Navigation Links
High doses of 'load' slows loss of bone in spinal cord injury
Date:2/16/2012

Loss of bone density leads to brittle bones that fracture easily. It is a major complication of spinal cord injury (SCI), which affects about 250,000 Americans every year.

A new clinical trial conducted by University of Iowa researchers shows that delivering high doses of "load," or stress, to bone through programmed electrical stimulation of the muscle significantly slows the loss of bone density in patients with SCI.

The focus on quantifying the effective dose of load is one of the study's most important aspects, says Richard Shields, P.T., Ph.D., a professor and director of the UI Physical Therapy and Rehabilitation Science Graduate Programs. The study also is the first to carefully test the impact of different doses of load in humans with paralysis.

Previous research had suggested that stressing or loading bone through muscle contractions could slow the loss of bone density, but results from clinical trials have been mixed.

"Thirty years ago a clinical trial concluded that putting patients with SCI in an upright weight-bearing position with braces or standing frames did nothing to prevent loss of bone density," Shields says. "The novelty of our study is we have designed a method for individuals with paralysis to stand (bear weight) while superimposing a dose of muscle force using programmed electrical stimulation of the muscle."

The study findings, published in the journal Osteoporosis International in December 2011, reveal that only high "doses" of muscle force are effective for significantly reducing bone loss.

"The previous studies, without muscle activation, were like doing a drug trial where the dose of drug was too low, or below 'therapeutic threshold,' to cause an effect," Shields explains.

The UI researchers have also recently shown that the electrical stimulation strengthens muscle by activating genes that promote muscle growth and endurance, and improve glucose metabolism.

Testing doses of load

The clinical trial developed by Shields and his team is based on biomechanical modeling and information from bone biology studies that show that bone cells, called osteoblasts, produce new bone only when the load is high enough.

The study compared the effect of "high dose" loads of 150 percent of body weight (induced by electrically stimulating the quadriceps muscle in one leg while the patient was supported in a standing position) with "low dose" load of 40 percent body weight (assisted standing with no electrical stimulation) and "no dose" loads of 0 percent body weight (sitting). Participants were asked to perform their training five times per week for three years and had their bone mineral density and muscle strength tested several times over the study period.

"When we applied a load of 1.5 times their body weight using electrical stimulation of the quadriceps muscle we saw a significant impact on the bone density as well as the expected growth of the skeletal muscle," says Shields.

Specifically, the study found that after three years, average bone density in the femur was almost 40 percent lower in patients who received low dose or no dose load compared to patients who received high dose. The study also showed that high dose load slows the deterioration of the trabecular bone -- the type of bone found at the joint ends of long bones where fractures most often occur.

"Keeping 40 percent of the bone material in the bone should translate into improved overall health along several dimensions, including reducing the risk of fracture, as well as reducing other common complications stemming from SCI, like kidney stones and diabetes," says Shields.

A unique feature of the study was that patients in the high dose group only received muscle stimulation on one leg. This meant that the patients' non-treated leg provided a "within subject" control that clearly contrasted the effect of high dose compared to low dose when all other factors were the same.

Usability key for translating study findings to therapy

Shields notes that for any treatment regimen to be truly useful for patients, it must be something that a patient can easily incorporate in his or her daily life. The study suggested that participants found it fairly easy to stick with the training program. In addition, six of the seven participants on the high-dose protocol were able to participate from home using a specially modified wheelchair that raised them to a standing position and custom-designed stimulators that automatically logged the participant's training.

"It is much harder to make brittle bones strong again. So in a situation where we know that loss of bone density will occur, like SCI, we need an intervention that prevents or at least slows down the loss of bone density," Shields says. "This study provides evidence that there is a mechanical dose of load through muscle force that the skeleton can respond to that has an effect."


'/>"/>
Contact: Jennifer Brown
jennifer-l-brown@uiowa.edu
319-356-7124
University of Iowa Health Care
Source:Eurekalert  

Related medicine news :

1. ASTRO publishes supplement on protecting cancer patients by reducing radiation doses, side effects
2. Children with food allergies should carry 2 doses of emergency medicine
3. Botox reduces wrinkles even in less frequent doses
4. High doses of antioxidant supplements induce stem cell genetic abnormalities
5. Organic Clothing – Is Your Clothing Delivering Death in Small Doses?
6. Cumulative Radiation Doses Seen in Cardiac Imaging
7. High doses of ursodeoxycholic acid ineffective for NASH patients
8. Higher Statin Doses Linked to Fewer Heart Attacks, Stroke
9. Yale researchers find double doses of chicken pox vaccine most effective
10. Study confirms 2 vaccine doses protect children from chickenpox
11. Preparing Small Doses of Medication From Syringes Called Risky
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
High doses of 'load' slows loss of bone in spinal cord injury
(Date:3/28/2017)... ... March 28, 2017 , ... Alert Sentry Group LLC., a leader in the ... Systems), the iSAFE and the iSAFE Plus. These iSAFE products are the most affordable ... the iSAFE and iSAFE Plus offer direct GPS Location and two-way calling with the ...
(Date:3/28/2017)... Switzerland (PRWEB) , ... March 28, 2017 , ... ... for laboratory instruments are critical to ensuring high-quality results and maintaining GMP and ... Qualification of Laboratory Instruments in accordance with GMP requirements " these requirements are ...
(Date:3/28/2017)... (PRWEB) , ... March 28, 2017 , ... ... direct measurement of corrosive ions found in power plant water and steam. , ... such as turbines and boilers, leading to extensive maintenance and unplanned shutdowns. Monitoring ...
(Date:3/28/2017)... Los Angeles, CA (PRWEB) , ... March 28, ... ... Pediatrics credential, which will be offered by the American Association of Integrative Medicine ... Saturday presentations for healthcare providers at the AutismOne 2017 Conference in Colorado Springs. ...
(Date:3/28/2017)... Francisco, CA (PRWEB) , ... March 28, 2017 , ... ... treatment, is proud to announce a new blog post about women’s hair loss. Although ... suffer from hair loss as they age. Menopause or genetics can be two reasons ...
Breaking Medicine News(10 mins):
(Date:3/28/2017)... TORONTO , March 28, 2017 /PRNewswire/ - StarFish ... medical device development firm, announced today that it has ... -based medical device industrial design and productization organization.  ... throughout North America with easier ... talent spanning the design, engineering, regulatory, and manufacturing process. ...
(Date:3/28/2017)... Mass. , March 28, 2017  Akcea Therapeutics, a ... additions to the company,s board of directors: ... Venture Partners. Mr. Gabrieli will serve as chairman of the ... , former chief commercial officer of Forest Laboratories. ... Global Biolink Partners. "We are excited ...
(Date:3/28/2017)... , March 28, 2017 ... to reach USD 8.0 billion by 2025, according to ... increasing incidence of infectious diseases and cancer is expected ... in disease diagnosis over the coming years. In addition, ... of autologous and allogenic stem cell therapy, due to ...
Breaking Medicine Technology: