I have been thinking of skeletons lately, especially since Halloween was just yesterday. Our skeleton is made up of about 206 bones. Some individuals may have a varying number of ribs, vertebrae, and digits, so they technically could have more bones. When we think of our skeleton, we usually think of it as a static structure, something that just gives us structural support, but bone is so much more than that!
Bone has some very important functions in the body, such as locomotion – it gets us from one place to another, it helps to protect our organs and soft tissues, it stores calcium and phosphate that we can release into the bloodstream when needed, it manufactures bone marrow stem cells and other substances, which in turn produce red and white blood cells as well as our platelets, it even helps us to breathe! All in all, our skeleton does some pretty amazing work for us.
What I find so fascinating about bone is that is a dynamic hard tissue that undergoes a continuous remodeling process…meaning it is constantly undergoing a breakdown and buildup of tissue. This process is necessary in order to maintain skeletal strength and integrity.
The problem becomes when our bones do not produce as much bone matrix as it breaks down. This negative bone balance is what leads to osteopenia and osteoporosis. So, if the goal is to build more bone than we are breaking down, what needs to happen? Well – we need the optimal environment to support greater bone deposition. This includes proper nutrition, a balanced hormonal environment, and exercise.
Proper nutrition includes getting in the US RDA for the following vitamins and minerals:
· Calcium: If you do not get enough calcium through food or supplements, your body will take the calcium it needs from your bones.
· Vitamin D: Necessary for calcium to be absorbed in the intestine.
· Magnesium: Low magnesium can increase the activity of bone break down and decrease the activity of bone building.
· Phosphorous: Part of the bone mineral matrix and important for neutralizing acidic foods that could otherwise be harmful to bone.
· Potassium: Certain potassium salts neutralize acids that come from the body’s metabolic processes.
· Vitamin A: Influences bone-building cells and bone breaking down cells. Too high or too low and our risk of fractures increases
The growth of the skeleton, its response to mechanical forces, and its role as a mineral storehouse are all dependent on the proper functioning of a number of systemic or circulating hormones. We can put these hormones into three categories: calcium regulating hormones; sex hormones and other systemic hormones.
Calcium regulating hormones do exactly what they say…they regulate calcium in the body. For example, parathyroid hormones will move calcium from the bloodstream to the bone and vice versa depending on the amount of calcium circulating in the body. Calcitriol will stimulate the intestines to absorb enough calcium and phosphorus which then supplies it to the skeleton. Our sex hormones (estrogen and testosterone) regulate the growth of the skeleton and are responsible for maintaining the mass and the strength of bones. Other systemic hormones that may affect bone growth include thyroid hormone and cortisol. Too much of either of these hormones can either cause too much bone break down or block bone growth. A simple blood test can help determine if your body is in balance. If you are experiencing hormonal imbalance you can work with your physician to improve the hormonal environment.
So, what do we need to know about exercise to maximize our bone building capabilities? In order to build bone through activity, we need to focus on four key concepts; strain magnitude, strain rate, strain distribution, and strain cycle. This may sound a little overwhelming but let’s put it in the simplest terms we can… the exercise you should perform to build bone density include those activities that elicit a significant amount of intensity to the muscles. You need to do more than your normal daily activities in order for bone to be stimulated to produce more bone. How can this be accomplished? The following activities are great for stimulating bone production:
· Weight lifting: Lift weights that are heavy enough so that you can only lift it for 6-10 repetitions. You should not be able to complete 11 reps…if you can then increase your weight.
· Hopping, jumping, skipping: These types of activities help to stimulate bone formation using just your body weight.
· Aerobic or cardiovascular exercise: The key point with these types of activity is that they must be weight bearing. Activities that are non-weight bearing such as swimming or cycling do not produce enough ground reaction forces (the force exerted by the ground on a body in contact with it), which is critical for bone development.
What about walking for bone health? Unfortunately, if you are an active individual, walking will not produce enough intensity to stimulate bone growth. This is not to say walking is not a great exercise because it is a wonderful low impact activity that provides many benefits for your heart, weight management, and disease prevention such as diabetes and certain cancers, we just can’t rely on it for bone health.
Check out our exercise videos for bone health on the website!