3.6.2. Improving Flexibility

Stretching Techniques

Research has identified multiple stretching techniques that aid in improving ROM. Regardless of the specific technique or specific mode used, each technique can be performed using either active or passive mode. Active stretching, also called unassisted stretching, is done individually without an external stimulus. Passive stretching, or assisted stretching, is when a partner or trainer is used as the stimulus in the stretching exercise. Both modes are effective and can be applied to each of the techniques described below.

Static Stretching

The technique most commonly prescribed and used to improve flexibility is the static stretch. A static stretch involves slow, gradual, and controlled movements. The muscle group is stretched toward the end of the joint’s ROM until the point of mild discomfort is reached. Once that point is reached, the stretch is held in a “static” position for 30 to 90 seconds. After the prescribed time, the stretch can be repeated.

Some of the major advantages of static stretching are that it is

  • generally considered safe (some common stretches are “contraindicated”),
  • simple to perform, and
  • effective at increasing ROM.

The only major disadvantage comes from stretching too much, which can reduce strength and may make joints unstable. Of course, this potential risk applies to all of the techniques.

Ballistic Stretching

Ballistic stretching involves forceful bouncing or ball-like movements that quickly exaggerate the joint’s ROM without holding the position for any particular duration. This type of stretching involves dynamic movements somewhat like those done by athletes during sports events. In that regard, ballistic stretching is seen as being very specific to particular sports and athletes. However, one criticism of ballistic stretching is that because of the short duration of the stretch and the forceful nature of ballistic movements, the muscular contraction from the stretch reflex may cause muscle soreness or even injury. For that reason, many experts regard ballistic stretching as unsafe. Also, many researchers contend that it is less effective at improving ROM. Nonetheless, the American College of Sports Medicine (ACSM) still lists ballistic stretching as one method to effectively increase flexibility.

Dynamic Stretching

Ballistic stretching is a form of dynamic stretching. However, when referring to dynamic stretching routines, most fitness professionals are referring to dynamic movements that do not involve forceful bouncing motions. Instead, dynamic stretching, in this context, suggests performing exaggerated sports movements in a slower, more controlled manner. For example, a sprinter may use several exaggerated stride lengths before a race to improve hip ROM.

An advantage of dynamic stretching is its ability to target and improve dynamic flexibility, which in turn may improve performance. A disadvantage comes from the movements involved, which often require good balance and coordination. Since mastering the correct form requires time and a certain level of athleticism, dynamic stretching may not be suitable for certain populations.

Proprioceptive Neuromuscular Facilitation (PNF) Stretching

This type of exercise usually involves a partner. The cycle starts with a stretch. This movement is immediately followed by an isometric muscle contraction of the same muscles just stretched- they contract while pushing back against resistance (provided by the partner). This contraction is then followed by another passive stretch. This type of stretch is also named contract-relax stretch because of the sequence of movements involved. Other types of PNF stretching involve different sequences of stretching and contracting movements including additional steps.

As the name of the technique implies, PNF stretching emphasizes the natural interaction of the proprioceptors with the muscles to increase the ROM during the stretch. Remember that during the stretch, the muscle spindles cause two responses: the stretch reflex and the reciprocal inhibition (the relaxing of the antagonist muscle). After 5 seconds, the GTOs then override the muscle spindle’s signals causing autogenic inhibition. Because the muscle is relaxed, it can be stretched more easily.

Creating an Effective Stretching Program

The ACSM has made specific recommendations on how to design a flexibility program. However, before examining these recommendations in depth, you should first evaluate your current flexibility status by assessing various joints’ ROM. Specifically, performing the sit-and-reach test will assess your hamstring and lower back flexibility while using a goniometer can be used to assess your ankles, knees, hips, neck and shoulders.

Setting Goals

Once you determine which of your joints are the most and least flexible, you can set some realistic goals to improve or maintain your ROM. Be specific when you set goals. Instead of just saying, “I want to increase my flexibility,” identify the specific area of the body you intend to improve. You will also want to make sure your goal can be measured. A better way to state your goal is, “I will improve my sit-and-reach score by 4 cm by the end of the semester.” Notice this goal, as stated, includes a specific area, is measurable, and includes a deadline. By stating your goal properly, you will increase the likelihood of achieving it.

Applying the FITT Principle

As mentioned previously, the ACSM and CSEP have made recommendations for designing a flexibility program based on the FITT Principle (Frequency, Intensity, Time and Type). https://csep.ca/news.asp?a=view&id=140&pageToView=9

As the ACSM recommends, your flexibility program should include multiple stretching exercises that target all major joints, including the neck, shoulders, elbows, wrists, trunk, hips, knees, and ankles.

After selecting your exercises, follow the recommendations below when performing your routine:

  • frequency: Stretch a minimum of 2-3 days per week, ideally 5-7 days per week.
  • intensity: Stretch to the point of tightness or mild discomfort.
  • time (duration of each stretch): Stretch for a minimum of 10 seconds for very tight muscles with an emphasis on progressing to 30-90 seconds. Complete 2-4 repetitions of each stretch.
  • type (mode): Select the technique that best suits your circumstances: static, dynamic, ballistic, or proprioceptive neuromuscular facilitation.

When to Stretch

Although stretching can be done any time, the ACSM traditionally recommends that flexibility training be incorporated into the warm up or cool down phase of an exercise session. Recent studies suggests that stretching before an exercise session will compromise the force-producing capabilities of muscles and should be avoided. Therefore, it is recommended that stretching be restricted to after the warm- up or workout, when the temperature of the body and muscles has increased. Additional evidence pertaining to this concept shows that applying heat packs for 20 minutes to increase muscle temperature can increase hamstring flexibility more so than 30 seconds of static stretching. These findings confirm that temperature also plays a significant role in muscle ROM.

The link below offers guidelines about how certain types of stretching before performing activities can affect strength and performance:


Stretching Safely

In addition to warming up your muscles before performing stretching exercises, additional precautions can be taken to ensure the safety of your routine. When muscles are stretched quickly and forcefully, the stretch reflex can be activated. This creates significant tension because the muscle fibers will not only be stretching but also attempting to contract. As mentioned previously, this is one of the reasons ballistic stretching may not be suitable for everyone. To avoid this, stretch slowly and in a controlled fashion while holding the stretch for 10 seconds or more.

Stretches to Avoid

Research indicates that some stretches are contraindicated, which means they are not recommended because they provide little to no benefit and may cause injury. To avoid injury, it is important to consider personal limitations before performing a stretch exercise.

Assessing Your Flexibility

The first step in creating a successful flexibility program is to assess your own flexibility.

Assessment Exercises

Terminology Checklist

Static flexibility: the outermost limit of a stretched muscle measured while holding a stretch in place. This can also refer to a technique used to improve the outermost limit of a stretched muscle performed by holding stretches for 15-60 seconds.

Dynamic flexibility: the relative degree of ease a muscle can move through a normal range of motion. The can also refer to a technique used to improve static flexibility and ease of motion done by performing exaggerated movements.

Elasticity: the ability of the muscle to return to its resting length after being stretched.

Plasticity: the tendency of a muscle to assume a greater length after stretching.

Proprioceptors: sensors within muscles that send feedback to the central nervous system conveying muscular length and tension. The two primary sensors related to flexibility are Golgi Tendon Organs (GTO’s) and muscle spindles.

Joint structure: the fixed arrangement of a joint that is a determining factor for range of motion. An example would be ball-in- socket joint or modified hinge joint.

Myotatic reflex: a reflexive stimulus of the muscle to contract as a muscle is being stretched.

Reciprocal inhibition: the principle that when one muscle is stimulated to contract the opposing muscle is will relax.

Autogenic inhibition: an inhibitory reflex that allows one sensor in the muscle to override the signals of another sensor. Also called the inverse myotatic reflex.

Active stretching: a mode for stretching that is unassisted or involves no internal stimulus.

Passive stretching: a mode for stretching that uses an external source such as a partner or gravity to assist in the movements.

Ballistic stretching: a technique used to improve range of motion performed by gently bouncing back and forth to stretch and relax the muscle.

Proprioceptive neuromuscular facilitation (PNF): a technique used to improve range of motion performed by a sequence of stretching and contracting muscles. These sequences target the neuromuscular structures to facilitate relaxation of reflexive activity.


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Fundamentals of Health and Physical Activity by Kerri Z. Delaney and Leslie Barker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.