spinal biomechanics in swimming

Spinal Biomechanics in Swimming

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Spinal biomechanics in swimming, aren’t they the darnedest!

As I review my mentoring notes, I commonly cross bits of information which I happily translate into swimming biomechanics. In preparation for my spinal biomechanics, prevention, and rehabilitation lecture I encountered a few interesting notes. Now it is important to keep in mind, a lot of the research on spinal mechanics is performed on porcine models. If the research wasn’t on porcine models, it was likely performed on corpses. Luckily, newer research on spinal biomechanics is actually analyzing actual humans.

As I was analyzing my notes, I started at the cervical spine and began thinking about freestyle breathing. The freestyle breath is the most commonly used breath in the sport, but many swimmers perform it improperly. In fact, many people are classified as “armpit breathers”, a non-scientific term for swimmers who appear to be smelling their armpit as they breathe. Many feel this is simply due to improper breath timing, which can undoubtedly cause armpit breathing, but I think spinal biomechanics also play a role in those process.

The cervical spine has three main planes of motion: saggital, frontal, and axial (for more informational on planes, check out the Start Here section). Freestyle breathing should be a uniplanar movement in the axial plane (rotation). However, many swimmers perform rotation and side bending (in the frontal plane) as one movement. This is likely due to the configuration of the cervical spine, specifically the facet joints. The facet joints help control motion, but also contribute to motion as their congruency encourages movements in specific motions. As the neck rotates, the facet joints slide backwards resulting in a coupling motion of side bend.

These biomechanics suggest it is more favorable to side bend your head during rotation, than to simply rotate your head! So, freestyle breathing may actually require actions opposite of normal function! Swimming is a tough sport already, now it requires moving against the body!

Lumbar Spinal Biomechanics in Swimming

Last week I discussed an interesting note on the cervical spine. This week we will address the thoracic and lumbar spine. Now the lumbar spine has been discussed greatly in the past (check out  Trouble Shooting Series: Lumbar SpineLow Back Instability in Swimmers). If you’re looking for more information on the lumbar spine, please read these first, since they address a lot of information. However, one interesting note about the lumbar and thoracic spine is their coupled motions.Coupled motions are simply, motions in different planes of motion which complement each other. For swimming, not all of these coupled motions matter for swimming, but if you can integrate your swimming and spinal mechanics, you’ll be running up a smaller and easier hill!
Unlike the cervical spine, it is believed the thoracic and lumbar spine rotate and side bend in opposite directions when the spine is in neutral or extension. For example if your spine is in neutral, then your rotate to your right side, your spine will naturally side bend left. This coupled motion is likely why many swimmers hula-hoop down the pool.
Luckily, there is a simple biomechanical solution, flex the lumbar spine (slightly, remember staying relaxed is key) to alter the coupled motions. When the lower spine is flexed, side bending and rotation occur to the same side. For example, if you are in slight flexion and rotate right, you will side bend right. Now, even the slightest side bending during long axis strokes likely impedes forward velocity, but it is likely easier to feed control side bending on the same side as the rotation, than motions occurring on opposing sides.
Use biomechanics for your benefit! Keep your lumbar spine in slight flexion to facilitate same sided coupled motions!

Pelvic Spinal Biomechanics in Swimming

This part will cover the pelvis, an unknown structure for many in the swimming community, but an essential component for anyone performing dolphin kicks or short-axis strokes. Allan Phillips has addressed this topic previously (pelvis precision), but I feel it is essential to emphasize one crucial point regarding the pelvis, the interaction between the pelvis and hips.

Biomechanically, the pelvis and hips work as a unit. Unfortunately, many swimmers do not use these parts properly. For example, when the pelvis posteriorly tilts, hip flexion is facilitated and hip extension is inhibited. Opposing, if the pelvis is anteriorly tilted, hip extension is facilitated and hip flexion is inhibited.

For those working on their undulation or butterfly, these concepts must be appreciated, to allow for greater hip motion and strength. For more information on this complex, please watch friend of the blog Bret Contreras explain this interaction in regards to weight lifting.

For those seeking a practical implication, simply ensure all your swimmers are able to differentiate their pelvis from their spine and hips. This simple skill will provide them the tools for undulation and butterfly enhancement. One simple test is the pelvic rock. Once this is achieve, swimmers can work on performing this motion in coordination of their hips in the water for further transference.

Written by Dr. GJohn Mullen, DPT, CSCS.
Originally published January 2013.

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