As a physician, first and foremost it must be said that any and all exercise has health benefits for the person suited for it. Before embarking on any exercise program you should consult your doctor to see if you have any limitations and that exercise is safe to do. Specifically, there are some injuries/illnesses where cycling may not be recommended. That said, for the majority of people, cycling has numerous beneficial effects.
Probably one of the most important benefits of cycling is an improvement in cardiovascular health. Cycling is predominantly an aerobic activity therefore your heart blood vessels and lungs are all getting a workout. You will have increased body temperature, sweats, and breathe deeper which will improve your overall fitness. This type of exercise actually strengthens the muscles of the heart and lowers your resting pulse. Cycling can be performed at a steady rate and can be performed as part of an interval training program. Since cycling utilizes the largest muscle groups which are located in the legs, the heart rate will be raised which will help to improve stamina.
One so reasons why cycling can be so beneficial to health is because it has a lot of fun! People of all ages from young children to older adults love it and it is a low impact exercise which allows it to be performed for most people throughout their lives. People can ride their bicycles almost anywhere and anytime of the year and without spending as much money as many other fitness programs. Also, a high level of skill is not required. Even if you haven't been on a bicycle for a very long time it truly is as the saying goes"like riding a bike". This phrase is utilized so often because many people have not cycled since they were children yet they are able to easily pick it up as adults because once the skill is learned, it truly is not forgotten.
As expected, cycling greatly increases the muscle tone in the legs, thighs and buttocks; however, it is also great to improve the mobility of the hip and the knee joints. Also, cycling works on your core muscles due to the need for balance in this activity. Improved coordination is also part of this process due to the fact that the entire body is involved in cycling. As you can imagine hand eye coordination, body to eye coordination, arms to legs as well as feet to hand coordination are all improved. Contrary to popular belief, even your arm muscles will be getting a workout particularly relating to steering. As you would expect with increased cardiovascular fitness and increased muscle tone and strength, weight loss also will come along. Because this type of exercise is so much fun, people tend to do it more and therefore makes it easier to lose weight. It is said that steady cycling burns around 300 cal per hour. Given that people often lose track of how much time they are actually cycling, you can imagine how many calories they may actually be able to burn in one given ride.
One should also not forget the benefits of exercise in relation to mental health. Exercise has been shown to reduce depression and anxiety as well as an overall improvement in self-esteem and sense of happiness. Particularly for people who are depressed, being outdoors is very beneficial to healing and it takes a person's mind away from their day to day stressors that they constantly see in their home.
Although it has not been completely proven through research, it is felt that cycling may lower the risk of cancer including breast and colon cancer, diabetes and dementia.
As beneficial as cycling can be, it should not be the only exercise that you perform. Over-exercising in any given sport can lead to stress/strain injuries. Cycling should be incorporated into a larger fitness program which includes resistance training as well as different types of interval cardiovascular exercise. Since cycling improves both stamina and cardiovascular fitness, it can be used as a basic type of training in all types of fitness programs as well as for elite athletes.
As with all exercise programs, including cycling, routines should start slowly to build up endurance and to prevent injury. It is important not to go from a "couch potato" to Olympic level trainer in one day! Stamina can be built from initially cycling at a low intensity and then built up to a more demanding activity. Do not forget to use protective gear including helmets, kneepads, elbow pads as well as other safety items depending on your skill level.
There are numerous research articles on this subject. Here are a few if you would like to read further:
Bike For Your Life, Bicycle Association & Cyclists' Public Affairs Group, London, 1995. Heart disease would decline 5-10% if one-third of short trips shifted from driving to bicycling.
"Cycling and Health Promotion," British Medical Journal, Vol. 320, 1 April 2000, p. 888. http://bmj.com/cgi/content/full/320/7239/888
“Cycling to School and Cardiovascular Risk Factors:A Longitudinal Study” Journal of Physical Activity and Health, 2011, 8, 1025 -1033 http://lin.ca/sites/default/files/attachments/anderson_cycling_cardiovascular%5B1%5D.pdf
Federal Highway Administration, Benefits of Bicycling and Walking to Health, National Bicycling and Walking Study #14, USDOT, FHWA, Bicycle & Pedestrian Program, Washington DC, 1992.
Oja, P., Titze, S., Bauman, A., de Geus, B., Krenn, P., Reger-Nash, B. and Kohlberger, T. (2011), Health benefits of cycling: a systematic review. Scandinavian Journal of Medicine & Science in Sports, 21: 496–509. doi: 10.1111/j.1600-0838.2011.01299.x
Maxine JE Lamb MPH, Nynke Halbesma PhD andSarah H Wild MBBChir, PhD* (2013) “Cycling as a mode of transport: a possible solution for the increasing burden of type 2 diabetes?” Practical Diabetes Volume 30, Issue 7, pages 286–289, September 2013