Downhill Injuries 2 (FR) have some- (XC) bicycles are relatively light Freeride On-the-site and clinical management overuse injuries (13). Suchreported injuries in are 45% tobikers 90% (13). of Injury-related mountain costfor of the care cyclists can becial a burden for significant cyclists finan- andgeneral health (46). care However, the in potential risks of are outweighed by the health- related benefits of riding a bike. plans for MTB injuriesknowledge depend of on the sport, the the understanding injury mechanism, and precipitating factors. Prevention of MTB injuries en- tails recognition of both traumaticoveruse and mechanisms (34). There iscity a of pau- high-qualitygard evidence with to re- sport-specific pathogenesis, , MD, MPH, FACSM Cross-country The bicycles enable the rider to navigate thru terrains, such Bike fit is the process of making the cyclist and treatment, and prevention of the most common overuseinjuries. MTB We present aries brief and introduction illnesses to associated common with MTB. inju- Bicycle Types as footpaths, single-tracks, forest, unconventional urban, and mountainous area. The slippery androutes uneven surface usually of consists these ofThere is rocks, no uniform mud, definition for dirt, bicycleIn types this and used article, in we tree MTB. will roots. discuss injuriesbicycles: related 1) to the following weight bicycles suitable for ascending andtracks descending single- or footpaths for long(DH) bicycles durations have stronger of components and time; with thea 2) rider in more upright position, enable themfrom to difficult make terrains; rapid descents 3) what similar geometry and components to DH bicyclesenable which the riderstechnical to stunts and rapid ascend descends in various any(Table challenging terrain tracks, 1). in The additioncontrast FR to to DH bicycles bicycles (Fig. have 1). a shorter wheelbaseBike Fit in geometry compatible to minimize theprove risk the of performance injury at andbike the im- fit same is time aHowever, (34,53). most studies Improper precipitating on bike factor fit have forperformance addressed the many cyclists’ rather overuse than injuries. its effect on biomechanics and ; and Morteza Khodaee 1 ,MD verall injury rates in Olympic renders the rider vulnerable to November/December 2017 & : Morteza Khodaee, MD, MPH, FACSM, Ruhollah Nourian ; PORTS 1 S 6 & 412 Y Department of Family Medicine, University of Colorado 2 Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction 2017 by the American College of Sports Medicine Volume 16 *

OMPETITIVE Abstract With the increasing popularity of mountaincycling, biking, also and known the as riders off-road pushingcorresponding the increase sport in into extremes, injury. therevolve Almost has the two been upper a thirds extremities, ofaffect and acute the a injuries lower similar in- extremities. proportionsport for Mountain of severe biking overuse spine injuries. appears injuries Newwith to trends of popularity be injury of patterns a are mountainprotective observed high-risk gear, bike improving technical trail proficiency, and parks physicalsomewhat fitness and may decrease the freeride risk cycling.rider of Using interface areas injuries. and with Simple the modifications bicycleoveruse (bike in fit) injuries. also bicycle- may Bike decrease some fitduring the provides sport. the In clinician thisday management review, with strategies we and postural monitoring also the correction discuss injury the trends. importance of race- With the boom of outdoor activities in the United States, Sports Medicine Research Center, Tehran University of Medical Sciences, Current Sports Medicine Reports Copyright Tehran, Iran; and Department of Family Medicine, University of Colorado SchoolAFW of Clinic, Medicine, 3055 Roslyn St., Denver,[email protected]. CO 80238; E-mail: 1537-890X/1606/404 School of Medicine, AFW Clinic, Denver, CO Address for correspondence 404 1

Introduction the popularity of mountain biking (MTB), alsoroad known cycling, as has off- followed the trend (23). Inthe the United number States, of mountainlion bikers in 2006 has to increased 8.32 million from inin 2015 6.75 (23). popularity Despite of mil- the the increase sport, theacute reported injuries national frequency appears of to beconflicting the decreasing in local patterns the ofalmost United injury a States, frequency third (35). of With injuriesamong the occurring sports during leading the to race, highsports MTB o (20). is During themountain bikers 2012 reported acute Summer or overuse Olympics,had injuries, half 21% led of which of the cyclistsFifty percent to of lose recreational bikers atmountain and least 80% bikers one of have professional training/raceinjury day reported directly related (20). to at the sport leastof (35). Microtraumatization contact one and noncontact major areasvibration, due severe in to addition to repetitive forces fatigue, and Mountain Biking Injuries Majid Ansari, MD C

Downloaded from https://journals.lww.com/acsm-csmr by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3Le0ic6pTQVA6uok+T1gQk2DOuVs2UQ+FWIjZcvNMoLSN+519DE4z8g== on 07/06/2019 Downloaded from https://journals.lww.com/acsm-csmr by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3Le0ic6pTQVA6uok+T1gQk2DOuVs2UQ+FWIjZcvNMoLSN+519DE4z8g== on 07/06/2019 Table 1. 10- change in knee flexion. A knee flexion angle of 25- to 30- Average characteristics of common off-road bicycles. appears to be suitable for manual (static) bike fit methods, - - Fork while the value is 30 to 40 for most motion-capture Wheel Size Travel Rear HTA STA Weight methods (52). Calibrating the process with knee angle mea- Discipline (inches) (mm) Suspension (-) (-) (kg) surement during standing might lead to better accuracy for

a the latter method and minimize the observed difference (52). XC 26 , 27.5, 29 100 Yes/No 68-73 72-75 8-10 After adjusting the seat height, fine-tuning the process to FR 26, 27.5, 29a 175 Yes 63-65 74-76 14-17 prevent excessive pelvic sway in frontal plane also has been DH 26, 27.5, 29a 200 Yes 63-64 57-60 15-18 advocated (41). Saddle height determination based on leg length alone may be inaccurate (17). a Currently less common variants. HTA, head tube angle; STA, seat tube angle. Saddle Setback Fore/aft positioning of the saddle also affects the kine- injuries (17). Traditionally, after goal-setting with the rider, matics of the knee joint (19). The Knee Over Pedal Spindle the bike fit starts with obtaining a medical history and physical (KOPS) rule might be helpful in most of the cases. After examination with special emphasis on spine and lower-extremity early saddle height adjustment, a plumb-line anterior to the problems. Afterward, on-the-bike-fit begins with stepwise modi- knee should cross the center of the pedal axis with cranks in fications in bike-rider interface. Then, the degree of trunk incli- horizontal position. For most of the bicycles with conven- nation, position of the shoulders, and cervical spine ergonomics tional seat tube axis, this adjustment will place the greater are noted (34). The pedals, shoes, saddle type, height, and tilt, trochanter in alignment with the seat-tube (Fig. 1). crank size, handlebar type and width, headset height, length and inclination might be adjusted or modified (Table 2) The Foot-Shoe-Pedal Interface (13,17,19,62). Applying the motion-capture technology, Frontal plane suboptimal moments in lower extremities 2- and 3-dimensional kinematic modelings have become avail- (including knee varus or valgus, and tibial rotational forces) able in addition to more traditional techniques with no proven have been suggested as precipitating factors for chronic knee superiority between the methods with regard to injury or problems in cyclists (22). Various insoles and wedges are used performance or comfort (34). for cyclists to address these problems, with no significant ef- fect on performance (22). Varus wedges may be beneficial for Saddle Height cyclists with forefoot varus deformity, while forefoot inversion An increase in knee flexion during cycling (e.g., due to low wedges may be beneficial for riders with foot pronation (17). saddle height) is correlated with patellofemoral pain syn- Changing the Q-Factor (interpedal stance width) also is an drome (PFPS), while decreased knee flexion (e.g., due to ex- easily performed, but not free of limitations, method of cessive saddle height) has been linked to hamstring injuries (52). changing frontal plane kinematics (22). Cleat rotation (float) One of the common methods to determine the saddle adjustment also might help cyclists with meniscal and height is the knee flexion measurement when the pedal is at intra-articular knee problems (22). the lowermost position (52). Changes in neuromuscular ac- tivation patterns after altering the saddle height have been Acute Injuries observed in gastrosoleus, quadriceps, and hamstring muscles, The most common mechanism of acute severe injury for with lowered seat reducing the activity of gastrosoleus and competitive mountain bikers has been falling forward (64.9%), hamstring, and increasing the activity of quadriceps (53). A and 85.6% of such injuries have occurred while riding DH (14). change of 2.6 to 2.9 cm in saddle height corresponds to about Falling forward had led to a significantly higher Injury

Figure 1: Schematic bicycle diagram. CS, chain stay; TT, top tube; R, reach; ST, seat tube; STA, seat-tube angle; HT, head tube; HTA, head-tube angle; WB, wheel base; TT, top tube; SH, saddle height. www.acsm-csmr.org Current Sports Medicine Reports 405

Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Table 2. Common modifiable bike fit area problems based on common chronic injuries in mountain bikers (13,17,19,21,62). Injury/Interface Saddle/Buttocks Handlebar/Hand Foot/Shoe/Pedal

Neck pain Improper saddle tilt, too high Long stems, low handlebars NA Ulnar/median neuropathy Forward tilt, too aft Low or narrow handlebars NA Chronic LBP Improper tilt Low handlebars NA Genitourinary complaints Improper tilt/height Long stems, low handlebars NA Patellofemoral pain syndrome Too low, too fore NA Hyperpronation, improper positioning, cleat valgus tilt ITBFS at the knee Too high, too aft Low handlebars Hyperpronation, improper positioning and cleat float and tilt Quadriceps/infrapatellar Too low, too fore NA Hyperpronation, improper tendinopathy positioning and cleat float and tilt Achilles tendinopathy Too low NA Hyperpronation, posterior positioning and excessive float Metatarsalgia NA NA Cleat position too forward

NA, not applicable.

Severity Score (ISS) and emergency department admission 2009 biking season in a MBTP, 86% of injury visits to a local rates than falling to the side (14). Different injury patterns emergency center were male, and 52% of cases were visited have been reported in three studies (Table 3). between 1 p.m. and 4 p.m. (5). Upper-extremity fractures consisted 74.2% of all fractures, and 11.2% of all patients Patterns of Injury had traumatic brain injury. Almost 9% of patients required Various terrain conditions and participants in the sport transfer to a higher-level trauma center (5). have led to a variety of injury patterns among mountain bikers. Mountain biking is reported as a common cause of sports With only severe injuries included in a study conducted in related fracture, constituting 7.4% of such fractures, occurring 1995, injury rate per exposure was similar between DH and mainly in the male (92%) and upper extremities (93%)(2). XC races (38). However, when comparing the injury rate per Approximately 7% to 15% of all acutely injured competitive 1000 h, the DH cyclists had a significantly higher injury rate mountain bikers in 1995 had fractures, while among recrea- in comparison to XC cyclists. The injury rates were 7.5 and tional cyclists in an MBTP in Scotland, fractures, head injuries, 3.1 per 1000 h for female and male XC cyclists, respectively and dislocations consisted 37%, 13%, and 8% of all injuries, (p = 0.01); while the rates were 46.8 and 42.7 per 1000 h for respectively (38). Two thirds of all fractures occurred in the female and male DH cyclists, respectively (p 9 0.05)(38). upper extremities, and 45% of all injuries happened in the FR A European study reports an injury rate of 1.1 per 1000 h park. The injury rate was 1.5 per 1000 biker exposure (1). of MTB similar between the competitive and recreational Predictive factors for increased risk of MTB crashes in- cyclists (25). Of all injuries during a seven-stage XC race clude prior history of crashing, riding in the dark or in a requiring medical care in the United States, 68% affected the group (60). Riding errors, trail conditions, obstacles, fatigue, skin and soft tissue, and all musculoskeletal injuries (23% of all injuries) were in the wrist area (45). In a 6-month-long prospective study of self-reported DH Table 3. injuries, there was an injury rate of 16.8 injuries per 1000 h of Patterns of acute injury in different reports. exposure with 31% requiring medical attention, and 13% United severe enough to restrict participation in the sport (10). Country States (35) (9) Canada (54) Lower leg and forearm were the two most common sites of ISS NA Median, 9 Q12a injury, considering all reported injuries. The injury rate was significantly higher during the race. The injury rates for XC The most common Soft tissue Spine Spine male and female cyclists was reported 6.8 and 12 per 1000 h, site of injury respectively (10). Male patients (%) 65 93 88 An emerging trend is the growing number of mountain Spine injuries (%) NA 36 65 bikers attracted to mountain bike terrain parks (MBTP), which facilitate the DH rides and provide the cyclists with a Head injuries (%) 6 25 57 variety of technical trail features, leading the riders to spend Upper-extremity 28 21 16 more time riding DH at high speeds (55). Mountain bike fractures (%) terrain parks have become a common location for MTB in- Lower-extremity 4210 juries where the overall acute injury rate for recreational fractures (%) mountain bikers is reported to be as high as 15 in 1000 ex- posures with 87% of injured riders being male (1). During the a Severe injuries.

406 Volume 16 & Number 6 & November/December 2017 Mountain Biking Injuries

Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. and poor weather also are among the most commonly cited causes of injury (10). Riding DH, at higher speeds and com- peting in MTB races also are reported as predisposing factors (36,38). For recreational riders in MBTPs, riding unfamiliar bicycles and being faster than usual can be regarded as injury risk factors, while jumping, using safety equipment other than helmets, and using a new bike increase the risk of hospitali- zation due to trauma (55).

Head, Face, and Neck Injuries Head injuries lead to concussions, skull and facial frac- ture, cerebral contusion, and intracranial hemorrhage. In one study, oromaxillofacial trauma, fractures, soft tissue inju- ries, and dental trauma accounted for 55%, 23%, and 22% of cases, respectively (24). Dental trauma also has been reported in 25% of the mountain bikers. In case of avulsion- type dental trauma in remote areas with minimal access to Figure 2: Knee laceration as a result of a fall during a mountain bike race. dental health services, preservation of the avulsed tooth in commercially available cell physiological wet media is advisable Morel-Lavalle´e lesion is typically caused by a crush injury until replantation (48). from a motor vehicle accident (31). In cycling, shearing forces due to a fall can cause separation of the superficial fascia from Acute Spine Injuries the underlying deep fascia, commonly seen in greater tro- Mountain biking may lead to catastrophic spine injuries, chanter/hip and lateral knee among cyclists (12,26,31). The especially while riding DH (44). Mechanical bicycle dysfunc- potential dead-space is subsequently filled with fluid, blood, tion should be considered as a cause, while high DH speed, necrotic fat susceptible to infection (12,26). A palpable fluc- technicality of the terrain, and the rider’s poor judgment of tuant mass, pain, hyposthesia, and limited mobility may be the terrain situation also may be the precipitating factors. A presenting symptoms. Treatment may include aspiration and broken helmet and head trauma might be a clue to the compression. Large and chronic lesions recur without surgical likelihood of spine injury. intervention (12,26,31). In 107 cases of acute spine injuries in MTB in a level 1 trauma center, 95% were male (18). Only two were profes- Friction Injuries sional cyclists and injured during a race. Mountain biking Blisters are the result of constant friction of the skin and spinal injuries consisted almost 4% of all spinal injuries (18). are relatively common among mountain bikers. Risk factors Cervical spine injuries were diagnosed in 74% of cases. Eighty- for the formation of blisters include heat, moisture, ill-fitting four percent of riders had used helmets and/or body armor. shoes, and increased repetitive activities (43). Painful blisters Fifteen percent of patients had documented coexisting brain can be punctured while trying to keep the blister roof intact. injury. The ISS did not differ significantly in those with helmet Preventive measures include wearing appropriate footwear, (16.4) versus those without helmet (16.3). gloves, taping, moisture wicking synthetic socks, and dry socks. Chest and Abdominal Trauma Applying drying powder or petroleum jelly also may help. Chafing is a painful superficial oozing inflammatory der- Bicycle handlebars and bar ends are the common causes of matitis common in endurance and ultraendurance athletes chest and abdominal injuries in MTB. Chest wall injuries are secondary to skin rubbing against skin or clothing. The thighs, common (35), and pneumothorax/hemothorax may follow (29). groin, and axilla are the most common locations (30). Blunt abdominal trauma may lead to solid-organ injuries, Abrasions (road rashes) are superficial (no deeper than with spleen being the most frequently injured organ (33). epidermis) injuries often due to friction or a scrape caused by a fall. Bleeding, if present, is minimal (Fig. 3). Chafing and Skin and Soft Tissue Injuries abrasion are common among mountain bikers (10,35,37,40,45). Skin and underlying tissues are vulnerable to injury sec- Chafing and abrasions can be treated by cleaning with soap ondary to trauma, mechanical friction, pressure, and the envi- and water and drying the areas. Applying a drying powder, ronment. As a result, management of skin trauma is commonly petroleum jelly, aquaphor, topical antibiotic, or topical steroids mandated for mountain bikers. also may alleviate the pain. Traumatic Lacerations are quite common among mountain bikers Environmental-Related Injuries mainly due to direct trauma as a result of a fall or equipment Mountain biking races are held in a variety of geographic failure (Fig. 2) (10,35,37,40,45). A primary step is to control locations with some extreme climate changes (e.g.,heat,cold, the bleeding which is typically performed by direct pressure. altitude, wind, lightning, and thunder). Tetanus immunization status should be evaluated. Early an- esthesia leads to easier wound inspection and neuromuscular Altitude Illness examination. Irrigation with normal saline (tap water if not With athletes experiencing rapid ascent, usually at altitudes available) particularly with a protective cup is recommended. of 2500 m or above, come the risk of altitude illness. Risk www.acsm-csmr.org Current Sports Medicine Reports 407

Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Cold Injuries Hypothermia occurs when the core body temperature drops below 35-C(95-F). Hypothermia can happen at the end of an ultraendurance mountain bike race or when a cy- clist stops on the course for a long time. Inexperienced ath- letes can become exhausted faster when the weather changes unexpectedly (wind, rain, and snow) (57). Ultraendurance mountain bike courses with the possibility of water immer- sion (crossing rivers) and nocturnal cycling in lower temper- atures increases the risk of hypothermia. Obtaining core body temperature measurement (rectal) is essential in the diagnosis of hypothermia. The first priority in management of athletes with hypothermia is stopping heat loss by removing wet clothes and insulating the body with blankets and garments (passive rewarming). Figure 3: Lateral thigh abrasion as a result of a fall during a Frostnip is the result of superficial cold-induced vasocon- mountain bike race. striction in the skin usually occurring at freezing tempera- tures. The superficial layers of skin crystalize in the cold or factors are rapid ascent, living at a low altitude, intense wind, resulting in skin blanching and numb patches mostly in physical exertion, young age, and history of altitude illness. the nose, ears, chin, and cheeks. Because the tissue does not Altitude illness spectrum may be present in mountain bikers freeze, immediate rewarming can prevent tissue loss and in milder forms, acute mountain sickness, or more advanced long-term damage (15). Frostnip is reversible and resolves stages like high-altitude pulmonary edema (HAPE), or very rapidly with gentle rewarming without any sequelae, but it rarely high-altitude cerebral edema (HACE). Acute mountain warns of risk of frostbite (57). sickness is the most common presentation of altitude illness Frostbite is a freezing cold injury to the skin and underlying with symptoms, such as headache, anorexia, nausea, vomiting, tissues with formation of crystals in the extracellular space dizziness, fatigue, and difficulty sleeping (32). Slow ascent to between cells (15,57). Frostbite occurs at a temperature be- altitude is the hallmark of prevention for all acute high alti- low 0-C(32-F). Exposed areas (nose, ears, cheeks, and digits) tude illnesses, which is usually not applicable because of the are affected usually with more than half of the cases occurring nature of the MTB. Acclimatization is another effective pre- in the toes (57). Constrictive and wet clothes increase the risk ventive strategy. Pharmacologic prevention includes the use of of frostbite. The best treatment approach is rapid rewarming acetazolamide. Athletes with acute mountain sickness should with warm water (37-Cto40-C) (15,57). not continue ascent until symptoms resolve and should con- sider descent if medical management does not resolve symptoms (30,32). Athletes with HACE or HAPE should immediately de- Chronic/Overuse Injuries scend to a lower altitude and be followed up for medical man- The overuse injuries occur in a wide spectrum of cycling agement (32). proficiency levels and among all disciplines of cycling (17). The riders are prone to overuse injuries due to repetitive nature of cycling and their need to maintain a close contact Heat-Related Illness with bike interfaces. The average mountain biker will rotate Heat-related illnesses represent a variety of disorders from the pedals almost 3600 to 6000 times per hour, and rides mild heat edema to heat stroke. Other than sunburn, other j taking up to 12 hId 1 have become commonplace for many forms of heat-related illnesses are uncommon among moun- riders. Force is mainly generated in a sagittal plane. Thus, any tain bikers. Risk factors for heat-related illnesses include ex- muscle imbalances in other planes may contribute to such tremes in age (G15 years or 965 years); comorbid medical chronic injuries (13). For example, abnormal hip abductor conditions; medication use (e.g., alcohol, diet pills, thyroid function has been linked to PFPS and iliotibial band friction agonists, A-blockers, diuretics, and illicit drugs); fitness sta- syndrome (ITBFS) through pelvic coronal stabilization defi- tus; poor acclimatization, long high-intensity physical activi- cit. Suboptimal foot position also can negatively affect the ty; environmental conditions (temperature, humidity, and sun kinetic chain during cycling and possibly lead to a significant exposure); and the availability of water, rest, and shade (57). number of injuries in cyclists (34). Sunburn is caused by sun’s ultraviolet radiation especially during midday. Sunburn is a significant risk factor for further heat-related illness. High altitude increases the ultraviolet Upper-Extremity Overuse Injuries intensity, so participants of events at high altitude should be Ulnar and median neuropathies are common among cy- aware of this risk (30). Frequent use of a broad spectrum clists, with ulnar neuropathy (cyclist’s palsy) being present in sunscreen with SPF 930 and wearing protective clothing is 19% to 35% of the cyclists (4). Ulnar neuropathy is possibly recommended (57). Cold compress or rinsing/bathing the caused by continuous pressure, tension, and vibration of the area with cool water might be helpful (28). Mild sunburns nerve in Guyon’s canal and is usually manifested by pares- can be treated with aloe vera while more severe burns should thesia and pain in the fourth and fifth fingers and hand in- receive silver sulfadiazine creams (28). The presence of blis- trinsic muscle weakness (3,58). Improper reach, narrow ters, swelling, and exudates signifies increased severity and handlebars, gloves with poor padding, poor postural habits, should be treated as direct contact burns (28). longer rides, and increased weight may be precipitating

408 Volume 16 & Number 6 & November/December 2017 Mountain Biking Injuries

Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. factors. Diagnosis of ulnar neuropathy in a cyclist increases Improper bike fit, training errors, and concurrent sport ac- the likelihood of coexisting thoracic outlet syndrome (dou- tivities may underlie these pathologies. ble-crush syndrome) (58). This requires a detailed physical Ice, relative rest, range of motion, eccentric, and lumbopelvic examination and reevaluating the cyclist’s posture on and off stability exercises bike fit, cleat modification, and foot orthotics the bicycle (Table 2). have been successfully used to treat these tendinopathies (62). Extracorporeal shockwave therapy and platelet-rich plasma may help with symptoms, but more methodologically sound Knee Pain studies are needed to routinely incorporate them in treatment Prevalence of knee pain is 20% to 27% among mountain plans (11,59). bikers (13). The PFPS, ITBFS, and tendinopathies have been mentioned as common chronic knee injuries in cyclists (34). Foot Injuries Patellofemoral pain syndrome is a commonly encoun- With clipless stiff-soled cycling shoes primarily used in XC tered diagnosis among cyclists and is typically manifested cycling, riders in DH and free ride disciplines usually use by retroptellar or anterior knee pain (16). Risk factors for shoes with more pliable soles. While the clipless shoes provide developing PFPS are high training volume (longer training the cyclist with mechanical advantage in energy transfer chain hours) and intensity (e.g., prolonged climbs and higher during cycling, they potentially expose the cyclist to some injuries gears), low pedaling cadence, low- or excessively anterior including metatarsalgia (62) and Morton’s neuroma (34). seat position (increased intra-articular friction forces), and higher knee flexion range of motions (poor bike fit includ- Cervicalgia ing long-for-height cranks). Patellar maltracking, functional With a prevalence of 16% to 43%, neck pain is a common malalignment during cycling (resulting from improperly wide complaint among mountain bikers (13). Weakness and fa- seats or Q-factor, genu valgum or pes planus) and decreased tigue of cervical stabilizers lead to recruitment of muscles, lumbopelvic stability and impaired hip abductor function such as levator scapula and trapezius, to keep the neck ex- also may exist (13,34,62). Diagnosis and correction of con- tended. Microtraumatization and fatigue of these accessory tributing factors, vastus medialis obliquus (VMO) retraining, cervical extensors may lead to pain and formation of trigger pain medications (7), and proper bike fit may be effective in points within them (13). treatment of PFPS (13,34). In contrast to and especially aero positioning, The ITBFS is thought to be due to repetitive friction of the MTB imposes less cervical extension and protrusion (34). ITB while moving from anterior position (in knee exten- Combined with a significantly higher degrees of thoracic sion) to posterior position (in knee flexion) and vice versa at kyphosis (49) and flexed arms with scapular protraction and the so-called impingement zone located adjacent to lateral pectoral shortness, mechanical disadvantage of cervical spi- condyle while extending the knee from 30- of flexion (34). nal stabilizers is likely. The abovementioned malalignments are Positioning the saddle too high, or too ‘‘aft [posterior],’’ or similar to the circumstances of ‘‘upper crossed syndrome’’ (47) improper cleat position, and an increase in overall training contributing to cervicalgia, thoracic outlet syndrome, and volume may be precipitating factors. Knee malalignment, cervicogenic headaches. foot hyperpronation, and internal tibial rotation may be Bike fit, postural corrective exercises, strengthening of cer- precipitating factors (62). Correction of bike fit, myofascial vical spine stabilizers, physical modalities, acupuncture, and release techniques for ITB band, hip abductor stretches, osteopathic manipulative techniques are helpful. Using a acupuncture, physical modalities, and local corticosteroid lighter helmet, removing the helmet shades and cameras, and injections are effective treatments. correcting the helmet position also should be considered. Pes anserine bursitis and medial plica syndrome are other causes of anterior knee pain in mountain bikers. Analgesics, Low Back Pain physical modalities, hamstring stretching, and local corti- Low back pain (LBP) is a common complaint among costeroid injections may be beneficial (62). mountain bikers with a prevalence of 24% to 41% (13). Despite its high prevalence, there is a paucity of high-quality Tendinopathies research on precipitating factors of LBP in mountain bikers. Tendinopathies may be a sequel of excessive repetitive The majority of available studies point out improper bicycle angular traction during cycling. fit, riding technique, and training methods thru epidemio- Patellar tendinopathy is a common condition among cy- logical data (56). Hamstring shortness, anterior pelvic tilt, clists which usually present with focal tenderness over the and hip flexor hyperactivity (13), and deficiency of lumbo- injured part of the tendon (62). Precipitating factors include sacral core stabilizers (56) also may contribute to chronic genu valgum, foot hyperpronation, and internal tibial ro- LBP. Similar to nonathletes, smaller diameter of transversus tation (62), increased training volume, repetitive jumps, and abdominis and cross-sectional area of lumbar multifidus concurrent sporting activities. muscles are reported in mountain bikers with chronic LBP in Achilles tendinopathy may develop after microtraumatization contrast to healthy counterparts (56). of the tendon after repetitive plantar flexion during power phase No research has addressed sports-specific treatment of of pedaling. Precipitating factors include with gastrosoleus chronic LBP in mountain bikers (34,56). Core stability ex- shortness (62), improper saddle height, foot hyperpronation, ercises (56) may be useful in the prevention and treatment of soft shoes, and improper cleat position (34). LBP in mountain bikers (56). In addition to these exercises, Other tendinopathies encountered in mountain bikers bike fit, correction of technical errors, physical modalities, involve iliopsoas, hamstrings, and tibialis anterior tendons. postural corrective exercises, osteopathic manipulation, and www.acsm-csmr.org Current Sports Medicine Reports 409

Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. acupuncture may be of value in the treatment of chronic requires hours of preparation and planning (40). Course LBP in mountain bikers. medical directors and volunteer physicians should be familiar For acute LBP in mountain bikers, a thorough evaluation with the common injuries and illnesses unique to their races. with special attention to disc disease is necessary (34). Thera- The medical director needs to work closely with the race di- peutic exercises, myofascial release techniques, physical rector and local officials to create a medical protocol appro- modalities, and acupuncture may be of benefit. priate for their specific race. Because these events typically take place over a large geographic area, developing a clear Genital and Saddle Area Injuries communication plan within the medical team is crucial in Genital area numbness (GAN) and erectile dysfunction ensuring that proper care is being provided to the athletes. (with prevalence of 50% to 91% and 13% to 24%, re- Cyclists must often navigate long distances over a variety of spectively) are two of the most common chronic injuries of terrain in temperatures ranging from below freezing to above genitourinary system in male cyclists (27). Other complaints 40-C. Despite the fact that most injuries encountered by the include dysuria, scrotal abnormalities, urogenital, and perineal mountain bikers during a race are minor, occasional life- pain. Impingement of the pudendal nerve in Alcock’s canal due threatening injuries can happen (10,35,37,40,45). So, the to stretching, vibration, and ischemia has been proposed as the medical team should be prepared and plan for evaluation, cause of pudendal neuralgia and paresthesia in cyclists (51). In stabilization, and evacuation of the injured athletes in different contrast to road cycling, the more upright riding posture of sections of the race. mountain bikers leads to higher loading of buttocks area (42). Poorly fitted bike, saddle type, increased riding distance, Discussion and Recommendations prolonged seated position without standing, and high body The observed variety of severity and patterns of injury in weight appear to be contributing factors. Correction of these different studies are likely due to different injury definition factors, physical and manual therapy, and minimally invasive and methodology (1,2,5,10,25,36,38,45,55,60). Because interventions to block or ablate the pudendal nerve may be seeking the new challenges and riding the ‘‘gnarlier’’ terrains effective treatment methods. Male mountain bikers also have are part of the sport, the injury patterns might be changing a significantly higher rate of abnormal ultrasonographic find- over time. Thus, the authors recommend employment of ings in scrotums compared with noncyclists and road cyclists, active injury monitoring systems especially in areas more (94%, 16%, 48%, respectively) (46). attractive to mountain bikers such is MBTPs and also during There is a paucity of published data regarding the chronic the races to identify new acute injury trends and to prevent urogenital problems in female cyclists (27). Female cycling- potentially unsafe practices. For overuse injuries, most stud- related urogenital complaints include perineal dermatologic ies have used a self-reporting system. A standardized injury problems, vulvar edema, incontinence, stranguria and dys- definition and implementation of an injury surveillance pro- uria, external genital and perineal numbness, and pain (27). gram is recommended. Body mass index, estimated cycling distance per season, and An interesting recent trend to monitor is the availability increased saddle width were modifiable precipitating factors and increasing popularity of electrical mountain bikes for various complaints. Postride insertional dyspareunia was (eMTB), specifically for the XC discipline. While the eMTB reported in 40% of sexually active female cyclists with no are primarily intended to assist the cyclists ascend, they can significant precipitating factor in multivariate analysis (27). potentially be used to reach higher-speed DH, increasing the injury rate. Meanwhile, these bicycles can be attractive for Preventive Equipment more senior cyclists with a variety of medical predispositions There are no regulations to mandate the use of helmets for to ride terrains previously not accessible, and likewise potentially recreational riders throughout the United States (34). How- increase their injury rate. ever, using helmets is required by many MBTPs. Wearing In MBTP areas and during MTB races, the prehospital helmets by cyclists during competitive US races is mandated medical team should be prepared to manage fractures, head, by the governing organizations. Despite the supportive bio- face, and spine injuries, lacerations, abdominal trauma, and mechanical data on likely benefits of helmet use on attenua- rib fractures (35). Facilitation of early responders’ access to tion of impact forces during head trauma, the role of helmet the site of incident, providing them with proper equipment, use in actual prevention of brain injuries in cyclist populations is and coordination of patient transfer plan with near trauma not clear (8,39). Helmet use in mountain bikers has not been centers appear to be of utmost importance. fully studied, and most studies address the urban cyclists (34). Further research is required to study crash characteristics Despite conflicting results, helmet use may have some protective and reach preventive strategies for MTB acute injuries (9). effect against head injuries (50). Only 4.4% of mountain bikers Including the bicycle industry and component manufac- have been reported to use mouthguards in a multinational turers in these studies may lead to availability of bicycles study (48). This low prevalence of usage has been attributed to less prone to mechanical failure during such circumstances. several reasons by cyclists including interrupting communica- Also, further investigation of the effects of protective gear tion with other cyclist and breathing (48). There is no regula- design on injury prevention should be stressed. One partic- tion or evidence of benefits on the use of other preventative ularly interesting area for future research is the recent use of equipment, such as full facemasks, goggles, and elbow pads. anisotropic foams in bicycle helmets to reduce acceleration forces during impact (61). Race Day Management Many mountain bikers do other sports, including road Medical coverage of mass MTB events are complicated cycling, skiing, and mountaineering, with almost tasks and bring unique logistical challenges which often all having their respective patterns of chronic injuries. The

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Copyright © 2017 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. interaction of these sports in the epidemiology and patho- 20. Engebretsen L, Soligard T, Steffen K, et al. Sports injuries and illnesses during the Y genesis of MTB injuries can be of interest for further research. Summer 2012. Br. J. Sports Med. 2013; 47:407 14. 21. Farrell KC, Reisinger KD, Tillman MD. Force and repetition in cycling: possible implications for iliotibial band friction syndrome. Knee. 2003; Y Conclusion 10:103 9. Mountain biking is a popular sport with significant health 22. FitzGibbon S, Vicenzino B, Sisto SA. Intervention at the foot-shoe-pedal in- terface in competitive cyclists. Int. J. Sports Phys. Ther. 2016; 11:637Y50. benefits. However, depending on the type of MTB and the 23. Foundation TO. 2016 Outdoor Recreation Participation Report. 2016. technical difficulty of the terrain, there are potential risks for 24. 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