If you ever took a physical education class in elementary or junior high school, you probably started many of those periods by stretching before exercise. However, there is a growing consensus that the practice of static stretching before physical activity is not ideal, and can even damage performance in some instances.
The Alleged Purpose of Stretching
Stretching before exercise is meant to limber up the body, increase flexibility, and elongate the tissues being stretched. This assumes that the muscles being stretched are currently too short to perform the job, which is not always the case. A 2009 study in Medicine & Science in Sports & Exercise found that the ability of field-based athletes to sprint repeatedly was diminished by stretching prior to taking the field.
Many people think of stretching as “warming up” prior to physical activity, and that would make more sense if stretching were actually the best way to warm the body. For the sake of clarity, “warming up” is literally the act of getting warm and getting a sweat going. If flexibility is the goal, then stretching makes sense. If, however, the goal is to get loose and warm on behalf of peak performance and to prevent injury, there are better ways to go about it than stretching.
A dynamic warm-up is generally an activity or series of activities that increase the body temperature, lubricate the joints that are going to be involved in the exercise to come, and introduces as much flexibility as necessary, but not more. Hopping on a treadmill for 5 minutes, jumping rope, jumping jacks, and running in place are all examples of dynamic warm-ups that are better than stretching before exercise, if increasing muscle and body temperature is the goal.
A movement-specific warm-up is a different sort of dynamic activity that is of the greatest use to people who are about to lift weights. Rather than stretching before exercise, you perform the warm-up for a movement with the movement itself.
Using the barbell back squat as an example, here’s how it might look. Typically, if you are a stretching devotee, you might precede your squat workout by stretching your glutes, your hamstrings, your quadriceps, your hip flexors, and your adductors. If instead you were performing a movement-specific warm-up, you would put the empty barbell on your back and perform a set of squats in the 12-15 rep range.
This would start to warm the muscles involved in squatting, and prepare the body for the movement. After adding pounds (jumps of at least 30 pounds are recommended), perform another set of squats. The goal is not to exhaust yourself, but to increase the weight while loosening up the body as you advance to your working sets. By the time you have your workout weight on the bar, your body is ready to go. Nothing feels tight, nothing feels cold, and no stretching was required.
If you are going to stretch, it is best to do it after your workout. During the cool down phase of your training session, the muscles that were subjected to stress start to rigidify and shorten. If you take a few minutes to gently stretch them out, your mobility will be better the next day, and you will have reduced soreness. These are benefits that stretching before exercise can’t offer.