Less time spent sitting may lengthen telomeres and protect DNA from age-related damage, a new study shows. However, the researchers found no significant association in telomere length with increased exercise in this small randomized trial.
"We're excited about this study," said lead author Mai-Lis Hellenius, MD, PhD, a professor of cardiovascular disease prevention in the Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. "Long telomeres are linked to a longer, healthier life."
Per Sjögren, PhD, from the Unit of Clinical Nutrition and Metabolism, Department of Public Health and Caring Sciences, Uppsala University, Sweden, and colleagues published the study online September 3 in the British Journal of Sports Medicine.
Telomeres are sections of DNA that protect the ends of chromosomes from damage during cell division. Telomeres tend to shorten with age, and previous research has linked shorter telomeres with shorter life spans and increased risk for some types of cancer and cardiovascular disease.
"Our DNA will be damaged during a lifetime," Dr. Hellenius said. "It's damaged by bad diets, smoking, infections, and so on. Our capability to copy and produce new DNA and new cells is so important."
Previous research has shown that people who exercise more tend to have longer telomeres.
In the current study, Dr. Sjögren and colleagues analyzed the length of telomeres a subset of people who had participated in a randomized exercise trial. The original study included 101 predominantly sedentary and overweight people adults aged 68 years at baseline. The investigators randomly assigned half of the participants to an exercise program and the other half to their regular behavior.
They asked the participants to keep a 7-day diary and to wear a pedometer to measure the number of steps taken every day. They also asked them to fill out a questionnaire tallying up the amount of time spent sitting down each day.
As the researchers reported previously, the time spent exercising, as well as the number of steps taken daily, increased significantly in the group assigned the exercise program, whereas the amount of time spent seated fell in both groups ( Br J Sports Med. 2011;45:158). Various risk factors for heart disease and stroke also improved in both groups, particularly those on the exercise program, who lost more weight than their counterparts left to their own devices.
In the current subset analysis, the researchers examined telomere length from blood samples drawn at baseline and after the 6-month intervention in 49 randomly chosen participants. They found that the number of daily steps taken was not associated with changes in telomere length.
An increase in moderate-intensity physical activity correlated to a shortening in telomere length in both groups, but this finding was not statistically significant. However, a reduction in the amount of time spent sitting in the exercise group was associated with telomere lengthening in blood cells.
"We hypothesise that a reduction in sitting hours is of greater importance than an increase in exercise time for elderly risk individuals," the researchers conclude.
Dr. Hellenius acknowledged that the study was a small one and needed to be replicated before drawing conclusions from it. However, she notes, other research has also shown that people who spend more time sitting have shorter lives, regardless of whether they also exercise regularly.
"So I think you can say to our patients yes, it's important to break up sedentary time and take a break for 1 or 2 minutes every 30 minutes," said Dr. Hellenius.
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Showing posts with label sedentary. Show all posts
Showing posts with label sedentary. Show all posts
Thursday, 11 September 2014
Friday, 19 July 2013
Stop idling, move more to avoid diabetes
Time spent in sedentary behavior — sitting or lying down — has a stronger impact on diabetes risk than does moderate to vigorous physical activity (MVPA) in adults, new research shows.
"This is the first work to demonstrate that sedentary behavior might have a greater bearing on diabetes risk factors than exercise in adults at risk of the disease," said lead author Joseph Henson, a PhD student from the Leicester Diabetes Center, United Kingdom.
Mr. Henson stressed, however, that sedentary behavior "is not simply a lack of exercise," and trying to reduce it "shouldn't be used as a substitute for exercise; they should be treated independently.
"This requires a paradigm shift, so that people at high risk of developing type 2 diabetes think about the balance of sedentary behavior and physical activity throughout the day," he added, noting that sedentary time occupies a much larger portion of the day than time spent in physical activity.
Sedentary Time Affects Glucose, TGs, and HDL Cholesterol
In their study, Mr. Henson and colleagues analyzed individuals with known risk factors for type 2 diabetes from 2 ongoing diabetes-prevention programs in the UK: 153 from the Sedentary Time and Diabetes (STAND) study (mean age, 33 years; 29% men) and 725 from the Walking Away from Diabetes study (mean age, 64 years; 65% men).
They examined the extent to which sedentary time, breaks in sedentary time, MVPA, and total physical activity were independently associated with cardiometabolic risk factors. Accelerometers were used to assess sedentary time, MVPA, and total physical activity. Breaks in sedentary time were defined as a transition from a sedentary to an active state.
Following adjustment for various covariates, including MVPA and body mass index (BMI), there were detrimental linear associations of sedentary time with 2-hour plasma glucose (P < .001), triglycerides (P= .001), and HDL cholesterol (P = .029).
Breaks in sedentary time, total physical activity, and MVPA were significantly inversely associated with measures of adiposity, but not with any other cardiometabolic variables after adjustment for sedentary time and BMI.
The findings were consistent across a diverse age range, providing evidence that the negative consequences of excess sedentary time exist from young adulthood through older ages (ages 18 to 74 years), another unique aspect of the study, said Mr. Henson. He noted that previous studies that have shown detrimental effects of sedentary behavior have been performed in older adults in the general population.
"The findings from this study may have important methodological and public-health implications," he and his colleagues point out. "This…provides novel objective evidence that, in individuals at high risk of type 2 diabetes mellitus, sedentary time may be a more important indicator of cardiometabolic health than MVPA."
Diabetes Prevention Should not Overlook Sedentary Time
The results also have implications for diabetes and cardiovascular disease prevention programs, they say.
"This may raise questions regarding the prescription of optimal daily human movement for health. As such, diabetes and cardiovascular [disease] prevention programs concentrating solely on MVPA may overlook an area that is of fundamental importance to cardiometabolic health.
"Along with messages related to accumulating at least 150 min/week of MVPA, which forms the cornerstone of diabetes-prevention programs, such interventions may be more effective if individuals are further encouraged to simply sit less and move more, regardless of the intensity level," they add.
Future Study Will Try to Tease out Biological Mechanism
Mr. Henson stresses nevertheless that the research "is still only a cross-sectional, observational study," which should serve as a stimulus for further work, including tightly controlled experimental studies in different populations.
To this end, he and his colleagues plan to conduct another study, assessing individuals at risk of diabetes who will be assigned to 1 of 3 groups: sitting all day, walking about for 5-minute intervals twice an hour, and standing for 5-minute intervals twice an hour. They plan to try to tease out the biological mechanisms that are at play, Mr. Henson explained.
"This is the first work to demonstrate that sedentary behavior might have a greater bearing on diabetes risk factors than exercise in adults at risk of the disease," said lead author Joseph Henson, a PhD student from the Leicester Diabetes Center, United Kingdom.
Mr. Henson stressed, however, that sedentary behavior "is not simply a lack of exercise," and trying to reduce it "shouldn't be used as a substitute for exercise; they should be treated independently.
"This requires a paradigm shift, so that people at high risk of developing type 2 diabetes think about the balance of sedentary behavior and physical activity throughout the day," he added, noting that sedentary time occupies a much larger portion of the day than time spent in physical activity.
Sedentary Time Affects Glucose, TGs, and HDL Cholesterol
In their study, Mr. Henson and colleagues analyzed individuals with known risk factors for type 2 diabetes from 2 ongoing diabetes-prevention programs in the UK: 153 from the Sedentary Time and Diabetes (STAND) study (mean age, 33 years; 29% men) and 725 from the Walking Away from Diabetes study (mean age, 64 years; 65% men).
They examined the extent to which sedentary time, breaks in sedentary time, MVPA, and total physical activity were independently associated with cardiometabolic risk factors. Accelerometers were used to assess sedentary time, MVPA, and total physical activity. Breaks in sedentary time were defined as a transition from a sedentary to an active state.
Following adjustment for various covariates, including MVPA and body mass index (BMI), there were detrimental linear associations of sedentary time with 2-hour plasma glucose (P < .001), triglycerides (P= .001), and HDL cholesterol (P = .029).
Breaks in sedentary time, total physical activity, and MVPA were significantly inversely associated with measures of adiposity, but not with any other cardiometabolic variables after adjustment for sedentary time and BMI.
The findings were consistent across a diverse age range, providing evidence that the negative consequences of excess sedentary time exist from young adulthood through older ages (ages 18 to 74 years), another unique aspect of the study, said Mr. Henson. He noted that previous studies that have shown detrimental effects of sedentary behavior have been performed in older adults in the general population.
"The findings from this study may have important methodological and public-health implications," he and his colleagues point out. "This…provides novel objective evidence that, in individuals at high risk of type 2 diabetes mellitus, sedentary time may be a more important indicator of cardiometabolic health than MVPA."
Diabetes Prevention Should not Overlook Sedentary Time
The results also have implications for diabetes and cardiovascular disease prevention programs, they say.
"This may raise questions regarding the prescription of optimal daily human movement for health. As such, diabetes and cardiovascular [disease] prevention programs concentrating solely on MVPA may overlook an area that is of fundamental importance to cardiometabolic health.
"Along with messages related to accumulating at least 150 min/week of MVPA, which forms the cornerstone of diabetes-prevention programs, such interventions may be more effective if individuals are further encouraged to simply sit less and move more, regardless of the intensity level," they add.
Future Study Will Try to Tease out Biological Mechanism
Mr. Henson stresses nevertheless that the research "is still only a cross-sectional, observational study," which should serve as a stimulus for further work, including tightly controlled experimental studies in different populations.
To this end, he and his colleagues plan to conduct another study, assessing individuals at risk of diabetes who will be assigned to 1 of 3 groups: sitting all day, walking about for 5-minute intervals twice an hour, and standing for 5-minute intervals twice an hour. They plan to try to tease out the biological mechanisms that are at play, Mr. Henson explained.
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