hiking, biking, tennis, dancing, gardening, water aerobics and swimming can be paced at medium or high intensity.
Impact Level and Bone Density
Exercise helps maintain the bones. Weight-bearing exercise and strength training can increase bone mineral density or reduce losses. Swimming laps is good aerobic exercise but is performed while the body is supported -- that is, not bearing weight. A review of how swimming affects the bones, published in August 2013 in "PLOS ONE," found that swimming does not increase or decrease bone mineral density. Running and jogging are good for bones but are high impact. Hiking uphill with a heavy backpack is a high-intensity activity that is weight bearing and low impact.
The importance of physical activity to good health has become so clear that the U.S. Department of Health and Human Services released "Physical Activity Guidelines for Americans" for the first time in 2008. However, people resuming or increasing exercise after an accident or surgery or during and after pregnancy, adults with osteoarthritis and older adults should seek advice from a doctor about a low-impact exercise regimen and the intensity of exercise that is best for their situation.