Cycling is a low-impact activity that doesn't produce the jarring to the spine or joints that exercises like running or jumping do. Regular cyclists have a reduced risk of heart disease, high blood pressure and cholesterol and a decreased risk of stroke, diabetes and some types of cancers. Cycling also strengthens and tones the hamstrings.

Hamstrings

The hamstrings are one of three posterior thigh muscles and tendons that run from the pelvis to the knee. They are responsible for flexing the knee and bending the hip. While cyclists tend to feel their quadriceps working more than the hamstrings, the hamstrings play two roles in a cyclist's pedal stroke, which, in turn, strengthens and tones the muscles with every revolution.

Pedal Stroke

Half of a cyclist's pedal stroke is devoted to producing power, while the other half allows for recovery. Power is produced when a rider's feet are between 12 o'clock and 6 o'clock. The hamstrings work from the hip along with the calves, glutes and quadriceps to produce a strong forward momentum. On the backside of the stroke, between 6 o'clock and 12 o'clock, the hamstrings engage once again. This time they engage at the knee, helping to stabilize it. The hip flexors and calves are also active during the recovery portion of the stroke.

Other Benefits

Cycling tones and strengthens your hamstrings, especially when you engage in a seated climb. When you slide back on your saddle, you engage the glutes and hamstrings, forcing them to grow stronger and more powerful. The strong hamstrings that you develop through cycling will also help to stabilize your spine and protect your lower back from pain during cycling and other activities. It's important, however, not to overstress your hamstrings during cycling, which can lead to injury. This can be caused by a saddle that's too far back or too high.

Strengthening

Many cyclists rely on their quadriceps more than their hamstrings. If you actively work to engage the hamstrings, you'll not only increase your power on the bike, but you will also increase the strength of your hamstrings. Begin with single legged pedaling drills and focus on keeping your core stable as you actively engage your hamstrings on the recovery phase of the pedal stroke. Once you learn to incorporate them into your stroke, focus on using them to generate power as you crest a hill, accelerate quickly or wind up for a finishing sprint.