The Importanct of Evidence-Based Practice: The Example of Exercise for Osteoporosis
Osteoporosis and osteopenia are common issues that affect the life expectancy and quality of life in nearly 40 million Americans. These conditions, which both indicate a decrease in bone mineral density, which we can consider as bone strength, occur in men and women of all ages but are most predominate in post-menopausal women. People affected with osteoporosis or osteopenia have reduced strength and resiliency in their bones leading to an increased likelihood of fractures. Fractures are linked to significantly increased all-cause mortality in older women as well as impaired mobility and quality of life so it is imperative that bone health be maintained.
One of the best ways to accomplish this is through exercise. With every muscle action and every contact with the ground, bones have some force exerted against them and they respond by becoming stronger. Increasing the amount of activity and exercise is therefore a viable way to increase bone strength. But what type of exercise will work best? A review of randomized, controlled trials evaluated various types of exercise to see which would have the greatest impact. The results varied based upon the body part. We will discuss the impact on two common sites of osteoporosis: the spine and neck of the femur. In the spine, bone mineral density responded positively to two types of exercise: Weight-bearing low force activity such as walking or Tai Chi and non-weight-bearing-high-force exercises. In the neck of the femur, a positive effect was observed in response to non-weight-bearing high force exercises. Non-weight-bearing high force exercises include exercise machines (such as the leg extension, leg press, hip abductor, hip adductor and hamstring curl) performed with almost as much weight as possible.
Look at that list of non-weight-bearing high force exercises again. If you have read my other posts or talked with me before, it is obvious that I am not a fan of those machines. In fact, some of them are on my list of top things to avoid at the gym. The motor patterns reinforced by these machines seem unproductive to me and they develop strength in very limited, non-functional actions. Worst of all, these machines allow you to develop more strength than your body can handle, which can lead to terrible movement habits and possibly injury.
In my mind, well coached and well-performed squats, deadlifts, hip hinges and farmers walks would be way more helpful for developing bone density. But, the evidence is right there, pointing at me, saying that these much-maligned-machines may have some usefulness after all. Perhaps the machines were only helpful for the subjects tested because they didn’t have good coaching. Perhaps the researchers simply found it easier to compare exercise machines. Perhaps I am a good enough coach that I can overcome these obstacles and increase my clients bone density without using the machines. So, I find myself in a quandary: Follow the evidence and use the machines or trust my own education, intuition and instinct. The question is best answered with humility. I honestly don’t know if better results can be obtained without using the machines. It seems likely to me but at the end of the day, there is not evidence to directly support it. So, I would like to take a moment to apologize to all machine advocates out there and also endorse the use of these machines for increasing bone mineral density in the spine and neck of femur.
If you have osteoporosis, osteopenia or are at risk, this discussion was likely very useful for you. But if you don’t, it still offers a valuable lesson. No expert can know everything. Even strictly within the field of exercise, there are countless complicated decisions that cannot be answered through logical reasoning and intuition. When it comes to your health and fitness, you deserve to know that you are making the best decision. Always ask your trainers, instructors and health care providers why they are doing what they are doing. Ask about the evidence they have supporting them. There are a lot of things that don’t have clear evidence-based answers but it never hurts to ask. It will make you a better client and make us better trainers.