While researchers have been unable to unequivocally validate the proposed benefits of flexibility training, there is evidence that indicates that flexibility training contributes to enhanced muscular relaxation, decreased risk of injury, improved range of motion, improved muscular balance, and improved performance of certain sports-related activities. (Source: Ace Personal Training Manual P.305-307).

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Techniques Used to Increase Flexibility

There are four basic types of stretching techniques: static, ballistic, proprioceptive neuromuscular facilitation (PNF) and active isolated stretching (AIS).

Static

The static technique is the most traditional type and involves a slow, gradual, and controlled stretch through a full range of motion. Health professionals advocate this technique as the least likely to cause injury.

Static stretches should be part of every five to 15 minute warm-up routine. This type of pre-activity stretch should focus primarily on the muscles that will be used in the activity to follow, and is aimed at decreasing tissue stiffness, improving muscle circulation and readying the muscles for more vigorous activity, while decreasing the risk of tears or tendon stretching.

Ballistic

The ballistic or dynamic technique is more controversial since it involves rapid, uncontrolled bouncing or bobbing motions (such as bouncing down repeatedly to touch your toes). This type of stretching is not considered useful and can lead to injury (such as muscle tears) because is does not allow your muscles to adjust to, and relax in, the stretched position; It may instead cause them to tighten.

Consequently, many trainers, physical therapists, and physicians feel ballistic stretching is a higher risk stretching technique and should be avoided unless specifically needed to prepare for a ballistic sports activity. (Source: Ace Personal Training Manual P.311) 

PNF

Proprioceptive Neuromuscular Facilitation (PNF) is a more advanced form of flexibility training that involves both the stretching and contraction of the muscle group being targeted.

PNF stretching was originally developed as a form of rehabilitation. It is excellent for targeting specific muscle groups, increasing flexibility, and improving muscular strength.

This technique must be done with at least two people because it is impossible to complete most of the stretches by oneself. Specifically, PNF should be conducted under the guidance of a knowledgeable and experienced fitness professional; this will help minimize the chances of injury to the muscles, such as that caused by overstretching.

Example of a PNF Exercise:

Lie on your back on a comfortable surface. Raise one leg vertically and have your partner grab your foot. Your partner then presses the foot gently backward until you feel tension on the hamstring (the muscle on the rear of your thigh). You then contract the muscles as you attempt to move your leg back down, with your partner resisting the movement.

AIS

Active isolated stretching (AIS) was pioneered by Aaron L. Mattes. The technique was originally practiced on patients who required post surgery rehabilitation and has attributes similar to strength-training workout.

With AIS you gently stretch a specific muscle, hold the stretch for two seconds and then release (stretch is never held more than two seconds). The stretch is repeated for several repetitions with each subsequent movement exceeding the resistance point by a few degrees.

Increasing the stretch a few degrees at a time allows the muscle to adjust more gradually to the stretch.  The stretches are typically performed in sets of a specific number of repetitions, with the goal of isolating an individual muscle in each set.

Flexibility training is an essential part of a well-balanced exercise program. Whatever your workout routine, be sure to stretch before and after your exercise session. Doing this will maximize your performance during your workout and help relax muscles post workout.