The problem in athletes is that “the calcium hormones” serve 2 purposes:
- regulating blood-calcium level
- maintaining bone health
In athletes, loading is increased and thus more micro-fractures have to be repaired; more damaged cells (due to the increased loading) have to be replaced by new ones. The damaged cells are decomposed and the calcium is deported by osteoclasts. To maintain bone health, these damaged cells have to be replaced by new ones. Thus osteoblasts have to compose more pre-calcified bone-matrix. This requires increased activity of osteoblasts, and thus osteoblast apoptosis is also increased in athletes.
So far so good.
But the hormones that regulate bone formation and resorption for bone-maintenance, also regulate blood-calcium level. If much calcium is consumed, more calcium has to be temporarily stored into the bones prior to excretion, to prevent elevation of blood-calcium level (excessive calcium in the blood blocks respiration for blocking muscle functioning)
This extra calcium can only be temporarily stored in the bones if it can precipitate on pre-calcified bone matrix, which is composed for this purpose by osteoblasts. Since it is calcium that is absorbed for the purpose of preventing elevation of blood-calcium level, this calcium will subsequently be deported to be excreted. Simply because the bones are designed according to a plan, which does not include holding on to redundant calcium.
In athletes, the loading on bones is so intense that maximum capacity of osteoblasts to compose new bone matrix is met. Just a small part of total bone cells is damaged every training session, but if the cells that have not been damaged that day have to compose new matrix anyway to absorb redundant calcium, osteoblasts will not be able to keep up with composing new matrix again when the cells are damaged due to loading the very next day.
Since regulating blood-calcium level has top-priority, repairing microfractures will not be complete.
You can compare it to an athlete that has to train every day but also has to do hard labour to make a living; such an athlete will never be able to increase muscle strength because he lacks time to recover.
If the bones (osteoblasts) of an athlete have to do both much recovery and have to process much calcium to prevent excessive calcium in the blood, osteoblasts productivity will be insufficient to do both.
Especially in athletes it is essential to prevent any unnecessary processing of calcium. Which means that the athletes should not absorb any more calcium than they need to maintain bone-health.
Thus it is also essential in athletes that they never consume large amounts of calcium in one meal (or supplement!); the more calcium consumption is spread through the day, the less redundant calcium needs to be temporarily absorbed in the bones.
In female athletes estrogen levels are decreased.
Unfortunately, estrogen maintains bone health by inhibiting uptake of calcium into the bones and deportation of calcium (also indirectly, through inhibiting PTH secretion) Thus the lower estrogen level, the more devastating the effect of excessive calcium intake will be. If estrogen levels are low, more calcium will be actually absorbed into the bones, increasing osteoblast activity and apoptosis.
If less calcium is consumed, the necessity of adequate estrogen levels is less strong.
|For the source of these documents visit: http://www.4.waisays.com/ by by Wai Genriiu|