Cycling is form of non-weight bearing exercise that conditions the cardiovascular system, muscles of the lower body, lower back and abdominal muscles. Revolving pedals allow a bike to move forward; the pedal stroke can be categorized into phases: forward, downward and upstroke. Each phase of the pedal stroke is associated with contraction of specific muscles of the lower body.
Muscle Recruitment
To move a bike forwards, the lower body propels bike peddles in a circular motion, similar to the hands of a clock. The stroke of the pedal has a forward, down, and pulling motion. Each of these specific motions is created by the contraction of specific muscles of the lower body. The revolving motion can also be identified by specific motions and associated muscles engaged during each motion.
Quadriceps Recruitment
The quadriceps include four muscle bellies located on the front and anterior thigh. The quadriceps originate at the anterior hip and femur and insert around the knee creating the quadriceps tendon. Contraction of the quadriceps causes extension of the knee and creates a downward force, for example, when climbing stairs or standing from a seating position. While cycling, the quadriceps are recruited during the forward, downward motion of each pedal revolution.
Gluteal Recruitment
Downward and forward motions of the pedal also occur with extension of the hip by contraction of the gluteus medius, gluteus minimus, tensor fascia latae and sartoirous. The gluteus medius and minimus are located on the back side or posterior side of the body. These muscles originate around the lower back and insert into femur or upper thigh. The tensor fascia latae and sartorious are located on the lateral side of the femur and anterior thigh.
Hamstring Recruitment
The upstroke of the pedal during each revolution is caused by the hamstrings, a group of three muscles on the posterior or back of the thigh. Hamstring muscles originate near the ishial tuberosity or "sits bones" and insert around the back of the knee. As these muscles contract, the knee is flexed, thereby aiding to the upward puling motion during each peddle stroke.
Recruitment of Additional Muscles
The foot also plays a major role in the revolution of the pedal while cycling. The motion of the foot around the ankle is controlled by two major muscles of the lower extremity, the tibalis anterior the and calf muscle group, which includes the gastrocnemius and soleus muscles. The tibialis anterior muscle is located on the anterior leg and helps dorsiflex the foot during the forward and downward motion of the pedal stroke. Calf muscles, which are found on the posterior leg, aid plantar flexion and are contracted during both downward and upstroke phases of a revolving pedal.
References
- "Journal of Biomechanics": Knee flexor moments during propulsion in cycling--a creative solution to Lombard's Paradox; R.J. Gregor; 1985
- Free Communications, Oral Presentations: Flexibility
- "Journal of Orthopaedic & Sports Physical Therapy"; Cycling Biomechanics: A Literature Review; Cheryl A. Wozniak Timmer, PT, MS; September 1991
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