Flexibility: Strength training vs. stretching
Let’s talk about flexibility for a bit. Flexibility is a topic around which there are a great many myths and uncertainties. Perhaps the most famous of which is that stretching before an athletic event helps to prevent injury during that event. This myth has long been debunked by many studies, and in fact we now know that much more important for presenting injuries is a good warmup lasting 8-12 minutes that builds from no activity to “game time” level intensity.
But I digress, because flexibility is still an important component of physical fitness and should still be considered as an element to be trained in the same way that muscle strength, size, or cardiovascular endurance might be (for example).
One thing to consider before stretching anything is: what are the goals to be accomplished with this training? In fact hopefully this is a consideration you might make before any training.
Flexibility for our purposes refers to the ability of the muscles to achieve a length sufficient to allow range of motion needed at a joint for a specific activity. For example, a football kicker needs flexibility of the glutes and hamstrings in her kicking leg to achieve the hip flexion required for a good punt. Similarly a baseball pitcher requires flexibility of the lats, pec major, and teres major to achieve the shoulder rotation required for a wicked wind-up in throwing a 100MPH fastball.
An example more of us might easily relate to is that our calf musculature -the gastrocnemius and soleus amongst others- need flexibility to achieve ankle dorsiflexion (approximation of the shin and the foot) to execute a beautiful squat. If you don’t believe me try doing a high quality squat after you come out of casting from a broken ankle! Similarly, to deadlift well, the hamstrings need to be flexible enough to let the hips flex through the lowering part of the exercise.
All this to say that flexibility needs to service function. An athlete needs flexibility enough to execute their athletic movement patterns. And we all need flexibility enough to execute the movements we perform in daily life! Since all of our movements must be beautiful (right!), flexibility for us is the muscle mobility required to move beautifully!
Now, does this mean that we need embark on a rigorous program of daily stretching so that we can improve our ranges of motion to “beautiful” proportions? Interestingly, the answer to that question is “not necessarily”!
It’s true that regular static stretching does improve flexibility - and remember of course that good quality static stretching is as much if not more about time under tension more than the intensity of stretch. So hold those stretches for at least 30 seconds, and to be honest I personally like I like a couple of mins!
But did you also know that strength training through range of motion has been shown in multiple research studies to be effective for training flexibility. In fact, if you want to improve your flexibility, research shows that strength training is effective to a level on par with consistent static stretching.
The reason for this effect is not entirely clear but theories mostly surround what are known as neurophysiological changes to the muscle. Neurophysiological factors describe the input of the brain, spinal cord and peripheral nerves to the muscle. These are important factors for the baseline tone (tightness) of a muscle as well as its strength and power. This can include things like reduced nerve stimulus to the muscle reducing baseline muscle tone or an increase in stretch tolerance (we’re simply better able to “take it” in heavier stretches). Interestingly, the longheld hypothesis that the muscle fibers themselves elongate has some, but less supporting evidence.
Consider those hamstrings on our football kicker. The ones she needed flexible so that she could punt the ball down the field. She could conceivably train hamstrings length with a high quality deadlift protocol (probably a straight leg romanian deadlift).
Think about the feeling of dropping into the descent phase of a deadlift. Notice how your hamstrings act as the “brake” on the descent, preventing further movement when the exercise is performed correctly. The more flexible your hamstrings the further into movement you’ll be able to descend. Happily, according to the research, the more you deadlift, the more flexible your hamstrings will become.
Of course, one of the tricks here is to exercise through the full amount of your available range of motion. This means you execute your exercises to the depth and length that your body allows. This practice is known to be important for muscle strength/size gains and it’s a common cheat in the gym to perform shallow reps. So, now that you have read this, never again will you half ass on range of motion in a rep!
Check out the video above. I describe the use of strength training to train flexibility. I use the deadlift as an example of how you use this motion to train hamstrings for both strength and length!
Consider this concept the next time you are in the gym. And if you didn’t already have good reasons to strength train through your full range of motion, well now a very good one more!
Further reading (if you really want to impress your friends)
Blazevich, A. J., Cannavan, D., Waugh, C. M., Miller, S. C., Thorlund, J. B., Aagaard, P., & Kay, A. D. (2014). Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans. Journal of Applied Physiology, 117(5), 452-462.
Bloomquist, K., Langberg, H., Karlsen, S., Madsgaard, S., Boesen, M., & Raastad, T. (2013). Effect of range of motion in heavy load squatting on muscle and tendon adaptations. European journal of applied physiology, 113(8), 2133-2142.
Konrad, A., & Tilp, M. (2014). Increased range of motion after static stretching is not due to changes in muscle and tendon structures. Clinical Biomechanics, 29(6), 636-642.
McHugh, M. P., & Cosgrave, C. H. (2010). To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian journal of medicine & science in sports, 20(2), 169-181.
Morton, S. K., Whitehead, J. R., Brinkert, R. H., & Caine, D. J. (2011). Resistance training vs. static stretching: effects on flexibility and strength. The Journal of Strength & Conditioning Research, 25(12), 3391-3398.
Pinto, R. S., Gomes, N., Radaelli, R., Botton, C. E., Brown, L. E., & Bottaro, M. (2012). Effect of range of motion on muscle strength and thickness. The Journal of Strength & Conditioning Research, 26(8), 2140-2145.
Simão, R., Lemos, A., Salles, B., Leite, T., Oliveira, É., Rhea, M., & Reis, V. M. (2011). The influence of strength, flexibility, and simultaneous training on flexibility and strength gains. The Journal of Strength & Conditioning Research, 25(5), 1333-1338.