Research clearly shows that increased physical activity, regardless of its intensity, is linked to a significantly lower risk of death. Even light exercise, such as walking, can make a difference.
The researchers came to this conclusion after analyzing data from published research that had involved the use of wearable trackers to measure physical activity in middle-aged and older adults.
A recent BMJ The article gives a full account of the systematic review and meta-analysis.
The analysis also found that sitting for more than 9.5 hours per day is linked to a significantly higher risk of premature death.
The results largely confirm those of previous studies on the links between physical activity, sedentary behavior and longevity.
According to the researchers, most health guidelines regarding minimum levels of exercise have relied primarily on studies using self-reported activity levels.
The researchers note that their new survey is important because they only included studies measuring physical activity using accelerometers. These wearable motion sensors can track the amount and intensity of activity during waking hours.
The team also wanted to clarify the effect of sedentary behavior. The guidelines advise people to spend less time sitting, but they do not say how harmful sitting is.
Another issue that the new study clarifies is the contribution of low-intensity activity.
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While the guidelines cite light activity as a good start to this level and beneficial for health, the main emphasis is on moderate and vigorous activity.
Does this mean that light activity has less impact on health and longevity, especially for middle-aged and older adults, than moderate, vigorous activity?
“Answer these questions [has] great importance for the promotion of health ”, state two of the authors of this new study, Ulf Ekelund and Thomas Yates, in an accompanying BMJ opinion piece.
Ekelund is a professor at the Norwegian School of Sport Science and the Norwegian Institute of Public Health, both in Oslo, Norway. Yates is Professor of Physical Activity, Sedentary Behavior and Health at the University of Leicester in the UK.
For their study, Professor Ekelund and his colleagues set out to examine the links between physical activity, sedentary behavior, and risk of death in middle-aged and older adults.
Their analysis included data on a total of 36,383 adults with a minimum age of 40 and a mean age of 62.
The data came from eight studies that tracked activity using motion sensors for up to 1 week and followed participants thereafter for an average of 5.8 years.
The studies classified physical activity as light, moderate or vigorous and estimated the daily time spent in each.
Researchers give examples of light physical activity such as walking, washing dishes and cooking.
Moderate activity includes mowing grass, brisk walking, and vacuuming, while digging, jogging, and carrying heavy weights are examples of strenuous physical activity.
The team ranked the results into quarters, ranging from the 25% most active participants to the 25% least active participants.
Of the participants, 5.9% (2,149 people) died during follow-up. The researchers used these deaths to calculate the risk of dying from the most active to the least active participants.
After adjusting the results for factors that might influence them, the team found that any level of activity – whether light, moderate, or vigorous – was linked to a significantly lower risk of death during follow-up.
The most active 25% of participants had a 60-70% lower risk of death compared to the least active 25%. There were about five times as many deaths in the least active group compared to the most active group.
Additionally, sitting for a total of 9.5 hours per day or more, not including time spent sleeping, was linked to a statistically significant increased risk of death.
The researchers suggest that the results reinforce the fact that any level of physical activity – even light exercise that is within the reach of most people – is beneficial.
They observe that the effect sizes in their results are about double the size of previous studies that relied on self-reported data.
Professor Jochen Klenk from the University of Ulm in Germany and Professor Ngaire Kerse from the University of Auckland in New Zealand discuss the results and impact of wearable motion sensors on this type of research in a
They note that the introduction of wearable sensors has allowed researchers to collect more accurate and objective measures of levels and amount of physical activity.
“But,” they warn, “inconsistencies and uncertainties remain, especially regarding the magnitude of the effects and the contribution to health of low levels of physical activity.”
However, the analysis that entered the new results was based on high quality studies, harmonized methods and used data on more than 36,000 people. The total scope covered over 240,000 person-years of follow-up and 2,100 events.
This gave the authors “sufficient statistical power” to allow them to “differentiate between different levels of intensity – including low-intensity physical activity,” the reviewers note.