Cycling is an aerobic endurance sport. Unlike exercises like jogging, cycling is low-impact, meaning that it puts little pressure on the joints, especially the knees. Other benefits of regular cycling include a decreased risk of heart disease, stroke, diabetes and some types of cancers. Cycling involves the main leg muscles, which are responsible for producing the power used to turn the pedals and propel the bike forward.
Main Leg Muscles
The muscles attached to the tibia or shinbone and fibia, the thigh bone, do most of the work for cycling. Muscle tissue is made up of thousands of thin fibers that receive messages from the brain to contract. As you pedal, your quadriceps, gluteals, hamstrings and calves, including the gastrocnemius and soleus, contract. The quadriceps and hamstrings make up the bulk of the pedal stroke as they continue to contract, thus causing your feet to pedal in circles. Muscles also contain fast and slow twitch fibers. Fast twitch fibers enable you to sprint or quickly accelerate, while slow twitch enable you to pedal for hours at a moderate intensity. Fast twitch fibers tire quickly.
Power Phase
During the pedal stroke, you enter the power phase when your feet are positioned between 12 and 5 o'clock. This is when your muscles powerfully push the pedals. During this time, the hamstrings, which run from the pelvis to the back of the knee, extend the hip, especially when the heel drops slightly. The gluteal muscles also assist with this action. The hamstrings are also responsible for bending the leg, whereas the quadriceps make it possible to straighten the leg. This set of muscles runs from the pelvis and attaches at the knee.
Upstroke
Once your foot reaches the 5 o'clock position, your leg muscles begin to transition into the back stroke. The gastrocnemius and the soleus, or calf muscle, control the movement of the foot on the pedal. The deep muscles control the toes. The calves enable you to point your toes down slightly, which transfers power from the quadriceps, hamstrings and gluteals, to the pedals, therefore projecting the bike forward. The upstroke provides a short recovery for the major leg muscles as the pedal drives the foot upward toward 12 o'clock. At this point, your major leg muscles prepare for another powerful push.
Increase Strength
Cycling strengthens and tones the leg muscles. To build strength, it's important to continually challenge your muscles with difficult terrain or by increasing the intensity of your ride. For additional strength, and to avoid muscle imbalance issues, add exercises like squats, lunges, plyometrics, standing calf raises, and leg presses to your off-season training routine. These will help train the muscles you use on the bike, and develop stabilizer muscles such as your core and lower back.
