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  • Writer's pictureGary Moller

Low bone mineral density and Stress Fractures in Endurance Athletes

There seem to be more stress fractures happening nowadays

My impression is that stress fractures among endurance athletes are more freequent because more people than ever are seeking our assistance with this injury. I am not alone in having this opinion.

Take a few minutes later to read some of the research here about the incidence of stress fractures in athletes.

Image: Fit Kiwi ably demonstrating the "Lift & Press", the best bone-building exercise there is

What are stress fractures?

A stress fracture is a crack in the bone, caused by repeated stress that exceeds the rate of repair and strengthening which is the normal response to repeated compression, bending and twisting pressures on the bone. Think of a stress fracture as being like what happens to a wire that progressively weakens (metal fatigue), then finally breaks in two, when it is repeatedly bent back and forth.

For a more detailed explanation, please read this article written for stress fracture patients. Its a good article but far too light on the nutrition side of things which is so important for making a quick and full recovery.

Back in the"good old days", stress fractures were seen mostly in athletes doing daily extreme exercise, such as running 100 miles, or more, in a week (100 miles a week was a training target, for a few weeks at a time, during a training phase, for many Lydiard Method trained runners during the 60's and 70's and few suffered stress fractures).

What is rather disturbing nowadays is the majority of stress fracture cases coming to our attention are being suffered by runners and triathletes who may be doing as little as 30 kilometers of running a week. Stress fractures are occasionally seen in swimmers and cyclists. You wouldn't think swimming and cycling can cause stress fractures, but they do, usually affecting the pelvis and lumbar spine.

By the way, the last swimming-related stress fracture I got to see was in a young male swimmer with a lumbar spine stress fracture. The solution was a coaching one and involved cleaning up his tumble turns.

This article tries to answer the question, "Why?" and outline the measures we can all take to ensure we have strong bones.

It is thought that some forms of exercise are no good for increasing bone strength

Moderate exercise, including running, cycling and swimming will help produce and maintain strong bones, perhaps as effectively as regular weight training. However, there is still the widespread view among many health and fitness experts that non weight-bearing exercises, such as swimming and cycling, do not promote bone strength. There is also the contradiction that stress fractures are more common in distance runners, mostly females. If running builds bone, then how come so many runners suffer stress fractures and often have bone scan results that show low bone mineral density? (I'll explain in this article why the answer is more complicated than just too much running).

It is not uncommon for distance runners, cyclists and other endurance athletes, to have low mineral density of bones like the heel, shin, hips, pelvis and spine and for this to have no obvious association between sporting type or nutrition. The only obvious common factor is endurance training and possibly under-eating. Its not that simple. I'll try to explain as best I can what I think is going on and offer solutions. What you will learn is that there is no single "fix", such as a wonder drug, nutrient or exercise, like abdominal exercises or futilely trying to "engage your glutes". The solution is getting a complex mix of factors in balance while eliminating others altogether, or as best as one can.

Image: Fit Kiwi once again demonstrating near perfect technique. Yes, Fit Kiwi can swim!

Why do many experts believe that swimming and cycling do not build strong bones?

The belief that cycling and swimming do not build bone and may actually cause low bone density is misplaced. This belief prevails due to a number of studies of elite cyclists and swimmers that found the paradox of low bone density in these athletes. At the time of these studies it seemed obvious, if you want to study the effects of cycling on bone density, then you might as well study professional cyclists, rather than recreational ones. To their great surprise, it was found that the professional cyclists had low bone density as compared to recreational cyclist and sedentary people.

The hypothesis, to explain this unexpected finding, was that bones need the stress of gravity bearing down upon them during exercise in order to stimulate bone strengthening. This view was supported by studies of bone density in astronauts. "Fair enough", you may think, but there was one major oversight with these studies.

Please go here to read more about the research into bone density and cycling.

The researchers failed to take account of the widespread legitimate and illegitimate use of steroids, including inhaled asthma medication.

Asthma medication is in widespread use among these athletes, whether they are truly asthmatic or not. These drugs are beneficial for performance and recovery, so many athletes wising to gain the competitive edge, or just trying to keep up with the competition who are abusing steroids, resort to steroids, either illegally, or by getting a questionable medical exemption for their use.

Much of the steroid use by these athletes may never be admitted to, even if the researchers thought to ask, and therefore this is one most important factor that was overlooked by osteoporosis researchers. Long term use of these drugs drains the body and bones of calcium which no amount of beneficial exercise can ever compensate for.

The researchers also failed to consider the consequences of prolonged stress and exhaustion as well as the finer details of diet (more about these later).

Asthma drugs, steroids and the epidemic of osteoporosis and arthritis

The widespread prescribing of steroids, particularly for asthma, is one explanation for why we have a growing epidemic of osteoporosis and arthritis in the general population some 20-30 years after these drugs came into widespread use. In my opinion most of this prescribing of steroids as being excessive and often irresponsible. The majority of asthma cases can be successfully remedied by non-drugs methods, including teaching a person how to breathe in a healthy way.

The tsunami wave of bone diseases that are hitting us today, along with companion diseases such as hypothyroidism, anxiety, depression, "brain fog", adrenal fatigue, gall bladder disease, bowell disease, cardiovascular disease (arteriosclerosis), most autoimmune diseases and chronic fatigue, coincides as the first generation of medicated asthmatics from the '70's and 80's hit middle age. All steroids, including Prednisone and the drugs group of antihistamines, have similar effects of draining the body of calcium. Similar patterns exist with other meds, such as those commonly prescribed for high blood pressure and depression. Please refer here for more about steroids, asthma and osteoporosis.

Chronic stress and bone loss

When a person is stressed, the adrenal glands respond by injecting a squirt of multiple stress hormones, including cortisol, into the circulation. This initiates the "Fight or Flight Response", or "General Adaptation Syndrome" model, as first described by Dr Hans Selye in the 1950's when he conducted experiments on laboratory animals. The dear Dr Selye tortured the animals daily by administering progressively stronger electric shocks, while monitoring their behavioural and physiological responses, all of which were ultimately negative to eventually being deadly!

Please take a few minutes to watch this short lesson that describes Dr Selye's general adaptation syndrome model

Endurance training for many hours, day after day, is frankly too stressful for any creature, including Humans, to handle, stimulating either chronic elevated levels of cortisol, or frequent periods of elevated cortisol followed by long periods of low cortisol, or chronically low levels (the latter two being known as the "Tired Athlete"). This condition is best referred as "adrenal fatigue" a term first described by Dr James Wilson. You can learn more about adrenal fatigue at this excellent website.

The two images below, show a laboratory test that confirms this person has "adrenal fatigue". The readings show normal cortisol levels in the morning. However, as the day progresses, the subject is unable to maintain anything near adequate cortisol levels and is consequently feeling dead tired by mid afternoon. This is the profile one typically sees in burned out athletes who suffer recurrent injuries, who seem to catch every illness, who heal slowly and poorly and who may present with thyroid and other hormone related issues. The lowest testosterone levels I have ever seen in males have been in exhausted triathlete and Iron Man athletes.

Adrenocortex Stress Profile

Cortisol Values

Please contact me if you want to have this cortisol test done on yourself

Cortisol (cortisone) is, of course, the original steroid, produced by the cortex of the adrenal glands, is how pharmaceutical versions, such as Prednisone and Fludrocortisone, get their names. Cortisol is necessary for the regulation of inflammation and aiding healing, but it is not healthy at all, if constantly elevated, or wildly fluctuating from high to low. As with any steroid hormone, when in excess, cortisone drains calcium and other minerals from the bones, hence the link between chronic stress and bone loss.