The REAL Truth on Whether Indoor Cycling Bulks Up Your Leg

Celebrity trainer Tracey Anderson in Redbook magazine, stated that “Spinning may burn calories in the short term, but if that’s all you’re doing, it’ll bulk your thighs…[and can actually make you gain weight].”…but is that really true?

The simple fact is that there is no evidence to support her assertion. Numerous experts agree, including exercise physiologist Michele Olson, Ph.D., professor of Exercise Science at Auburn University Montgomery (quoted in Stephenson’s response), citing recent studies that have shown women actually lose fat from their guts and lower bodies when they cycle often, even though their thighs may look temporarily pumped after a workout.

The scientific research to support indoor cycling as a meaningful and effective way to lose weight and maintain fitness is also very well documented. Most notably, the Bianco, et al. (2010) study found that indoor cycling training was an efficient method for weight loss in women, and Valle et al. (2010) observed significant reductions in body mass and fat percentage in body mass index in subjects who participated in an indoor cycling program for 12 weeks.

In addition to collecting and conducting research, we’ve been working with cyclists of all levels for over 20 years, and have  deep practical experience understanding how cycling affects people’s bodies. Consider the body “archetype” of professional road cyclists. They are all on the leaner side of the athletic body type spectrum, not the bulkier one. And while their leg muscles may be chiseled, they are not “bulky”—any ‘bulkiness’ would be attributable to their body type (i.e., endomorph), not to cycling.

 To get scientific for just a moment, hardcore cycling requires a large proportion of fast-oxidative glycolytic (FOG) muscle fibers. These are the fibers that allow a rider to go long, go fast and explode at the right times without fatiguing too quickly.  Thicker fibers only develop as a result of heavy loads, time under tension and, of course, genetics. Spinning®, which was created as a sports-specific indoor training program for cyclists, is a program tailored for 30-90 minute classes—the thicker fibers can’t sustain this type or duration of activity, and therefore do not develop in response to Spinning® or other indoor cycling programs.

 So, when it comes to Anderson’s statement about spinning bulking up the thighs, there’s just no facts to back it up.