Resolving leg numbness in racing car drivers
A number of V8 Supercar drivers have mentioned times they have encountered leg numbness or that feeling of 'the leg going to sleep" while racing. Will Davison has spoken candidly about battling with right leg numbness intermittently for years. In 2012 at Symmons Plains he reported a circulation issue, and having tried to resolve it through treatment on his back and tweaking the seat position. Kurt Kostecki crashed in Townsville 2016 in his first main series race citing leg and foot numbness as the cause. The 18-year-old collected the wall on lap 51 or 70 after his foot went to sleep early in the race. A big change from the usual 21 lap Development series races his body was used to. Kurt was quoted as saying; “As soon as my foot went to sleep I had to wriggle my toes and ultimately lost concentration. “I was left-foot braking just to try to get my foot to come back and when I was thinking of my foot it was taking my concentration away from managing the car and trying to get the best out of it.” Scott Pye too was heard on the radio in one of the two races at the 2016 Sydney 500 reporting that he couldn't feel his leg. "My bums gone to sleep completely, it's down my leg and everything."
So what causes the leg numbness these drivers are talking about? A number of causes could be responsible whether due to disease, illness, degeneration, injury or more simply a functional limitation. It's important to always rule out more serious medical causes through proper investigation. From my experience though the most common causes are biomechanical in which the problems are specifically activity related. The real cause could be very different for each driver.
When the right leg becomes numb while driving the blood flow to the nerve is decreased to the point the nerve stops functioning. This is due to compression of the nerve or stretching of the blood vessels that supply the nerve. Even slight blood flow decrease supplying the nerve can be enough to affect the nerve impulses and cause the leg to feel like it is 'falling asleep.' The challenge is figuring out where the compression lies. Is it coming from the spine or down the track of the nerve in the buttock, thigh, leg or foot?
We know how physically demanding racing a V8 Supercar is. Especially the repeated high braking forces through the right leg coupled with G force and vibration. (To read more about the physicality of motorsport read my previous blog post here.)
Andre Heimgartner is a 21 year old V8 Supercar driver who was in his second year in the series. It was July 2016 when Andre first consulted me and discussed worsening right leg numbness. This issue had been a problem intermittently since he was 16 and varied depending on the type of car he was in, length of the race and physical demands. Through the first half of the 2016 season he found the set up of the LDM Holden Commodore to have exaggerated the problem. At it's worst the numbness would commence at lap 5 and come and stay throughout the race. Andre would need cross his let foot over the right to get on the throttle on the straits and shake the right leg around to return blood supply. He was able to manage the symptoms and likely a testament to his driving skills and use of his left leg that control of the car wasn't affected. None the less it was a needless distraction that I knew Physiotherapy could solve.
We did a full musculoskeletal assessment plus ergonomic assessment involving sitting in the race car. I also referred him for a lumbar MRI to rule out any missed pathology which returned a normal result. In a nutshell the key findings were limited hamstring flexibility, neural mobility and spinal mobility. Andre didn't have adequate muscle, joint and nerve flexibility to ensure blood supply to the nerve wasn't obstructed as the driving demands increased. When correlating Andre's body mechanics to his ergonomic driving position I realised that it wasn't where it needed to be to ensure he was comfortable in the car and able to perform efficiently.
Treatment initially focussed on manual Physiotherapy to loosen soft tissue and joint stiffness in the lumbar spine as well and stretching and neural gliding techniques. We did this treatment immediately prior to all races Reid Park, Townsville (July 2016). Immediately following the first race the numbness pushed out from 5-15 laps. I had also advised Andre of self assisted mobility exercises and stretches and to limit long periods of standing at the track in between races. We also experimented with some dynamic tape which seemed to help thoraco-lumbar trunk proprioception and further decrease the intensity of the numbness when it did set in. In addition strategies in the car which involved pelvic tilting plus some foam additions to bolster the seat insert all helped further. Andre had a home stretching and mobility program which he duly completed.
By the Sundown 500 on 18th September 2015 Andre completed the whole weekend a 25 lap stint on the saturday and a 65 lap stint on the sunday with no leg symptoms. So I was confident we were on the right track so to speak. Andre remained symptom free though Bathurst and the Gold Coast enduro's. Some mild numbness symptoms did creep in at Pukekohe (New Zealand) in November which seemed attributable to a slight drop in hamstring flexibility and the physical nature of that track particularly in terms of numerous fast corners. The problem was again completely resolved through the Sydney 500 races in early December.
Andre still needed to gain some more trunk stability to improve spinal fatigue so we've been working on that over summer. This involves two clinical pilates sessions a week in the studio in addition to all the strength and conditioning work he does with his performance coach Josh Webb. We'll expand the endurance stability work to simulate race environments before the off season is over. It was really great work by a young athlete and to beat a problem such as this in a relatively short time frame.
It would be interesting to gather more data and assessment findings from other drivers regarding their numbness issues. Looking at onboard footage of different drivers it's interesting to see the different driving positions. Analysing joint geometry and comparing symptoms or lack thereof would yield further information. I've treated drivers from other racing series and particularly thoracic lumbar back and low back pain is quite common however specific leg numbness issue less so. This could be attributed to shorter races and custom seats rather than a standard race tech seat plus personalised insert in supercars. Interestingly vibration has also been a factor reported with motorcycle racers affected with nerve related numbness to both their arms and legs. There isn't any data to my knowledge on vibration in V8 Supercars.
Race car drivers spend much of their developmental years in go karts and often open wheel cars before they are fully grown. I would strongly suggest young drivers have a Physiotherapy assessment early in their careers to screen for abnormalities. Equally; all drivers should have any pain or injury fully assessed and treated by a Doctor or Physiotherapist as soon as they notice it's a problem.
This blog post and case study contains clinical findings and personal opinions of the author. Consult your Doctor, Physio or registered health professional for an accurate diagnosis of your own specific health concerns.
Nicole Bryant is a Melbourne based Physiotherapist with a special interest in Motorsports.
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