MYTH: You Should Stretch before you Exercise

When I teach, I always tell my students about those guys in the stretch area before they workout.  Often times, they have their socks pulled up to their knees and they are reaching for their toes, doing twisting and bouncing movements.  They also like to grab a hold of a rail or an exercise machine.  Observing them for a period of months to years, I notice that neither their performance nor flexibility has improved.


Pre-stretch can cause Injury
Think about it, if your muscles are not “warm” they are going to be less supple. If you stretch it while it’s “cold”, you are more susceptible to tearing muscle fibers (micro-tears).   However, you could be asking, “I thought that you are supposed to stretch to warm up the muscle?” I understand the dilemma, but what you have to understand is that stretching does not warm up your muscles (related article).  


You have to increase heart rate
In order to warm up the muscles, you should do a moderate intensity cardiovascular exercise such as walking on a treadmill or riding a bike for at least 10-15 minutes. This is known as a general warm-up.  This kind of warm-up increases heart rate, which will actually increase blood flow to the muscles and connective tissues (i.e. ligaments and tendons), therefore, preventing injury and tightness.   Increased blood flow increases temperature of the muscle.  Traditional stretching does not increase blood flow.  Once you have done this, you may do static stretching.  However, it must be controlled.  Additionally, it is not absolutely necessary.


Pre-stretch impairs performance
The same micro-tearing that increases injury also impairs performance (related article).  These micro-tears cause inflammation, which in turn makes muscles less pliable.  When the muscle fibers are impaired, your muscle force production will be impaired.  


Improper stretching potentially decreases flexibility
If you chronically bombard your muscles with stretching the wrong way, the fascia and other tissues (like tendons and ligaments) begin to thicken and shorten.  That's the reason why "pre-stretchers" never improve flexibility.  In time, you are more likely to suffer from chronic injuries as a result.  Acutely, the inflammation caused by pre-stretching also decreases flexibility.


When and how should you stretch?
As a reminder, stretching is meant to improve flexibility (range of motion) and to help you recover (it can improve strength and power too, but that’s another topic). This means, you would stretch after your training session (whether it’s weight lifting or aerobic training) to decrease the tightness that you often feel and decrease the likelihood of injury.  Once again, stretching alone does not increase blood flow to the muscles.  Thereby, it makes more sense to stretch a muscle when it is warm.

Here are tips on stretching
 after exercising:

• Breathe into the stretch.
• Don’t hold your breath.
• Never push to the pain of pain, but just the brink of discomfort.
• Hold stretches for more than 15 seconds.
• NEVER bounce.
• Drink plenty of water.
• Have someone stretch you via PNF (proprioceptive neuromuscular facilitation).

Admittedly, there is one form of stretching that can be acceptable before fitness training.  It is called dynamic stretching.  However, it is still recommended to do a general warm-up before doing this.  Dynamic stretching is active and mimics movements that are similar to the activity you are doing.  Usually, this type of stretching is reserved for competitive athletes and fitness professionals who understand it conceptually.

Written by:


Kelly Huggins


Exercise Science, B.S.