If everyone managed at least half the recommended level of physical activity then one in ten early deaths could be prevented, say a team led by researchers at the University of Cambridge.
Physical activity – particularly when it is moderate-intensity – is known to reduce the risk of cardiovascular disease and cancer. The NHS recommends that adults should aim to do strengthening activities that work all the major muscle groups on at least 2 days a week, and do at least 150 minutes of moderate intensity activity a week (for example, brisk walking, dancing, cycling, playing tennis, or hiking) or 75 minutes of vigorous intensity activity a week. Exercise should be spread "evenly over 4 to 5 days a week, or every day", explained the NHS.
According to the British Heart Foundation, heart and circulatory diseases cause a quarter of all deaths in the UK, which equates to more than 160,000 deaths each year – an average of "460 deaths each day or one every 3 minutes". A similar number of people die from cancer each year in the UK (around 167,000 according to Cancer Research UK), which also equates to "nearly 460 every day".
Professor James Woodcock, from the MRC Epidemiology Unit at University of Cambridge School of Clinical Medicine and one of the study authors, said: "We know that physical activity, such as walking or cycling, is good for you, especially if you feel it raises your heart rate."
Lead author Dr Leandro Garcia, from the Centre for Public Health at Queen's University Belfast, and the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, said: "Moderate activity doesn’t have to involve what we normally think of exercise, such as sports or running. Sometimes, replacing some habits is all that is needed."
Disease Burden of Inactivity
The authors pointed out that, although it is known that higher levels of physical activity are associated with lower rates of premature death and chronic disease outcomes, "the shape of the dose-response association has been more difficult to determine and has not been established for a range of chronic diseases".
They highlighted that accurate estimation of the dose-response association between physical activity and disease outcomes is needed for assessing the "disease burden of physical inactivity" and the potential impact of changes to population levels of physical activity.
For the new study, published in the British Journal of Sports Medicine, researchers from the MRC Epidemiology Unit at the University of Cambridge set out to explore the amount of physical activity necessary to have a beneficial impact on several chronic diseases and premature death.
The researchers performed a systematic review and meta-analysis of 196 peer-reviewed articles, covering more than 30 million participants, from 94 large study cohorts, which they said enabled them to "produce the largest analysis to date of the association between physical activity levels and risk of heart disease, cancer, and early death".
Half of Recommended Weekly Activity Achieves Significant Benefits
They found that, apart from work-related physical activity, 2 in 3 people reported activity levels below 150 minutes per week of moderate-intensity activity, and fewer than 1 in 10 managed more than 300 minutes per week.
"In general, higher activity levels were associated with lower risks of all outcomes," they said.
Compared with inactive individuals, adults who achieved the 150 minutes of moderate-intensity activity had a 31% lower risk of all-cause mortality, a 29% lower risk of cardiovascular disease (CVD) mortality, and a 15% lower risk of cancer mortality. If all individuals accumulated at least 150 minutes a week, then 15.7%, 12.3%, and 7.1% of all-cause, CVD-related, and cancer-related deaths, respectively, would "potentially have been averted", the authors pointed out.
The researchers also calculated that if everyone in the studies had done the equivalent of at least 150 minutes per week of moderate-intensity activity, around 1 in 6 (15.7%) premature deaths, 1 in 9 (10.9%) cases of CVD, and 1 in 20 (5.2%) cases of cancer, would have been prevented.
They explained that "beyond" 150 minutes per week of moderate-intensity activity, the additional benefits in terms of reduced risk of disease or early death were "marginal".
"Even half this amount came with significant benefits," they explained. "Accumulating 75 min per week of moderate-intensity activity brought with it a 23% lower risk of early death."
"If everyone managed at least 75 min per week of moderate-intensity physical activity, around 1 in 10 (10%) premature deaths, 1 in 20 (5%) cases of cardiovascular disease, and nearly 1 in 30 (3%) cases of cancer, would be prevented," they said.
Seventy-five minutes per week of moderate activity was also enough to reduce the risk of developing cardiovascular disease by 17% and cancer by 7%. For some specific cancers, the reduction in risk was greater, they alluded – head and neck, myeloid leukaemia, myeloma, and gastric cardia cancers were between 14-26% lower risk. For other cancers, such as lung, liver, endometrial, colon, and breast cancer, a 3-11% lower risk was observed, highlighted the authors.
Small Increases Reap Substantial Protection
Dr Soren Brage from the MRC Epidemiology Unit, and one of the authors, said: "If you are someone who finds the idea of 150 minutes of moderate-intensity physical activity a week a bit daunting, then our findings should be good news. Doing some physical activity is better than doing none. This is also a good starting position – if you find that 75 minutes a week is manageable, then you could try stepping it up gradually to the full recommended amount."
Professor Woodcock said: "What we’ve found is there are substantial benefits to heart health and reducing your risk of cancer even if you can only manage 10 minutes every day."
The authors concluded: "Our findings suggest an appreciably lower risk of mortality, cardiovascular diseases, and cancers from the equivalent of 75 minutes/week or less of moderate-intensity aerobic physical activity (i.e., half the recommended minimum levels)."
"Small increases" in non-occupational physical activity in inactive adults could reap the reward of "substantial" protection against a range of chronic disease outcomes, they suggested.
"11 minutes a day – 75 minutes a week – of moderate-intensity physical activity – such as a brisk walk – would be sufficient to lower the risk of diseases such as heart disease, stroke, and a number of cancers," the authors said.
Funding for the study was provided by the Medical Research Council and the European Research Council. The authors declared no conflicts on interest.