A new study finds that exercising during leisure time is linked to a lower risk for high blood pressure in people who do not do much exercise.
Researchers came to this conclusion after carrying out a meta-analysis that pooled results from 13 studies examining links between exercise and blood pressure.
They found people who did more than 4 hours per week of exercise in their leisure time, as opposed to work time, had a 19% lower risk of high blood pressure, compared with people who did not do much exercise at all.
Writing about their work online this week in the American Heart Association journal Hypertension, the researchers also found no solid link between physical exertion at work and lower risk of high blood pressure.
The American Heart Association defines high blood pressure as having readings at or above 140 mm of mercury for the upper number or 90 or more for the bottom number.
This definition puts around 78 million US adults in the high blood pressure category.
High blood pressure typically has no symptoms and remains undetected and untreated in many people.
Co-author Dr. Bo Xi, a lecturer at the Shandong University School of Public Health in Jinan, China, says current health guidelines that urge people to exercise more for the benefit of their health do not distinguish between physical activity at work and for leisure, but "given the new findings, perhaps they should."
The team pooled data covering nearly 137,000 people in the US, Europe and East Asia who had healthy blood pressure on enrollment to their particular study.
Over a follow-up period ranging from 2 to 45 years, more than 15,600 of the participants developed high blood pressure.
The team found exercising more than 4 hours per week in leisure time was tied to a 19% lower risk for developing high blood pressure, compared with exercising less than 1 hour per week.
The researchers also detected a "dose-response" relationship between recreational physical activity and blood pressure: the more people exercised in their leisure time, the less likely they were to develop high blood pressure.
Even people who only did between 1 and 3 hours per week of leisure-time physical activity had an 11% lower risk of high blood pressure, they found.
However, they found "no significant association" between work-related physical activity and lower risk for high blood pressure.
Leisure exercise different than work-related activity
While the findings may suggest the more recreational exercise you do, the more you protect yourself from developing high blood pressure, Dr. Xi points out they do not prove it. The link may not even be causal.
People who exercise in their leisure time may just have healthier lifestyles, says Dr. Xi.
However, co-author Wei Ma, associate professor at the Shandong University School of Public Health, says high blood pressure is a risk factor for cardiovascular and kidney disease, so it is important to prevent and control it, and nevertheless recommends:
"To try to lower your risk of high blood pressure, you should exercise more in your leisure time."
While the team did not examine the reasons behind their findings, Prof. Ma points out that physical activity at work is different to leisure time exercise.
Work-related activity, such as in farming or industry, may involve heavy lifting, standing for long periods and doing repetitive work.
But leisure time exercise may affect high blood pressure in a number of ways, such as helping retain a healthy weight, improve insuling sensitivity and reduce resistance to flow in blood vessels, Ma adds.
Funds for the study came from the Independent Innovation Foundation of Shandong University, the Research Fund for the Doctoral Program of Higher Education of China and the Foundation for Outstanding Young Scientists in Shandong Province.
Another US study reported earlier this year found that breaking a sweat reduces stroke risk. Those findings revealed that physically inactive people have a 20% higher risk of stroke or TIA (transient ischemic attack or mini-stroke), compared with those who exercise enough to break a sweat four or more times a week.