Walking for just 2.5 hours a week could add more than seven years to your life, researchers believe.
The study found even half of that is beneficial, with 75 minutes of brisk walking a week enough to extend life by almost two years.
The analysis of the lives of more than 600,000 men and women aged 40 and over also added weight to the idea that it is possible to be fat and fit.
The experts from the US government’s medical research agency and Harvard University crunched the results of six previous long-term studies into health and lifestyle.
The analysis focused on moderate exercise – defined as walking fast enough to break into a sweat but slow enough to hold a conversation.
The benefits were clear, with two and a half hours of brisk walking a week adding 3.4 years to life on average.
Doing twice this added 4.2 years, while walking for seven and a half hours weekly added 4.5 years to life.
The biggest gains were seen in people of a healthy weight, where two and a half hours of moderate exercise a week extended life by more than seven years, the journal PLoS Medicine reported.
However, people of a healthy weight who didn’t exercise could expect to die 3.1 years earlier than obese people who did stay active – a finding that underlines the importance of exercising whatever your weight.
The study also revealed the association between physical activity and life expectancy was similar between men and women, and that black people gained more years of life expectancy than white people.
The relationship between life expectancy and exercise was stronger among those with a history of cancer or heart disease than those with no history of either disease.
Dr. I-Min Lee, the study’s senior author, said: “We must not underestimate how important physical activity is for health – even modest amounts can add years to your life.”
A new study suggests that moderate exercise and a regular intake of oily fish fatty acids keeps elderly immobility at bay.
Findings of a recent trial show that women aged over 65 who received omega-3 fatty acids gained almost twice as much muscle strength following exercise than those taking olive oil.
A larger trial is planned to confirm these findings and to determine why muscle condition improves.
The findings are being presented at the British Science Festival in Aberdeen.
Some studies have linked diets high in omega-3 – commonly found in oily fish such as mackerel and sardines – to potential health benefits, such as a lower risk of coronary heart disease.
During healthy ageing, muscle size is reduced by 0.5-2% per year.
This process – known as sarcopenia – can result in frailty and immobility in old people.
US data shows that 25% of people aged 50-70 have sarcopenia and this increases to more than half of those aged over 80 years.
A new study suggests that moderate exercise and a regular intake of oily fish fatty acids keeps elderly immobility at bay
According to Dr. Stuart Gray from the University of Aberdeen, the cost of sarcopenia is immense; either in direct nursing and care costs or in hospital admissions through falls.
“Around one-and-a-half percent of the total US healthcare budget is spent on sarcopenia-related issues,” he said.
The rate of muscle loss is dictated to some extent by lifestyle – consumption of a low protein diet and a sedentary lifestyle are known to exacerbate muscle loss.
Previous studies demonstrated that livestock fed on omega 3-rich diets had increased muscle bulk.
This prompted Dr. Stuart Gray to investigate whether these fatty acids could help reverse sarcopenia in the elderly.
In his initial studies, he showed by MRI imaging that middle-aged rats taking fish oil supplement had a lower loss of lean mass than counterparts fed a normal diet.
“The fish oil seemed to be having anabolic [muscle-building] protective effects in the rats, but rats aren’t humans, so the next step was to try it in humans,” he said.
Dr. Stuart Gray recruited 14 women aged over 65 years and asked both groups to undergo a 12 week exercise programme consisting of two 30-minute sessions of standard leg muscle exercises.
Half the women were given the omega-3 fatty acids EPA and DHA, whist the other half received an olive oil placebo (negative control).
At the start and end of the trial, the women’s leg muscle strength was measured.
The results were compelling. Women receiving olive oil increased their muscle mass by 11% whilst those receiving EPA and DHA showed a 20% increase – a statistically significant improvement.
But as Dr. Stuart Gray was quick to point out, not all fish oil supplements contain beneficial amounts of these fatty acids.
He said: “One of the problems with a lot of these supplements is that the amount of EPA varies.
“A capsule containing one gram of fish oil might only contain 100 milligrams (mg) of EPA and some might contain 400.”
His advice for anyone wanting to improve their intake of dietary EPA and DHA was to take a supplement that contained the highest levels of these two fatty acids.
Alternatively, half of the average portion of oily fish contains equivalent amounts of beneficial EPA and DHA as those used in the trial.
The researchers have now received funding to carry out a larger trial that includes 60 people aged over 65 years to confirm the beneficial effects of the fatty acids. The new trial will recruit similar numbers of men and women.
Previous research has shown that men and women differ in their ability to synthesize new protein and also in their response to exercise.
“Older women have similar levels of protein synthesis to younger women whereas older men have lower levels compared to younger men.”
“Older men adapt to exercise and increase their protein synthesis. Older women don’t do this to a great extent, although their basal levels of synthesis are higher,” Dr. Stuart Gray explained.
Assessing whether women and men respond differently to exercise and fatty acid supplements will be one of the questions that the new trial will address.
The trial is scheduled to start in the next month and will recruit people from the Aberdeenshire area.