Modern motocross racing is a very demanding and a highly injury rated sport. Within a wide range of injuries, cervical spine injuries are most feared and can even end up in different forms of ...paraplegia. Worn around the neck and with a non-permanent connection to rider, neck braces primarily offer a protective purpose to prevent cervical spine injuries. Beside the protective purpose, neck braces can have a supporting or a fatigue effect to the rider's neck muscles, where the effects depend on the specific neck brace design and the contact occurring between helmet and brace. Within a field test one subject was measured. During on- track measurements the contact incidents of neck brace and helmet were recorded utilizing a self-made sensor construction. The sensor construction was based on 12 electrical push-buttons and was mounted at the helmet's underside. Contact data was stored using two portable data-logging systems. Additionally muscular activity of m. sternocleidomastoideus (scm) and the upper part of trapezius (trap) were recorded while riding using a portable EMG-system. The acquired EMG data delivered information about a change of neck muscle activity while riding with the neck brace system. Activation levels and distribution of muscular activity of m. sternocleidomastoideus and m. trapezius show divergent activation levels and a changed distribution of muscular activity in response to wearing a neck brace. Related to the data of specific contact areas, it could be observed that almost one fifth of total riding time, contact between helmet and neck brace could be recorded. Low and high frequent contact areas of helmet and neck brace were calculated for total riding time, single laps and specific events, whereby a decreasing trend of contact incicdents by increasing riding time was observed. The EMG and contact data obtained delivered information about a connection of the changes of neck muscle activity and the frequent contact areas of helmet and brace. It can be concluded that driving with neck brace affects the activation levels and distribution of muscular activity of the muscles observed. According to the recent results, the correlation of contact and EMG data could be used for further neck brace design improvements and specific design adaptations to special requirements of several bike sports.
The aim of this study was to investigate the physiological demands of Supercross BMX in elite athletes. Firstly athletes underwent an incremental cycling test to determine maximal oxygen uptake ...(VO2max) and power at ventilatory thresholds. In a second phase, athletes performed alone a simulated competition, consisting of 6 cycling races separated by 30 min of passive recovery on an actual BMX track. Oxygen uptake, blood lactate, anion gap and base excess (BE) were measured. Results indicated that a simulated BMX performed by elite athletes induces a high solicitation of both aerobic (mean peak VO2 (VO2peak): 94.3±1.2% VO2max) and anaerobic glycolysis (mean blood lactate: 14.5±4. 5 mmol x L(-1) during every race. Furthermore, the repetition of the 6 cycling races separated by 30 min of recovery led to a significant impairment of the acid-base balance from the third to the sixth race (mean decrease in BE: -18.8±7.5%, p<0.05). A significant relationship was found between the decrease in BE and VO2peak (r = - 0.73, p<0.05), indicating that VO2peak could explain for 54% of the variation in BMX performance. These results suggest that both oxygen-dependent and -independent fuel substrate pathways are important determinants of BMX performance.
We describe the treatment of a 29 year-old professional motocross rider, who sustained a perilunate dislocation in his right wrist and a distal radius fracture and dorsal dislocation of his left ...wrist during a race. Both wrists were treated acutely during a single operating session. Surgery consisted in open reduction, k-wire fixation and mini-anchor repair of the scapho-lunate and luno-triquetrium ligaments on the right wrist, while closed reduction and percutaneous k-wire fixation was used in the left wrist. Follow-up at 6 months has shown satisfying radiological and functional outcomes in both wrists. The rider ultimately returned to motocross 5 months following surgery.
Simulation of engine components enables early design verification and reduced development time while helping racing teams in getting new knowledge. This article presents a multidiscipline dynamic ...test bench and a benchmark of two different connecting rods for HONDA CRF250R. The test bench embeds mechanical and control system modeling and simulation including electric starters, ignition timing, power control as well as sensors and actuators enabling closed-loop systems. A non-linear finite element program that combines the traditional separate multi-body simulation and finite element modeling and simulation tasks captures all load cases and dynamic effects in one single run. Model reduction techniques are applied to optimize simulation speed and results accuracy. The virtual test bench captures dynamic engine effects and efficiently provides new knowledge about engine performance and integrity.
Maximising power output during the initial acceleration phase of a bicycle motocross (BMX) race increases the chance to lead the group for the rest of the race. The purpose of this study was to ...investigate the effect of non-circular chainrings (Q-ring) on performance during the initial acceleration phase of a BMX race. Sixteen male cyclists (Spanish National BMX team) performed two counterbalanced and randomized initial sprints (3.95s), using Q- ring vs. circular chainring, on a BMX track. The sample was divided into two different groups according to their performance (Elite; n = 8 vs. Cadet; n = 8). Elite group covered a greater distance using Q-ring (+0.26 m, p = 0.02; D = 0.23), whilst the improvement for the Cadet (+0.04 m) was not significant (p = 0.87; D = -0.02). Also, there was no significant difference in power output for the Elite group, while the Cadet group revealed larger peak power with the circular chainring. Neither lactate level, nor heart rate showed significant differences due to the different chainring used. The non-circular chainring improved the initial acceleration capacity only in the Elite riders. Key PointsThis work provides novel results demonstrating very significant improvements in the sprint performance of BMX cycling discipline using a non-circular chainring system.This study seeks a practical application from scientific analysisAll data are obtained in a real context of high competition using a sample comprised by the National Spanish Team.Some variables influencing performance as subjects' physical fitness are discussed.Technical equipment approved by International Cycling Union is studied to check its potentially beneficial influence on performance.
The objective of this study was to examine the effect of sodium bicarbonate (NaHCO3-) ingestion on performance and perceptual responses in a laboratory-simulated bicycle motocross (BMX) qualification ...series. Nine elite BMX riders volunteered to participate in this study. After familiarization, subjects undertook two trials involving repeated sprints (3 x Wingate tests WTs separated by 30 minutes of recovery; WT1, WT2, WT3). Ninety minutes before each trial, subjects ingested either NaHCO3- or placebo in a counterbalanced, randomly assigned, double-blind manner. Each trial was separated by 4 days. Performance variables of peak power, mean power, time to peak power, and fatigue index were calculated for each sprint. Ratings of perceived exertion were obtained after each sprint, and ratings of perceived readiness were obtained before each sprint. No significant differences were observed in performance variables between successive sprints or between trials. For the NaHCO3- trial, peak blood lactate during recovery was greater after WT2 (p < 0.05) and tended to be greater after WT3 (p = 0.07), and ratings of perceived exertion were not influenced. However, improved ratings of perceived readiness were observed before WT2 and WT3 (p < 0.05). In conclusion, NaHCO3- ingestion had no effect on performance and RPE during a series of three WT simulating a BMX qualification series, possibly because of the short duration of each effort and the long recovery time used between the three WTs. On the contrary, NaHCO3- ingestion improved perceived readiness before each WT.
The sport of motocross entails off-road motorcycle racing and is associated with a high incidence of traumatic injury. While prophylactic knee braces are routinely worn, there has been anecdotal ...concern that brace use is linked to femoral shaft fractures. While this risk remains unreported in the medical literature, preventing this complication has played a role in new commercial knee brace designs. We present two cases in which two motocross riders sustained transverse femoral shaft fractures at the proximal portion of each respective knee brace. The fracture locations measured on anterior-posterior radiograph were 22 and 21.1 cm proximal to the center of the knee, which is also the recommended proximal extent of motocross knee braces. We propose that the rigid knee brace protects the ligamentous knee structures but may focus undue force on the proximal aspect of the brace. New knee brace designs have incorporated features to dissipate the potentially injurious force to prevent femur fracture. While knee braces undoubtedly help prevent ligamentous knee injury, these cases question the safety of standard brace design and highlight the need for further brace development to better protect the patient’s bony structures, in addition to the knee joint.
Neck braces are designed to prevent traumatic injuries of the cervical spine by transferring the forces occurring at the head and spine to adjacent body structures, mainly the torso. Gorasso and ...Petrone (2013) showed that neck braces can influence the muscular activity of the neck during motocross riding, but their results only refer to one analysed neck brace system. Based on their results, this work analyses the effect of different neck brace designs on muscular activity of the neck during specific events in motocross riding. During on-track-measurements the muscular activity of m. sternocleidomastoideus and the upper part of m. trapezius were recorded in three different conditions: driving without neck brace (C1); driving with neck brace system A (C2); driving with neck brace system B (C2). For all the conditions mentioned the following riding events were examined: (a) turn, (b) bumps and (c) jump. Based on the results, it can be concluded that wearing a neck brace during motocross riding has various effects on the muscular activity of the neck. Depending on the neck brace design, the effects can be an increased or a decreased activity of the involved muscles and a change in the distribution of muscular activity in the neck. According to the recent results and with additional research, an improved neck brace system with optimized design can be developed, which not only serves protective purposes, but also can help to relieve the riders neck muscles during riding.
Background: The effectiveness of prophylactic knee bracing in preventing knee injuries during sports has been evaluated; however, because of the variability in study conclusions, the topic remains ...controversial. Despite a paucity of data, the authors believe that prophylactic knee bracing is frequently used in off-road motorcycling.
Hypothesis: No statistically significant difference exists in the frequency and types of knee injuries incurred between braced and nonbraced riders using commercially available knee braces in off-road motorcycling.
Study Design: Descriptive epidemiology study.
Methods: Data from 2115 off-road motorcycle riders was obtained using an Internet-based survey over a 1-year period. Participants were grouped by use or nonuse of prophylactic knee bracing, and an incidence rate ratio was used for injury rate comparison.
Results: Participants recorded 39 611 riding hours over the study period. A total of 57 riders (2.7%) sustained at least 1 knee injury, for a total of 89 injuries. The most common injuries involved the anterior cruciate ligament, menisci, and medial collateral ligament. There was a significantly higher rate of overall injuries in the nonbraced group versus the braced group (3.675 vs 1.587 per 1000 rider hours, P < .001). Significantly higher incidence rates of anterior cruciate ligament rupture (1.518 vs 0.701 per 1000 rider hours, P = .0274) and medial collateral ligament injury (0.799 vs 0.111 per 1000 rider hours, P = .002) were found among nonbraced riders compared with braced riders.
Conclusion: The most common knee injuries in off-road motorcycling involve the anterior cruciate ligament, menisci, and medial collateral ligament. The use of prophylactic knee bracing appears to have a beneficial effect in preventing medial collateral ligament and anterior cruciate ligament injuries as well as overall knee injury occurrence. These findings may be applicable to other sports that involve similar forces and mechanics.
Motocross racing is a popular sport; however, its impact on the growing/developing pediatric spine is unknown. Using a retrospective cohort model, the authors compared the degree of advanced ...degenerative findings in young motocross racers with findings in age-matched controls.
Patients who had been treated for motocross-related injury at the authors' institution between 2000 and 2007 and had been under 18 years of age at the time of injury and had undergone plain radiographic or CT examination of any spinal region were eligible for inclusion. Imaging was reviewed in a blinded fashion by 3 physicians for degenerative findings, including endplate abnormalities, loss of vertebral body height, wedging, and malalignment. Acute pathological segments were excluded. Spine radiographs from age-matched controls were similarly reviewed and the findings were compared.
The motocross cohort consisted of 29 riders (mean age 14.7 years; 82% male); the control cohort consisted of 45 adolescents (mean age 14.3 years; 71% male). In the cervical spine, the motocross cohort had 55 abnormalities in 203 segments (average 1.90 abnormalities/patient) compared with 20 abnormalities in 213 segments in the controls (average 0.65/patient) (p = 0.006, Student t-test). In the thoracic spine, the motocross riders had 51 abnormalities in 292 segments (average 2.04 abnormalities/patient) compared with 25 abnormalities in 299 segments in the controls (average 1.00/patient) (p = 0.045). In the lumbar spine, the motocross cohort had 11 abnormalities in 123 segments (average 0.44 abnormalities/patient) compared with 15 abnormalities in 150 segments in the controls (average 0.50/patient) (p = 0.197).
Increased degenerative changes in the cervical and thoracic spine were identified in adolescent motocross racers compared with age-matched controls. The long-term consequences of these changes are unknown; however, athletes and parents should be counseled accordingly about participation in motocross activities.
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