Stretching has been an area of argument between all types of health care practitioners for years. Conflicting messages have been thrown around questioning the effectiveness of static stretching, dynamic stretching, proprioceptive neuromuscular facilitation (PNF), or no stretching at all. If you’ve ever wondered what stretching actually does to your muscles and joints, this article is for you.

To tackle the effectiveness of stretching, we have to understand how a muscle works. A muscle is made up of thousands of long and thin cells that span its entire length. These cells contract when the brain sends an electrical voltage through the nerves. The contraction occurs from the binding and releasing of tiny mechanisms in the cells called actin and myosin. Like a climber uses their hands to reach and pull up a length of rope, actin and myosin pull to contract the muscle. Sometimes those actin and myosin do not properly release which is what causes our muscles to get “knots” in them. A stretch is therefore theorized to pull the muscle cells to passively break up those stuck bonds and bring the muscle back to “normal”. 

There are 3 types of typical stretches:

1. Static stretching
2. Dynamic stretching
3. Proprioceptive neuromuscular facilitation (PNF)

1. Static stretching is when you just stretch a muscle and hold it for a few seconds to a minute. It can be held at any percentage of the maximum stretch and is held in that position until it’s released. Generally, a static stretch is used as a relaxation technique.

2. Dynamic stretching is when you move the tight muscle through its entire range of motion from minimal stretch to maximal stretch in a few seconds. This is like when runners do “high knees” or “heel to butt kick” stretches to warm up and reduce injury. 

3. PNFs are when you stretch the muscle and then fire the muscle in that stretched position without letting it contract. This is an advanced form of stretching that aims to increase the range of motion of a muscle or joint and reduce pain. 

What the evidence says: 

For athletes, holding long static stretches before performing have been shown to have a reducing effect on their peak performance ability. Shorter duration static stretches still need more data to make any conclusions. 

longer stretch durations (e.g., ≥60 s) likely elicit performance impairments

The limited data available on the impact of longer-duration SS on eccentric strength suggest that a small negative effect may be likely; nonetheless, the influence of shorter durations of SS on eccentric strength remains to be studied properly.