Author Archive: Joel
Subtracting sitting versus adding exercise on glycemic control and variability in sedentary office workers
A new study published in the journal of Applied Physiology, Nutrition and Metabolism examines the metabolic impact of adding exercise vs reducing sitting time.
The abstract, via the journal of Applied Physiology, Nutrition and Metabolism:
Recent evidence suggests that, like adding exercise, reducing sitting time may improve cardiometabolic health. There has not been a direct comparison of the 2 strategies with energy expenditure held constant. The purpose of this study was to compare fasting and postmeal glucose and insulin concentrations in response to a day with frequent breaks from sitting but no exercise versus considerable sitting plus moderate exercise. Ten sedentary overweight/obese office workers were tested in 3 conditions: (i) walking per activity guidelines (AGW): sitting for majority of workday with a 30 min pre-lunch walk; (ii) frequent long breaks (FLB): no structured exercise but frequent breaks from sitting during workday with energy expenditure matched to AGW; and (iii) frequent short breaks (FSB): number of breaks matched to FLB, but duration of breaks were shorter. Plasma glucose and insulin areas under the curve were measured in response to a meal tolerance test (MTT) at the end of the workday and interstitial glucose was evaluated throughout the day and overnight using continuous glucose monitoring. Using repeated-measures linear mixed models, area under the curve of plasma glucose or insulin after the MTT was not different between conditions. Glycemic variability was lower in FLB compared with AGW (p < 0.05), and nocturnal duration of elevated glucose (>7.8 mmol/L) was shorter after FLB (2.5 ± 2.5 min) than AGW (32.7 ± 16.4 min) or FSB (45.6 ± 29.6 min, p = 0.05). When energy expenditure was matched, breaks from sitting approximated the effects of moderate-intensity exercise on postmeal glucose and insulin responses and more effectively constrained glycemic variability.
The full text of the article can be found here.
Due to the increasing prevalence of childhood obesity, the association between classroom furniture and energy expenditure as well as physical activity was examined using a standing-desk intervention in three central-Texas elementary schools. Of the 480 students in the 24 classrooms randomly assigned to either a seated or stand-biased desk equipped classroom, 374 agreed to participate in a week-long data collection during the fall and spring semesters. Each participant’s data was collected using Sensewear® armbands and was comprised of measures of energy expenditure (EE) and step count. A hierarchical linear mixed effects model showed that children in seated desk classrooms had significantly lower (EE) and fewer steps during the standardized lecture time than children in stand-biased classrooms after adjusting for grade, race, and gender. The use of a standing desk showed a significant higher mean energy expenditure by 0.16 kcal/min (p < 0.0001) in the fall semester, and a higher EE by 0.08 kcal/min (p = 0.0092) in the spring semester.
The full text article is available for free here.
A recent story in the New York Times, “Steve Jobs Was a Low-Tech Parent,” discusses tech CEOs — including the late Steve Jobs — who understand the importance of limiting screen time.
From the story:
When Steve Jobs was running Apple, he was known to call journalists to either pat them on the back for a recent article or, more often than not, explain how they got it wrong. I was on the receiving end of a few of those calls. But nothing shocked me more than something Mr. Jobs said to me in late 2010 after he had finished chewing me out for something I had written about an iPad shortcoming.
“So, your kids must love the iPad?” I asked Mr. Jobs, trying to change the subject. The company’s first tablet was just hitting the shelves. “They haven’t used it,” he told me. “We limit how much technology our kids use at home.”
Click here to read the story in full for free.
Desk-based workers’ perspectives on using sit-stand workstations: a qualitative analysis of the Stand@Work study
A new paper published in BMC Public Health examines worker’s perspectives on sit-stand workstations. From the abstract:
Prolonged sitting time has been identified as a health risk factor. Sit-stand workstations allow desk workers to alternate between sitting and standing throughout the working day, but not much is known about their acceptability and feasibility. Hence, the aim of this study was to qualitatively evaluate the acceptability, feasibility and perceptions of using sit-stand workstations in a group of desk-based office workers.
This article describes the qualitative evaluation of the randomized controlled cross-over Stand@Work pilot trial. Participants were adult employees recruited from a non-government health agency in Sydney, Australia. The intervention involved using an Ergotron Workfit S sit-stand workstation for four weeks. After the four week intervention, participants shared their perceptions and experiences of using the sit-stand workstation in focus group interviews with 4-5 participants. Topics covered in the focus groups included patterns of workstation use, barriers and facilitators to standing while working, effects on work performance, physical impacts, and feasibility in the office. Focus group field notes and transcripts were analysed in an iterative process during and after the data collection period to identify the main concepts and themes.
During nine 45-min focus groups, a total of 42 participants were interviewed. Participants were largely intrinsically motivated to try the sit-stand workstation, mostly because of curiosity to try something new, interest in potential health benefits, and the relevance to the participant’s own and organisation’s work. Most participants used the sit-stand workstation and three common usage patterns were identified: task-based routine, time-based routine, and no particular routine. Common barriers to sit-stand workstation use were working in an open plan office, and issues with sit-stand workstation design. Common facilitators of sit-stand workstation use were a supportive work environment conducive to standing, perceived physical health benefits, and perceived work benefits. When prompted, most participants indicated they were interested in using a sit-stand workstation in the future.
The use of a sit-stand workstation in this group of desk-based office workers was generally perceived as acceptable and feasible. Future studies are needed to explore this in different desk-based work populations and settings.
The full-text is available for free via the BMC Public Health website.
From Stone Hearth Newsletters:
The study, published in today’s online edition of Mayo Clinic Proceedings, examined the association between fitness levels, daily exercise, and sedentary behavior, based on data from 2,223 participants in the National Health and Nutrition Examination Survey (NHANES).
The team of physician-researchers analyzed accelerometer data from men and women between the ages of 12 and 49 with no known history of heart disease, asthma, or stroke, and measured their average daily physical activity and sedentary behavior times. Fitness was estimated using a submaximal treadmill test, and variables were adjusted for gender, age, and body mass index. The findings demonstrate that the negative effect of six hours of sedentary time on fitness levels was similar in magnitude to the benefit of one hour of exercise.
“We also found that when sitting for prolonged periods of time, any movement is good movement, and was also associated with better fitness,” said Dr. Jacquelyn Kulinski, a recent graduate from the UT Southwestern Cardiology Fellowship Training Program and first author of the paper. “So if you are stuck at your desk for a while, shift positions frequently, get up and stretch in the middle of a thought, pace while on a phone call, or even fidget.”
The full article is available here.
Dr Catrine Tudor-Locke of the Pennington Biomedical Research Center describes the pros and cons of pedal and treadmill desks.
From PLOS ONE:
Excessive sedentary time (SED) has been linked to obesity and other adverse health outcomes. However, few sedentary-reducing interventions exist and none have utilized smartphones to automate behavioral strategies to decrease SED. We tested a smartphone-based intervention to monitor and decrease SED in overweight/obese individuals, and compared 3 approaches to prompting physical activity (PA) breaks and delivering feedback on SED.
Design and Methods
Participants [N = 30; Age = 47.5(13.5) years; 83% female; Body Mass Index (BMI) = 36.2(7.5) kg/m2] wore the SenseWear Mini Armband (SWA) to objectively measure SED for 7 days at baseline. Participants were then presented with 3 smartphone-based PA break conditions in counterbalanced order: (1) 3-min break after 30 SED min; (2) 6-min break after 60 SED min; and (3) 12-min break after 120 SED min. Participants followed each condition for 7 days and wore the SWA throughout.
All PA break conditions yielded significant decreases in SED and increases in light (LPA) and moderate-to-vigorous PA (MVPA) (p<0.005). Average % SED at baseline (72.2%) decreased by 5.9%, 5.6%, and 3.3% [i.e. by mean (95% CI) −47.2(−66.3, −28.2), −44.5(−65.2, −23.8), and −26.2(−40.7, −11.6) min/d] in the 3-, 6-, and 12-min conditions, respectively. Conversely, % LPA increased from 22.8% to 26.7%, 26.7%, and 24.7% [i.e. by 31.0(15.8, 46.2), 31.0(13.6, 48.4), and 15.3(3.9, 26.8) min/d], and % MVPA increased from 5.0% to 7.0%, 6.7%, and 6.3% (i.e. by 16.2(8.5, 24.0), 13.5(6.3, 20.6), and 10.8(4.2, 17.5) min/d] in the 3-, 6-, and 12-min conditions, respectively. Planned pairwise comparisons revealed the 3-min condition was superior to the 12-min condition in decreasing SED and increasing LPA (p<0.05).
The smartphone-based intervention significantly reduced SED. Prompting frequent short activity breaks may be the most effective way to decrease SED and increase PA in overweight/obese individuals. Future investigations should determine whether these SED reductions can be maintained long-term.
The full text is available free via PLOS ONE.
A new review in the journal Mental Health and Physical Activity looks at the potential impact of sedentary behaviour on mental health:
It is generally understood that regular moderate to vigorous physical activity (MVPA) promotes good health from head to toe. Evidence also supports the notion that too much sitting can increase all-cause mortality and risk of chronic diseases such as diabetes. Moreover, there is evidence that daily MVPA may not offset negative effects of sedentary behavior on systemic risk factors. We extend the discussion to brain structure and function and argue that while MVPA is recognized as a protective behavior against age-related dementia, sedentary behavior may also be an important contributor to brain health and even counteract the benefits of MVPA due to overlapping or interacting mechanistic pathways. Thus, the goals of this review are (1) to outline evidence linking both PA and sedentary behavior to neurobiological systems that are known to influence behavioral outcomes such as cognitive aging and (2) to propose productive areas of future research.
The full article is now available via the journal Mental Health and Physical Activity.
Dr Meredith Peddie of the University of Otago (New Zealand) is currently looking for a PhD/MSc student to investigate the energy expenditure and possible dietary compensation associated with prolonged sitting, continuous physical activity, and regular activity breaks.
The full posting can be found below:
University of Otago Scholarships to undertake a PhD are available to those candidates with an excellent academic record.