More about cycling and bone strength

[Zen]

Dr. Gabe Mirkin's Fitness and Health E-Zine
November 1, 2009

No Evidence Cycling Weakens Bones

No data exists in the scientific literature showing that
any type of exercise weakens bones. Bone growth depends on the
forces exerted on them by gravity and contracting muscles. So any
activity or exercise that causes you to contract your muscles will
strengthen bones (Medicine & Science in Sports & Exercise,
November 2009).
Previous studies showed that world class cyclists had
reduced bone densities in their spines. However, bone density
tests do not measure bones strength. They measure how much bones
block X-rays that try to pass through them. The only way to measure
bone strength is to see how much force it takes to break a bone.
The most likely explanations for broken bones in cyclists
are high-impact crashes and/or lack of vitamin D. I recommend
that all cyclists get a blood test called Vitamin D3 in December or
January. If it is below 75 nmol/L, they are deficient in vitamin D
and at increased risk for breaking bones. To prevent fractures,
they should do winter training in the southern sunbelt or take at
least 800 IU of Vitamin D3 per day.
A recent review of 12 blinded, controlled scientific
studies showed that oral vitamin D reduced non-vertebral and hip
fractures in patients over 65 years of age (Evidence-Based Medicine,
October 2009). Blood levels of vitamin D below 75 nmol/L cause
parathyroid hormone levels to rise too high, which causes
osteoporosis. A main function of vitamin D is to increase calcium
absorption from the intestines into the bloodstream. When blood
levels of vitamin D fall below 75 nmol/L, levels of ionizable
calcium drop. This causes the parathyroid gland to produce large
amounts of its hormone. Higher than normal blood parathyroid
hormone levels take calcium out of bones to cause osteoporosis.

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[Biciclista]

thanks . I think the suggested dose of 800 units is a little low.

[OakLeaf]

So what he's saying isn't really related to cycling at all - he's saying that DEXA scans etc. are great for selling pharmaceuticals but irrelevant to risk of fracture.

Figures.

[spokewench]

Something about that articles bothers me? - Breaking bones is due to a Vitamin D Deficiency and Cyclists should get the test. Am I wrong or is vitamin D gained through exposure to sun, as well as other things? Don't cyclists get a lot of vitamin D exposure? I know I always have; even if I try to wear sunscreen (not always successful).

spoke

[SLash]

Something about that articles bothers me? - Breaking bones is due to a Vitamin D Deficiency and Cyclists should get the test. Am I wrong or is vitamin D gained through exposure to sun, as well as other things? Don't cyclists get a lot of vitamin D exposure? I know I always have; even if I try to wear sunscreen (not always successful).

spoke

Not necessarily, I am in the sun a lot, between swimming, riding and yard work, and I tested low for Vitamin D (32 ng/ml) a couple of months ago. I was shocked because of how much time I spend outside, but my doctor said that studies have shown the sun isn't an adequate source of Vitamin D for people over ages 35-40 (I'm 55). Prior to testing me he said if my level was normal he wanted me to take 1,000 IU a day, and if it was low 50,000IU in one pill, one time a week for 12 weeks, then retest, if it is normal he will put me on 1500 IU daily for life, if it is still low 50,000 IU for 12 more weeks. I trust my doctor, he's excellent, and he says low Vitamin D is one of the most mis-diagnosed and misunderstood health problems (because of the other health issues it causes)that people have that could be easily treated and isn't.

[xanesdoc]

+1 SLash. I live in Atlanta and spend at least 5 days a week outside playing tennis, golf or riding my bike. When my GYN wanted to check my Vitamin D level two years ago, I laughed and said mine will be sky high. Well I was shocked when it came back at 6! After taking 50,000 units of Vit. D weekly for 3 months, my level increased to 54. I currently take 50,000 every 2 weeks and my levels stay between 50-60. I now wonder if I need to get it into the 75 range. I will check with my MD.

[cylegoddess]

Calcium is laid on by stressing bones to the limit. Usually it takes strength training. That 2x per week,on graduated( and must be graduated or doesnt work after a while) course will do the trick. Cyclists most likely gain some from strain put on femurs, tibia, hips etc but very little for axial spine, arms, back etc. I do supplements, and calcium too but according to textbooks for fitness cert 3( as compiled by Aus Institute of Sport and USA Sports College( forget name, is very big)

8 to 10 times, 60 % of rep max( the most you can do in one rep), 2-6 reps, 2- 3 times a week.

Thats for regular health. Prevents oesteo, hip fracture, general aging nastys.

[Zen]

See Wolff's Law

[staceysue]

Since I got my road bike, I've noticed how much cycling feels like flying sometimes. Maybe all the high speeds have given our bodies the message they need to be lighter and more birdlike. Bird bones are light and strong. We're not getting weaker, just lighter!

[BleeckerSt_Girl]

I thought the issue was that bicycling didn't help prevent bone loss the way other sports and exercise can do (jogging, weight lifting, dancing, jump roping...).
Not that cycling 'caused' bone loss.
Um...certainly someone who sits on a couch all day would have more bone loss than someone who cycles regularly, right?

[Crankin]

I think there are some that think that the heavy sweat rate of elite cyclists can cause bone loss or add to it. Don't quote me... but mostly what you said is the truth.
My Vitamin D test came back "normal," but I don't know what the numbers were. I will wait until I go see the endocrinologist and see what she recommends. Definitely won't stop cycling because I have osteoporosis. Hoping I will be a candidate for Reclast, as per my earlier post. I am sort of waiting for a fight from this woman; I saw her a couple of years ago for a thyroid issue and she is not exactly a paragon of friendliness, although she knows her stuff. I guess these specialists are so used to seeing people who have such bad health habits, they don't know what to do with someone that actually knows something and is going to question stuff.

[BleeckerSt_Girl]

I guess these specialists are so used to seeing people who have such bad health habits, they don't know what to do with someone that actually knows something and is going to question stuff.

There are some people just don't like to have their expertise questioned by anyone, regardless of how much or how little they might know.
I had a smart young woman doctor who I liked a lot at first, but she began to lecture me like I was a stupid child or something, so I gave her the ol' Heave Ho. LOL

My new doctor happens to be a cyclist himself, so we share many of the same life philosophies. (I ran into him on bikes in Great Barrington, by the way Robin, and his office is ONE BLOCK from our house!...talk about good karma).
Sadly, we sometimes need to change doctors when they are not working out well for us.

[OakLeaf]

Sadly, we sometimes need to change doctors when they are not working out well for us.

And then you get a black mark on your record for "doctor shopping" and being a "difficult patient," and it becomes really difficult to establish a good relationship with a new doctor.

[Biciclista]

And then you get a black mark on your record for "doctor shopping" and being a "difficult patient," and it becomes really difficult to establish a good relationship with a new doctor.

seriously? where is that black mark???

[OakLeaf]

Oh, not a literal "black mark," but medical records are full of doctors' subjective impressions of patients' personalities and "compliance" (which means "not questioning" and "getting better promptly" as much as it does "following instructions"). Now, sometimes they're spot-on, but often there are underlying issues (medical or psychosocial) that the doctors don't spend enough time to be able to identify/diagnose; and very often, if a doctor can't find a diagnosis to explain a patient's symptoms, or if a diagnosed condition is refractory to treatment, the doctor will implicitly or explicitly blame the patient.

Obviously, doctors who do this are disproportionately represented when patients fire their doctors.

But then, when the patient goes to a new doctor, if the medical records get transferred (which they should, so the new doctor has a complete history and doesn't have to repeat tests, etc.), the new doctor is "infected" by the first doctor's opinion of the patient.

I used to represent disability claimants, so reading sick people's medical records is what I did all day long. It was an education in more ways than one.