As children, pretty much all of us learn to ride a bike and as we do so, we are inevitably told: "Once you learn, you'll never forget." It should come as no surprise, then, that one of the healthiest things you can do as an adult is to wend your way back through time and memory by riding a bike.

An easy way to exercise, cycling provides an excellent aerobic workout while being easy on the joints. It may seem counterintuitive, but cycling involves every single part of the body and does not solely strengthen the leg muscles; riding a bike will tone and build muscles throughout your body. Regular cycling improves mobility of hip and knee joints while also helping you to regain lost coordination and balance.

Cycling is associated with improved cardiovascular fitness, as well as a decrease in the risk of coronary heart disease. According to the British Medical Association, cycling just 20 miles a week can reduce the risk of coronary heart disease by 50 percent. As with any regular exercise, it also helps to reduce stress.

Steady cycling burns approximately 300 calories per hour. For those intent on losing weight, a program of 30 minutes cycling every day of the week will burn about 11 lbs. of fat in a year. Since exercising builds muscle, cycling also will naturally boost your metabolic rate. If you cycle outdoors far from the city, you will commune with nature while breathing more deeply, more fully. Unlike sports that require either a high level of skill or a substantial time commitment, biking can be done on your own time and at your own pace. Best of all, because it improves muscle function gradually, there's little risk of strain.

Promoting cycling for health reasons suggests the benefits outweigh the disadvantages, but as is the case with everything, risks do exist.

Pollution

Although society as a whole would gain if a general shift occurred from cars to bikes, as air pollution emissions would certainly decrease, individuals who choose to cycle instead of driving a car encounter some negatives. For instance, the increased physical activity of riding a bike may be beneficial for your health, but inhaling more pollutants because of an increased breathing rate has the opposite effect. A review of recent studies, all of which assessed the benefits and risks of a cycling as compared to driving, summed up the results.

In various studies of air pollution exposure levels associated with different modes of transport, the emphasis is placed on fine and ultrafine particulate matter because these are the main pollutants related to human health effects. Driving or cycling in traffic may result in air pollution exposures that are substantially higher than overall urban background concentrations so even relatively short times spent in traffic may contribute significantly to daily exposures. Overall, air pollution exposures experienced by car drivers were modestly higher than those experienced by cyclists; however, increased physical activity results in higher minute ventilation (volume of air inhaled in one minute) for cyclists than for car drivers, with estimates from two Dutch studies reporting that the minute ventilation of cyclists was 2.3 times and 2.1 times higher than that of car drivers.

Therefore, inhaled doses of particulate matter and, to a lesser extent, elemental carbon may be higher for cyclists when compared to drivers. The difference in exposure between cyclists and car drivers depends on a large number of factors, such as selected route, car speed, trip duration, car type, ventilation status (open windows), driving behavior, and weather conditions. Most of these factors can be adjusted to lessen potential negative effects in either case.

Accidents

When cycling, the risks of being involved in traffic accidents as well as the severity of an accident, may increase. In the Netherlands, one study compared the risks of a fatal accident for car drivers and cyclists, including the risk to other road users; the analysis excluded date taken from motorway accidents because cyclists cannot use these roads. Mortality rates were similar for car drivers and cyclists, though adults older than 50 were less frequently involved in fatal accidents when driving a car than when cycling, while the opposite was true for adults younger than 50. Another study showed that in different European countries, the number of traffic deaths of cyclists was inversely related to the amount of cycling, suggesting a "safety-in-numbers" effect.

Because chosen route exerts a substantial influence on safety, actual risk may be smaller because cyclists would, in all likelihood, choose a lower-traffic route than the main roads analyzed within the studies.

And this naturally brings us to biking trails.

Safest Routes

Many towns and cities, especially those in the western U.S., have established trails that are meant to accommodate cyclists and pedestrians while remaining inaccessible to cars. To find those nearest you, simply search the internet for bike trails. Another possibility for biking in a place segregated from cars are rail-trails, which are public paths created from former railroad corridors.

Most are flat or follow a gentle grade and traverse urban, suburban, and rural terrain. Rail-with-trails often run parallel to a still-active rail line. Generally, the rail and trail share an easement; some trails are adjacent to high-speed, high-frequency trains (often separated by extensive fencing), while others run alongside tourist railroads and slow-moving excursion trains. Through a provision of the National Trails System Act, these out-of-service rail corridors can be used as trails until a railroad needs the corridor again for train service. More than 4,000 miles of rail corridor in 33 states have been preserved in this way. As a result, more than 100 trails currently exist in the U.S. In addition, the Rails-to-Trails Conservancy (RTC) program has acquired more than 650 miles of corridor and has identified more than 1,400 rail-trails, with at least one in every state.

For more information on cycling along a scenic rail-trail, go here.

Source: De Hartog JJ, Boogaard H, Hoek G. Do the Health Benefits of Cycling Outweigh the Risks? Environmental Health Perspectives. 2010.