Old age and Bone mineral density

Bone Density and Exercise

Weight Bearing Exercise Increases Bone Density and Reduces Osteoporosis Risk

By Elizabeth Quinn, About.com Guide

Updated August 10, 2011

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

See More About:

• strength
• fractures
• exercise physiology
• injury prevention

Exercise and Bone Density

In 2009, researchers from the Bone & Joint Injury Prevention & Rehabilitation Center at the University of Michigan reviewed research as far back as 1961 to determine the impact exercise has on bone density and bone health.They found three characteristics of exercise have the largest impact on increased bone density. They are:

• Strain magnitude of the exercise (This is higher in exercise such as gymnastics and weightlifting where the force or impact of the exercise is greatest).
• Strain rate of the exercise (This is higher in exercise such as jumping or plyometrics where the rate at which the impact is felt is high).
• Strain frequency of the exercise (This is higher in exercise such as running, where the impact to the bones occurs frequently during the exercise session).

The magnitude, rate and frequency of the strain during exercise all play a role in developing greater bone density, but the researchers didn't determine which is the most important of the three. They did say that increases in bone density can be had in as little as 12 to 20 minutes of weight-bearing exercise, three days a week.
Evidence also shows that exercise may help build and maintain bone density at any age. Studies have seen bone density increase by doing regular resistance exercises, such as lifting weights, two or three times a week. This type of weight-bearing exercise appears to stimulate bone formation and retain calcium in the bones that are bearing the load. The force of muscles pulling against bones stimulates this bone-building process. So any exercise that places force on a bone will strengthen that bone.

The Best Exercises for Increasing Bone Density

Experts recommend the following forms of exercise for all athletes in order to increase bone density and prevent bone loss:

• Weight Training, especially the Squat Exercise
• Plyometrics
• Jump Training
• Stair Running
• Body Weight Exercises
• Jump Roping
• Running
• Hiking
• Backpacking

Cycling, Swimming May Decrease Bone Density

Swimming and bicycling are not considered weight-bearing exercises and aren't usually listed on the list of exercise that increases bone density. In fact, there is some evidence that elite level cyclists actually lose bone density during high intensity training and racing.Several studies, including one in 2008, found lower bone density in elite level cyclists who train for hours on the bicycle.
Researchers are not entirely sure the cause of the bone loss in cyclists, but the current theories include:

• The non weight-bearing nature of cycling put little strain magnitude (see above) on the bones.
• Minerals, including calcium, are lost at an enormous rate during hours of sweating.
• The possible energy imbalance (more calories are used than consumed) during hours of intense exercise.

Preventing Osteopenia and Osteoporosis

Low bone density, referred to as osteopenia, can lead to osteoporosis and a significant risk of bone injury, including stress fractures, and other fractures.

Other Risk Factors for Low Bone Density

• Amenorrhea
• Eating Disorders
• Low body weight (<132 li="li" pounds="pounds">
• A diet low in calcium or vitamin D.
  The current recommended intake of calcium for adults is 1,000 milligrams per day, and the recommendations for vitamin D are from 200 to 600 international units per day. Search Calorie Count to find foods rich in
  • Calcium
  • Vitamin D

Nutrition and Exercise Best for Building Strong Bones

Building and maintaining bone mass requires more than weight-bearing exercise alone. A combination of good nutrition and weight-bearing exercise is the ideal way to build bone mass. Once we reach about age 30, we don't build bone as readily so building adequate bone density early in life is the best way to prevent osteoporosis later. As an adult, the best way to maintain the bone mass is the same way you build it -- getting adequate calcium in your diet and doing weight-bearing exercise.