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.

Friday, February 17, 2017

Measurement of availability and accessibility of food among youth

Availability and accessibility of foods are regarded as important determinants of food choice and nutrition behavior, because it makes sense that people -children as well as adults- tend to eat what is easily available and accessible to them. To study the relevance of availability and accessibility, good, i.e. valid and reliable, measures of availability and accessibility are needed. In a paper just published in the International Journal of Behavioral Nutrition & Physical Activity, we present and discuss the results of a systematic review of the psychometric properties of measures of food availability and accessibility among youth. A secondary objective was to assess how availability and accessibility were conceptualized in the included studies.
We reviewed studies studies published between January 2010 and March 2016 that reported on at least one psychometric property of a measure of availability and/or accessibility of food among youth were included.
A total of 20 studies were included. While 16 studies included measures of food availability, three included measures of both availability and accessibility; one study included a measure of accessibility only. Different conceptualizations of availability and accessibility were used across the studies. The measures aimed at assessing availability and/or accessibility in the home environment, the school, stores, childcare/early care and education services and restaurants. Most studies followed systematic steps in the development of the measures. The most common psychometrics tested for these measures were test-retest reliability and criterion validity. The majority of the measures had satisfactory evidence of reliability and/or validity. None of the included studies assessed the responsiveness of the measures.

Tuesday, February 14, 2017

Screentime and soft drinks

Extensive sedentary time, i.e. (uninterrupted) sitting for too long, and especially sitting in from of TV's or other 'screens' have been associated with unfavorable cardiometabolic health. Apart from sitting too long itself, TV time may be accompanied by snacking and sugary drinks, which may lead to excess calorie intake, unnecessary weight gain, and eventually to overweight and obesity. In a study just published in the journal PLOS One we explored if children who spend more time sitting behind or before 'screens' TV, PC, tablet et cetera, i.e. 'screen-based sedentary behavior' drink more sugar-sweetened soft drinks. The study also assessed if such an association between screen-based sitting time and sugary drinks intakes differed according to level of education of the parents.
Data were collected from 7886 children participating in the EuropeaN Energy balance Research to prevent excessive weight Gain among Youth (ENERGY) survey conducted in eight European countries.
In six of the eight included countries, children who reported to watch more TV also reported to drink more soft drinks, but there was no significant association between computer use and soft drink consumption in six of the eight countries. In Norway and Hungary, the association between TV viewing and soft drinks was stronger for children from lower educated parents.

Tuesday, February 7, 2017

The DONE framework for determinants of nutrition and eating

The question of which factors drive human eating and nutrition is a key issue in many branches of science, and is of utmost importance to inform health promotion interventions and policies. In a paper just published in PLOS One, we describe the creation, evaluation, and updating of an interdisciplinary, interactive, and evolving “framework 2.0” of Determinants Of Nutrition and Eating (DONE). This endeavor was part of the DEDIPAC (determinants of diet and physical activity) joint action within the Healthy Diet, Healthy Life European joint programming initiative. A similar exercise was done and already published for sedentary behavior (the systems of sedentary behavior (SOS) framework). The DONE framework was created by an interdisciplinary workgroup in a multiphase, multimethod process. Modifiability, relationship strength, and population-level effect of the determinants were rated to identify areas of priority for research and interventions. External experts positively evaluated the usefulness, comprehensiveness, and quality of the DONE framework. An approach to continue updating the framework with the help of experts was piloted. The DONE framework can be freely accessed via the lead university for DONE, i.e. university of Konstanz in Germany,
and used in a highly flexible manner: determinants can be sorted, filtered and visualized for both very specific research questions as well as more general queries. The dynamic nature of the framework allows it to evolve as experts can continually add new determinants and ratings. We anticipate this framework will be useful for research prioritization and intervention development.