What Is It? A muscle strain is a stretch or tear of muscle
fibers. In the leg, muscle strains happen when a muscle is
either stretched beyond its limits or forced into extreme
contraction. Because the leg has many different muscles, it is
vulnerable to several different types of muscle strains. Some of
the more common ones are: - Calf muscle strain (gastrocnemius
strain). The calf muscle typically gets strained when the foot
suddenly bends upward, stretching the calf muscle beyond its
limits. At the time of injury, you may hear or feel a pop inside
your calf -- the sound of the muscle tearing or shearing away
from the Achilles tendon. Calf muscle strains are common in
athletes, especially tennis players and joggers. However, they
also can happen during a simple stroll, if your foot flexes
upward when you step into a hole in the sidewalk or if your heel
slips off the edge of a curb. - Plantaris strain. The plantaris
is a thin muscle that begins at the lower end of the femur (the
large bone of the upper leg), s