How Weight Training Builds Stronger Bones And Prevents Osteoporosis

 

Osteoporosis is an ever increasing problem worldwide as people are living longer and the population continues to age. More prevalent among women than men, some estimates report than as many as one in five American women over the age of 50 have osteoporosis. An insidious disease that weakens bone tissue, one of the worst aspects of osteoporosis is that there are no symptoms during the early stages and without a bone mineral density test it can be difficult to detect before it advances to a point where it becomes painfully symptomatic. Most learn of their condition after experiencing a bone fracture as about half of all women over the age of 50 will suffer a fracture of the wrist, hip or spine as a direct result of bone loss. Osteoporosis can be caused by many different factors which are usually lifestyle or hormone related. Excessive alcohol consumption, smoking, poor diet and inactivity are some of the known risk factors as are other circumstances which are not as controllable such as family history or hormone treatments. While there are effective treatments available for osteoporosis today the best defense is to prevent it altogether. Exercise, specifically weight bearing exercise has been shown to be an effective preventative measure against osteoporosis. In an earlier post How Muscles Get Bigger And Stronger we explored how muscles respond to weight training and in this article we will take a look how bones benefit as from resistance exercise.

 

The word osteoporosis means porous bones and one can easily understand that a bone thats porous would be weak and vulnerable to fractures. Bones weaken as a result of a process called demineralization. Demineralization occurs when our bones lose important minerals such as calcium. If left untreated our bones will no longer have the structural capacity to support the weight of our body and the forces we create when we are physically active- thus resulting in a fracture. Since we can see them all the time most of us are very much aware of our muscles, but we don’t think much of how our bones work in conjunction with them. When you flex your muscles as in a biceps curl for example, the muscles of your biceps generate force that allows you to lift the weight. This force is transferred throughout the muscle and to the tendons at both ends. The tendons are connected to the bones of your arm and cross over your elbow joint. Joints act as levers- which are rigid objects used with a pivot point to increase the amount of mechanical force our body generates to allow us to lift an object. Activation of the biceps muscles in our upper arm causes rotation of the forearm at the elbow (pivot point) which allows us to lift the weight during a curling exercise. Now according to Newton’s third law of motion, for every action there is an equal and opposite reaction. That being said since bones provide the framework for our muscles every muscular contraction will produce forces that act directly on the bones in our body.

Since bones provide the frame for our body tissue our skeleton is always under some degree of stress. As you read this blog post the force of gravity is bearing down on your bones even though you cant really feel it. Too much stress can lead to bone damage at a microscopic level- in pretty much the same way it does in your muscles and like our muscles when bones are damaged they need to be be repaired. According to Wolff’s law, the bones in a healthy person or animal will adapt to the loads they are placed under so if the forces acting on a bone increases, the bone will remodel itself over time to become stronger and denser to be able to cope with the load that it has to bear. In essence it’s a stress response in keeping with the laws of general adaption. From a physiological point of view, stress isnt always a bad thing as we perceive it in our everyday lives. Quite simply stress is the reaction of our body to stimulation or forces that puts it out of balance- ( a balance that we refer to as homeostasis.) If the forces are too great or too sudden – like the forces acting on your bones during a car accident or a fall from a great height- your bones can’t adapt fast enough or deal with the sudden overload and a fracture will occur. Also if a force is continuously applied through repetitive strain and your bones don’t have enough time to rest and recuperate it can also result in a fracture- in this case a stress fracture. This is what happens to many runners and aerobics aficionados after years of doing the same activity over and over again. On the other side of the spectrum, if there is a reduction in the forces on your bones, be it from being bed ridden or from living a predominantly sedentary lifestyle, your bones will remodel themselves to be weaker and less dense as a result. Just like your muscles if you dont use it- you lose it.

 

 

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How Muscles Get Bigger & Stronger

 

 

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June 20, 2011 • Posted in: Diet News

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