Author Topic: biking beats walking  (Read 3295 times)

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Offline johnsondasw

Re: biking beats walking
« Reply #1 on: September 26, 2010, 10:59:43 pm »
However, it's good to mix it up, as biking is not weight bearing enough to promote bone density. I also think it's good to vary exercises to avoid overuse injuries.  I enjoy long walks (of at least 5 miles, usually more).  In the past 3 days, on day 1 I got a 7.5 mile walk, day 2, 42 mile bike ride and day 3, 10 mile walk.  This was a little more intense than normal.  I just recently started this long walk stuff.  I find if I take days off from biking to walk or go rock climbing, I'm actually much stronger on the bike.
May the wind be at your back!

Offline whittierider

Re: biking beats walking
« Reply #2 on: September 27, 2010, 01:38:32 am »
Quote
as biking is not weight bearing enough to promote bone density.

Actually, that does not explain why pro cyclists are much more likely to have very low bone density that sedentary youngish people are.  I would argue that anyone who does frequent, out-of-the-saddle, hard efforts in the hills, or better yet, sprints, is basically doing weightlifting.  Professional riders can (and do) leg press over a thousand pounds in the weight room, but are still very susceptible to osteoporosis, because they lose so much calcium in their sweat and don't replace it.

According to this .pdf article, sweat has about 28mg/l of calcium, and the typical calcium intake is 500mg/day with a 30% absorption efficiency which means your body absorbs about 150mg/day.  I have sweated as much as 3 gallons in one very warm afternoon century, which would mean more than twice the typical daily absorption in calcium beyond the usual non-cycling need.  The simple solution is to supplement.

Calcium absorption will also be hampered by a deficiency of vitamin D.  I think however that most cyclists probably get enough vitamin D from being in the sun if they're not depleting it with prescription drugs or smoking.

The fact that long, hard rides also produce a lot of acid that the body tries to neutralize with calcium it takes from bones if necessary must also be considered.  I don't know however if that calcium eventually comes out in the sweat, or the urine (or maybe both).  In either case, I'm sure it further increases the supplementation need.
« Last Edit: September 27, 2010, 01:42:08 am by whittierider »

Offline johnsondasw

Re: biking beats walking
« Reply #3 on: September 27, 2010, 12:57:31 pm »
Quote
as biking is not weight bearing enough to promote bone density.



  I think however that most cyclists probably get enough vitamin D from being in the sun if they're not depleting it with prescription drugs or smoking.


This is true for us up here in the north (Washington State) for about 6 months of the year.  Some of us really need to supplement from about Oct 25 to April 15.  Where I live, we literally go a whole month without seeing clear sunlight at all.   
May the wind be at your back!

Offline DaveB

Re: biking beats walking
« Reply #4 on: September 28, 2010, 12:13:54 pm »
Calcium absorption will also be hampered by a deficiency of vitamin D.  I think however that most cyclists probably get enough vitamin D from being in the sun if they're not depleting it with prescription drugs or smoking.
A factor in Vitamin D deficiencies, even for those out in the sun a lot, is our current use of high-SPF sun blocks since we've been warned about the effects of UV radiation causing skin cancer.  Most people I know slather SPF 30 or above on every square inch of exposed skin every sunny day.   

The nice thing about Vitamin D supplements is that they are cheap.  A 400 count bottle of 2000 IU Vitamin D capsules is less than $10.

Offline whittierider

Re: biking beats walking
« Reply #5 on: September 28, 2010, 03:42:23 pm »
I wouldn't worry about the high-SPF sunblocks.  Even if their protection held up all day without gradually diminishing, a true SPF of 50 still lets enough through to sunburn sensitive-skinned people if you're out in the sun all day like you might be on tour.  It does break down though, and I don't re-apply unless I have an opportunity to cool off and stop sweating and wash off the crystals from the sweat and the road dirt that has stuck to the sunscreen (which I probably wouldn't get if I used fenders).  I usually just keep going instead.  Supplementing vitamin D would help though.

Offline DaveB

Re: biking beats walking
« Reply #6 on: September 29, 2010, 09:49:42 am »
Supplementing vitamin D would help though.
There is no downside to suplimenting Vitamin D.  It's cheap, it's not at all toxic unless you take grossly excessive amounts and it provides a necessary vitamin for the many days when we don't get outside at all or are bundled up in cold weather clothing.