Active people may encounter groin strains or hip injuries as a result of certain high-intensity sports such as hockey or squash, although these injuries can occur during any activity, from running to Pilates.

Because doctors measure pregnancy from the start of your last menstrual cycle, when you're four weeks pregnant, you may just have missed your first menstrual period. At this point, implantation of the embryo just occurred around one week ago, but already your baby is making his presence felt through hormonal changes.

Your calf muscles get a daily workout -- they can become tight from exercise, walking or even excessive sitting. Stretching the gastrocnemius and the soleus muscles before exercise helps with flexibility but sometimes even stretching causes pain along the back of your lower legs.

Numerous conditions can cause waist and leg pain. According to the MedlinePlus website, leg pain can be caused by structures within the leg itself or it can be caused by problems in other parts of the body, such as the waist or pelvic girdle.

Pain in the calf muscles can occur while swimming. This primarily happens when the toes are kept pointed -- called the plantar flexion action -- throughout the activity.

Your legs and the connecting ball and socket joints rely on one another to perform singular tasks. Often when one hurts, it affects the other. There are a number of reasons why your leg and the connecting ball and socket joint are in pain. The treatments also vary, depending on the cause.

Numerous conditions can cause sharp pain in the left leg. According to the University of Maryland Medical Center, leg pain can be dull, aching, shock-like, cramp-like or burning.

There are two muscles in the back of the lower leg or calf that, if injured, can produce pain when you squat. Squatting stretches those muscles because your foot is flexed upward. Injury to those muscles is called a strain and the severity of the injury determines treatment and the length of healing time.

The simultaneous occurrence of fever and leg pain often points to the presence of an infectious or autoimmune disorder. Infections of the leg skin, joints or bones frequently cause the abrupt onset of fever and pain. Gradually evolving pain with intermittent fevers provokes suspicion for a chronic condition.

Because the bones of the musculoskeletal system are all connected, an imbalance in one area, such as hip alignment, can cause pain elsewhere. This is also true because misaligned bones can trap nerves, sending impulses to other areas of the body, such as the legs. In some cases, a hip deformity may be to blame.

Leg tingling a common symptom that occurs as a result of nerve compromise. Although pain may accompany tingling, it does not always have to. Tingling has a number of causes, each of which will be diagnosed in different ways, so you should see your doctor if your tingling is of concern to you.

Because of their location in the body, the sartorius and gracilis muscles are particularly vulnerable, not just to trauma but to general wear and tear.