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By Alison McGinnis, PT, DPT, FAFS

Posted in Blog.

April 22nd, 2019

The Science of Stretching

Stretching is something most of us either do regularly or think we should do regularly.

It is the first thing many of us think about as a way to treat an injury or prevent one from occurring.

But there is a lot that goes into choosing a stretch, you want to ask; how should I be stretching, when is it best to stretch and which muscles should I be stretching. It can be hard to keep it all straight.

Let’s start with a few definitions:



  • Dynamic stretching means that you are moving gradually and smoothly through a range of motion to the end range then returning to the starting position. The stretch is never held in any one position for a period of time.
    • ACTIVE: You are moving in and out of a stretch on your own (no external force)
    • PASSIVE: An external force (i.e. a strap, person, or gravity) is moving your limb in and out of a stretch for you


  • Static stretching means you have moved to an end range position and hold there for the duration of the stretch. Can be active, you have moved into that position yourself and passive would be when something pushes or pulls you to a position and is being held.
    • ACTIVE: You have moved into a position and are holding it on your own
    • PASSIVE: An external force (i.e. a strap, person, or gravity) is pushing or pulling you into a stretch that is being held (no movement)



Dynamic (active) stretching is ideal for preparing the body for activity. It moves the muscles or joints through a full range of motion to increase blood flow, increase heart rate, reduce tension, and wake up the muscles for use. They can be used both during the warm up and cool down periods around an activity. They can also be used first thing in the morning or after bouts of prolonged sitting to improve general mobility and daily function.


*The below are examples of Dynamic-Active Stretches to do prior to a workout


3D Kneeling Hip Flexor Stretch

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3D Calf Stretch

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Static (passive or active) stretching is mainly used to increase flexibility. Some activities or sports require a greater range of motion at a joint, and static stretching can be used to gain mobility over time. This new range of motion must be incorporated into a strengthening routine, otherwise, this may lead to decreased performance or injury. More flexibility is not always the most desirable outcome as increased stability is required to control this new range of motion. As a rule of thumb, it’s ideal to have about 10% more range of motion at each joint than is required for the task at hand, whether that be stride length in running or doing the splits in gymnastics.



Dynamic stretching can be done at any time. As long as you are moving through the available range of motion at a smooth comfortable speed, this type of stretching is fine to do before or after a workout, or any time during the day to improve mobility. According to the National Strength and Conditioning Association, static stretching prior to activity may decrease power output, muscle force production, movement/reaction time, running speed, and muscular endurance. This means static stretching may be detrimental to athletic performance, and therefore should not be performed prior to activity.


Caution should be used for any muscle that is strained. If you have recently injured a muscle, the best policy is to leave it alone and not put excessive tension/pulling on it. Stretching an injured muscle either statically or dynamically can pull on the newly healing muscle fibers and cause them to re-tear, further lengthening the recovery time. Instead, focus on mid-range dynamic stretching and foam rolling until the tissues have healed.


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