Friday, August 31, 2012

"Stretching Before Workouts Makes You Weak!" Mostly True, But Your Workout Volume Will Decline Even More. Plus: Stretching vs. Doms & Stretching for Couch Potatoes

Image 1:Avoid performing stretches before your workout; if you don't do them at all, things like this are out of reach and for the avg. 'no stretcher', 'all bencher', the hunched over look is just right around the corner.
Stretching is one of those topics most trainees are not really interested in. In that most of you are probably happy that most researchers agree that passive stretches, as they may have been prescribed 50 years ago, are counter-indicated before workouts. And though the experts still disagree on whether or not certain active stretching regimen may be useful, most trainees read the headline "Stretching Before Your Workout Reduces Your Strength" once and gave up the in their eyes bothersome, unnecessary ("I've never hurt myself, although I never stretch, bro!") and with the said headline "officially" detrimental pre-workout routine and spend the they otherwise have invested in a couple of stretches either guzzling a caffeine-laden pre-workout product (which is by the way to be consumed 30-45min before a workout) or doing another three to five sets of bench presses, biceps curls and crunches, before, during or after their workout. Even if we discard the fact that neither of those practices will be largely beneficial, this does still raise the question...

Is stretching actually detrimental? And if so, how detrimental is it?

When Renato Barosso and his colleagues from from the Laboratory of Neuromuscular Adaptations to Strength Training at the School of Physical Education and Sport of the University of Sao Paulo recruited the 12 young strength-trained men (20.4 years, 67.9, 173.3cm), they probably had a very similar question on their minds.
Figure 1: Graphical outline of the time-course of the 2 x 4 (1RM or maximal repetition) testing sessions (Barosso. 2012)
As you can see in figure 1 this was a trial in which all participants ,who had been familiarized with the respective protocols on 3 familiarization sessions on separate days, underwent every of the three stretching sessions which consisted of three sets of the supine knee flex, side quadriceps stretch, the sitting toe touch which were performed in the form of
  • static stretches (SS) This is probably what you would call "the classic stretch", where you hold each stretch for 30s, make a 30s pause and continue
  • proprioceptive neuromuscular facilitation stretching (PNF) You perform a passive stretch and hold the stretching position for approximately 5 seconds; then, you perform a 5s near-maximal isometric contraction (Sheard . 2010), relax and passively hold the stretching position for another 20s
  • ballistic-stretching (BS) Same procedures as in the static stretch session, but instead of holding the stretching positions for 30 seconds, the subjects had to bob in 1:1-second cycles for 1 minute
and the non-stretched control workouts with subsequent 1RM or maximal number of repetition tests. With the 3 + 1 conditions and the two measuring outcomes being tested on different occasions, this sums up to a total of 8 testing sessions of either 1-RM max leg presses or 80%RM leg presses to failure.
Figure 2: Absolute changes in ROM during the "sit and reach test" (in cm) and rel. changes compared to no-stretching condition in 1-RM strength and maximal number of reps during 80%RM leg presses (data based on Barroso. 2012)
As you can see in figure 2 this is not one of the many SuppVersity posts that's going to bust a myth. Stretches, no matter how you perform them, will negatively effect your strength on the subsequent workout; only the PNF protocol with its short bursts of maximal contractions, however, lead to statistically significant, yet still relatively small (-5.4%) reductions in 1RM strength. What will suffer much more than your strength, though, is your ability to endure longer workouts, or I should say, longer sets: With reductions of
  • -8.2 reps (-23%) after the "classic" static stretching routine
  • -7.5 reps (-21%) subsequent to the PMF stretching routine, and
  • -6.4 reps (-18%) in the maximal rep test after the ballistic stretch
it seems counter-indicated to perform any of these before your training session (the mean number of reps in the control condition was 36).

But doesn't stretching help against soreness? No! Neither pre- nor post-workout stretching offer a significant protection against muscle soreness, a Cochraine Review by Herbert et al. from July 2011 found "improvements" of 0.5 or 1pt, respectively, on a 1-100pts soreness scale after reviewing 12 relevant randomized controlled studies, of which one had more than 2,000 subjects (Herbert. 2011).
So, aside from preventing shortening of the muscles and increasing flexibility is there another reason to stretch? Yes! One surprising finding is that if you are a total couch-potato and don't train at all,  40min of stretching performed 3x / week over the course of 10-weeks will not just increase your flexibility (18.1%), they will also bump your standing long jump (2.3%), vertical jump (6.7%), 20-m sprint (1.3%), knee flexion 1RM (15.3%), knee extension 1RM (32.4%), knee flexion endurance (30.4%) and knee extension endurance (28.5%) performance... what? You are no couch-potato? Great, but these results do still tell you that part of the detrimental effects of stretching on your training performance may well be mitigated by the "training effect" - it's a stressin mini "workout" for your muscles and you would not do 100 body weight squats before your 80% 1RM max-rep test, either - would you?
Despite the fact that the most-heard science based argument against stretching before a workout does in fact involve its well-established negative effects on maximal strength performance, Nelson et al., Franco et al. and Marques et al. reported similar results for knee flexor exercises performed with 40, 50 and 60% of the body weight (Nelson. 2005), 1-3 sets of 20 reps of bench presses (Franco; 2009) and rep-max tests at 40, 60 and 80% knee extensions and bench presses on non-trained individuals (Marques. 2011) as Barroso et al. in the study at hand. The real "news" is thus...
"[...] that not only SS and PNF but also BS impaired the number of repetitions and the total volume (i.e., number of repetitions x external load) performed after stretching when compared with NS [and] that in strength-trained individuals, only the PNF stretching mode impaired the maximal strength production." (Barroso. 2012)
In a more general context, the latter finding, i.e. the influence of the exercise status on the strength declines subsequent to static stretches before a workout, is probably of even greater significance than the notion that you will hamper your strength endurance (note: I stick to this term here, although I am aware that most of you won't think of training at a 80% RM as "strength endurance" training): the questionable significance of data that was generated in an experiment with strength training rookies for the average physical culturist.

In the case of the effects of classic static stretching and ballistic stretches before a workout on the performance during a subsequent 1-RM max strength test, it is now clear that the results from rookies, whose performance drops compared to the no stretch condition, regardless of the protocol, the rookie data is of little to no value for anyone with a coupe of months, let alone years of weight lifting experience.

Bottom line: Irrespective of the last-mentioned problems, the take home message from this and previous studies would be the same for all strength athletes who don't just walk into the gym, crank out a single max set and head home again - Refrain from performing any kind of quasi-static stretching protocol before your workout - and don't forget to look at the study population the next time you see one of the rare studies on resistance training ;-)

References:
  • Franco BL, Signorelli GR, Trajano GS, de Oliveira CG. Acute effects of different stretching exercises on muscular endurance. J Strength Cond Res. 2008 Nov;22(6):1832-7. 
  • Herbert RD, de Noronha M, Kamper SJ. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD004577.
  • Marques MC, Costa PB, da Silva Novaes J. Acute effects of two different stretching methods on local muscular endurance performance. J Strength Cond Res. 2011 Mar;25(3):745-52. 
  • Nelson AG, Kokkonen J, Arnall DA. Acute muscle stretching inhibits muscle strength endurance performance. J Strength Cond Res. 2005 May;19(2):338-43.
  • Sheard PW, Paine TJ. Optimal contraction intensity during proprioceptive neuromuscular facilitation for maximal increase of range of motion. J Strength Cond Res. 2010 Feb;24(2):416-21.