Sunday, June 18, 2017

Patterns of objectively measured sedentary time in 10- to 12-year-olds

In a study just published in BMC pediatrics we examined the frequency of sedentary 'bouts' of different durations and the total time spent in sedentary on a weekday, a weekend day, during school hours, during after-school hours and during evenings among 10- to 12-year-old Belgian children. The study was part of the “EuropeaN Energy balance Research to prevent excessive weight Gain among Youth” (ENERGY)-project. We looked at total sitting time as well as different bouts of sitting, because uninterrupted sitting may be more harmful.
Accelerometer data were used to assess sedentary time and sedentary bouts. Differences in total sedentary time, sedentary bouts of 2–5, 5–10, 10–20, 20–30 and ≥30 min and total time accumulated in those bouts were examined on a weekday, a weekend day, during school hours, during after-school hours and in the evening period.
More than 60% of the participants’ waking time was spent sedentary. Children typically engaged in short sedentary bouts of 2–5 and 5–10 min, which was almost 50% of their total daily sedentary time. Although the differences were very small, children engaged in significantly fewer sedentary bouts of nearly all durations during after-school hours compared to during school hours and in the evening period. Children also engaged in significantly fewer sedentary bouts of 5–10, 10–20, and 20–30 min per hour on a weekend day than on a weekday.
Although primary school children spend more than 60% of their waking time sitting, they generally do interrupt their sitting time frequently. Children’s sedentary bouts were slightly longer on weekdays, particularly during school hours and in the evening period.

Tuesday, May 30, 2017

Who sits too much in Europe? A hierarchy of sociodemographic correlates of sedentary behavior

Too much sitting (extended sedentary time) is recognized as a public health concern in Europe and beyond. People who sit too much too long have lower cardio metabolic health and increased risk of premature death. Identifying population subgroups that sit too much may help to develop targeted interventions to reduce sedentary time. In a paper just published in Preventive Medicine, with Dr. Jeroen Lakerveld as first author (Jeroen is leader of the so-called Upstream Team, a research network focusing on environmental determinants of physical activity, dietary behaviours and chronic disease risk), we explored the relative importance of socio-demographic correlates of sedentary time in adults across Europe. We used data from 26,617 adults from 28 EU member states who participated in the 2013 Special Eurobarometer study on sport and physical activity. Their self-reported sedentary time was dichotomized into sitting less or >7.5h/day. A Chi-squared Automatic Interaction Detection (CHAID) algorithm was used to create a 'tree' that hierarchically partitions the data on the basis of the independent variables (i.e., socio-demographic factors) into homogeneous (sub)groups with regard to sedentary time. This allows for the tentative identification of population segments at risk for too much sitting. Eighteen and a half percent of respondents reported sitting >7.5h/day. Occupation was the primary discriminator. The subgroup most likely to engage in extensive sitting were higher educated, had white-collar jobs, reported no difficulties with paying bills, and used the internet frequently.

Sunday, April 30, 2017

Barriers to healthy eating and dietary behaviours in European adults

Dietary behaviours may be influenced by perceptions of barriers to healthy eating. In a study just published in the European Journal of Nutrition, we used data from the Spotlight project, a large cross-European study (N = 5900) to study potential determinants of energy balance behaviours and obesity, to explore associations between various perceived barriers to healthy eating and dietary behaviours among adults from urban regions in five European countries and examined whether associations differed across regions and socio-demographic backgrounds. Gabi Pinho is
first author on this study.
We tested associations between barriers (irregular working hours; giving up preferred foods; busy lifestyle; lack of willpower; price of healthy food; taste preferences of family and friends; lack of healthy options and unappealing foods) and dietary variables using multilevel logistic regression models. We explored whether associations differed by age, sex, education, urban region, weight status, household composition or employment.
Perceived ‘lack of willpower’, ‘time constraints’ and ‘taste preferences’ were barriers most strongly related to dietary behaviours, and the association between various barriers and lower intake of fruit and vegetables was somewhat more pronounced among younger participants and women.

Saturday, March 25, 2017

Validation and refinement of prediction models to estimate exercise capacity in cancer survivors

Exercise and physical activity is important for rehabilitation among cancer survivors. In a recent individual patient data meta analysis, we concluded that exercise, and particularly supervised exercise, effectively improves quality of life and physical fitness in patients with cancer with different demographic and clinical characteristics during and following treatment. Although effect sizes were small, there is consistent empirical evidence to support implementation of exercise as part of cancer care.
In order to test the effects of exercise interventions, to tailor exercise interventions, and to monitor progress among cancer survivors and patients with cancer, valid and reliable measures to assess exercise capacity are needed. In a paper just published in Archives of Physical Medicine and Rehabilitation -with Dr. Martijn Stuiver as first author- we tested the validity and clinical usefulness of the Steep Ramp Test for estimating exercise tolerance in cancer survivors, by external validation and extension of previously published prediction models for maximal or peak oxygen consumption (VO2peak; which is regarded as the gold standard measurement of cardiorespiratory fitness) and peak power output (Wpeak). Based on this study we concluded that predictions of VO2peak and Wpeak based on the steep ramp test are adequate at the group level, but insufficiently accurate in individual patients. The multivariable prediction model for Wpeak can be used cautiously to aid endurance exercise prescription.

Wednesday, March 22, 2017

Differences in Commuting to School and Work across Europe

In a study just published online in Preventive Medicine -with Dr. Saskia te Velde as first author- we explored if how school children and their parents commute to and from school and work across Europe, and if these modes of commuting are related to demographic variables, such as country of residence, sex, parental education, and ethnicity, and to weight status.
This study was part of the ENERGY project; children's weight and height were objectively measured; parents self-reported their weight and height and self-reports of mode of commuting and demographics were obtained.
There were marked differences between countries, especially regarding cycling to school, which was common in The Netherlands and Norway and rare in Greece and Spain. Mode of commuting was not associated with weight status in children, but parents who rode their bike to work were significantly less likely to be overweight or obese. Demographic variables were associated with mode of commuting in children and parents. For example: boys were more likely to cycle to school at least four days per week; girls were more likely to walk; children from lower educated parents were less likely to cycle, and children from ethnic minority groups were more likely to walk.


Tuesday, March 21, 2017

Social support and physical activity in young women in disadvantaged neighborhoods

People tend to become less physically active in transitioning from adolescence to adulthood. Evidence suggests that social support as well as 'intrapersonal' factors  such as self-efficacy, outcome expectations, enjoyment) are associated with physical activity. The aim of a study just published in PLOS One was to explore whether cross-sectional and longitudinal associations of social support from family and friends with leisure-time physical activity (LTPA) among young women living in disadvantaged areas were mediated by these intrapersonal factors, i.e. to explore if social support may help to increase self-efficacy, enjoyment et cetera, to help to increase LTPA. Firsts authors is Anouk Middelweerd, en this study was in close collaboration with and making use of data available at the Institute for Physical Activity and Nutrition at Deakin University, Australia.
Survey data were collected from 18–30 year-old women living in disadvantaged suburbs of Victoria, Australia as part of the longitudinal READI study.
Results from the cross-sectional analyses suggest that the associations of social support from family and from friends with LTPA are mediated by PA enjoyment, outcome expectations and self-efficacy. However, longitudinal analyses did not confirm these findings.

Tuesday, February 21, 2017

Validation of the Fitbit One for assessing physical activity

Accelerometer-based wearables can provide the user with real-time feedback through the device's interface and the mobile platforms, and this may help to encourage people to get and remain physically active. However, meaningful feedback can only be provided if such wearables validly measure physical activity levels. Very few studies have focussed on the minute-by-minute validity of wearables, which is essential for high quality real-time feedback. In a study just published online by the Journal Medicine & Science in Exercise & Sports we aimed aims to assess the validity of the Fitbit One compared to what is considered a 'gold standard' for assessing physical activity, i.e. the ActiGraph GT3x+. We looked at validity in measuring steps taken, and time spent in moderate, vigorous, and moderate-vigorous physical activity) among young adults using traditional time intervals (i.e., days) and smaller time intervals (i.e., minutes, hours).
Thirty-four healthy young adults participated and wore the ActiGraph GT3x+ and a Fitbit One for one week. As compared to ActiGraph the Fitbit One systematically overestimated physical activity for all aggregation levels: on average 0.82 steps per minute, 45 steps per hour, and 677 steps per day. Strong and significant associations were found between ActiGraph and Fitbit results for steps taken, and weaker but statistically significant associations were found for minutes spent in moderate, vigorous and moderate-vigorous physical activity for all time intervals.
We conclude that although the Fitbit One overestimates the step activity compared to the ActiGraph, it can be considered a valid device to assess step activity also for real-time minute-by-minute self-monitoring. However, agreement and correlation between ActiGraph and Fitbit One regarding time spent in moderate, vigorous and moderate-vigorous physical activity were lower.