Understanding the Role of Exercise and Bone Health

Understanding the Role of Exercise and Bone Health

Bones play many roles in the body. Providing structure, protecting organs, anchoring muscles, and storing calcium are just a few of their roles. So while it is important to build strong and healthy bones during childhood and adolescence, you can take steps during adulthood to protect bone health as well.

The skeleton undergoes continuous remodeling throughout life. Mature bone tissue is removed, and new bone tissue is formed. Bone remodeling is a highly regulated process that maintains a balance between bone resorption and formation. (2) The majority of people reach their peak bone mass around age 30. After that, bone remodeling continues, but you lose slightly more bone mass than you gain (1)

The aging process, various diseases, and medications can cause bones to become very weak and fragile over time. This condition is referred to as osteoporosis. Osteoporosis is a common metabolic disorder (more prevalent in women than men) in which there is a decrease in bone mass which can increase the risk of bone fracture. Bone tissue is constantly being broken down and replaced, but osteoporosis occurs when new bone cannot keep up with the loss of old bone.

Aging is a risk factor for osteoporosis because there is a decrease in the number of osteoblasts (cells responsible for bone growth) relative to the demand for bone formation. The trabecular bone (spongy/porous components) beneath the cortical bone (strong compact bone, found on the outer layer of long bones) is more porous and weakened in osteoporosis. Therefore, bones of the wrist, hip, and spine, which possess more trabecular bone, are more susceptible to fractures. (3).

Dr. Julius Wolff, a German anatomist, and surgeon created a theory that states that bones will adapt to stress placed on them. If bones are subjected to heavier loads, the bones will adapt and will become stronger internally so they can bear the weight of the increased load. Conversely, if the bones are subjected to a decrease in weight, they may become weaker and less dense. For example, if your job requires you to perform carry or lift weights as a construction worker might do, your bones will adapt and strengthen over time to better support this task. On the other hand, if you don’t place any demands on a bone, the bone tissue will weaken over time. (4)

Exercise is important for building strong bones when we are younger, and it is important for maintaining bone strength when we are older. What exercises are best for good bone health? Any exercise is good because all exercise causes muscles to contract against bones, which stimulates bones to strengthen. Make sure you speak to your healthcare professional prior to beginning an exercise program so they can discuss any possible concerns with becoming more active.

A combination of weight-bearing and resistance exercises are the most beneficial routine. Weightbearing exercises are those that place weight on the bones. These exercises are the most valuable for bone health because both muscles and gravity stress the bones. Examples of weight-bearing exercises are walking, jogging, hiking, stairs, dancing, household chores, and yard work. Resistance exercises also strengthen bones and can include free weights, weight machines, or resistance bands. An individual should focus on the major muscle groups in the legs, arms, and trunk. Weightbearing exercise is recommended for at least 30 minutes a day, 3 or 4 times a week. Resistance exercise can be done 2 or 3 times a week, allowing for recovery in between workouts. (5)

Individuals that have been diagnosed with osteoporosis should be aware that not all types of exercise are appropriate for their condition. Exercises that are to be avoided are high-impact exercises. Running increases the stress on your bones to provide more strengthening benefits. However, if your bones are weak from osteoporosis, something as high impact as running can lead to a fracture. Jumping activities involve abrupt and explosive loading or impact when your feet hit the ground, exposing an individual to potential fracture.

Other activities to be avoided when diagnosed with osteoporosis are exercises that involve bending and twisting. Examples to avoid would be sit-ups and toe touches. Both exercises involve bending forward, which puts stress on the joints in your spine that can result in a compression fracture of the spine.

The impact of falls is compounded in people with osteoporosis, often resulting in multiple fractures. Both Pilates and Yoga are activities that can help improve strength, balance, and flexibility, all of which can help in preventing falls. But some poses or movements can increase mechanical stress on the spine and put fragile bones at risk for fracture. Some of these movements can be modified by a physical therapist to allow you to benefit from the activities but reduce your chance of injury.

Not necessarily everyone diagnosed with osteoporosis should avoid all these exercises. Your healthcare provider will determine which activities are safe for you depending on your history of fractures, the severity of osteoporosis, and overall health. There is no one-size-fits-all exercise prescription. Everyone will be different based on their current health. If you are unsure if it is safe to begin an exercise program, speak to your physician prior to
beginning. (6)

References

Bone health for life: Health information basics for you and your family. National Institute of Arthritis and Musculoskeletal and Skin Diseases. https://www.bones.nih.gov/health-info/bone/bone-health/bone-health-life-health-information-basics-you-and-your-family. Accessed Jan. 25, 2019.

Hadjidakis DJ, Androulakis II. Bone Remodeling. Ann NY Acad Sci. 2006 Dec; 1092:385-96.

NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy. Osteoporosis prevention, diagnosis, and therapy. JAMA. 2001;285:785–95.4.

Wolff, J. (1892) 1986. Bone Remodeling. Berlin: Springer-Verlag.

https://www.ncys.org/wp-content/uploads/2022/02/2022_St_Exercise-for-bone-health-1.pdf

https://creakyjoints.org/diet-exercise/exercises-avoid-with-osteoporosis