Indoor cycling does more than build a strong cardiovascular system. This intense class, in which you are led over a series of simulated hills and flat roads, experiencing virtual wind and competitive riders all set to the beat of music and a driven instructor, also builds strong leg muscles.
The down portion of the pedal stroke primarily targets your quadriceps, which are located in front of the thighs, while the motion of pulling up the back edge of the stroke targets your hamstrings at the back of the thighs.
The muscles of the calf work for a majority of the pedal stroke, especially if you push down and pull up with your toes. Both the large, bulging gastrocnemius and smaller, internal soleus are activated by pedaling.
Back and Upper Body
Your upper body supports you as your rest your hands on the handlebars, but this region doesn't provide any real power. Your back muscles, particularly the erector spinae that run along the spine, help stabilize and support your torso as you ride in a pitched-forward position.