How Exercise Influences Bone Health

Exercise helps prevent bone loss

 

Osteoporosis is a disease characterized by the thinning or weakening of the quantity and quality of bones. All adults, especially as they age, need to be aware of how their skeleton changes and how these changes may increase the risk for fracture.

 

Osteopenia identifies the early stages of this bone loss. Clinical testing is typically done by a Bone Mineral Density test. This bone deterioration can happen slowly over many years without symptoms.

 

Either way - a diagnosis of osteoporosis or an observation of osteopenia – the message is the same. You either have lost or are losing skeletal bone at a faster than desired rate and are at a higher risk for fractures. Needless to say, this is a situation we all want to avoid.

 

How Exercise Prevents Bone Loss

 

You have probably heard that exercise is an important strategy for preventing bone loss and maintaining good skeletal health. Why is that?

 

Like most organs/tissues, skeletal bone is constantly remodeling. Bone remodeling is a lifelong process where mature bone is removed (a process called resorption) and new bone is formed (called ossification). Cells called osteoclasts are responsible for the breakdown (resorption) while cells called osteoblasts handle new bone ossification. When we are young, we make new bone faster than we remove old bone and we increase our bone mass. Through our 20s this starts to shift, and we begin to lose bone mass faster than it is created.

 

How does exercise stimulate the proactive or “good” bone-building actions of the osteoblasts? Although precise mechanisms are still being discovered and better understood, the simple answer is that exercise and physical activity is an effective way to stress the skeletal bone and stimulate remodeling. These stresses or forces happen in two primary ways:

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External bone loading stress/forces (Gravity or ground-reaction force)

 

Think of this as the compressive force exerted onto your bone due to gravity or impact. For example, simply standing or walking applies a vertical compression force to the bones of your leg (femur, tibia, fibula) in proportion to your body weight. Adding a modest “impact component” such as landing from a step (low), a jog stride (moderate), or a jump (high) is a greater compression force and will stimulate bone generation (ossification) even more.

 

Internal bone loading stress/forces (muscle or joint-reaction force)

 

These are the forces placed on the bone from a contracting skeletal muscle. The pulling force is typically greatest where the muscle’s tendon attaches to the bone and the force applied to the bone will stimulate bone generation. All forms of movement/exercise create these internal forces. However, strength or resistance training exercises generate these forces most significantly.

 

The American College of Sports Medicine position statement on Exercise and Bone Health identifies the optimal strategies for making the skeleton more resistant to fracture:

  1. Maximize the gain in bone mineral density (BMD) in the first three decades of life
  2. Minimize the decline in BMD after the age of 40 due to endocrine changes, aging, a decline in physical activity, and other factors

Even if we're past this skeletal bone-accumulating stage of life, we can still be mindful of this incentive as we encourage our kids and grandchildren to be physically active. Running, jumping, playing sports – having fun and moving. Add the importance of building a healthy skeletal reserve for the later years to the dozens of other benefits of physical activity.

 

The Best Exercises After Age 40


Exercises with the greatest positive influence on bone health are:

  • Strength training with resistance exercises (applies regular/consistent internal forces)
  • Activities with repetitive low-moderate impact (applies repetitive compression forces)
  • Weight bearing endurance activities (applies repetitive compression forces)

Please note: Bone-growth-stimulating higher impact activities such as running or jumping may be inappropriate for someone with orthopedic problems, balance concerns, cardiovascular issues, or other limiting factors. Please consult your medical provider or a certified fitness professional before starting any vigorous exercise program.

 

Strength Training


Internal bone loading forces are especially pronounced with strength training. The increased intensity (heavier loads) typically used in strength training are especially effective at stimulating bone regeneration. Therefore, strength training is a key strategy in attaining/maintaining good bone health. If you aren’t strength training yet, bone health is yet another reason to consider it. There are many different styles, programs, and possibilities for getting started. A basic program performed 2 times a week is a good place to start.

 

Aerobic Exercise


Aerobic activity is movement that is continuous and rhythmic in nature. Try to use weightbearing exercises as much as is appropriate for your body. Walking is weight bearing with low (but repetitive) impact forces with each step. Exercise modalities such as swimming and biking are not considered weight bearing even though they are an excellent form of exercise for other health benefits.

 

Posture and Balance Training

 

Although posture and balance training may not directly influence bone health, they are an integral part of preventing fractures for those with osteoporosis. Postural training may help you maintain the strength in the muscles in your upper back to maintain your spinal health and flexibility. Balance training will help with the prevention of the falls that lead to fractures.

 

So, what’s the take home message here? What exercise should I do to keep my bones as healthy as possible?

 

First, be aware that any physical activity/movement is a step in the right direction. So, if you are exercising – keep it up. Think about how much weight bearing, low-moderate impact, repetitive exercise/movement (like walking) you’re getting. Try to get 20-40 minutes of this type of exercise on most days.

 

If you are not currently exercising, consider getting started. Can you start a walking program? Have you done any strength training? Not sure how to get started? We can help!

 

Good luck with your fitness endeavors and let’s keep those skeletons strong!

 

Contact the Fitness Center

 

Looking for some tips on how to get started? Contact the Fitness Center:

 

(608) 263-7936

fitnesscenter@uwhealth.org