Friday, 10 March 2017

I would walk 500 miles... or maybe just 8 miles (a day).

"Desk-bound workers should ‘walk EIGHT miles a day’ to slash risk of heart attacks or stroke" went one headline talking about the findings reported by William Tigbe and colleagues [1]. Drawing on data from over 110 postal workers - "(55 office-workers, 5 women, and 56 walking/delivery-workers, 10 women)" - who wore "activPAL physical activity monitors for seven days", researchers observed some potentially important trends.

Alongside wearing their activity monitors, participants were also assessed on the basis of weight, height, and blood pressure; also providing blood samples pertinent to analyses for cholesterol and triglycerides. Such collected data were used to assess cardiovascular risk based on the PROCAM risk calculator.

Results: those who were described as office workers and had a 'desk job' were generally larger at the waist and showed a slightly larger body mass index (BMI) score. They were also deemed to have an elevated risk of cardiovascular disease (over 10 years) compared with the walking/delivery workers. These observations were discussed in terms of the sedentary behaviours associated with their desk job. By contrast, those who delivered post (i.e. were active for large parts of the day) fared quite a bit better than their desk-bound colleagues, bearing in mind that all study participants were fairly healthy to begin with in terms of being non-smokers for example and not being in current receipt of blood pressure or glucose lowering medicines at time of study.

The 'walk 8 miles a day' headline that followed the Tigbe study was derived from the observation(s) that: "Those with no metabolic syndrome features walked >15 000 steps/day, or spent >7 h/day upright." Metabolic syndrome refers to a collection of symptoms - "a combination of diabetes, high blood pressure and obesity" - that increases the risk of adverse events associated with cardiovascular (dys)function. It seems that being active, or at least not being sedentary, is important for our health - a shocker indeed!

I've covered some of the other research in this area before (see here and see here for examples) and so the Tigbe results really don't come as a surprise. The strengths of the study are multiple in terms of objective measuring of activity (not reliant on the 'how much activity/exercise did you do today' type questionnaires) and all those biochemical measurements taken for participants to complement such findings. Yes, the sample size is OK but not particularly large and yes, these were pretty healthy participants to start with, but the results are nonetheless important.

Obviously one has to be a little careful so as not to imply that being active is the only thing that leads to good health and wellbeing. Science has already heard about how 'you can't outrun a bad diet' [2] and for some people, walking 15,000 steps every day or even standing up for 7 hours a day is going to be a big ask. But as part of a package of 'interventions' to potentially ward off metabolic syndrome or related issues [3], the idea that we should all be quite a bit more active is one that really should be given a lot more consideration...

Music to close, and with the title to this post, what else could I offer?

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[1] Tigbe WW. et al. Time spent in sedentary posture is associated with waist circumference and cardiovascular risk. Int J Obes (Lond). 2017 Jan 31.

[2] Malhotra A. et al. It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med. 2015 Aug;49(15):967-8.

[3] Alexander DD. et al. A Meta-Analysis of Randomized Controlled Trials and Prospective Cohort Studies of Eicosapentaenoic and Docosahexaenoic Long-Chain Omega-3 Fatty Acids and Coronary Heart Disease Risk. Mayo Clinic Proceedings. 2017; 92: 15-29.

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ResearchBlogging.org Tigbe WW, Granat MH, Sattar N, & Lean ME (2017). Time spent in sedentary posture is associated with waist circumference and cardiovascular risk. International journal of obesity (2005) PMID: 28138134