The muscles, ligaments and tendons of the foot are a complex system and any number of injuries or issues can cause pain in the foot and surrounding area. If you've already talked to your doctor and determined that you need to focus on stretching the foot flexors, try some basic stretches that you can do nearly anywhere. If you haven't talked to your doctor, do so before trying any therapies on your own.
Among the movements your foot and ankle make is foot flexion, which means moving the foot down. The flexor hallucis brevis and the flexor hallucis longus are among the tendons that help you flex your big toe downward. The flexor hallucis longus muscle, which extends into the longus tendon, starts at the back of the leg, while the flexor hallucis brevis starts at the back of the foot. The flexor digitorum longus tendons, meanwhile, start at the back of the leg and help the other toes bend down or "flex." The posterior tibialis starts at the back of the leg and ends at the bottom of the foot, allowing you to bend your ankle downward. Since most of these tendons start at the back of the leg, proper stretches should incorporate that area.
Stretching the big toe will help lengthen or "stretch" the flexor hallucis longus. With your shoes off, stand near a wall and place your hands on the wall for stability. Keep your heel and ball of your foot on the floor as you place your toes up against the wall. The foot you are not stretching can be placed slightly back from the wall for balance. Slightly bend the knee of the stretched foot and push forward, suggests sports medicine physician Dr. Thomas L. Sevier on the ASTYM therapy website. You should feel a stretch in the calf, ankle and the bottom of the foot. Hold the stretch for about 30 seconds.
Also beneficial may be stretches that focus on the gastrocnemius and soleus muscles of the calves. Get near a wall and then place one foot slightly ahead of the other, keeping both feet flat on the floor. Keep the front knee bent in a soft lunge and the back knee straight. Focus on keeping your weight on the back foot as you lean forward into the wall, feeling a stretch in the back leg's calf muscle, which is also called the gastrocnemius. Hold for about 30 seconds. To focus instead on the soleus muscle of the calf, keep the same position, but bend both knees slightly.
Using an exercise band or a strong elastic can also help you stretch the tibialis and gastrocnemius-soleus complex. If you don't have a band, use a towel instead. Sit on the floor with your legs straight in front of you and then wrap the band around your foot, just below the toes. Pull on the ends of the band with your hands to create tension in the band and then point and flex your foot, repeating the move on each foot for a total of 10 times.