Research Review: Comparison of stretching protocols on hamstring flexibility

Getting my Masters degree in Kinesiology was a really fun time – except for the times you would get so frustrated by your research project that it would bring you to tears or the fear of being ripped to shreds during your thesis defense or the first time you ever said to an academic panel, “Well, they say stretching twice per day significantly improves hamstring flexibility.”

Every newbie makes this mistake at least once – once you are a veteran it is actually fun to watch as at least one of the academic’s eyes will widen at the mention of ‘them’.  Then they speak and it may take the simple form, “Who are they?”  Or there may be swearing involved and perhaps a little crying.

The bottom line is academics hate them.  If you’re sharing actual academic material then you better know who, what, where and how you came upon it.

Now, the field of strength and conditioning is a little funny because discoveries are made in the gym using a research method that we will call ‘trial and error’.  Somebody tries something (probably something they saw someone else do) and they decide whether it works or not.  If it works, they tell two friends, who tell two friends, who tell two friends and one of those friends is an academic geek, so he or she designs a research study to see if it actually works or not.

So quite often when someone says ‘they say’ in strength and conditioning, they mean Mike Boyle or Mark Verstegen.  And for me, if it is working for them, then I am happy to give it a try, but I still take solace in the comfort of my academic papers (especially if the research supports what we are already doing :)).

So I am gonna go research geek on you now and share a great article I found yesterday called:

Effect of Stretch Frequency and Sex on the Rate of Gain and Rate of Loss in Muscle Flexibility During a Hamstring –Stretching Program: A Randomized Single-Blind Longitudinal Study

Cipriani,, DJ, Terry, ME, Haines, MA, Tabibnia, AP, and Lyssanova, O. J Strength Cond Res 26(8): 2119-2129, 2012

This is a brand new article, so it truly is the cutting edge stuff, so let me boil it down for you…

  • There were 62 subjects – average age 24.9 years; range 18-46
  • They looked at the rate of gain and loss of hamstring flexibility over an 8-week period (4 weeks of stretching; 4 weeks of no stretching)
  • There were 5 different research groups based on the frequency of stretching: 1) daily, twice per day; 2) daily;  3) 3-4 times per week, twice per day; 4) 3-4 times per week, once per day; 5) control group – no stretching
  • The stretch used was the standing hamstring stretch held for 30 seconds, followed by a 10 second rest and another 30 second hold (so 60 seconds in total)

So what did they find at the end of the four week stretching portion of the study?

  • Gender had no impact on flexibility gains
  • All four groups improved hamstring flexibility significantly over time, without a significant difference between them.
  • Changes from week to week were not significant, in other words, there was not a week where the majority of the change took place.
  • Statistically significant gains in hamstring flexibility were achieved by week two.
  • When the groups that stretch more than three times per week were compared to the group that only stretched three times per week, there was a greater gain in hamstring flexibility (24.9% improvement vs. 16.8%)

And how about once the stretching stopped?

  • All groups lost some of their new found flexibility, but they still maintained a statistically significant improvement compared to their baseline (retained approximately 11.2% of their overall gain)
  • All four groups lost flexibility at a similar rate once the stretching stopped (mean loss of 9.2 degrees of motion)

So what does this mean to you?

Well, basically it supports the idea that something is better than nothing.  So even if you can only find three times per week to do your stretching, you will see gains.  However, if you stretch twice per day on those three days, then you get basically the same results as someone who stretches once per day every day and that is a worthwhile finding.

I would even go so far as to say, if you are really pinched for time, then stretch only three times per week, but do this; do your full flexibility routine once per day and then add a second bout of stretching on that same day, but this time only focus on your problem areas.  So skaters might focus on their hip flexors, while goalies may focus on their adductors (groins) and hip rotators.

Finally, if you don’t keep it up you will lose some of your gains, but even after 4-weeks of not stretching the subjects retained 11% of their gains, so you do not need to panic if you miss a week of stretching, just get back in your routine as quickly as you can.

Hope you enjoyed that little trip down memory lane, back to my Grad School days – that was fun!

PS – yes you can still get the new Hockey Speed Secrets program for free when you sign up for or – it will be in your dashboard waiting for you.