Stretching: Good or Bad?


Stretching has been researched in the literature with a plethora of results in regards to whether its effect on muscles allow for desired outcomes in a given situation. There are many different factors to consider when applying a stretch technique and to which population. Is the stretching being done to simply gain additional range of motion? Is it being used to attain better performance during a competition? Or is it being used as part of a larger rehabilitation protocol?

Before diving into the different "alleged" benefits of stretching, let's break down the different types. 

What is it?

In general, the way stretching is described and named can be organized a number of different ways depending on the source. However, ultimately there are only 3 types of stretching categories: Static, Dynamic, and Pre-Contraction. 

  • Static stretching is the type that you see everyone using at the gym when it comes to trying to touch their toes (minus the bouncing, we'll get to that later). To be more specific, this type is when a person holds a muscle in an elongated position for a set amount of time (usually 15-30 seconds) where tension is felt and then repeated multiple times (3-5 sets). This type of stretching can be further broken down into 2 subcategories:
    • Active (Self Stretch): As the name implies, you perform this type of static stretching independently.
    • Passive (Partner Stretch): As the name implies, you perform this type of static stretching with a partner assisting the held position.
  • Dynamic stretching can be generally understood as performing a stretch with motion. This type can be broken down in 2 subcategories:
    • Active: This type involves moving a limb to the point of maximal tension (end range) and repeating that motion several times. 
    • Ballistic: This type is where you see people perform a bouncing-like motion when trying to stretch. It involves rapid, alternating movement and is not recommended for individuals to perform due to the adverse risk of injuries. 
  • Pre-Contraction stretching is when a muscle contracts prior to being stretched. This type is a bit more unique in comparison to the previous two in that it contacts many different subcategories:
    • Proprioceptive neuromuscular facilitation (PNF) is the most common sub-type and the only one I'll mention. PNF is unique in that it is used to decrease deficiencies in strength, flexibility, and coordination in response to demands that are placed on the neuromuscular system. As for stretching, it's performed when a patient maximally contracts the muscle at mid to end-range(about 5 seconds) followed by a pull towards the maximal muscle length while holding that lengthened position for about 10-30 seconds. One of the rationales behind PNF stretching is reciprocal inhibition which basically means the muscle on one side of a joint is relaxing to accommodate the muscle contraction on the other side of the joint.

Between the different types of stretching, which ones are more beneficial for any given situation?? Well, what are the goals for doing so?

Benefits

When it comes to gaining range of motion, one has to consider whether the person is actually increasing the length of the muscle (while performing the stretch) or whether that person is tolerating the tension forces being placed on the muscle better.  Typically, a standardized load is required to measure the extensibility of the muscle whereas a non-standardized load is used to quantify an increased tolerance to a particular stretch. This is important to consider when reading some of the results of other studies being published. Some studies show that static stretching is effective at increasing ROM but when it is being done prior to an exercise (as a warm-up), it becomes detrimental to strength and performance in running and jumping.  When comparing static vs. dynamic, they both appear similarly effective at improving range of motion. However, dynamic stretching has been shown to improve a person's power as well as jumping and running performance. 

But what about pre-contraction stretching? While browsing through different studies, it has been shown that PNF stretching is just as effective, if not better, as static and dynamic stretching for gaining ROM. However, a study done by Babault et al. showed that static vs. pre-contraction performed acutely tended to decrease strength in that particular muscle.  With that being said, it's important to consider what stretch is being performed for: performance purposes or elongating muscle. 

When considering the wide range of ages and different sexes, which stretching technique is most beneficial? In general, there are many articles that use different interventions concurrently with stretching such as strengthening, balancing, and/or cardiovascular activities. Because of this, it is unclear whether or not the stretching techniques were the sole proprietor of the gained ROM or if the other interventions played a role. However, it has been shown in multiple studies that older adults (>65 years old) benefit more with ROM from static stretching. In a clinical commentary on muscle stretching written by Phil Page, he noted "men and older adults under 65 years respond better to contract-relax stretching, while women and older adults over 65 benefit more from static stretching. 

Take home message

So when you break it down, which stretch will more than likely help for a given situation? If you're looking for elongating muscle tissue, all three stretches are beneficial. If performance is the goal, stick with active dynamic stretching. When determining which stretch to use based on an injured person, use your discretion as to which stretch will be more comfortable for them to allow the benefits they need. For example, individuals who exhibit hamstring strains (specifically athletes) tend to recover more efficiently using aggressive static stretching verses any others. As with anything, if you're unsure what to do, seek assistance from another professional who may have more experience to helping.