How Surfski Equipment Tweaks can Reduce Injuries Part 3 (Numb Legs)
Last week I received a friendly reminder via email, asking when part 3 in the series was going to be posted. To be honest I had forgotten about my promise and the reminder was appreciated. Here is part 3.
Numb leg syndrome is my nemesis. It almost chased me away from paddling completely. But I am glad to say that I have figured out how to solve this most painful of problems. There are many factors involved with this condition, but the focus of this blog series is on equipment so I won’t be going into the deeper issues at play.
Being a Sports Scientist I took a rather analytical approach to the problem. Although I knew I could probably lick the issue via technique, stretching etc, I just did not have the patience so I went looking for a quick fix. And found it.
Anatomy first. The Sciatic nerve starts at the nerve roots in your lower back. It then travels through your butt muscles, down your hamstrings and calves and into the soles of your feet. Irritation anywhere along this path can cause symptoms, but in most paddlers, the point of irritation is in the bum! Armed with this info I went looking at surfski cockpits to find the common denominator.
While it differs for some, for most, a tight fitting cockpit that squeezes your butt cheeks together are the worst for numb legs. This has the effect of compressing the sciatic nerve and soon you feel like you are driving your boat with lead weights for legs. The solution was obvious, stop the squeeze.
I started with a foam strip down the middle of the cockpit running fore and aft. This worked but only after I had built the ridge so high, I felt like I had been roggered by a rugby team by the end of each paddle. No numb legs but pseudo sodomy was not acceptable. Taking another look at the cockpit shape, I figured if I could flatten out the base of the cockpit, ie make it less curved, then I might be onto something. Less curve means less squeeze. After some experimentation I managed to build a foam seat that did just that. It’s a combo of a small but fairly wide central ridge to stop the buttock squeeze (minus the sodomy effect) with a trimmed butt pad that lifts me up slightly from cockpit floor. This has the effect of lifting me away from the curve on sides of the cockpit effectively “flattening” the cockpit floor. I have been using the pad for several years now and move it from boat to boat with great success.
But I still was not completely happy. The raised central ridge on the prototype still left me feeling a little exploited on the longer paddles. I started reducing the amount of padding in key areas and finally hit on the minimum amount of padding needed in just the right places to solve my problem. The hassle has been that this is now so fine tuned I need to redo the process each time I sit in a new boat. Hence the prototype has stayed in use for guest appearances in other boats.
For my Fenn Elite I have the solution sorted. The Elite cockpit was the worst for me, going numb after just 5 min and completely dead after 10. The Elite is unique in that the cockpit is the same height as the heels and the seat bucket shape forces one to slump with a rounded lower back. This stretches the sciatic nerve, exacerbating the nerve irritation. I solved this by building a rectangular block cut from 4 buts pads which sits between my coccyx and the back of the cockpit. It serves to force more of a hollow into my lower back relieving pressure on the nerve. I have not found this necessary on other makes of ski’s that have a higher seating position relative to the heels.
Half the problem solved but I was still being squeezed by the cockpit and numb legs prevailed. Imagine a butt pad cut in the shape of a squashed figure 8 or hour glass. The widest part being the top and bottom. These wide sections are placed under the back of the thighs and the lower back. The narrow part joining the top and bottom, runs between the butt cheeks. This narrow section is still quite wide to remove the roggering effect. The net result is you are ever so slightly raised up by the pad under the legs, bum and the butt cheeks. The sit bones have no pad under them at all. This has been just enough of an alteration in body position to remove all pressure on the nerve and I now have full sensation in my legs after the longest paddles.
I have made a few tweaks to the original design. I have cut away significant material around the coccyx to avoid excessive pressure which can become really painful. I also sometimes add a second layer of foam under the central ridge if I am struggling. I have also fitted a heel block to the foot plate. I have very tight hamstrings and this helps tremendously to ease the tensions and symptoms. It also seems to encourage a far stronger leg drive.
Pictures of the my mobile butt pad as well as my Fenn Elite specific butt pad can be seen here. You will have to log in to view the pics however. Forgive the red tape but I am just trying to dangle a carrot to try and build this site’s mailing list. Sign up is quick and easy. Pics of the heel pad also included.
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Would love to hear your feed back, questions and how you have solved this problem.