Category: Public Health
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.
The Heart Foundation of Australia has created a series of excellent workplace wellness posters targeting sedentary behaviour that can be printed off from their website.
Sit-Less PostersA range of four posters that act as a visual cue to prompt workers to stand or move more frequently in a workplace setting. These posters also provide imagery on ways that people can reduce extended sitting throughout the day.
Download your copies :
More workplace wellness resources are available via the Heart Foundation website.
Earlier this week we posted the abstract of a study concluding that sedentary behaviour may not have health effects independent of physical activity. David Dunstan and colleagues have responded with a comment on the article, available via PLOS ONE.
From the comment:
Maher and colleagues report findings from a secondary analysis of accelerometer data collected as part of the US National Health and Nutrition Examination Survey (NHANES). They found no associations of sedentary time with cardiometabolic risk biomarkers, when controlling for a measure of “total physical activity” that was composed of time spent in both moderate- to vigorous-intensity and light-intensity physical activity (that is, all non-sedentary time), weighted by intensity (accelerometer counts). On this basis, they concluded that sedentary time may not have health effects independent of physical activity. Leaving aside legitimate concerns with interpreting null results in this fashion, a broader conclusion that might be drawn is that there is limited (or no) merit in searching for “independent” effects of behaviours that are unavoidably “interdependent”.
Both the full article and the full comment are available via PLOS ONE.
A new study published in PLOS ONE suggests that sedentary behavior may not be associated with health independent of total physical activity. From the abstract:
Recent literature has posed sedentary behaviour as an independent entity to physical inactivity. This study investigated whether associations between sedentary behaviour and cardio-metabolic biomarkers remain when analyses are adjusted for total physical activity.
Cross-sectional analyses were undertaken on 4,618 adults from the 2003/04 and 2005/06 U.S. National Health and Nutrition Examination Survey. Minutes of sedentary behaviour and moderate-to-vigorous physical activity (MVPA), and total physical activity (total daily accelerometer counts minus counts accrued during sedentary minutes) were determined from accelerometry. Associations between sedentary behaviour and cardio-metabolic biomarkers were examined using linear regression.
Results showed that sedentary behaviour was detrimentally associated with 8/11 cardio-metabolic biomarkers when adjusted for MVPA. However, when adjusted for total physical activity, the associations effectively disappeared, except for C-reactive protein, which showed a very small, favourable association (β = −0.06) and triglycerides, which showed a very small, detrimental association (β = 0.04). Standardised betas suggested that total physical activity was consistently, favourably associated with cardio-metabolic biomarkers (9/11 biomarkers, standardized β = 0.08–0.30) while sedentary behaviour was detrimentally associated with just 1 biomarker (standardized β = 0.12).
There is virtually no association between sedentary behaviour and cardio-metabolic biomarkers once analyses are adjusted for total physical activity. This suggests that sedentary behaviour may not have health effects independent of physical activity.
The full study is available via the journal PLOS ONE.
New study suggests that prolonged sitting is linked to excess mortality. From Stone Hearth Newsletter:
Led by Cornell University nutritional scientist Rebecca Seguin, a new study of 93,000 postmenopausal American women found those with the highest amounts of sedentary time – defined as sitting and resting, excluding sleeping – died earlier than their most active peers. The association remained even when controlling for physical mobility and function, chronic disease status, demographic factors and overall fitness – meaning that even habitual exercisers are at risk if they have high amounts of idle time.
The full article is available via Stone Hearth Newsletter.
New paper published in the American Journal of Preventive Medicine. The abstract:
Desk-based office employees sit for most of their working day. To address excessive sitting as a newly identified health risk, best practice frameworks suggest a multi-component approach. However, these approaches are resource intensive and knowledge about their impact is limited.
To compare the efficacy of a multi-component intervention to reduce workplace sitting time, to a height-adjustable workstations-only intervention, and to a comparison group (usual practice).
Three-arm quasi-randomized controlled trial in three separate administrative units of the University of Queensland, Brisbane, Australia. Data were collected between January and June 2012 and analyzed the same year.
Desk-based office workers aged 20-65 (multi-component intervention, n=16; workstations-only, n=14; comparison, n=14).
The multi-component intervention comprised installation of height-adjustable workstations and organizational-level (management consultation, staff education, manager e-mails to staff) and individual-level (face-to-face coaching, telephone support) elements.
MAIN OUTCOME MEASURES:
Workplace sitting time (minutes/8-hour workday) assessed objectively via activPAL3 devices worn for 7 days at baseline and 3 months (end-of-intervention).
At baseline, the mean proportion of workplace sitting time was approximately 77% across all groups (multi-component group 366 minutes/8 hours [SD=49]; workstations-only group 373 minutes/8 hours [SD=36], comparison 365 minutes/8 hours [SD=54]). Following intervention and relative to the comparison group, workplace sitting time in the multi-component group was reduced by 89 minutes/8-hour workday (95% CI=-130, -47 minutes; p<0.001) and 33 minutes in theworkstations-only group (95% CI=-74, 7 minutes, p=0.285).
A multi-component intervention was successful in reducing workplace sitting. These findings may have important practical and financial implications for workplaces targeting sitting time reductions.
The full study is available via the American Journal of Preventive Medicine.