In many cases, the benefits of sports outweigh the risks of overexposure to pollutants.

Cycling and walking are two active modes of transport beneficial to health as they increase the body’s physical activity. But active transport also increases the amount of inhaled polluted air, which could have a negative impact on health.

So can we pedal safely in the city?

In 99% of cities, the benefit of sports is higher than the risk associated with pollution

An international team of researchers assessed the benefit/risk ratio of active transport in a polluted environment (2). The researchers modeled the effects of cycling and walking in different polluted environments and measured a duration from which there were no more health benefits. The effects on all-cause mortality were tested.

The study found that only 1% of the world’s cities have a level of pollution such that outdoor physical activities are detrimental to health: the health benefits of walking or cycling exceeded the risks associated with inhaling polluted air.

For Audrey de Nazelle, of Imperial College London, “The good news is that all over the world, in 99% of cities, it is safe to bike up to two hours a day.” According to Marko Tainio, who conducted this research, “even in Delhi, one of the most polluted cities in the world with pollution levels ten times those in London” people should spend more than five hours a week cycling so the risks of pollution prevail over health benefits.”

It is still better to avoid the proximity of cars

A study of the Harvard School of Public Health (3) somewhat nuances this idea: by sharing the road with cars, a cyclist increases by more than 30% his exposure to air pollutants than if he pedals on a bicycle path separated from the road .

In the city, pollution emissions related to road traffic are responsible for a significant part of air pollution. Among the air pollutants are: fine particulate matter (PM 10 and PM 2.5, PM = particulate matter), nitrogen dioxide NO2, carbon monoxide (CO) and ozone (O3).

Researchers in Boston have measured the pollution along 5 of the city’s cycle routes, including bicycle lanes directly adjacent to the road, bicycle lanes separated from the road and roads shared by buses and bicycles. The researchers surveyed these routes by bicycle with a pollution measuring device. In particular, they have measured two known elements to increase cardiovascular risk and the risk of lung cancer: carbon black (black carbon) particles and nitrogen dioxide.

Carbon black particles are emitted by exhaust (including diesel engines) and represent a relevant tracer of road traffic pollution. Nitrogen dioxide is a toxic gas produced by combustion. It causes inflammation of the airways.

The results show pollutant concentrations are one-third higher on bicycle lanes adjacent to roads than on more distant cycle lanes. The air quality is particularly bad at the intersection where the cars stop and restart. Conclusion: if you have a choice, opt for the green routes.

And in the gym the air is also polluted

You want to get into the gym to avoid pollution? This may not be the best idea … The quality of the air in the gyms is influenced by the maintenance of the buildings, the building materials, the type of ventilation but also by the occupancy rate and the type of activities carried out.

In a recent study (4), researchers placed equipment to analyze air quality in gyms in Lisbon. Carla Ramos, author of the study, obtained permission from 11 gyms to dispose of the equipment to analyze the air quality in both the weight rooms and the small ancillary rooms. The devices have been programmed to analyze pollutants in the air in late afternoon and evening when attendance levels are higher. The researchers assessed the pollutants generally found in indoor air: carbon monoxide, carbon dioxide, ozone as well as airborne particulate matter (dust) and chemical products (including formaldehyde) released by carpets, cleaning products, furniture, paint.

Researchers found high levels of airborne particulate matter, formaldehyde, and carbon dioxide (CO2) in gyms. The concentrations of these pollutants exceeded the European standards generally accepted for indoor air quality. The levels of these pollutants were particularly high during aerobics classes, during the time when people are confined in small rooms, move a lot and breathe heavily.

High concentrations of particulate matter and chemicals, such as formaldehyde,  in the air are the most worrying problem. “They can cause asthma and respiratory problems,” says Carla Ramos. “Carbon dioxide, even if it is not toxic, could also be a source of concern.” At high concentration, it can train physical fatigue and cognitive confusion, which is not desirable during an aerobics course, adds Carla Ramos.

References

(1) Chen H1, Goldberg MS, Villeneuve PJ. A systematic review of the relation between long-term exposure to ambient air pollution and chronic diseases. Rev Environ Health. 2008 Oct-Dec;23(4):243-97.

(2) Tainio M, de Nazelle AJ, Götschi T, Kahlmeier S, Rojas-Rueda D, Nieuwenhuijsen MJ, de Sá TH, Kelly P, Woodcock J. Can air pollution negate the health benefits of cycling and walking? Prev Med. 2016 May 3. pii: S0091-7435(16)00040-2. doi: 10.1016/j.ypmed.2016.02.002.

(3) The Boston Globe. Cyclists, don your gas masks. By Kevin Hartnett.

(4) C.A. Ramos, H.T. Wolterbeek, S.M. Almeida. Exposure to indoor air pollutants during physical activity in fitness centers. Building and Environment 82 ( décembre 2014) 349-360

Can we do sports when we live in a polluted city?
Nutrition and Innovation

Athletes who receive omega-3 fatty acid supplements have improved muscular function and less muscular fatigue

A new study by researchers at the University of Toronto and published in the Journal of the International Society of Sports Nutrition reports omega-3 fatty acid supplements can improve neuromuscular function and reduce muscular fatigue among athletes. Those who received omega-3 for 3 weeks had a 20% increase in their muscular function in the thigh.

Omega-3 fatty acids are polyunsaturated fatty acids in the form of long chains in fatty fish, shells, crustaceans, and chicken eggs fed with flax seeds. They can also be synthesized from the alpha-linolenic acid of rapeseed, flax seeds, walnuts…

“The ability of skeletal muscles to generate strength and withstand fatigue is essential in sports performance,” explain the authors in their article. “Training adaptations of skeletal and neuromuscular muscular systems modulate the ability to generate muscular strength and fatigue resistance.”

“Many studies have evaluated the effect of nutritional supplements on bodybuilding (protein supplementation) and methods for enhancing endurance performance (carbohydrate load).” But to date, few studies have focused on the effect of nutritional supplements on the neuromuscular system.

The central and peripheral nerves are composed of fatty acids, essentially polyunsaturated. “Omega-3 is an integral part of neurons, nerve endings, myelin and muscle membranes.” And more and more evidence suggests that omega-3 improves neuronal function and adaptations to exercise. “Omega-3 supplementation would be able to improve the velocity of nerve conduction, membrane fluidity, sensitivity to acetylcholine and also reduce inflammation after exercise.”

The researchers conducted their study on 30 male athletes on average 25 years old and trained about 17 hours per week. Participants received either the seal oil supplement containing long chain omega-3 (375 mg eicosapentaenoic acid EPA, 230 mg docosapentaenoic acid DPA, 510 mg docosahexaenoic DHA acid per day) or placebo for 3 weeks. The athletes passed tests at the beginning and end of the study.

The results show omega-3 supplements are associated with a significant increase in the level of EPA in the blood compared to placebo-receiving participants. But the researchers did not find any difference between the two groups for the levels of DPA and DHA.

Omega-3 supplements allowed a 20% increase in muscle function of the thigh, evaluated by electromyography of the extensive external muscle, compared to placebo. Omega-3 supplements were also associated with a reduction in muscle fatigue.

“To our knowledge, this study is the first to evaluate the effects of omega-3 fatty acid supplementation on athletes by measuring both the changes in neuromuscular function and performance,” the authors say. “This study shows omega-3 supplements increase muscle activation and reduce fatigue.” According to the authors, there is sufficient evidence to conclude omega-3 has a beneficial effect among athletes.

The authors explain that omega-3 modifies the composition of the cell membrane and its fluidity, which could stimulate the nerve function. “Omega-3 supplementation may have altered the membrane dynamics of the muscle and improved the conduction of muscle action potential through the working muscle.” “Altering the membrane dynamics may have attenuated muscle damage.”

Similarly, in the group having received omega-3, the attenuation of muscle damage could maintain the conduction of the action potential in the muscle, now thus the excitation-contraction coupling and finally the generation capacity of muscular strength.

This study is in addition to the already existing evidence of omega-3 benefits in the nutrition of the athlete.

Reference

Lewis EJ, Radonic PW, Wolever TM, Wells GD. 21 days of mammalian omega-3 fatty acid supplementation improves aspects of neuromuscular function and performance in male athletes compared to olive oil placebo. J Int Soc Sports Nutr. 2015 Jun 18;12:28. doi: 10.1186/s12970-015-0089-4. eCollection 2015.

Omega-3 improves sports performance
Nutrition and Innovation

Physical activity fights against inflammation, and the more you do it, the more it decreases.

Running, swimming, biking, tennis … Physical activity has many benefits, especially because it helps reduce inflammation. An article in the European Journal of investigation explains how physical exercise works.

The longer it is, the better

Chronic inflammation is linked to all kinds of diseases including type 2 diabetes and heart disease. But when muscles work, muscle cells release interleukin-6 (IL-6) and interleukin-10 (IL-10), two mediators playing an important role in the fight against inflammation.
Il-6 and IL-10 act both by decreasing the levels of TNF-alpha protein, itself causing inflammation in the body but also by inhibiting the signaling effects of the interleukin-1-beta protein which causes inflammation and damages the pancreas cells.

According to the authors of the article, longer the duration of physical activity, the greater the amount of IL-6 released-the first cytokine detectable during physical activity is important. For example, after a 30 minute workout, IL-6 level can be multiplied by 5 while after a marathon it can increase by a factor of 100. The level of IL-6 increases until the end of the physical activity session and then decreases rapidly to return to the level of prior physical exercise.

Interleukins 6 and 10 are not the only molecules involved in the anti-inflammatory effect of physical activity. For example, studies have shown regular exercise increases the level of interleukin-15 in muscle cells. However, IL-15 reduces the accumulation of abdominal fat, which itself promotes inflammation. By reducing abdominal fat, physical exercise therefore fights against inflammation.

In practice

“Physical activity represents a natural method for combating inflammation and improving metabolism should be part of the treatment of people with chronic diseases such as diabetes or heart disease,” concludes the article. In practice, chronic inflammation can be reduced from 20 minutes of walking. If you’re not athletic but you want to get on with it, we can progressively intensify the rhythm of the outings, of sports sessions from 15 to 40 minutes of running at slow pace (30 minutes to 2 hours biking (or 10 to 20 minutes of running time (20 minutes to 1 hour) with a steady pace.

A natural anti-inflammatory: running (pedaling, swimming…)
Nutrition and Innovation

Among professional athletes, training associated with dietary proteins would stimulate the diversity of the intestinal flora.

For a healthy and diversified intestinal flora, it would be better exercising than eating yoghurts with active bifidus. According to an Irish study, sports associated with a large consumption of proteins would promote the bacterial diversity of the intestinal flora.

Intestinal flora plays an important role in digestion, but also immunity. An intestinal flora whose diversity is reduced is associated with obesity and health problems. On the other hand, a diversity of the bacterial species present in the intestinal flora is linked to favorable metabolic profiles and a better immune response.

To learn about the impact of physical exercise on the intestinal flora, researchers have been interested in professional rugby players. Indeed, the lifestyle could influence the composition of the intestinal flora. The fecal and blood samples of 40 professional players who participated in an intense training program were compared with those of 46 healthy men. The witnesses were not professional athletes but their ages and sizes matched those of the players. All participants filled out food questionnaires and answered questions about their physical activity.

The researchers have dosed the level of creatine kinase in the blood, an enzyme marker of muscle damage and therefore is proof of an extreme exercise. Athletes had high amounts of creatine kinase but levels of markers of low inflammation. The diversity of their intestinal flora was greater, with a number of different bacterial types more important. For example, athletes had more akkermansiaceae, bacteria associated with low rates of obesity and metabolic disorders.

Overall, rugby players ate larger amounts of all types of food. But proteins accounted for 22% of their energy intake compared to 15-16% for the control group. This was explained by the consumption of meat and meat products but also of protein dietary supplements. The athletes also ate more fruits and vegetables.

For the authors, these results show that exercise, in addition to diet, is an important factor in the microbial diversity of the intestinal flora.

Reference

F. Clarke, E. F. Murphy, O. O’Sullivan, A. J. Lucey, M. Humphreys, A. Hogan, P. Hayes, M. O’Reilly, I. B. Jeffery, R. Wood-Martin, D. M. Kerins, E. Quigley, R. P. Ross, P. W. O’Toole, M. G. Molloy, E. Falvey, F. Shanahan, P. D. Cotter. Exercise and associated dietary extremes impact on gut microbial diversity. Gut, 2014; DOI: 10.1136/gutjnl-2013-306541

Exercise promotes the diversity of the intestinal flora
Nutrition and Innovation

Plunging into cold water after exertion decreases aches.

The body aches are caused by micro-traumas to the muscular fibers after a sports training. A normal phenomenon but can be problematic by preventing the athlete from quickly resuming his training at full capacity.

Many people are struggling to endure these pains sometimes even to the point of not doing sports anymore. This is not advisable because with the workout your muscle fibers strengthen and the aches decrease over time, sometimes going as far as disappearing. Meanwhile, researchers have validated a method which has been used for a few years by high-level athletes to reduce body aches: cold baths.

Researchers from the Cochrane group reviewed all studies on the use of cold baths to prevent aches, compared to rest. After analyzing 19 studies they conclude that cold baths are effective in solving this problem. But be careful, cold baths must be at a temperature of 15 degrees maximum and last at least 15 minutes. On the other hand, researchers indicate that the efficiency of cold baths is not demonstrated in comparison with active recovery methods (return to sports quickly with light training to accelerate the disappearing of the pain) for which new studies are needed but the cold baths have the advantage of saving time and being simple to set up.

How do cold baths reduce body aches? The micro-traumas to the muscular fibers that are causing the body aches are responsible for calcium leakage within the fibers. This phenomenon is toxic and triggers a delayed inflammatory reaction, hence the onset of aches 24 to 48 hours later. The sensitivity of muscle fibers to calcium depends on the temperature: it increases when it’s hot and decreases when it’s cold. By dipping into an icy bath after effort, the toxicity of calcium is reduced and thus the release of the inflammatory substances causing the pain. But the anti-inflammatory effect of the cold is in fact known for a long time: this is why ice pockets are applied to certain wounds.

Reference

Bleakley C., McDonough S., Gardner E., Baxter G. David, J. Ty Hopkins, and Gareth W Davison. Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. The Cochrane Library, Feb 2012.

A cold bath against muscle soreness
Nutrition and Innovation