The effects of static stretching on strength, flexibility and muscle growth. What does the research have to say?
In this article we will quickly discuss the effects of stretching in specific protocols. We will answer the following questions.
1) Does static stretching affect muscle growth?
2) Does it compromise strength gains?
3) Does it improve flexibility?
From there on, I will leave you with a take away section on how to apply this to real life scenarios.
Let us introduce our subjects and describe the workout
9 untrained males in their 20s, were recruited for this study.
What did the training protocol look like?
The program lasted for 10 weeks and the subjects were divided into two groups. One group performed single leg extension to failure (80% relative intensity) twice per week. The other was identical with the only difference of performing a lying down quad partner stretch for 2 sets of 25 seconds, with a 8/10 “pain perception” before the leg extension.
After the initial 5 weeks the subjects would perform a 1 rep max and adjust the training load for the following 5 weeks.
What were the findings?
We will break down these findings by answering the previous questions above
1) First, we must define what leads to muscle growth. To keep things simple in the context of this article, the main driver of muscle growth is volume. How do we calculate volume and what does it mean? Calculating volume is quite simple, this is done by multiplying sets x repetitions x load. The main caveat of volume is that for the individual to “grow” he/she must ensure that over time the amount of work being done increases. this can manifest itself in many different ways such as: increasing repetitions, sets, weight, tempo, longer workouts, increasing frequency of the actual muscle being worked, and so on. Now the description is out of the way, let us move on to the findings.
The total reps performed, and total volume load were about 15-20% higher for the group only doing leg extensions to failure without stretching. Therefore, stretching right before lifting leads to a decrease in the amount of work being done in a session.
2) What about strength gains? It seems that strength gains were essentially identical between groups for the unilateral leg extension.
3) This will come as no surprise, but it was observed that the stretching group significantly increased range of motion compared to the non stretching group.
Even though this study demonstrated that there were no differences in strength gains. This information should be taken with a grain of salt. There have been may studies done in the athletic literature dictating that performing a “dynamic warm up” is much more conducive towards strength and power improvement. Specifically, towards explosive power movements, static stretching can hinder and reduce performance. Another argument can be made on the opposite spectrum as well, if an athlete shows extreme symptoms of “musculature tightness” one can make the case that a mild static stretching protocol pre workout (4-5/10 pain perception) can improve range of motion which has the potential to lead to strength gains. This is another example of how this is very context specific.
Now that we have all this information how can it be applied to your workouts? As previously stated, a dynamic warm up is a much better option compared to static stretching. However, this does not mean that it does not have any application in the gym. As a simplified rule of thumb, my recommendation is to perform static stretching either post work out or on rest days. As shown above, this can lead towards greater ranges of motion, potentially enabling further strength, power, and muscle gains.
References MASS volume 1 issue 2