April 14, 2020
This is a question that I hear from people every couple of months. As part of nearly all my rehab plan I will include some form of stretching, and every now and then a patient asks me if "these exercise will make my joints weak"?
These questions always come from an article that they read online, where a number of studies over the last few years have shown a decrease in leg strength due to stretching. Another study has shown that stretching can even effect sprint times.
These studies have shown a scientifically significant decreases in strength - roughly 8% decrease in leg strength and an increased in 20 meter sprint times by 0.04 seconds. Looking at these figure lets put them in practice perspective. 0.04 seconds in a 20 meter sprint will make no difference to 99.9% of us. It may be the difference in a gold or silver, or a medal or not during the Olympics but in everyday terms none of us will notice the effects of stretching on our times.
The strength difference due to stretching is a little more significant. If you are squatting 100kg in the gym, you will have to drop your squat weights to closer to 90kg, just because you stretch before instead of after. This can make a difference in your training week on week. It can also be demotivating seeing your strength decrease just because your routine is backwards.
However their is one major clause in all of this. The effects of stretching only become apparent when you stretch for 60 seconds or greater on each muscles. A joint review by Australian and UK universities has found that if you stretch each muscle for less than 45 seconds no difference in muscle strength has been recorded.
So if you keep your pre-workout stretches to a practical 20-30 seconds prior to a workout you should have no fear of it effecting your performance. In fact it will improve range of movement, decrease injury risk and improve your functional movements.Stretching prior to a workout should be kept short and focus on increasing your heart rate and body temperature slowly. After a run your focus your attention on losing up the muscles with longer stretches and foam rolling.