Exercise and Bone Health: A Guide to Maintaining Healthy Bones
Our bones play many important roles: they support the body, protect our organs, and provide a place for muscles to anchor themselves. Importantly, they also store calcium, which we need to build and maintain strong bones.
Osteoporosis, which is weak bone density, is one of the biggest problems encountered later in life, particularly for women. After age 60, 1 in every 10 females has osteoporosis. After age 70, it affects 1 in 5 females. Among women 55 years and older in the US, there were almost 1.7 million hospitalizations for fragility fractures in 2011.
“Bones are important to get us through life. And we need to build our bone bank when we are young,” says Elizabeth Matzkin, MD, an orthopedic surgeon and surgical director for women’s musculoskeletal health in the Department of Orthopaedic Surgery at Brigham and Women’s Hospital. “As we get older we are going to lose bone mass and that can be a problem later in life with osteoporosis and fragility fractures.”
During crucial early years, up to age 25 or so, we are can strengthen bones through exercise. Beyond that age, we cannot appreciably add bone density. But the right exercise throughout life, together with adequate nutrition, is the best hedge against osteoporosis.
Bones may look solid and unchanging, they are actually living tissue. Bone continually changes or “remodels,” with new fresh bone replacing old bone to maintain bone health and function. As we age, the balance of remodeling may shift, leading to a loss of bone mass – and potentially osteoporosis and fractures.
Starting early in life, exercise can build up that early bone mass and, with age, maintain it.
Not all exercise is equal
“If we impart stress, or exercise, to our bones, we actually make bones stronger,” Dr. Matzkin explains. Weight-bearing exercise at all stages of life is the key. These activities cause the body to bear its own weight, working the bones and muscles against gravity. They including walking, jogging, running, tennis or racquetball, soccer, basketball, and dance. Strength training, such as lifting weights (even light weights) also strengthens both muscles and bones. All of these contribute to a process that helps turn on bone-forming cells.
Some other common activities, while good for overall fitness and heart health, do not build bone strength. Two examples are biking and swimming. Neither requires the body to bear its own weight, so they do not contribute to building bone.
“Exercise should be performed at a minimum of 30 min per day, 5 times per week, for average adult as recommended by the US Centers for Disease Control and Prevention,” says Dr. Matzkin. “Children ages 7 to 19 or so should probably do 60 minutes of activity daily.”
With age, you may need to modify the intensity of exercise – but you should continue putting stress on the bones to maintain their strength.
Beware over-training among young athletes
It is important not to deplete bone during what should be prime bone-building years, through the teens and into the early 20s. Over-training, especially in young athletes, can adversely affect bone health — with lifetime consequences.
An adolescent or 20-year-old who is training hard and not getting adequate nutrition can be depleting their bone health without realizing it. These athletes may not seem like they are over-training and in fact may not be training more than their peers. But if their diet is not providing enough nutrition for their level of activity, the resulting negative energy balance can deplete bone mass. Inadequate nutrition can lead to abnormal menstruation and a low bone mass, which often manifests as stress fractures.
“Often it’s late when we catch it,” says Dr. Matzkin. “A young woman may present to my office with a bone stress injury from exercise. When questioned, many have never started their period or have stopped menstruating due to an energy imbalance.”
For these young athletes, physicians at BWH provide guidance on improving nutritional and caloric intake to meet training requirements while also achieving a favorable energy balance to strengthen bones and enhance long-term health.
The balance of exercise and nutrition differs from one person to the next. ‘Some people get tons of exercise, and they are ok if they get adequate rest and nutrition,” Dr. Matzkin adds. “But if you do too much exercise without appropriate nutritional support, you get breakdown of bone.”
What else is good or bad for bone health?
Calcium and vitamin D are important, and most people get enough from a healthy diet. Other people may require supplements. But intake of calcium and vitamin D alone won’t provide optimal bone health without exercise, rest, and appropriate nutrition.
It’s also worth noting that extra calcium, beyond the recommended amount for your age and sex, will not make bones stronger or make up for prior bone loss.
You also can optimize bone health by avoiding smoking, alcohol use and certain medications that can deplete bone. Your doctor will advise you of that downside of any medication you may be prescribed.
Elizabeth G. Matzkin, MD, Surgical Director, Musculoskeletal Health at Brigham and Women’s Hospital, explains why exercise is important to bone health and maintenance.