My childhood experiences with ritualized, organized war games, that is to say sports (namely football and wrestling) were initiated with a particularly peculiar ritual called stretching. To the alien anthropologist these behaviors could have been interpreted as a supplication to the divine powers for assistance in the upcoming skirmish, and indeed maybe they were. Whatever the case, the question remains as to whether they were successful in that endeavor. Does stretching improve performance?
I found a review paper written by M.P McHugh and C.H. Cosgrave published in the Scandinavian Journal of Medicine and Science in Sports in 2010 addressing this question. This paper is titled “To stretch or not to stretch: the role of stretching in injury prevention and performance” but we’ll save the injury part for another day and just look at performance. To narrow down the question, we are asking if stretching (not flexibility) immediately prior (not afterwards, or daily etc) to testing has an effect on strength and power.
The duration, intensity and type of stretching varied in the studies reviewed but most were in the range of 5-8 minutes of actual stretching time with more than a few studies using 60 minutes total. This review also cited papers showing that at least five minutes total of actual stretching time is necessary to have a measurable flexibility improvement lasting more than 10 minutes.
Stretch-induced strength loss is a well documented phenomenon with numerous studies showing that stretching a relaxed muscle results in an acute loss of strength afterwards. Average strength loss after a 30-60 min stretching session was 22% and 8% after shorter sessions. This loss of strength is accompanied by lower muscle surface EMG signal and has been documented on the non-stretched limb as well suggesting that the effect is mediated by the nervous system.
Stretch-induced power loss has also been documented but of a lesser magnitude; 3-4% average loss in vertical jump and 0-2% loss in sprint performance.
So it turns out that intensive passive stretching makes you weaker for a little while after but this phenomenon has two important practical caveats 1) dynamic stretching has been shown not to result in stretch-induced strength loss and 2) strength loss has been shown not to occur at longer muscle lengths.
Before we abandon pre exercise stretching altogether let’s talk how I apply the above information. In general I prefer dynamic stretching to passive stretching before lifting weights or jumping, sprinting dunking etc. But here are two examples in which I would recommend passive stretching before resistance training.
Since passive stretching results in muscle inhibition I can use it to specifically inhibit an overactive muscle. One example would be stretching the hip flexors before lunging exercise for a person whose hip flexor tightness prevents them from achieving a neutral hip position without excessive lumbar lordosis. In this case the muscles they are stretching are not the primary movers so no significant strength loss would result and the increased range of motion would force their hip stabilizers to work while their back is saved from a potentially compromising position.
If latissimus dorsi and teres major tightness is limiting one’s ability to reach overhead, I would stretch these muscles before doing an overhead lift such as a dumbbell press or handstands. Tightness in these muscles limits external rotation of the humerus and can contribute to shoulder impingement and compensation in the form of excessive movement somewhere else in the body such as the lumbar spine.
In conclusion, use pre-exercise passive stretching as a specific intervention to improve movement quality and don’t expect your best dunk after a nice long quad stretch.
This was not a systematic review including only high quality trials but a such a review was published in the clinical Journal of Sports Medicine by Ian Shrier in 2004 titled “Does Stretching Improve Performance” and found the same results for stretching immediately prior to testing. Of note the later study also examined the effects of regular stretching (not before exercise) and found that over time it improves force, jump height, and speed.