Backpack straps can decrease blood flow in the shoulder and arm

More than 92 percent of the children in the U.S. carry backpacks. Typically the backpacks are loaded with almost one-fourth of the child’s body weight (22 percent) and worn with only one strap. Last year, a team of physician researchers examined the effect heavy-loaded backpack straps can have on children. They found the straps can significantly increase pressure when the load is ten percent or more. They also found that strap pressures with loads as small as ten percent of bodyweight can obstruct localized blood flow and contribute to shoulder fatigue.

This year the team has examined pack straps and adults. In some professions, such as the military, firefighting and mountain rescue, the packs may equal as much as 60 percent of adult body weight. The findings of the most recent study indicate that even light loads of 26 pounds can decrease upper extremity blood flow, and may result in a loss of fine motor control and increased fatigue.

The studies were conducted by Timothy Neuschwander, Brandon Macias and Alan Hargens, all of the Department of Orthopaedic Surgery, University of California–San Diego. Dr. Neuschwander will present the team’s findings, Backpack Straps Decrease Upper Extremity Blood Flow, at the 121st Annual Meeting of the American Physiological Society, part of the Experimental Biology 2008 scientific conference.

Backpack straps typically rest on an area of the body where they may compress the axillary vein which causes abnormally high blood pressure inside the veins and a subsequent decrease of blood flow in the shoulders and arms. The researchers speculated that blood flow of the large and small vessels of the upper extremity area would decrease in an individual while wearing a backpack.

To test their theory, they examined eight healthy volunteers, six men and two women between the ages of 18-30. The right brachial artery was measured using ultrasound and the index finger pulp microvascular flow was measured using the photoplethysmography method. Baseline flows were measured immediately before and ten minutes after donning a 26 pound backpack. A ten minute testing period was chosen because people typically wear a backpack for at least ten minutes. This amount of time is also sufficient to measure flood flow.

After wearing the pack for ten minutes, brachial artery blood flow decreased from 2.66± 0.36 to 1.52± 0.27 mL/s (p<0.05, paired T-test), and index finger microvascular flow decreased from 100 percent to 46±6 percent (p<0.05, paired test).

The researchers concluded that backpack loads of just 26 pounds decrease upper extremity macrovascular and microvascular blood flows, and may result in a loss of fine motor control and increased fatigue. According to Timothy Neuschwander, MD, the first author of the study and a physician, “We surmise that the mechanism of diminished blood flow is likely due to strap compression of the axillary vein. We think that backpack straps may benefit from a redesign that skirts the vein leading from the upper extremity to the heart.”

Source: American Physiological Society

Related stories:

At risk for peripheral arterial disease? Simple quiz provides key so you can circulate better
Ten million Americans have peripheral arterial disease (PAD), and research shows that the highest risk populations include African-Americans (twice as likely to develop clogged leg arteries), seniors (12-20 percent develop PAD) and diabetics (one in three who are over the age of 50 develop PAD). Legs for Life®—a community health and public information program—recommends that older Americans take its free, online self-assessment quiz.
Back to School Reminder: Kids Should Go for Safety, Not Style
(PhysOrg.com) -- School children across the world may speak different languages but there is one experience an estimated 90 percent of all students share: wearing a backpack. Researchers from the University of San Diego, California School of Medicine say those students also share a common problem: low back pain due to overloaded backpacks.
Daily walk can help control diabetes
(PhysOrg.com) -- Just an extra 45 minute walk a day can help people control Type 2 diabetes, according to a new study at Newcastle University. Dr Michael Trenell and Prof Roy Taylor, who led the research, showed that people with Type 2 diabetes who walk regularly can keep some of the effects of the disease at bay.
Sight Recovery After Blindness Offers New Insights on Brain Reorganization
Studies of the brains of blind persons whose sight was partially restored later in life have produced a compelling example of the brain's ability to adapt to new circumstances and rewire and reconfigure itself.
Catheter repair of mitral valve improves heart size, symptoms
A catheter-mounted device that acts like a clothespin to clip together the flaps of a leaky heart valve is not only reducing the abnormal backflow of blood from the left ventricle to the left atrium, it is helping to shrink the enlarged, overworked heart and relieving symptoms of fluid overload—all without open-chest surgery. These are the one-year findings in a small group of patients enrolled in the Endovascular Valve Edge-to-Edge Repair Study (EVEREST), which is evaluating the use of the MitraClip for the treatment of mitral regurgitation (MR).
Novel small molecule therapy shows benefit for anemic patients via hydration of red blood cells
Researchers are identifying innovative therapeutics for sickle cell anemia that focus on specific factors in the disease's progression, such as the important role of hydration of the red blood cells. According to a study prepublished online in Blood, the official journal of the American Society of Hematology, a novel small molecule therapy called senicapoc showed efficacy in maintaining hydration of red blood cells and increasing hemoglobin levels in patients with sickle cell anemia. Sickle cell anemia affects about 70,000 Americans, and millions worldwide.
Mapping the selective brain
Researchers have added a new piece to the puzzle of how the brain selectively amplifies those distinctions that matter most from the continuous cascade of sights, sounds, and other sensory input. Whether recognizing a glowering face among smiling ones or the unmistakable sound of a spouse calling one’s name, such “categorical perception” is central to sensory function.
Under magnetic force, nanoparticles may deliver gene therapy
After binding DNA segments to tiny iron-containing spheres called nanoparticles, researchers have used magnetic fields to direct the nanoparticles into arterial muscle cells, where the DNA could have a therapeutic effect. Although the research, done in cell cultures, is in early stages, it may represent a new method for delivering gene therapy to benefit blood vessels damaged by arterial disease.

News discussion:

Medicine & Health news