May 9, 2013


What is stretching, and what does it really do? Part I

I have seen quite a bit of research in recent months on stretching and the negative effects it is alleged to have on performance. Apart from what I consider to be terminal errors in the experimental design what is never made clear is just exactly what kind of stretching is being done in these researches. And, as it happens, a number of people have written to me recently asking me to talk about stretching and what it can do for you.

I have been a stretching and conditioning teacher for nearly 30 years. In that time I have never seen any authority on stretching actually recommend slow static stretching be done before the execution of something like a squat or a deadlift. Yet the researchers look precisely at this recommendation. Had anyone asked me to comment on the likelihood of this protocol resulting in a loss of capacity to demonstrate maximum strength I would have answered this way: yes.

The reason is that slow static stretching calms the neural system down which is precisely the opposite state one needs it to be in to be able to demonstrate maximum speed or strength. Calming the system down results in the experience of being more relaxed; high muscle tonus is interpreted by the brain as a state of readiness. If tonus is decreased by conscious efforts, readiness is reduced, not enhanced. To prepare oneself for any activity that requires the neural system to be operating at peak efficiency, one needs to ramp the system up, not calm it down. And I have found the best way to do that is to engage in the activity itself at a submaximal level of intensity. And this is precisely what you see if you watch an experienced group of Olympic or powerlifters preparing for a maximum lift everywhere these things happen.

About 10 years ago an Olympic sprinter called me asking if I could help with his many-times recurring hamstring problem. He said he was hoping that I could show him a better way to stretch his hamstrings. When we met as part of the assessment process I asked him to bend and touch his toes and he was flexible enough to lay his whole body on his thighs with straight legs. I asked him to show me how he stretched his hamstrings and he sat down on the floor and did the hurdler hamstring stretch. He was extremely flexible in the hamstrings by any measure—and I told him that the lack of flexibility was unlikely to be his problem.

We went out on the oval behind my place and, via my trusty binoculars, I watched him run across my vision, towards me, and away from me. One thing I noticed was the absolutely outstanding hamstring development his body displayed. What was also obvious was his strong anterior pelvic tilt and what appeared to be a lack of glute strength. Back in the clinic we played around with a few hip flexor stretches and it was obvious that his hip flexors were extremely tight. So we spent a good half hour working on this muscle group, especially rectus femoris. And he then went back to the airport and flew back to his home state.

Three days later my mobile phone rang and it was this athlete: he was very excited and a little mechanical voice called out, “Kit, Kit Kit”. I asked him what he was excited about and he said that his glutes were really sore today—and he went on to say that this was the first time time they had ever been sore after a sprint training session, the evening before.

This is a long way around to making a simple point: one use of stretching exercises is simply to release muscles which, in this case, were inhibiting the action of a primary strength group, the glutes. The further point is that no one needs very flexible hamstrings to run world record hundred meter pace. If you look carefully at one of the greatest technical practitioners of this event, Michael Johnson, you will see that his front leg is never lifted higher than the front leg’s hip (so, less that 90 degrees of flexion at the hip joint). Further, the front foot is never in front of the knee at any time in this event either (so, 90 degrees of knee flexion). If you can put your foot up on an 18 inch high block, then you are loose enough. From a range of movement perspective everyone on the planet has enough hamstring range of movement to run this sort of speed.

The critical flexibility in sprinters is the capacity for the hip flexors (at the front of the joint) to have a sufficient range of movement that the glutes can be active in that part of the range of movement they need to be: hip extension. To understand the significance of this, one needs to understand  the reciprocal inhibition reflex, one of the most important reflexes in the human body. In the sprinting action, if there is insufficient extensibility in the hip flexors, the brain will switch gluteus maximus off at the very point in the range of movement where it needs to be producing maximal force: as the body’s weight passes over the support leg. And it is no coincidence that the most commonly injured hamstring in sprinters and footballers is biceps femoris, the only hamstring muscle that can actually secondarily perform this hip extension movement.

I was able to attend a training session with the same sprinter a couple of weeks later. I was surprised to see that all of the trainees were sitting around preparing for the sprint session by doing long held static stretches of the hamstrings which in his case were already perfectly flexible. I asked him what he thought he was doing. He said, very reasonably, ‘stretching my hamstrings”, and I asked him “why?” I suggested to him to stretch the hip flexors instead and, moreover, to stretch them dynamically in the lunge position that we use in solo hip flexor stretching. And, further, to do this in bare feet so that the proprioceptors in the soles of the feet are maximally involved in the experience of the action. As well, I suggested to him that he reserve the slow held static stretches for after the training session and this time use these explicitly to calm the system down and help in the muscle repair process (by realigning the fascia through a process of what we call ‘interrogation of the body’, explicitly to finding out what the body needs following any strenuous activity). The conscious mind cannot know what this is; but by sitting down on the ground and going through a few stretches, the body will tell the owner of the conscious mind exactly what needs to be worked on. In my view this is far and away the most important use of slow held stretches.

In the summer of that season he was able to run his best ever hundred meter pace and without any hamstring problems. More to come.

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