Stretching Before Workouts: How Long You Hold Makes All The Difference

It is a common site to see a high-level athlete stretching before a competition.  This is despite a body of research that suggests long static stretches reduce muscular power, which can result in decreased performance.  So, if static stretching reduces performance why do we continue to see so many top athletes continue to perform stretches when they are getting ready to compete?

As usual the answer is a little more complex than we would like with some studies suggesting stretching will decrease performance and others suggesting a positive effect or at least an absence of any negative effects.  It seems the answer may lay with the issue of how long the stretch is held and how many times it is performed.

A large systemic review by Behm et al. (2015) of 125 studies involving static stretching found moderate reductions in performance when testing was done in the minutes following stretching.  There was a great deal of variability in results ranging from improvements up to 5% all to the way reductions in performance of up to 20.5%.  Clearly the specifics of the stretching protocol make a significant difference in the effects.

When studies measured aspects of power-speed there were reductions in performance reported 24% of the time, an improvement found 6% of the time and no significant changes 68% of the time.  When the studies focused on strength-based measures there were no significant changes 42% of the time, reductions 57% of the time and only one instance of an improvement.  While this moderate reduction in strength measures is larger than the overall small reduction for power-speed measures you do have to take into account that the studies measuring strength involved stretches held for significantly longer then for power-speed studies.  This difference in time could explain the greater reductions in strength.

Some interesting trends start to show up when you break down the studies to those in which the stretching was done for less then 60 seconds as compared to those in which it was done for more.  For power-speed tasks with less than 60 seconds of stretching there were no changes 76% of the time with reductions only 10% of the time and improvements 13% of the time.  For power-speed measures when the stretching was held for more than 60 seconds there were no differences only 61% of the time and reductions in performance 39% of the time.

When the measurements were strength based and the stretches were held for less then 60 seconds there were no changes 73% of the time and reductions in strength in the other 27% of the measures.  Strength measures with stretches held more then 60 seconds had no change only 44% of the time while over 55% of the measures showed reductions in performance.  Again there were more negative changes in the strength measures then the speed measures with an even larger impact when stretches were held over 60 seconds.

Why does stretching reduce force production?

While there is no conclusive answer as to why we see a reduction in force production so often after stretching there are a few theories that seem to best explain why.

Reduced central (efferent) drive:  Remember that much of the activity that happens at a muscle is the result of neuroreceptors and their associated afferent neurons sending messages back to the spinal cord.  That feedback is then acted upon by the central nervous system (CNS) and a message is sent back to the muscle through an efferent motor neuron (nerves that send messages to the muscle from the CNS telling the muscle to contract).  It is theorized that there are changes in the sensory feedback mechanisms that result in slower or reduced instructions from the CNS telling the muscles to contract.

Reductions in tendon stiffness: While we usually don’t associate the word stiffness with a positive effect in the body, when it comes to tendons sufficient stiffness is something we want.  You have a lot of force that you are trying to transfer (and quickly) through those tissues and if they have reduced stiffness the response rate and force transmission can be reduced.  If the tendon has reduced stiffness the muscle could be working at a shorter and weaker length.  Yes, it seems counter-intuitive that that a stretched muscle could be working at a shorter length but that could be an affect of reduced tendon stiffness.

Muscle damage or fatigue: Small amounts of muscle damage may occur as the result of stretching and that damage can reduce the contractile force capacity of the muscle.  The stretching may also reduce blood flow and the associated available oxygen to the muscle.  This could lead to a build up of metabolic end products and reactive oxygen species.

Diminished electromechanical coupling:  In order for a muscle to contract an action potential (electrical charge) must stimulate a release of calcium in the muscle that is necessary for the contraction process to take place.  The stretching could impair the transmission of the action potential slowing down the entire contraction process.

Intermittent vs. Continuous Static Stretching

To differentiate the effect of intermittent vs continuous stretching, Bogdanis et al. (2019) conducted a study that compared 3 static stretches held for 30-seconds each with a 30 second rest interval between stretches to holding a single 90-second static stretch.  This allowed for each testing situation to have the same total amount of time that the muscles were placed under stretch, just under different conditions.  The subjects performed each testing protocol on different days and only stretched one leg.  The opposite leg served as a control.  Upon completing the stretching a single leg counter movement jump (CMJ) was performed immediately after and at 1, 2, 3, 4, 6, 8 and 10 minutes.

In the intermittent stretching group there was an increase in CMJ starting at the 2-minute mark and peaking at the 4th minute.  Compared to the control leg there was a peak 8.1% increase in CMJ at minute 4.  In the continuous stretching group there was an immediate decline in CMJ, and performance did not increase past baseline pre-stretching levels until 6 minutes in.  Decreases in CMJ for the continuous stretched leg were 12-17.5% less than in the control leg.  At all time conditions the intermittently stretched legs outperformed the continuously stretched ones.

Pinto et al. (2014) asked the question of what difference does a single bout of 30 seconds of stretching have as opposed to 60 seconds on vertical jump performance.  They found that 60 second stretches resulted in decreases in jump height, average power and peak power as compared to the 30 second bouts.  In this study only one round of stretches was performed but four different muscle groups were stretched.

Practical Applications

What does all this mean for your workout and performance?  If you or your client is an average person who is just trying to get fitter and healthier and little stronger the impact is not much.  The decreases in performance from stretching before activity are not going to impact your training.  Most people aren’t approaching their peak performances in everyday workouts and recreational sports.  So, go ahead and stretch a little before your workout if it makes you feel better.  It is probably best to keep stretches to 30 seconds and less.  If you feel an area needs more then one short stretch it is ok to repeat that stretch.  Save the longer, increased range of motion stretches for after you are done working out.

If you are a higher-level athlete for whom a few percentage points in performance will make a difference, then your pre-event stretching protocol does matter.  For this group the current data strongly suggests making sure that pre-event stretches are kept to 30 seconds or less.  Certainly, less than 60 seconds at the most.

A shortcoming of much of this research is that it is laboratory based and doesn’t necessarily accurately reflect the realities of real-life competition.  The timing between when stretches are performed and the impact on performance in real life can be much longer then in the studies.  Athletes may begin warming up as much as a half hour or hour before competition.  There are still many unanswered questions as to what impact stretching will have on performance if it is done with a longer gap between stretching and performance.  There are also issues of what difference does this have with highly trained athletes as opposed to recreational athletes and the average gym goer.  The impacts could be quite different because of long term training affects.  While these questions still exist and need to be studied, based on the current data the suggestions of limiting pre-training or pre-event stretches to less than 60 seconds and ideally less them 30 seconds are still recommended.


Behm, D.G., Blazevich, A.J., Kay, A.D. and McHugh, M. (2016) Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: A systematic review.  Appl Physiol Nutr Metab 41: 1-11.

Bogdanis, G., Donti, O., Tsolakis, C., Smilios, I. and Bishop, D. (2019) Intermittent but not continuous static stretching improves subsequent vertical jump performance in flexibility-trained athletes.  Journal of Strength & Conditioning Research 33:1:203-210.

Pinto, M., Wilhelm, E., Tricoli, V., Pinto, R. and Blazevich, A. (2014) Differential effects of 30-vs. 60-second static muscle stretching on vertical jump performance.  Journal of Strength & Conditioning Research 28:12:3440-3446.

Try Sprint Interval Training To Improve Your Running Performance

You have been hitting the trails, logging miles and doing everything that you are supposed to in order to improve your endurance and power.  Maybe you have a race coming up in a few weeks or you just want the personal accomplishment of getting through your regular run a little bit faster.  If you are finding that despite all your worthwhile efforts your performance has not changed in a meaningful way perhaps it is time to consider integrating sprint interval training into your program.

This week we take a look at an interesting study that shows a way for well trained individuals to really move the needle on their running performance with a minimal amount of time spent training.  As we go through the study keep in mind three things.  First, this study was conducted with subjects who were already well trained athletes.  We would expect to see positive changes in studies that take subjects who aren’t active and put them on aerobic/endurance/power based training plans.  If you are starting from a low level of fitness and get on a regular, supervised program most people will see a change for the better.  Taking a group of well trained athletes and coaxing a meaningful change in their performance is much more difficult and demonstrates the power of the training intervention.

Second, this study was done in a real world setting, not in a laboratory.  Often the changes that can be achieved in a very controlled setting working on a treadmill or cycle ergometer cannot be replicated in quite the same way in a real world setting.  If you cannot go out to the track, trail, road or gym and achieve the benefit of the specific plan studied then it might not matter all that much that it can produce an effect in the laboratory.

Third, this study achieved meaningful results with just a two week intervention.  Often we need data over much longer periods of time, weeks, months, even years to determine the impact of a particular intervention.  In the case of this study part of what was so interesting is that the trained athletes used as subjects achieved the beneficial effects of the sprint interval training program in just two weeks.  Who doesn’t want to do something that will improve their performance in such a short period of time?

The Study

In this study running performance was measured with a 3,000 meter time trial and a run timed to exhaustion at 90% of maximal aerobic speed (MAS).  The training program consisted of three workouts per week for two weeks.  In each workout the sprint intervals were 30 second all-out shuttle runs followed by 4 minutes of rest.  The subjects performed 4 rounds in their first workout, 5 rounds in their second, 6 rounds in their third and fourth workout, 7 rounds in their fifth workout and dropped down to 4 rounds in their sixth workout.

The total sprinting time over the two weeks totaled 16 minutes.  The entire 6 sessions only took 110 minutes including the rest time.  The shortest workout was 14 minutes and the longest was only 27.5 minutes.

To conduct the actual sprints, cones were placed every 5 meters for a 30 meter distance.  During the sprints the subjects would run to the 5m cone and back, then the 10m cone and back and so on until they reached the 30m distance.  They would continue running at full speed until the 30 seconds were up.

Three additional variables were also measured for each session.  1) The subjects peak power, which was considered the longest distance they ran in a 30-second period.  2) Mean power which was the total distance they ran for the session divided by the number of sets they ran that workout.  3) Fatigue index was considered the difference between the longest sprint they ran in any given workout and the shortest sprint they ran in the same workout.


Maximal aerobic speed saw a 2.8% increase.  This was significant though the effect size was small.  For the timed run at 90% of maximal aerobic speed there was a 42% improvement (158.9 seconds) which was considered a large effect size.  The timed 3,000 meter run saw a decrease of 50.4 seconds which is a 5.7% improvement in time.  The effect size is considered small-to-medium.

Peak power had a 2.4% improvement (3.06 m), significant but a small-to-medium effect size.  Mean power had a significant 2.9% improvement (13.9 m) for a medium effect size.  The fatigue index showed a positive trend with a medium effect size thought it did not reach a level of statistical significance.

Putting It All Together

So what does this all mean for most runners out there?  First and most importantly it shows that a very short 2-week low volume program can produce significant improvements in performance.  Most competitive runners already have fairly lengthy training programs and a schedule of competitions to plan around.  Even if you are not a competitive runner odds are that you still have a limited amount of time to train and are still interested in improving your performance.  A simple low volume, high-intensity program like this can quickly make positive improvements in both endurance and anaerobic performance.  Additionally this study demonstrates that the improvements are not limited to untrained subjects that will respond to just about any regular training protocol, already highly trained subjects can make significant improvements with this type of training.

Secondly a program like this does not require any special equipment.  A few cones make it look pretty but some water bottles, t-shirts, a big rock all work equally as well.  It is always nice to have a new training technique that doesn’t require you to open your wallet.  This study clearly showed that the results can be achieved in a real world setting without highly calibrated expensive laboratory equipment.

Third, all you need is a clear 30 meter space to run your sprints.  This means it can be done almost anywhere.  Even if you don’t have a full 30 meters you could still follow the program and simply limit the longest available distance to 20 or 25 meters.  Even if you have to train indoors because of weather it is still simple to perform a program like this.

Fourth, it is easy for multiple athletes to perform this program at the same time.  Individuals can set up right next to each other.  This makes it ideal for those working with teams to put everyone through the program together.  There is the added benefit that running against others often motivates people to push even harder.

A program similar to this can also be used as a tapering plan allowing for high intensities and low volumes to be programmed as you get closer to competition.

So why does such a short duration, low volume program produce such good results?  The leading theory is that this high intensity training technique leads to increases in enzymatic activity in both the aerobic and anaerobic energy systems.  It is also possible that this approach improved neuromuscular capacity which can result in improved running economy.

The use of shuttle runs was an interesting choice of the authors.  It allowed for high intensity training while ensuring that the improvements seen in the actual tests were not the result of skill acquisition but due to physiological adaptations.  As previously mentioned it also allowed for a small space to be utilized and a competitive atmosphere to be established between subjects.    This leads to the question of if another form of sprint interval training could produce similar results?  There is probably nothing magical about the use of shuttle runs in and of themselves.  The high intensity that they stimulate is most likely the key factor so it would not be reaching too far to assume that if the same intensity can be maintained for a full 30 seconds on a longer sprint, similar results would probably be achievable.  This eliminates the advantage of only needing a small space along with some of the mental variety that shuttle runs introduce but coaches shouldn’t feel limited to only using that one approach to including high intensity sprint intervals.

It would be interesting to compare the results of this study to slightly different training protocols. What would happen if you used a time different then 30 seconds for the sprints?  Do you need to go all the way up to 7 sets or can similar results be achieved if the volume is kept lower and only 4 or 5 intervals are used?  Would more intervals produce greater results or what happens if the program if followed for more than 2 weeks?  Like all studies, this one could had to choose a particular set of variables to use but the positive outcomes they produced makes you want to explore how those variables can be tweaked to produce even greater outcomes or optimize the time actually committed to the program.

There you go.  If you are looking for a way to improve running performance but do not have hours to commit over a prolonged period of time now you have a technique that will allow you to turbo-charge your training with a simple to perform, short duration low volume sprint interval plan.  Who doesn’t want to see a 42% improvement in their paced running and a 5.7% improvement in their race time for such a small amount of training?

Koral, J., Oranchuk, D., Herrera, R. and Millet, G. (2018) Six Sessions Of Sprint Interval Training Improves Running Performance In Trained Athletes.  Journal of Strength and Conditioning Research. 32(3): 617-623.