that cause a rippling motion on the skin's surface.
"This is the same thing that happens during an earthquake, but on a microscopic scale and at a higher frequency," Akkus said. "Instead of an earthquake-size opening, these cracks are about a tenth of a millimeter wide."
Accumulating cracks sometimes cause "spontaneous fractures" that occur without warning, afflicting the young and old alike, including athletes and elderly people suffering from osteoporosis.
A major factor in the crack formation is the dynamic process bones use to continually rebuild themselves. When bone is damaged, specialized cells bore tunnel-like holes to remove the damaged tissue and then fill in the resulting cavity with new bone.
"Bone is a very smart material because it can detect and repair damage," Akkus said. "That's what keeps your bones young. The repair process digs tunnels and fills them, digs tunnels and fills them. There is a continuous renewal, but it takes longer to refill the holes than it does to dig them, so there is always some porosity, which increases the stress locally in the most porous portions of bone."
Hard physical activity without rest increases the stress in these porous areas that are under repair.
"The localized stress in the porous portions then becomes very high, and this can result in a complete stress fracture," Akkus said.
One reason it's difficult to diagnose the hairline fractures is because they are caused by the gradual accumulation of microscopic cracks, which are not detectable with conventional imaging technologies.
"It's really hard to measure stresses in bone without cutting open the bone to study it," Akkus said. "And there is very little warning because you don't have horrible pain. You might have some discomfort, but you can keep exercising or whatever activity you are doing."
From 1 percent to 20 percent of U.S. basic training recruits expPage: 1 2 3 4 Related medicine news :1
. Early Warning System For Breast Cancer2
. Gene connected to Multi-System disorder discovered3
. Reviving the Immune System4
. Painkilling Patch As Effective As Intravenous Delivery Systems 5
. Wrestling found To Be Good for the Immune System6
. Computer System To Predict Deep Vein Thrombosis
. Gene-Nanoparticle Gene Transfer Is Better Than Viral Vector Transfer System8
. Nutrient Profiling System Launched By Food Officials in UK9
. Block Immune System Chemical For Treating Asthma10
. Smoking Hazardous To The Enzymes System In Lungs11
. HIIP- A Novel Inhaled Insulin Delivery System As An Alternative To Injectable Insulin Therapy