PHYSICAL INACTIVITY - THE SINGLE BEST PREDICTOR OF EARLY DEATH?
What do all of these chronic conditions have in common?
coronary heart disease,
type 2 diabetes,
mental health problems
musculoskeletal conditions such as chronic low-back pain.
Answer: there is strong evidence that these and (20 other chronic conditions) can be prevented or managed by adults doing 30 minutes of moderate intensity physical activity on at least 5 days a week.
Most of us are aware of the dangers of smoking, drinking, poor diet and stress when it comes to lifestyle disease, but there is clear evidence emerging that prolonged periods of physical inactivity is associated with a heightened risk of serious illness and premature death.
What EXACTLY is Physical Inactivity?
A type of lifestyle with little physical activity, which is defined by the World Health Organisation (WHO) as less than 150 minutes of moderate physical activity per week. 
Recent research suggests that sedentary behaviour is a significant risk factor for chronic disease and mortality. Dame Sally Davies, the chief medical officer of the UK, claimed inactivity was ‘a silent killer’. 
The biggest public health problem of the 21st century
A study of 54,000 people, published by Steven Blair, University of South Carolina, in the British Journal of Sports Medicine, reported that physical inactivity increased the risk of early death and were greater than the risks of smoking, diabetes, and obesity combined. This is represented in the chart below which also suggests that low cardiovascular respiratory fitness is more likely to be associated with premature death than obesity, smoking, hypertension (high blood pressure), elevated cholesterol or diabetes.
Physical activity is often overlooked when discussing health risk factors, the author of this study stated:
The attributable fraction (%) is an estimate of the percentage of deaths in a population that would have been avoided if there was an absence of a specific risk factor. For example around 16% of deaths for men and around 17% for women are attributed to physical inactivity. 
FATNESS vs FITNESS
Several studies suggest greater risks of early death for those who are inactive regardless of whether you are a normal weight, overweight or obese.
A study by a team from the University of Cambridge, recording and assessing exercise levels, waistlines and deaths of over 334,000 European men and women over 12-years, suggests that inactivity and sedentary behaviour carries a larger mortality risk than being overweight or obese. The study found that twice as many deaths may be attributable to lack of physical activity compared with the number of deaths attributable to obesity, but that just a modest increase in physical activity could have significant health benefits. 
Physical inactivity is a silent epidemic. Today, most of us are less active than previous generations and far less active than our ancestors of the past. According to The New York Times an Australian study found that for each additional hour of television a person sat and watched per day, the risk of premature death rose by 11 percent. Sedentary behaviour is also directly linked to back, neck and muscle pain. 
SITTING THE NEW SMOKING?
Prolonged periods of sustained sitting is being termed the new ‘smoking’ with some experts calling it the ‘pandemic of inactivity.’ A recent meta-analysis of 43 studies, amounting to more than 4 million people, found that significant periods of sitting were associated with a 21% increased risk of lung cancer and a 24% increased likelihood of colon cancer.  According to research commissioned by Public Health England (PHE) people spend nine hours on average sitting down, 60% of their waking time. For those working in offices 65-75% of working hours are spent sitting.  The dangers of prolonged sitting are a separate issue from inactivity alone.
TIME TO MOVE
Our bodies were designed to move and not just in relation to set periods of time for exercise. The positives of being active are well researched and documented especially in relation to health and wellbeing. Physical inactivity has been identified as the fourth leading risk factor for deaths globally (6% of deaths). This follows hypertension (13%), tobacco use (9%) and elevated blood glucose (6%). Being overweight and obesity, the fifth leading risk factor, are responsible for 5% of global deaths. 
We should avoid prolonged sitting and hours spent being sedentary and find opportunities for movement whenever we can. Walk more, take the stairs, avoid the lifts, carry groceries home, consider the use of standing desks and take regular movement snacks or breaks to walk around the office to decrease daily non-active minutes and mitigate the risks.
 World Health Organisation, Physical Activity (Jan 2015)
 Start Active, Stay Active, (Jul 2011)
 Blair S et al. "Physical inactivity: the biggest public health problem of the 21st century", Br J Sports Med (2009)
 Ekelund, U et al. "Activity and all-cause mortality across levels of overall and abdominal adiposity in European men and women: the European Prospective Investigation into Cancer and Nutrition Study", Am J Clin Nutr (Jan 2015)
 Owen, Neville et al. "Too Much Sitting: The Population-Health Science of Sedentary Behavior." Exercise and Sport Sciences Reviews (2010)
 Schmid D et al., "Television Viewing and Time Spent Sedentary in Relation to Cancer Risk: A Meta-Analysis", JNCI J Natl Cancer Inst (2014)
 Buckley JP et al. "The sedentary office: an expert statement on the growing case for change towards better health and productivity.", Br J Sports Med (Nov 2015)
 World Health Organisation "Global Recommendations on Physical Activity for Health." (2010)