Health advantages of exercise in outdoors and the impacts of air contamination

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Exercise is essential in avoiding heart and blood vessel disease in young people so long as they don’t undertake really laborious activity on days when air pollution levels are high, according to an across the country study of nearly 1.5 million individuals released today (Tuesday) in the European Heart Journal.

Until now, little has been understood about the compromises between the health advantages of exercise happening outdoors and the potentially harmful impacts of air pollution.

Previous research study by the authors of the present study had examined the concern in middle-aged people at a single point in time, but this is the very first time that it has been examined in individuals aged in between 20-39 years over a period of several years. In addition, the scientists wanted to see what happens when individuals increase or decrease their exercise in time.

The scientists from Seoul National University College of Medication (South Korea), led by Teacher Sang Minutes Park, took a look at info from the National Health Insurance Service (NHIS) in South Korea for 1,469,972 young Koreans residing in cities, who underwent 2 successive health assessments during two screening periods: 2009-2010 and 2011-2012. They followed up the participants from January 2013 to December 2018.

At each health check-up the individuals completed a questionnaire asking about their exercise in the past seven days and this information was converted into units of metabolic equivalent task (MET) minutes per week (MET-mins/week).

The participants were divided into 4 groups: 0, 1-499, 500-999 and 1000 or more MET-mins/week. European Society of Cardiology guidelines advise individuals ought to try to do 500-999 MET-mins/week and this can be achieved by, for example, running, cycling or hiking for 15-30 minutes five times a week, or brisk walking, doubles tennis or slow cycling for 30-60 minutes 5 times a week.

The scientists utilized data from the National Ambient Air Keeping Track Of System in South Korea to determine annual typical levels of air contamination, in particular the levels of small particle matter that are less than or equivalent to 10 or 2.5 microns in size, known as PM10 and PM2.5.

The quantity of exposure to air contamination was categorised at 2 levels: low to moderate (less than 49.92 and 26.43 micrograms per cubic metre, μm/ m3, for PM10 and PM2.5 respectively), and high (49.92 and 26.46 μm/ m3 or more, respectively).

Dr Seong Rae Kim, first author of the paper, said: “We found that in young people aged 20-39 years old, the danger of heart diseases, such as stroke and heart attack, increased as the quantity of exercise reduced between the two screening durations in the group with low levels of direct exposure to air contamination.

“However, in the group with high levels of direct exposure to air contamination, increasing the quantity of physical activity to more than 1000 MET-min/week, which is more than worldwide suggested levels for exercise, could negatively impact cardiovascular health. This is a crucial result suggesting that, unlike middle-aged people over 40, extreme exercise may not constantly be useful for cardiovascular health in more youthful adults when they are exposed to high concentrations of air pollution.”

He continued: “Eventually, it is vital that air contamination is improved at the nationwide level in order to increase the health advantages of exercising in young people. These are people who tend to take part in physical activity more than other age while their physical ability is at its best. If air quality is not enhanced, this could result in the occurrence of cardiovascular diseases really increasing in spite of the health advantages acquired from workout.”

The researchers adjusted their outcomes to take account of factors that could impact them, such as age, sex, home earnings, body mass index, smoking cigarettes and alcohol intake. Throughout the follow-up period there were 8706 cardiovascular occasions.

Among people exposed to high levels of PM2.5 air contamination, those who increased their exercise from 0 to 1000 MET-min/week or more between the 2 screening periods had a 33% increased threat of heart disease during the follow-up duration compared to those who were physically non-active and did not increase their exercise, although this result was somewhat weaker than that needed to achieve analytical significance.

This means an additional 108 people per 10,000 may establish heart disease throughout the follow-up period.

Amongst individuals exposed to low to moderate levels of PM2.5, those who increased their exercise from none to 1000 MET-min/week or more had a 27% reducedrisk of establishing heart disease compared to those who remained inactive, although this result was likewise not quite statistically significant. This implies 49 less individuals per 10,000 may develop heart disease during the follow-up period.

Dr Kim said: “These results are extremely near statistical significance. In truth, a more analysis presented in Figures 2 and 3 of our paper reveals that statistical significance was accomplished for increasing and reducing quantities of physical activity.”

For low to moderate levels of PM10 air contamination, there was a statistically substantial 38% or 22% increasedrisk of heart disease among individuals who began doing 1000 MET-min/week or more and after that minimized their activity to none or to 1-499 MET min/week, respectively, compared to individuals who maintained the exact same high level of activity. These outcomes were statistically considerable and mean that 74 and 66 extra people per 10,000 respectively would develop cardiovascular problems throughout the follow-up duration.

In general, our outcomes reveal that physical activity, particularly at the level suggested by European Society of Cardiology guidelines, is connected with a lower danger of developing heart and blood vessel disease among young people. Nevertheless, when air contamination levels are high, exercising beyond the recommended quantity might balance out or perhaps reverse the beneficial effects.”

Sang Minutes Park, Professor, Seoul National University College of Medicine, South Korea

The study can not show that air pollution causes the increased cardiovascular danger, just that it is associated with it. Other limitations are that there was no information on whether or not the workout happened indoors or outdoors; individuals might not have actually kept in mind correctly the quantity of workout they took in the 7 days prior to they attended their screening interview, although this is unlikely; PM2.5 data were only determined in three significant cities; and the researchers did not investigate the short-term impacts of direct exposure to air pollution.

Source:

European Society of Cardiology (ESC)

Journal referral:

Kim, S. R., et al. (2021) Association of the combined results of air pollution and modifications in physical activity with heart disease in young adults. European Heart Journal. doi.org/10.1093/eurheartj/ehab139.

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