Most people need a minimum of one hour exercise a day

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How Much Exercise Compensates for Sitting at a Desk for eight Hours A Day?

Diabetes in Control August 27th 2016

At least an hour of physical activity needed to offset risk for several chronic conditions and mortality

Sedentary behavior has been associated with increased risk of several chronic conditions and mortality. However, it is unclear whether physical activity attenuates or even eliminates the detrimental effects of prolonged sitting. A new study examined the associations of sedentary behavior and physical activity with all-cause mortality.

The meta-analysis of trials involving more than 1 million individuals was reported online July 27 in The Lancet. It is one of a special series of papers on physical activity.

The Lancet notes that its first series on physical activity in 2012 concluded that, “physical inactivity is as important a modifiable risk factor for chronic diseases as obesity and tobacco.” The meta-analysis found that 1 hour of moderate-intensity activity, such as brisk walking or riding a bicycle, can offset the health risks of sitting for 8 hours a day. Twenty-five percent of all individuals in the study reported this level of physical activity. The study also discovered that even shorter periods of 25 minutes a day can be beneficial.

For those of us who work by sitting at a desk, it can be very difficult not to sit while we do our jobs.  But, there are still many ways to get moving, like going for a walk during lunch, or even getting up and walking over to an associate to hand them a note instead of sending an email.  There are many ways to get in your physical activity.

According to the researchers, the data from more than a million people is the first meta-analysis to use a harmonized approach to directly compare mortality between people with different levels of sitting time and physical activity. They included 16 studies, with data on 1,005,791 individuals (aged >45 years) from the United States, Western Europe, and Australia.

Researchers divided the study participants into four groups based on their reported levels of physical activity: <5 min/day; 25-35 min/day; 50-60 min/day; and 60-75 min/day.

Researchers noted that, “Among the most active, there was no significant relation between the amount of sitting and mortality rates, suggesting that high physical activity eliminated the increased risk of prolonged sitting on mortality.” But as the amount of physical activity decreased, the risk for premature death increased.

Researchers found prolonged sitting associated with an increase in all-cause mortality, mainly due to cardiovascular disease and cancer (breast, colon, and colorectal), noting that, “A clear dose-response association was observed, with an almost curvilinear augmented risk for all-cause mortality with increased sitting time in combination with lower levels of activity.”

Compared with the referent group (i.e., those sitting <4 h/day and in the most active quartile [>35·5 MET-h per week]), mortality rates during follow-up were 12–59% higher in the two lowest quartiles of physical activity (from HR=1·12, 95% CI 1·08–1·16, for the second lowest quartile of physical activity [<16 MET-h per week] and sitting <4 h/day; to HR=1·59, 1·52–1·66, for the lowest quartile of physical activity [<2·5 MET-h per week] and sitting >8 h/day). Daily sitting time was not associated with increased all-cause mortality in those in the most active quartile of physical activity. Compared with the referent (<4 h of sitting per day and highest quartile of physical activity [>35·5 MET-h per week]), there was no increased risk of mortality during follow-up in those who sat for more than 8 h/day but who also reported >35·5 MET-h per week of activity (HR=1·04; 95% CI 0·99–1·10). By contrast, those who sat the least (<4 h/day) and were in the lowest activity quartile (<2·5 MET-h per week) had a significantly increased risk of dying during follow-up (HR=1·27, 95% CI 1·22–1·31). Six studies had data on TV-viewing time (N=465 450; 43 740 deaths). Watching TV for 3 h or more per day was associated with increased mortality regardless of physical activity, except in the most active quartile, where mortality was significantly increased only in people who watched TV for 5 h/day or more (HR=1·16, 1·05–1·28).

In conclusion, the researchers emphasized that high levels of moderate intensity physical activity (i.e., about 60–75 min per day) seem to eliminate the increased risk of death associated with high sitting time. However, this high activity level attenuates, but does not eliminate the increased risk associated with high TV-viewing time. These results provide further evidence on the benefits of physical activity, particularly in societies where increasing numbers of people have to sit for long hours for work and may also inform future public health recommendations.

In another study published online by JAMA Ophthalmology in August, they found that sedentary behavior may be associated with diabetic retinopathy.  The analysis included 282 participants with diabetes. The average age was 62 years, 29 percent had mild or worse DR, and participants engaged in an average of 522 min/d of SB. The author found that for a 60-min/d increase in SB, participants had 16 percent increased odds of having mild or worse DR; total PA was not associated with DR.  “The plausibility of this positive association between SB and DR may in part be a result of the increased cardiovascular disease risks associated with SB, which in turn may increase the risk of DR.  In order to prove a cause and effect of SB and worsening DR s larger study would be needed.”

Practice Pearls

  • Inactivity is linked to a decreased production of certain hormones.
  • We need to break up periods of sitting for prolonged periods with short bursts of activity.
  • Walking 5 minutes every hour can offset sitting for the other 55 minutes per hour.

Lancet. Published online July 27, 2016. Abstract Editorial How Much Exercise Compensates for Sitting at a Desk Eight Hours A Day?#848 (1)]–[www_diabetesincontrol_com_how_]-[MTExNjQyNDI1NTE1S0]–

Can your job cause type two diabetes?

A  study of English civil servants has shown that those who earn the least are almost twice as likely to get type two diabetes than those who earn the most.

The ones who earn the least are also over one and a half times more likely to be obese and also one and a half times more likely to pursue an unhealthy lifestyle. This lifestyle includes a group of factors including smoking, drinking excessively, having a poor diet and being physically inactive.

The group comprised of over 7000 adults and equal numbers of men and women and measurements were repeated over an average of 14 years. The authors of the Whitehall II study, do not discuss what the reasons may be for the associations but I can think of a few possibilities.

Healthy food such as meat, fish, eggs, cheese, butter, olive oil, fruit and vegetables cost a lot more than unhealthy food such as sausages, sausage rolls,  bread, pasta, pizza, chips, burgers,  vegetable oil and margarine. As you will know from our book, the cornerstone to preventing weight gain and controlling diabetes is a low carbohydrate diet that is plentiful in protein, vegetables, some fruit and naturally saturated and mono-unsaturated fats.

I’m not sure if the studied civil servants all worked in central London or not. If they did, it would be logical for those who earned more to be able to afford housing nearer their place of work, thereby having to spend less time commuting.

Spending more time travelling to work each day certainly can eat into time that could otherwise be spend on planning meals, shopping and undertaking planned exercise. Being able to have flexible working hours can also help people spend less time commuting and undergo less stress while they do so.

As employees rise higher in the civil service the annual leave time allowed tends to rise as well as the pay. This could also affect the time that could be spent on exercise as well as enjoyable pursuits.  As we know, many exercise options are free, but some are not, and with poor weather outside, exercise plans can slide.  Being able to go to a gym, tennis club or golf course can provide a social outlet as well as an opportunity to exercise. Exercise helps improve mood and relief stress as well as being an opportunity to gain muscle and being able to eat more calories a day and get away with it.

What about smoking and drinking then? Why are these behaviours more common in those who are paid less?

It has been known for a long while that those with less money tend to smoke more.  As for drink, the more affluent can certainly put away plenty of drink too, particularly the more affluent, executive middle class woman, compared to her shop assistant or factory working sister. Greater workplace stress and difficulty with the elusive work/life balance are thought to be factors for the higher earning woman.

What about mental health factors? It has been found that the lower choice someone has about their job role the higher their stress and the greater their chances are of becoming depressed. Perhaps the lower the job status the less autonomy civil servants have at work?  From my work in the police force and the NHS I have seen the opposite scenario as well. I have seen very able people refuse promotion because of the necessity to do a lot of unscheduled extra work and take on responsibility that seems relatively poorly rewarded financially as people rise up the hierarchy.

Television watching also tends to increase the amount of sugary food and drink consumed across all age groups according to a study. Do the more affluent watch less telly? Perhaps having a dining table and using it for family meals can be a factor in reducing our waistlines?

The reasons for the socio-economic differences in the causation of type two diabetes are up for discussion. But also up for discussion is what can we do to lessen the chances of being affected?

Being aware that your job could be putting you are more risk of type two diabetes is a first step. How can you get more control over how you do your job? Can you get flexi-time so as to make home arrangements and commuting less stressful?  Can you eat in a more healthful way? Can you make more time for exercise or incorporate physical activity into your working day? Are those self- soothing habits such as smoking, drinking and watching the telly stealing years from your life?

Sadly it looks like the workplace subsidised canteen and gym perks are becoming less likely rather than more likely. I would not be surprised to see these socio-economic differences between civil servants greatly amplified between people who are unemployed and those workers who are just scraping a living wage compared to  more affluent workers. And where type two diabetes goes so does the increased rates of complications, cardiovascular disease and cancer.

Based on Contribution of modifiable risk factors to social inequalities in type 2 diabetes: prospective Whitehall II cohort study. Silvia Stringhini et all. BMJ Sept 12 and BMJ learning module: The effect of television watching on dietary intake.