Physical Activity, Air Pollution and the Brain

Sports Medicine (Impact Factor: 5.04). 11/2014; 44(11):1505-1518. DOI: 10.1007/s40279-014-0222-6
Source: PubMed


This review introduces an emerging research field that is focused on studying the effect of exposure to air pollution during exercise on cognition, with specific attention to the impact on concentrations of brain-derived neurotrophic factor (BDNF) and inflammatory markers. It has been repeatedly demonstrated that regular physical activity enhances cognition, and evidence suggests that BDNF, a neurotrophin, plays a key role in the mechanism. Today, however, air pollution is an environmental problem worldwide and the high traffic density, especially in urban environments and cities, is a major cause of this problem. During exercise, the intake of air pollution increases considerably due to an increased ventilation rate and particle deposition fraction. Recently, air pollution exposure has been linked to adverse effects on the brain such as cognitive decline and neuropathology. Inflammation and oxidative stress seem to play an important role in inducing these health effects. We believe that there is a need to investigate whether the well-known benefits of regular physical activity on the brain also apply when physical activity is performed in polluted air. We also report our findings about exercising in an environment with ambient levels of air pollutants. Based on the latter results, we hypothesize that traffic-related air pollution exposure during exercise may inhibit the positive effect of exercise on cognition.

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Available from: Luc LR Int Panis, Aug 21, 2014
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    • "A high physical activity implies a high ventilation rate and thus a higher inhaled dose, but performing physical activity while being exposed to air pollution can also cause intermediary health effects like acute pulmonary effects, e.g. temporary decreases in lung function, acute cardiovascular effects (Bos et al., 2014; Strak et al., 2010; Weichenthal et al., 2011). Despite the fact that the relationship between PA and ventilation rate is uncertain because of complex lung physiology (EPA, 2011), incorporating ventilation rate can result in more detailed values of inhaled dose. "
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    ABSTRACT: Exposure to air pollution can have severe health impacts, especially for the elderly. To estimate the inhaled dose of air pollution, traditionally only the air pollution concentration at the home location is considered, without incorporating individual travel behavior and physical activity. This can lead to bias in health impact assessment and epidemiological studies, possibly underestimating exposure to air pollution and misinforming policy makers. Our paper addresses this issue using accurate 7-day GPS and accelerometer data on 180 participants aged between 58 and 65 living in Ghent (Belgium). NO 2 concentration for Belgium is available from a land-use regression model. Three methods are used to calculate the inhaled dose of NO 2. The first method is the traditional static method, using only the NO 2 concentration at the home location. The second method incorporates travel behavior using GPS data, thus looking at the NO 2 concentration at the exact location of the participant. The third method additionally incorporates accelerometer data and estimates the transport mode used and physical activity to calculate the ventilation rate. When incorporating geographical location, differences in inhaled dose of NO 2 depend on the NO 2 concentration at the home location and the individual travel behavior. When additionally incorporating ventilation rate, the inhaled dose of NO 2 increases by more than 12%. In addition to comparing these three methods with each other, the influence of transport mode is tested. Cycling is associated with increased inhaled doses of NO 2 relative to other modes. It is important for health impact assessment and epidemiological studies to incorporate individual travel behavior and physical activity to measure the inhaled dose of air pollution, and this can be done accurately using GPS and accelerometer data.
    Full-text · Article · Nov 2015
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    • "Nevertheless, it seems clear that air pollution from traffic (often measured as mass of PM10 particles, Black Carbon or nitrogen dioxide, NO 2 ) is associated with effects on the cardiovascular, immune, respiratory and central nervous systems. Healthy people who engage in active transport have a better life expectancy, but may nevertheless experience minor physiological effects when exercising in polluted places (Jacobs et al. 2010; Bos et al. 2013, 2014). "
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    ABSTRACT: Abstract Background: Int Panis et al. (2009) concluded that cyclists are much more exposed to air pollution compared to car passengers, due to higher ventilation. The VE for cyclists was found to be 4.3 times higher than for car passengers. We dig further into this high ratio, wondering if the high exposure is due to the speed at which the cyclists were cycling. We define the optimal speed as the cycling speed that minimizes inhalation of pollution and we ask ourselves the question if there is a more “optimal” speed at which those cyclists could have cycled during the field trips to reduce their exposure. Further we investigate the optimal speeds and differences in exposure between well trained and poorly trained cyclists. Methods: Maximal Exercise Test data are used to convert power into cycling speed. We check the result with real life cycling (heart rate and speed) during field trips. We group persons according to their VO2max, which is used as a measure for condition to check if differences depend on the physical condition of the test persons. Results / Conclusion: There is an optimal cycling power range that minimizes exposure. This optimal cycling power is associated with a minute ventilation below the first ventilatory point. When we convert power into cycling speed we get an optimal average interval of 18.6 - 21.8 km/h for men and 15.3 - 19.2 km/h for women. Note that this conversion is depending on cyclist, bycicle, road and weather conditions. Cycling with a speed above the optimal speed increases the exposure to air pollution. When comparing the optimal cycling speed with the speed cycled during the field trips, we conclude that cyclists in the field study tend to cycle at a speed that is slightly too high to optimize their exposure. Cyclists in Mol could have cycled 2.5 km/h slower, resulting in 10.7 % less pollution exposure, and 13.96 L/km less air intake. Unfortunately this small reduction in air intake will not offset the large difference between cyclists and car passengers (a factor of 4.3). We also look at the ventilation needs per kilometre at different cycling intensities. We conclude that it is important not to train in highly polluted areas. Finally, we don’t see any differences in L/km between well trained and less trained bikers around the “optimal interval” of relatively low speed. We do see that well trained cyclists can cycle at a higher speed without increasing their exposure per km distance. The interval of optimal speed tends to get wider when condition increases.
    Full-text · Chapter · Oct 2015
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