Dorothy Sears, PhD, and Dennis Perpetual, LVN, at the ACTRI clinic, where Sears conducted her sitting study.
March 22, 2018 | Patti Wieser
Get up! Prolonged sitting has been tied to cardiovascular disease and diabetes, but interrupting sitting with brief standing breaks could have health benefits. And the type of interruption may make a difference, especially for your heart.
A newly published pilot study of sedentary older women suggests that short standing breaks improve cardio-metabolic health. Lead researcher Dorothy Sears, PhD, with support from UC San Diego Altman Clinical and Translational Research Institute (ACTRI) through the Voucher Program, enrolled ten at-risk, overweight or obese postmenopausal women and tested three sitting interruption conditions.
“We found that when our study participants got up during the sitting conditions, they got better,” said Sears, an Associate Professor of Medicine at UC San Diego with a secondary appointment in Family Medicine and Public Health. The results were published in
PLoS ONE and contributed to Sears and her research colleagues landing a $9 million NIH/National Institute on Aging (NIA) P01 grant to conduct a larger laboratory sitting study and two other studies of sitting time and healthy aging.
The pilot study volunteers came to the ACTRI clinic for about seven hours each visit on four separate days. Four five-hour sitting conditions—three interventions and a control situation—were tested in randomized order. The interventions included standing for two minutes every 20 minutes, standing for 10 minutes every hour, and walking for two minutes every hour; the control situation encompassed sitting for nearly the whole time, with an allowance for a bathroom break. Each session focused on testing one condition.
The interruptions were designed to improve glucoregulatory and vascular outcomes, yet be easy to accomplish. “We wanted interventions to be modest in their intensity and something that people of almost any capacity could do,” Sears said. Two liquid meals were served during the testing times, breakfast and lunch. Cardiovascular and metabolic health were measured through blood pressure, heart rate and blood work collected every 30 minutes. “All along we were sampling blood and measuring glucose and insulin and then measuring flow-mediated dilation (FMD) at the beginning and end of each condition,” Sears said. FMD, measured through ultrasound, assesses vascular health.
“In just one day, during a five-hour period, we found health improvements,” Sears said. In particular, the 10-minute standing every hour condition resulted in improved FMD response, while the 2-minute standing and walking conditions were associated with significantly lower glycemic response following the second meal. The FMD response is important for heart health and the glycemic response indicates a person’s blood glucose (sugar) level. “Elevation of glucose over time in blood increases risk for type 2 diabetes, for cancer, and for cardiovascular disease. For people who already have diabetes, it increases the risk for complications from type 2 diabetes,” Sears said. “So lowering glucose after a meal is beneficial for many reasons.”
The study demographic was selected because postmenopausal women live a long time and across the lifespan are at high risk for cardio-metabolic disease, are the largest population of older adults, and use a disproportionate amount of healthcare dollars.
“The major story is a vascular story. And we are super excited to do the full study,” Sears said. She is returning to ACTRI for services in the fully-powered, NIH/NIA-funded study, and is grateful for the voucher support for the pilot.
“We received a generous voucher from ACTRI for clinic services, which covered the ultrasound,” Sears said. “We would not have been able to do the FMD—which was critical to the pilot study—without the ACTRI voucher.” In addition to the ACTRI voucher, she thanked ACTRI clinic nurse manager Maeve Taaffe, RN; registered diagnostic medical sonographer Minaxi Trivedi and cardiologist Dr. Luis Castellanos; and Dennis Perpetua, LVN, for their support in the pilot study. She was also grateful to Australian researchers Neville Owen and David Dunstan, who are experts in sedentary behavior and sitting times, for collaborating on protocol design and formulating questions for the pilot.
The pilot project concluded in July 2016. In June 2017, Sears and the research team received word they were awarded the NIH grant and soon after learned their publication had been accepted. The NIH-supported project, a P01 through the National Institute of Aging, includes a lab study, a randomized control trial and an epidemiological study. Sears will lead the lab study; UC San Diego professors Jacqueline Kerr, PhD, and Andrea LaCroix, PhD, are co-principal investigators of the P01 and will lead the randomized control and epidemiological studies, respectively. Kerr and LaCroix also collaborated on the pilot study. Sears’s lab project, very similar to the pilot, will enroll 78 volunteers and test two sitting interruption conditions and a control situation in three sessions.
The pilot and P01 came out of a larger discussion five years ago in the Department of Family Medicine and Public Health when then-chair Bess Marcus, PhD, encouraged researchers to study dimensions of sitting time and sedentary behavior through a program project grant. For Sears, that encouragement was the springboard to conduct studies that are right up her alley.
“I am very interested in prevention research, especially around cardio-metabolic chronic diseases like type 2 diabetes and cardiovascular disease and certain cancers related to obesity,” Sears said.
About UC San Diego Altman Clinical and Translational Research Institute:
UC San Diego Altman Clinical and Translational Research Institute (ACTRI) is part of a national Clinical and Translational Science Award consortium, led by the National Institutes of Health National Center for Advancing Translational Science. Established in 2010, ACTRI provides infrastructure and support for basic, translational and clinical research throughout the San Diego region to bring discoveries from the laboratory to the bedside, and facilitates training and education of the next generation of researchers. ACTRI carries out its activities in collaboration with institutional and corporate partners and currently has more than 1,425 members.