A proper stretching routine helps improve your running performance and speed. Dynamic stretching before a race warms up your muscles, preparing them for short and powerful bursts of energy. Post-race stretching, or static stretching, focuses on muscular elongation and relaxation and helps prevent soreness or strain.

A stiff neck can arise due to a variety of causes, such as sitting or standing with poor posture, sleeping in an awkward position, or turning your head repeatedly or suddenly.

The most common cause of broken ribs is a major blow to the chest, for example, from a fall or sudden impact, as in a sporting tackle. Often broken ribs are actually cracked or fractured and, while painful and tender, heal themselves over time.

Your gracilis is a long, slender muscle that runs down the inside of each thigh. It crosses from the lower end of your pelvis to the top of your tibia, the larger of the two bones in your lower leg. Because it crosses multiple joints, your gracilis performs multiple actions.

A lateral curvature of the spine to the left or right is called scoliosis, which commonly develops in people who participate in unilateral activities such as tennis. Scoliosis might also develop from birth defects of the spine or when one leg is longer than the other.

Stretching is an important part of any fitness program. Before physical activity or any kind of sporting event, it loosens muscles, allows for better movement and reduces your risk of injury. Incorporate the two types of stretches -- dynamic and static -- into your regular workout.

Stretching requires temporary lengthening of your muscle fibers. It is best to partake in flexibility training after a light warmup; this allows increased blood flow to the muscles which in turn increases mobility.

Your heel cords, or Achilles tendons, connect your lower calves to your heel bone and are made up of a strong, fibrous tissues that do not have much range of motion. Stretching your heel cords should improve their mobility without compromising their role to stabilize your joints.

Your triceps muscles are on the back of your upper arms. They contract when you straighten your arm and lock your elbows. The triceps fire up when you perform pushing or pressing movements, including pushups and the bench press. They also play a key role in throwing sports.

There are two types of splits, namely the front split and the side splint. In the front split, one leg is stretched in front of you and the other, behind you. In the side split, both legs are stretched out to your sides.

You might think that stretching is only for athletes, but everyone can benefit from stretching exercises. Stretching is an important component of physical fitness, according to the American Council on Exercise -- and without it, your joints can stiffen and your risk of injury increases.

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.