Originally Posted by
awsimons
erig, the point is not how much effort you put out. The problem, people theorize, is that your body is not supporting its own weight. Unless you have that 200 lbs of groceries on your back and you are out of the saddle the entire time, it is not helping you.
Astronauts lose bone mass in space because there is never any pressure on their bones, so basically, the bones atrophy.
I don't quite understand the way weight bearing on a bike differs from standing. Cyclists absolutely put huge forces on their legs, but the force on a cyclists hips is much less than say a runner..... I don't understand the mechanism, but bone loss in professional cyclists is very real.
People also theorize that it has to do with exercising with a calorie deficit. Professionals clearly can't feed their bodies enough calories to make up for what they expend during a long race. The body could be pulling nutrients from other parts of the body to make up for that. Hence bone loss.
I was hoping to find some people who have really looked into this issue and dealt with it. Speculation really doesn't help anything. But, my question was 'do people worry about bone loss' and it seems the answer so far is "No."
what i can see is that
force travels from feet to hips via legs' bones but on a bicycle because the angle hips-femur is not the same as when someone run or walk hips tend to handle flexion rather than pressure.
The other thing is that when someone walk or run, their is an impact on the hips from the feet on the ground which tends to reinforce bone structure. On a bicycle, on the other hand there isn't much impact
What i can see as well is that on a bicycle the pressure of the pedal is on the fore foot and because the foot acts as a spring some energy is dissipated
when you walk or run the pressure/impact is on the back of the foot or the side depending on if you tend to pronate, suppinate or have a more neutral footstep.
Another thing i see is that on a bike with spd type pedal at some time the pressure become negative when the cyclist move up his/her foot