Paraplegic subjects unable to walk have a 40% decrease in BMD within the pelvis and 25% in the lower limbs after a year of detention. Patients undergoing spaceflight or the absence of gravity have a 0.5% loss of bone calcium per month. It is unclear if this negative balance of bone is the result mainly due to increased absorption or a decrease in training. It has been shown that passive mechanical stress on bone of a paraplegic may decrease bone loss.
On the other hand, several studies have shown that athletes have between 25 and 30% more BMD than a commonplace subject with normal activity, including overhead activities including walking have a greater impact on bone than those who are swimming or cycling. Postmenopausal adult women subjected to work overload after 9 months the lumbar spine increased by 1.6% while the control women have decreased by 3.6% from baseline. In children under stress and impact activities have increased both in femoral neck BMD as radio, trochanter and lumbar spine.
In a longitudinal study in which 22 young cyclists were subjected to 10 hours per week of exercise bike for 2 years, BMD was lower than control subjects. All this helps to understand that only the high-resistance exercise and short-term impact stimulates BMD and that this effect is local and not systemic thing that becomes clear when we see that the cortical area of the humerus of the active arm of a tennis player holds up to 20% more bone than the contralateral arm
Only women who walked over 10 miles per week were so slight but significant higher BMD than those who walked only 1.5 km per week. Moreover postmenopausal women after 6 months of a program that included jumps, there was an increase of 4% in BMD. Finally do 10 minutes of work load is more productive than 30 minutes without charge for bone mass, this has been clearly demonstrated also in animals.
Tags: bone, bone mass, impact on bone, TYPE OF EXERCISE
