UPFRONT | Roundup RESEARCH Shoulder pain linked to Space travel is backbreaking increased risk of heart disease work: study A new study led by investigators at the University of Utah School of Medicine finds that individuals with symptoms that put them at increased risk for heart disease could be more likely to have shoul-der problems, including joint pain and rotator cuff injury. “If someone has rotator cuff problems, it could be a sign that there is something else going on. They may need to manage risk factors for heart disease,” said the study’s lead author Dr. Kurt Hegmann, professor of family and preventive medicine and director of the Rocky Mountain Center for Occupational and Environmental Health. The research was pub-lished in the J o u r n a l o f Occupational and Environmental Medicine. Repeated physical stress is most frequently blamed for ag-gravating shoulder joints and the muscles and tendons that sur-round them. Think about a pitcher who throws a baseball 100 times a day. While physical exertion can certainly be an irritant, accumu-lating evidence points to other factors that could also be at play. Previous research found that peo-ple who had an increased risk for heart disease also had a tendency toward carpal tunnel syndrome, Achilles tendinitis, and tennis el-bow – all musculoskeletal disor-ders. The current study by Hegmann and colleagues adds shoulder problems to the list and takes the connection one step further. The more heart disease risk factors that each of the study participants had racked up – including high blood pressure, high cholesterol, diabetes – the more likely they were to have had shoulder trou-ble. Thirty-six participants with the most severe collection of risk factors were 4.6 times more www.canadianchiropractor.ca RESEARCH likely than those with none of the risk factors to have had shoulder joint pain. They were also nearly six times more likely to have had a second shoulder condition, ro-ta t or cuff t endinopa th y. Participants with mid-level heart risk were less likely to have had either shoulder condition, at 1.5 to 3-fold. Shared trends bolster that there could be a relationship between heart risk and shoulder problems, but researchers will need to follow up with a prospec-tive study to prove cause and ef-fect. It may seem like physical strain would be at least just as likely to cause shoulder pain but data from the 1,226 skilled labourers who took part in the study suggest otherwise. Ergonomists carefully monitored airbag manufacturers, meat processors, cabinetmakers and skilled laborers. Every forceful twist, push and pull was factored into a strain index assigned to each worker. But a more straining job did not translate to an uptick in shoulder difficulties. Nor did more time spent doing other physical activities. “What we think we are seeing is that high force can accelerate ro-tator cuff issues but is not the pri-mary driver,” Hegmann said. “Cardiovascular disease risk fac-tors could be more important than job factors for incurring these types of problems.” He said it’s possible that con-trolling blood pressure and other heart risk factors could alleviate shoulder discomfort, too. The research was supported by the National Institute on Occupational Safety and Health and published as, “Association Between Cardiovascular Disease Risk Factors and Rotator Cuff Tendinopathy”. – Newswise Astronauts on long mis-sions in space have atrophy of the muscles supporting the spine – which don’t re-turn to normal even several weeks after their return to Earth, reports a study pub-lished in Spine. The results provide new insights into the elevated rates of back pain and spinal disc disease associated with prolonged spaceflight, report Dr. Douglas Chang of Uni-versity of California, San Diego, and colleagues. The data were obtained as part of a NASA-funded research study, led by Drs. Alan Har-gens and Jeffrey Lotz. Six NASA crewmembers were studied before and after spending four to seven months in “microgravity” conditions on the Interna-tional Space Station. Each astronaut underwent MRI scans of the spine before their mission, immediately after their return to Earth, and again one to two months later. The goal was to under-stand factors affecting lum-bar spine strength and low back pain during long-dura-tion spaceflight, as well as the spine’s response after returning to Earth gravity. Back pain is common during prolonged missions, with more than half of crew mem-bers reporting spinal pain. Astronauts are also at in-creased risk of spinal disc herniation in the months after returning from space-flight – about four times higher than in matched controls. These changes are accom-panied by an increase in body height (about two inches), thought to result from spinal “unloading” and other changes related to the lack of gravity. The research-er s u sed an im ag e “thresh-holding” technique to estimate lean muscle sep-arated from non-lean muscle components. The MRI scans indicated significant atrophy of the paraspinal lean muscle mass – which plays a critical role in spinal support and move-ment – during the astro-nauts’ time in space. The lean muscle, or “functional,” cross-sectional area of the lumbar paraspinal muscles decreased by an average of 19 per cent from preflight to immediate postflight scans. A month or two later, only about two-thirds of the re-duction had recovered. There was an even more dramatic reduction in the functional cross-sectional area of the paraspinal mus-cles relative to total par-aspinal cross-sectional area. The ratio of lean muscle decreased from 86 per cent preflight to 72 per cent immediately postflight. At follow-up, the ratio recov-ered to 81 per cent, but was still less than the preflight value. In contrast, there was no consistent change in the height of the spinal interver-tebral discs. Further studies will be needed to clarify the effects on disc height, and whether they contribute to the in-crease in body height during space missions, and to the increased risk of herniated disc disease. – Newswise February 2017 Canadian Chiropractor 11
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