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According to one study, pollution nullifies the benefits of exercise

By Meera Senthilingam CNN

(CNN) – Taking a long walk through polluted and traffic-laden streets in an attempt to get in shape has negligible benefits for your health, according to a new study.

United Kingdom investigators explored the benefits of walking in people older than 60 years and compared the impact on their health when walking through polluted urban streets versus in the open spaces of a park.

Perhaps not surprisingly, the people who walk in the park were better. The surprise was that the benefits of walking were negligible, in terms of boosting heart and respiratory health, by walking down polluted streets.

The findings, published on Tuesday in The Lancet, suggest that short-term exposure to traffic pollution prevents cardiorespiratory ̵

1; heart and lung – benefits of physical activity during that time.

[Click here to read the study]

"When you walk, your airways open … and your blood vessels dilate, or open … and these effects can last a few days. In a contaminated place, these effects are much smaller, so you have lost the benefits of exercise, "said Dr. Fan Chung, professor of respiratory medicine at Imperial College London, who led the study.

"When you exercise in polluted areas, breathe more, and you get more particles and gases that reach your lungs," he said.

Pollution versus park

Chung's team established the effects of pollution in people with heart and lung diseases, most of whom are over 60 years old, he said.

For a fair comparison, a healthy control group was included, but to the surprise of the researchers, they saw a significant impact of the contamination on everyone.

The team recruited 119 adults older than 60 years and divided them into three groups, depending on whether they were healthy or had heart disease or chronic obstructive pulmonary disease, known as COPD.

Participants were randomly assigned to walk for two hours on London's Oxford Street, a major commercial and highway district in the city, or in the open spaces of the 350-acre Hyde Park, just one mile away. A few weeks later, they walked in the other location.

Traffic along Oxford Street is restricted to allow mainly buses and taxis, which usually run on diesel fuel. In general, London violated the air pollution limits for 2017 only five days of the new year.

For all participants, walking in Hyde Park led to improvements in lung capacity and function, as well as to the reduction of arterial stiffness, which would otherwise be a risk factor for cardiovascular disease, up to 26 hours later.

However, when people walked down Oxford Street, researchers found a smaller increase in lung capacity and an increase in arterial stiffness, which could be attributed to exposure to carbon black soot and ultrafine particles from diesel exhaust, they said.

"In a contaminated place, the (positive) effects are much smaller," Chung said.

People with COPD had the worst case at Oxford Street, with their airways narrowing and their arteries hardening. They also reported more coughing, difficulty breathing, sputum and wheezing.

The team emphasized that some of the benefits of walking in the park could be affected by a more pleasant environment and less stress, but they believe that this does not explain the significant difference they saw.

"If people can not find a green place or a park to exercise, I think they should probably exercise indoors," Chung said.

Walking or not walking

"We are not talking about the very high levels of pollution that are seen in India or China, we are talking about the pollution that occurs on a normal day walking down the main street," he said. Chung. "At that level, we are seeing effects that deny the benefits of walking."

Considers that it is more important that people with heart and lung diseases avoid these areas and adds that despite being conducted in London, the study has global relevance.

"They would apply to European cities and cities in North America where pollution levels are more similar," Chung said.

Asian pollution is one or two orders of magnitude higher, and similar studies should be made at that level of pollution, he said.

However, recent studies in a range of age groups have found that physical activity is beneficial, even in the face of high levels of contamination.

A team investigation at the Diet and Activity Research Center of the University of Cambridge found that the benefits of walking and cycling are greater than the negative effects of air pollution, the opposite of this new study.

"Our model indicates that in London, hea" The benefits of active travel always outweigh the risk of pollution, "said lead author of the research, Marko Tainio, when it was published in 2016." Even in Delhi, one of the most polluted cities in the world, with pollution levels 10 times higher than in London, people would have to spend more than five hours per week before pollution risks outweigh the health benefits. "

In response to the new findings, Tainio said, "it is also important to note that this study looked at the short-term impacts. … These findings should be confirmed by long-term empirical studies that examine compensations for months and years. In addition, Professor Chung and his colleagues noted that the health benefits of walking were lessened, not completely, among healthy participants.

"The authors suggest that people avoid walking on crowded streets and walking in parks or green spaces, and we agree that this is good advice for the recreational walk for people who can make that choice," he added. "But for people who travel daily or shop, even in a city as polluted as London, we still encourage people to walk and ride a bike."

"This document highlights the health risks of walking on polluted roads for people over 60 with pre-existing medical conditions," said Ian Colbeck, professor of environmental sciences at the University of Essex. "However, we know from Another investigation that for the vast majority of the population, the benefits of any physical activity far outweigh any damage caused by air pollution, except for the most extreme concentrations of air pollution. It is important that people continue to exercise. "

Professor Stephen Holgate, Special Advisor on Air Quality at the Royal College of Physicians in the United Kingdom, believes that" we can fully rely on this (new) study that pollution is the factor responsible for changes in function pulmonary. "

Holgate, who was not involved in the new research, added that the sample sizes were small but that" the study deliberately selected COPD and ischemic heart disease in at-risk patients, and … in general, the findings add to the evidence of the importance of the effects of pollutants on vulnerable groups and have implications for the general pollution of vehicles (diesel, gasoline, brakes and tires) as sources of pollutants. "

Tainio stressed that encoding people to exercise could in turn reduce pollution levels.

" The authors do well to emphasize that policies must aim to reduce air pollution and noise levels in the streets to protect the vulnerable population from possible damage. For example, the planned removal of buses and taxis from Oxford Street should help achieve this, "he said.

" However, it is important to remember the role that walking and biking can play in helping to reduce air pollution. and the noise eliminating the motorized transport of the streets. "

TM & © 2017 Cable News Network, Inc., a Time Warner company, all rights reserved.

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