The question
Do indoor cycling (a.k.a. spinning) classes offer any benefits that I can't get from biking on my own?
The answer
In theory, cycling is cycling. The pulse of the music, the exhortations of your instructor and the presence of a group of like-minded exercisers do nothing to spin your pedals.
In practice, though, the ingredients of a typical indoor cycling class somehow combine to lift workouts to heights that most participants wouldn't achieve on their own. The alchemy of group exercise is well known to runners and aerobics classes, but spinning has found a recipe so powerful that researchers studying it have been forced to re-evaluate their definition of "maximal" exercise - and sound a warning for beginners who may wander into a class unprepared.
The current incarnation of group indoor cycling dates back to 1987, when South African-born cyclist Jonathan Goldberg first organized training sessions in the style he later trademarked as "Spinning." These days, more than half of Canadian sports clubs offer group cycling classes, according to figures from the International Health, Racquet and Sportsclub Association. In the United States, 1.6 million people took classes in 2007, while a further 10.6 million pedalled solo.
In a typical class, the instructor leads the class through a ride that varies dramatically in intensity, increasing and decreasing resistance to simulate hills and headwinds. Crucially, each person controls the resistance on her own bike - only the broad contours of the workout are synchronized.
"Successful instructors turn out to be really good at motivating people to push harder," says Carl Foster, an exercise scientist at the University of Wisconsin, La Crosse, and past president of the American College of Sports Medicine.
Dr. Foster and his colleagues recently enlisted 20 female students for a study of the physiological responses to indoor cycling, in order to investigate earlier reports that spinners could exceed their "VO{-2}max" - a measure of the maximum rate at which a person's body can send oxygen to its working muscles. The results, published last year in the Journal of Strength & Conditioning Research, confirmed the anomalous findings.
Spinning doesn't, in fact, have any magical effect on oxygen circulation. The results simply indicate that people in an ordinary cycling class managed to reach higher peak intensities than they did during the rigorous progressive exercise tests that doctors and researchers use to measure VO{-2}max - and much higher intensities than a typical gym user slogging away on a solitary exercise bike.
These peaks are only held for short periods of time, and the average intensity throughout the session is relatively moderate: typically 65 to 75 per cent of maximum intensity, Dr. Foster found. This pattern of highs and lows mimics the "interval" workouts used by endurance athletes to maximize fitness.
In general, this is a good thing. But it does carry risks for new gym users aged over 40, who may have undiagnosed heart disease, Dr. Foster cautions. These people should be wary of jumping straight into a program whose greatest strength is its ability to coax people into working harder than they thought they could.
One solution is health screening, which is often neglected at health clubs, Dr. Foster says. He recommends the Physical Activity Readiness Questionnaire (PAR-Q), a seven-question screening tool developed by the British Columbia Ministry of Health.
Some clubs offer classes for beginners, and good instructors will also be aware of the level of experience of their participants. For the most part, simply being aware of your limits and resisting the urge to push the resistance of your bike too high is the best strategy.
After you've been spinning for a few months, the greatest danger will have passed, Dr. Foster says. Then you're free to give in to what the music, the instructor and the group are urging you to do: Go all out.
Alex Hutchinson blogs about research on exercise and athletic performance at www.SweatScience.com.
The PAR-Q
The Physical Activity Readiness Questionnaire (PAR-Q) asks seven questions. If you answer "yes" to any of them, you should see a doctor before embarking on intense and unaccustomed exercise such as indoor cycling.
Has your doctor ever said that you have a heart condition and that you should only do physical activity recommended by a doctor?
Do you feel pain in your chest when you do physical activity?
In the past month, have you had chest pain when you were not doing physical activity?
Do you lose your balance because of dizziness or do you ever lose consciousness?
Do you have a bone or joint problem that could be made worse by a change in your physical activity?
Is your doctor currently prescribing drugs (for example, water pills) for your blood pressure or a heart condition?
Do you know of any other reason why you should not do physical activity?
Source: Public Health Agency of Canada
Alex Hutchinson