When you have a pain in the neck -- literally -- it could be caused by tension. Tension can set off a chain of events that leads to soreness at trigger points, which sometimes feels like knots in a muscle.

Physical exhaustion develops as a normal response to overexertion or not adequately resting between periods of physical activity. No matter the cause, physical exhaustion is a serious condition that should not be overlooked. Rest and recovery help you recover from exhaustion.

A bulging, or herniated disk occurs when the cartilage between your bones in your back (vertebrae) moves out of place. These disks are important in increasing the flexibility of your spine. In addition, they act as shock absorbers that decrease the pressure on your backbones when you are performing physical activity.

Your lumbar and sacral vertebrae are part of your lower back region. You have five lumbar vertebrae and five sacral vertebrae, the latter of which are fused together to form the sacrum. The two areas meet at the L5 and S1 vertebrae. This part of your spine can become stiff with age and lack of use.

Popliteus tendinitis is an inflammation of the tendons surrounding the popliteal muscle. The popliteal muscle is located in the back of the knee. The popliteal muscle can be come aggravated as a result of intense physical activity and is also common in those with frequent ankle sprains. According to MayoClinic.

A bulging disc, also known as a herniated, ruptured or slipped disc, occurs when the disc, which acts as a cushion between each vertebrae in the spine, is compressed and puts pressure on the surrounding nerves.

A muscle cramp is a sudden painful and involuntary contraction of one or more of your muscles. Long periods of exercise or fluid loss from sweating, vomiting or diarrhea may lead to muscle cramps.

The serratus posterior muscles in the lower back help your upper body and ribs twist and bend. This area of the back is especially susceptible to painful pulls and strains because it bears the weight of the upper body and is heavily involved in the moving process.

Lower back pain will affect over 80 percent of the population at some point in their lives, according to Spine Health. The muscles, joints and organs that contribute to lower back pain are symmetrical, meaning that pain on the left side will have the same causes as pain on the right side.

Plantar fibromatosis is a condition in which excess collagen or fibrotic tissue in the feet creates hard nodules just under the skin. These nodules typically occur on the bottom of the foot and right under the arch. The condition can cause pain, especially when standing and walking.

Spinal stenosis is a condition in which the vertebra become compressed, pinching nerves and causing severe back pain and even numbness. In severe cases, symptoms of spinal stenosis may also include loss of bladder and/or bowel control.

Your deltoid is the large layer of muscle that covers your shoulder. The deltoid is the first layer of muscle underneath your skin and helps you lift your arm over your head. Deltoid injuries include strains and tears of the muscle.