Johannes Brug, PhD: Physical environmental factors do predict specific physical activities; an N=2 study

Saturday, December 22, 2007

Physical environmental factors do predict specific physical activities; an N=2 study

In the last decade it has been posited that the so-called obesogenic environment is the main driving force behind the obesity epidemic. Experts claim that our environment characterised by an over-abundant availability of palatable energy-dense foods that can be eaten anywhere and anytime, as well as lack of opportunities to be physically active make people eat too much calories and burn too little calories, leading to unnecessary weight gain and eventually to overweight and obesity. However, the scientific evidence for the hypothesis that physical environmental factors predict eating and physical activity behaviours is not yet strong, probably due to a lack of well-designed studies. Over the past few years we have conducted a series of systematic reviews on the availbale studies on associations between environmental factors and different nutrition behaviours and physical activity. These reviews (of mostly cross-sectional studies, using weak measurement instruments and often failing to adjust for possible confounding factors) indicated that the evidence was not yet strong. Only for very few associations was convincing and consistent evidence found, and the evidence for social environmental determinants of health behaviours was much stronger than for physical environmental factors. Recent studies further indicate that individual factors such as motivation and abilities remain important predictors of health behaviours. (See a list of links to the pubmed abstracts of the scientific papers on these reviews later in this message). However, today I did an N=2 study that illustrated that physical environmental circumstances can determine specific forms of physical activity, if motivation and ablities are taken care of. For the first time this year the ice on a few canals in the Netherlands was strong enough to allow ice skating on natural ice. We have had a few days of frost now, and although the ice is hardly reliable yet, many Dutch grabed their skates and went for it (some did get wet). My wife and I found a nice stretch of great ice a bit north of Haarlem. The icy environment allowed us to act on our motivation and to use our abilities!