The biceps femoris is considered the "lateral" hamstring muscle and helps you to bend your knee in the same way that your biceps enables you to bend your elbow. This muscle attaches to the back of your thighbone and sit bone and then runs down the outside of your leg to attach to the calf bone. In addition to knee flexion, the biceps femoris muscles help you to extend your hips, walk, jump and run. They also keep you from falling forward and control how quickly you lower your body when you bend forward. You can stretch the biceps femoris from various positions -- sitting, lying supine and standing.
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Don't Just Sit There
While just sitting for long hours can lead to stiff biceps femoris muscles, you can perform a seated stretch for your hip extensors and the external rotators in your hips. Begin by sitting on the ground with your right leg extended in front of you. Bend your left knee and place your left foot against your right inner thigh, pulling your left foot up as close to your pelvis as possible. Put your hands flat on the ground beside your thighs for support. Bend forward and reach your hands toward your right foot, drawing your torso over your right knee while keeping your back straight. Hold the peak position for 10 to 30 seconds, repeating the stretch three to five times. Switch leg positions to stretch your left side.
Work Muscles in Pairs
Because muscles work in pairs, you can activate your quads and extend your knees to stretch the biceps femoris muscles. Known as active-isolated stretching, this type of stretching will not only lengthen the biceps femoris muscle but also relaxe the muscle and allow for a deeper stretch. For example, lie supine with your legs straight and together. Bend your right knee at a 90-degree angle and slightly adduct your right hip. Hold the back of your right knee with both hands. Slowly straighten your right knee, extending your right calf to the ceiling. Hold the peak position for two seconds and then return to starting position. Perform five to 10 reps for one to two sets and then switch legs to stretch the left biceps femoris.
Mimic a Dancer
Dancers regularly stretch their hamstrings by propping their leg up on a ballet barre and bending forward. The higher the barre, the greater the stretch. You can perform a similar advanced stretch by elevating one leg on a raised object, such as a bannister, kitchen counter, chair, bench or couch. If your biceps femoris is stiff, begin with a lower height. Place your right leg on whatever platform you choose, fully extending the leg while keeping your supporting leg straight. Grab your calf with both hands and slowly lower your chest toward your knees. Keep your back straight on the descent. If you're flexible enough, grab and pull your toes toward your shin, which will add even more muscles to the stretch. Hold the stretch for 10 to 30 seconds and then return to starting position. Reverse leg position and repeat the exercise.
Pull at Different Angles
When you stretch your hamstring muscles, explore different angles of the pull by slightly changing the position of your legs. For example, when performing a stretch with your leg raised on a platform, extend your working leg to the side instead of in front of you. Doing so will allow you to discover particular areas of tightness. If your biceps femoris is very stiff, begin a stretching regimen with simple knee extensions. Perform five to 10 minutes of light aerobic exercise to warm your muscles before stretching.