There are many different skill levels in the sport of motocross. In the amateur ranks, there is anywhere from beginner to expert to prove to the American Motorcycle Association that you, as a racer, is good enough to compete at the professional level. Racers at the professional level are required to race 30 total minutes for two different races throughout the day on changing course conditions to earn their overall score. For the terms of this post, we will talk about upper extremity muscular physiology required to race an event at this level. During a 30 minute race, the racers must hold onto the handlebars and preform multiple tasks as located on the handlebars of a race bike such as the controlling the gas, the front brake, and the clutch which leads to extreme strain in the muscles. Research shows that racers can reach EMG calculations that are higher than recorded in maximum grip strength tests (Konttinen et al., 2008). We also see blood lactate levels rising extremely from baseline of 0.2 mmol/L to levels above 4.8 mmol/L (Konttinen et al., 2008). Interpretation of this metric alludes to the limited availability of the mitochondria of the muscles to utilize oxygen, pushing glycolysis to preform anaerobically. This can lead to the introduction of acute onset compartment syndrome in the forearms. This condition is caused by a pressure increase in the fascial compartments caused by the limited expansion capability of the muscular fascia surrounding the forearm muscles. (Chandraprakasm and Kumar, 2011). The pressure increase can impede blood flow leading to necrosis and fibrosis as the pressure goes beyond systolic pressure. With the development of this syndrome, necessary functions become less precise leading to uncontrolled crashes. An appropriate way of relieving this is by preforming an endoscopic decompression by way of fasciotomy of the superficial flexor compartment (Jans et al., 2013). After this surgery, racers have shown a decreased subjective perception of symptoms from 7 to a 1.7 on a scale out of 10 showing an adequate response to the procedure.
Chandraprakasam, T., & Kumar, R. A. (2011). Acute compartment syndrome of forearm and
hand. Indian journal of plastic surgery : official publication of the Association of Plastic Surgeons of India, 44(2), 212–218. https://doi.org/10.4103/0970-0358.85342.
Jans, C, Peersman, G, Peersman, B, Langenbergh, T.V., Valk, J, and Richart, T. (2013).
Endoscopic Decompression for chronic compartment syndrome of the forearm in motocross racers. Sports Medicine (23):2522-2527. Doi: 10/1007/s00167-01403044-z.
Konttinen, T., Kyröläinen, H., & Häkkinen, K. (2008). Cardiorespiratory and Neuromuscular Responses
To Motocross Riding. Journal of Strength and Conditioning Research, 22(1), 202-9. doi:https://doi.org/10.1519/JSC.0b013e31815f5831.
Madi Hand:
ReplyDeleteAccording to Schmidt acute CS has a high false positive diagnostic rate, due to the non-specific diagnostic measures (2019). However, I investigated other ways to measure and help diagnose ACS. These devices called RFID Chips, that implanted non-invasively, this does not interfere with transportation (Schmidt 2019). Using new sensor technology of radiofrequency electromagnetic fields transferring data of the patient, allowing the physiological system to be measured (Harvey 2012). This is more of a monitoring program, but I think it could be very useful for motocross drivers.
Harvey EJ, Sanders DW, Shuler MS, Lawendy AR, Cole AL, Alqahtani SM, Schmidt AH. What's new in acute compartment syndrome? J Orthop Trauma. 2012 Dec;26(12):699-702. doi: 10.1097/BOT.0b013e31826df980. PMID: 22913965.
Schmidt AH. Novel Modalities to Diagnose and Prevent Compartment Syndrome. 2019 Sep 3. In: Mauffrey C, Hak DJ, Martin III MP, editors. Compartment Syndrome: A Guide to Diagnosis and Management [Internet]. Cham (CH): Springer; 2019. Chapter 17. PMID: 32091742.
I find motocross very interesting because of the amount of courage it takes to even try it. It looks fun when I see people do it and there are times when some fall and then get right back on it as if nothing happened, adrenaline levels must be too high in such instances. Lactic acidosis in motocross disrupts one’s pH balance which may lead to loss of oxygen. It makes me wonder what the regulations are in terms of health-related to professional motocross.
ReplyDeleteI looked into it and found that there is a continuous neuromuscular demand with muscular contractions in the lower and upper limbs of motocross riders due to the rise in anaerobic metabolism (Simoes et. al., 2016). You mentioned that the limited number of mitochondria leads to anaerobic glycolysis. I did not know motocross had this much impact on one's health but I guess if the number of mitochondria is limited or if there is not enough oxygen available, then the mitochondria will not be able to provide the energy that is needed for muscle contraction and activity. As a result, these processes will shift to other areas of the cell where they can do more harm than good. It makes sense how this could result in decreased muscular efficiency, fatigue, and eventually injury.
Simões, V. R., Crisp, A. H., Verlengia, R., & Pellegrinotti, I. L. (2016). Neuromuscular and Blood Lactate Response After a Motocross Training Session in Amateur Riders. Asian journal of sports medicine, 7(2), e23805. https://doi.org/10.5812/asjsm.23805