Non-Traumatic Bicycle Injuries A Review of the Literature

Transcription

1 Sports Med 2006; 36 (1): 7-18 REVIEW ARTICLE /06/ /$39.95/ Adis Data Information BV. All rights reserved. Non-Traumatic Bicycle Injuries A Review of the Literature Nathan J. Dettori and Daniel C. Norvell Olympic Research Inc., Seattle, Washington, USA Contents Abstract Overview Search Methods Definitions and Calculations Frequency of Sports-Related Injuries: Incidence and Prevalence How Cases Are Counted The Definition of Bicycle Riding Exercise and Parameters of Exposure Frequency of Bicycle-Related Non-Traumatic Injuries Overall Injury Frequency The Knee The Neck and Shoulder The Wrist and Hand The Buttock The Perineum The Back The Upper and Lower Leg Possible Mechanisms for Injury and Current Prevention Strategies Knee Injuries Neck/Shoulder Injuries Hand/Wrist Injuries Buttock Pain Genital Numbness and Erectile Dysfunction Back Injuries Upper and Lower Leg Injuries Limitations of the Literature Conclusion...17 Abstract Bicycle riding is a popular form of recreation, fitness and transportation in many areas of the world. Traumatic injuries associated with bicycle riding have been documented and intervention strategies have been successful. This has not been the case for non-traumatic injuries. The prevalence of non-traumatic bicycle injuries can be as high as 85%. The most common sites for non-traumatic cycling-related injuries include the knee, neck/shoulder, hands, buttock and perineum. Two categories of injuries that may have the greatest impact on disability include ulnar and median nerve palsy, and erectile dysfunction. Injury

2 8 Dettori & Norvell prevention strategies have been proposed to reduce non-traumatic injuries but these strategies remain untested. 1. Overview 3. Definitions and Calculations Routine physical exercise improves physical fit- ness, health and life expectancy. [1-4] One popular form of exercise used for recreation, fitness and transportation throughout the world is that of bicycle riding. The overall benefits of this popular exercise, however, must be weighed against the risks of both traumatic and non-traumatic injuries. Traumatic in- juries are better documented [5-7] and intervention strategies have been successful in reducing these injuries. [8-10] This has not been the case for non- traumatic injuries. The purpose of this article is to summarise the frequency of non-traumatic injuries in cyclists and to identify the parameters of bicycle riding that most influence the risks of non-traumatic injury. We will first define important terms and concepts. After the definitions are established, we will enumerate the frequency of non-traumatic injuries and common body parts affected. Finally, we will examine the possible mechanisms for injury and current prevention strategies. 2. Search Methods We searched the published literature in MED- LINE (1966 August 2004) to identify descriptive and comparative studies that documented the frequency of or prevention strategies for non-traumatic bicycle injuries. The search terms using PubMed included the following keywords: bicycle*, bicyclist*, bike, biking, cycle, cycling, saddle, handlebar, sprains and strains [11] and mononeu- ropathies. [11] We also reviewed the bibliographies of recent articles. From the above searches, we identified 80 potential articles that pertained to bicycle riding and injury. From these, ten articles reported on the frequency of non-traumatic injuries. These studies are summarised in this review. Lack of standardised definitions and reporting of exposures and injuries hamper interpretations and comparisons of results. While cases of traumatic injury readily present themselves to the emergency department, non-traumatic injuries are frequently not severe enough to cause an individual to seek medical care. Therefore, no record of these injuries is available for study. Consequently, researchers assessing the impact of non-traumatic injuries in cyclists depend on a sub-population of cyclists who participate in organised tours or bicycle rides. This allows them to define a denominator for calculating exposure and to survey participants in regard to non- traumatic injuries. Choosing an organised tour to study non-traumatic injuries is convenient. This should not be interpreted to mean that cyclists who do not tour do not develop non-traumatic injuries. In fact, the absolute burden of non-traumatic injuries in non-tour riders may be greater than in tour riders. For example, at the 1974 American College of Sports Medicine Meeting, 117 cases of handlebar palsy were reported in patients observed by a single physician over a 4-year period, most not associated with tour riding. [12] This section provides definitions to assist in interpreting the results of the studies presented in this article. 3.1 Frequency of Sports-Related Injuries: Incidence and Prevalence Injury frequency can be expressed in terms of injury incidence or prevalence. Incidence rates that quantify the number of injuries occurring per unit of person-time (or in bicycle riding, per unit of persondistance) at risk is the preferred measure of injury frequency and makes comparison of studies easier. Cumulative incidence, the number of cyclists sus- taining one or more new injuries divided by the number of cyclists at risk for injury, can also be used.

3 Non-Traumatic Bicycle Injuries 9 Unfortunately, incidence rates are seldom reported for non-traumatic injuries. The measure used more often is that of prevalence, the proportion of cyclists who report an injury after a certain bicycle tour. An overall prevalence is sometimes reported (the total number of cyclists who report one or more injuries during the tour divided by the number of cyclists at risk). However, the prevalence of injury by body part is most often reported, that is, the proportion of individuals who sustain a knee injury or back injury. In these cases, a cyclist can have more than one injury and each injury will be counted in the numerator. For example, in a population of cyclists, 40% can sustain a knee injury and 65% can report a back injury during the same ride. The sum of the proportions is >100% because a cyclist experiences more than one injury. traumatic injuries related to bicycle riding have rare- ly accounted for all of these parameters in determin- ing exposure. In most of the studies reviewed, a single bicycle riding event of several kilometres (exercise duration) over a few days (exercise frequency) is used. 4. Frequency of Bicycle-Related Non-Traumatic Injuries Ten studies attempt to quantify the impact of bicycle riding on non-traumatic injuries. Two stud- ies give an overall injury frequency measure (one study reporting cumulative incidence and one re- porting prevalence), while all report injury frequen- cies for various anatomic sites (table I). 4.1 Overall Injury Frequency 3.2 How Cases Are Counted In a cross-sectional study of 518 cyclists who self-reported their injuries, Wilber et al. [15] reported Most non-traumatic injuries are minor in the that 85% sustained one or more non-traumatic injusense that cyclists do not seek medical care for their ries during the year prior to the survey. Sixty injury. They may or may not stop bicycle riding (11.5%) had severe enough complaints to stop bicywhile the injury heals. This makes the task of defincle riding for a mean of 42.8 (±64.1) days while ing and counting an injury difficult. As a result, most another 14 (2.7%) had to quit bicycle riding altonon-traumatic injury studies of cyclists use selfgether. Thirty-one percent of the cyclists sought reported injuries in the numerator. There may be an medical treatment for their injuries and reported that attempt to quantify the extent of the injury (mild, their symptoms persisted an average of 3.7 (±8.4) moderate, severe; missed training days; prevented months. Female cyclists developed neck pain and bicycle ride completion). Usually, simply asking the shoulder pain more frequently compared with male cyclist if he or she sustained an injury and to what cyclists (odds ratios 1.5 [95% CI 1.1, 2.2] and 2.1 body part, prevails. Underreporting is likely. [95% CI 1.4, 3.1]), respectively. It should be noted that this study had a low response rate (518/2500), 3.3 The Definition of Bicycle Riding Exercise which may tend to overestimate the prevalence of and Parameters of Exposure non-traumatic injuries; those who have an injury The effect of exercise on conditioning is dependent may be more likely to respond to a questionnaire. on the exercise intensity, exercise duration and Dannenberg et al. [16] reported on 1638 riders who exercise frequency. For bicycle riding, exercise in- bicycled 546km (339 miles) over 6 days. Cyclists tensity refers to the speed of the cyclist while exer- who sustained non-traumatic injuries defined as cise duration refers to the amount of time spent in a self-reported pain, discomfort, swelling or bruising single bicycle riding bout (or the distance travelled received medical care provided at rest stops and at for that bout). Exercise frequency refers to the num- overnight camping sites during the ride. Seventy-six ber of bicycle riding sessions in a given period, riders sought medical care for non-traumatic injuries usually measured in bicycle rides per week. Vary for an incidence rate of 13.7 injuries per any of these parameters and one varies the amount person-miles ridden. Participants were more likely of exposure for injury. Published studies on non- to be treated by the medical staff for an overuse

4 Table I. Studies reporting the frequency of non-traumatic bicycling injuries by anatomical site Author (year) n Mean age Male Exposure Injury definition Frequency Anatomical injury site Injury (range or ±SD) (%) measure frequency (%) Kulund and 89 M: 27.9 (17 66) km, 80d Self-report of pain or Prevalence Knees 65 Brubaker [13] F: 23.6 (17 54) discomfort that made a Neck 3 (1978) portion of the trip Shoulders 9 unpleasant Hand/wrist 36 Buttock 9 Perineum 7 Back 15 Upper leg/hip 11 Lower leg/foot 13 Weiss [14] (±10) km, 8d Self-report of pain that Prevalence Knees 22 (1985) was uncomfortable, Neck/shoulders 21 changed their riding style Hand/wrist 10 or made them stop Buttock 33 Perineum 11 Upper leg/hip 2 Lower leg/foot 7 Wilber et al. [15] 518 M: 40.4 (±10.7) 57 1y prior to study Self-report of pain, Prevalence Knees 42 (1995) F: 36.6 (±8.9) discomfort, swelling, Neck 49 bruising Shoulders 30 Hand/wrist 31 Buttock 36 Back 30 Upper leg/hip 13 Lower leg/foot 22 Overall 85 Dannenberg (7 79) km, 6d Medical treatment Incidence Knees 24 et al. [16] Self-report of pain, Neck 24 (1996) stiffness, or swelling Shoulders 17 Hand/wrist 27 Buttock 42 Back 16 Upper leg/hip 25 Lower leg/foot 24 Overall 87 Andersen and (±8.6) km, 15 40h Motor or sensory Prevalence Hand/wrist 40 Bovim [17] symptoms Perineum 21 (1997) Self-report of numbness Numbness 13 or ED ED Continued next page 10 Dettori & Norvell

5 Non-Traumatic Bicycle Injuries 11 Table I. Contd Author (year) n Mean age Male Exposure Injury definition Frequency Anatomical injury site Injury (range or ±SD) (%) measure frequency (%) Salai et al. [18] km/wk Self-report of low back Prevalence Back 50 (1999) pain requiring analgesics and rest Sommer et al. [19] 100 Not given 100 >400 km/wk Self-report of numbness Prevalence Perineum 61 (2001) or ED Numbness 19 ED Patterson et al. [20] (23 56) km, 4d Motor and sensory Prevalence Hand/wrist 70 (2003) testing Incidence Hand/wrist 68 Subjective sensory Dettori et al. [21] (±9.2) km, Self-report of numbness Incidence Perineum 34 (2004) 1 7d 25 on the IIEF Numbness 4 ED Taylor et al. [22] Recreational, 25 on the IIEF Prevalence Perineum 17 (2004) competitive or ED professional bicycling ED = erectile dysfunction; F = female; IIEF = International Index of Erectile Function; M = male. injury if they normally bicycled <42km (26 miles) per week compared with those who bicycled >161km (100 miles) per week (relative risk 4.0 [95% CI 1.3, 12.1]). Following the ride, 87% of 1140 responders to a post-ride survey reported one or more non-traumatic musculoskeletal injuries. 4.2 The Knee One of the most common lower extremity nontraumatic injuries in cyclists involves the knee. On long rides, 21 65% of cyclists reported this injury. [13,14,16] For The Ride Across America, Kulund and Brubaker [13] cited this injury as the most prevalent. He did note that most the riders experienced this injury early in the ride and were able to ride through it indicating that this may be a minor problem. He did not report, however, the number of cyclists who were unable to finish the ride because of this injury. Wilber et al. [15] reported that 42% of cyclists who answered his survey described a knee injury in the year prior to the study. Almost half of these injuries were classified as mild, although no data were presented on the amount of training days lost due to knee injuries. Weiss [14] reported that >50% of the knee pain in his cohort of cyclists occurred around the patella. Lateral knee pain consistent with iliotibial band friction syndrome and medial knee pain were also frequently reported. In his study, women were more likely to report problems with their knees compared with men (37% vs 12%, respectively). 4.3 The Neck and Shoulder Neck and shoulder pain are sometimes grouped together as cyclists complain of injuries to areas that cross both sets of joints (such as the trapezius and levator scapulae muscles). This injury is common with a prevalence ranging from 9% to 49%. [13,14] Weiss, [14] in a tour of 871km over 8 days, noted that 66% of the riders complained of at least a mild neck/ shoulder injury while 20% reported that the injury caused them to be really uncomfortable, or caused them to change their bicycle riding style or to stop bicycle riding. Unlike the knee injuries, neck/

6 12 Dettori & Norvell shoulder injuries occurred more frequently during men participating in a 161km bicycle ride, 11 stated the later stages of the Bicentennial Tour. [13] that they had experienced a numb penis lasting from a few minutes up to 2 days. The symptoms usually 4.4 The Wrist and Hand occurred after bicycle riding 64km. Six stated that In 1895, Simpson [23] reported on the first nonit the injury was common to them, having experienced >20 times. [33] Andersen and Bovim [17] assessed the traumatic bicycle injury when he described a case of a long distance cyclist with ulnar neuritis. Since that prevalence of genital numbness and ED following a time, many case reports document the familiar patcomplained of penile numbness while 13% reported 540km ride, and reported that 22% of 160 men tern known as handlebar palsy. [24-30] The prevalence of hand and wrist non-traumatic ulnar or mediet ED. In a cohort study evaluating incidence, Dettori al. [21] reported 34% of 463 riders experienced an nerve compression that manifests itself in sensory or motor disturbance ranges from 10% to 70% (table penile numbness and 4% experienced ED. The prev- I). Andersen and Bovim [17] found 19% of 169 survey alence of ED among cyclists is generally thought to respondents of The Great Trial of Strength, a nonrecent Internet survey of cyclists aged years, be higher than among non-cyclists; however, in a stop 540km bicycle tour in Oslo, reported weakness of the hands while 40% complained of numbness or the prevalence of ED was 17%, similar to that of paraesthesias. Kulund and Brubaker [13] also found historical controls. [22] 36% of 89 riders complained of hand numbness in The Ride Across America. In a recent prospective 4.7 The Back study of the incidence of ulnar neuropathy, Patter- Fifty percent of 80 members from a noncompetison et al. [20] found 36% of 50 hands in 25 riders tive local bicycle riding club reported at least one participating in a 600km bicycle tour experienced episode of back pain with bicycle riding of sufficient motor weakness, 10% experienced sensory loss and intensity that use of analgesics and rest after bicycle 24% experienced both motor deficit and sensory riding was required. [18] No time period for the bicyloss. Other authors reported only on the prevalence cle riding exposure was reported. Wilber et al. [15] of hand complaints ranging from 10% to documented a back pain prevalence of 30% during a 31%. [14-16] 1-year period among male and female cyclists in 4.5 The Buttock California. Nearly 75% of those complaining of back pain identified the lumbar area as the location Buttock symptoms, which include ischial tuberamong of pain. The prevalence of back pain was 15 16% osity pain, chafing and ulceration, are among the riders of tours of a specified length who most commonly reported symptoms by cyclists, bicycled 545km [16] and 7242km, [13] respectively. ranging from 42% to 64%. [14,16] The prevalence of One study found that those aged <20 years were ischial tuberosity pain has been documented to be as three times more likely to complain of back pain high as 35% following an 871km event lasting 1 compared with those aged >40 years. [16] week. [14] On the same tour, chafing occurred in 8% of cyclists while skin breakdown and ulceration 4.8 The Upper and Lower Leg troubled 4%. [14] Many of these injuries were the Musculoskeletal complaints involving the upper result of under use, with reports of symptoms de- leg (hip and thigh), and lower leg (calf, ankle and creasing as more bicycle riding continued. [13,14,31] foot) are generally reported less frequently compared 4.6 The Perineum with other overuse injuries, with a prevalence ranging from 7% to 31%. [13-16] In three studies, Perineal numbness and erectile dysfunction (ED) 2 5% of bicycle riders experienced hip pain. [1,6,14,15] associated with bicycle riding in male cyclists were The prevalence of thigh pain in recreational cyclists first reported in case reports. [32-36] In a series of 20 has been reported to be 7% among men and 10%

7 Non-Traumatic Bicycle Injuries 13 among women. [15] Lower leg pain, including Achil- Any condition that causes the cyclist to increase les tendonitis, was experienced in 6% of cyclists in a trunk flexion, thereby becoming more aerodynamic, 545km event [16] and 10% in bicyclists riding will increase the neck hyperextension and load car- 7200km in 80 days. [13] rying responsibility of the shoulders. These include a handlebar reach that is too long, riding down on 5. Possible Mechanisms for Injury and the curved portion of the handlebars (the drops) or Current Prevention Strategies riding with aerobars. [11,30,41] Effort to raise the handlebars through various means is the prevention Improper mechanics and repetitive loading are strategy aimed at decreasing these injuries. No study believed to be key factors in the development of has been performed to test the effectiveness of this non-traumatic bicycle riding injuries (table II). prevention strategy. 5.1 Knee Injuries 5.3 Hand/Wrist Injuries Knee injuries in cyclists can be broadly categorised into three entities: patellofemoral inflammation, patella tendinitis and iliotibial band friction syndrome. [37-39] All three categories of injury are thought to relate to bicycle-fit problems listed in table II. Factors that contribute to increased forces between the patella and intercondylar groove of the femur are considered the cause of patellofemoral inflammation. These include having the saddle too low or pedalling in a gear too high. Malalignment of the patella relative to the intercondylar groove may also play a role in patellofemoral pain. Malalignment can be accentuated when the pedal cleat is rotated or one has excessive subtalar pronation. [38] Having the saddle too high or a cadence too fast may result in iliotibial band friction syndrome. The iliotibial band crosses the lateral femoral condyle when the knee flexes around 30º. A minimum knee flexion angle of approximately 33º occurred at a crank angle of 170º in one study, causing the authors to conclude that repetition of the knee in the impingement zone during bicycle riding aggravates the iliotibial band. [40] The prevention strategies aimed at correcting the bio-mechanical problems thought to be associated with knee pain in cyclists have not been tested. 5.2 Neck/Shoulder Injuries Cyclists ride in a horizontal position bearing much of their trunk weight through their arms and shoulders. This horizontal position forces the neck in hyperextension to allow the cyclist to see forward. Handlebar palsy is thought to be a compression syndrome caused by bearing a portion of the upper body s weight on the handlebars. The site of com- pression is the ulnar nerve at or around the canal of Guyon. The deep palmar (or motor) branch is fre- quently affected [20,25,26,28] but both motor and senso- ry branches can be involved. [27,29,30] This condition is generally self-limiting once bicycle riding is stopped but can last for several months. [17,26,29] Me- dian nerve compression is less common but has also been reported. [47] The site of compression is thought to be at the carpal tunnel and results from riding on the hoods (where the brake lever attaches to the handlebars). [47] Prevention strategies to reduce the prevalence of wrist and hand injuries in cyclists include wearing padded gloves, [11,41] changing hand positions on the handlebars frequently [11,41] and us- ing aerobars that allow riders to rest their forearms on pads. [30] Although frequently advocated, none of these strategies have been tested for effectiveness. 5.4 Buttock Pain Ischial tuberosity pain is thought to be the result of unaccustomed pressure from sitting on a hard narrow saddle. [14,31,42] Often cited recommendations to reduce this problem include padded shorts and wider padded saddles. [31,42] However, in one study, there was an increased prevalence of ischial tuberosity pain among cyclists with saddle padding com- pared with no saddle padding, and there was no association between padding in shorts and ischial tuberosity pain. [14] A saddle that is too high for an

8 Table II. Possible mechanisms for non-traumatic bicycling injuries and current prevention strategies advocated in the literature [11,13,16,18,21,30,33,37-46] Site of injury Possible condition Possible mechanisms Prevention strategies advocated in the literature Strategies tested? suggested in the literature Knee Patellofemoral inflammation Saddle too low and/or too far Proper saddle adjustment No forward Pronated foot Orthotics No Cleat rotated Cleat adjustment No Gears too high Gear down, especially early in season No Patella tendinitis Saddle too high Use floating pedal system No Gears too high Proper saddle adjustment No Excessive hills Gear down No Iliotibial band inflammation Saddle too high Avoid excessive hills No Saddle too far back Proper saddle adjustment No Cleat internally rotated Cleat adjustment No Neck/shoulder Foramen encroachment Handlebar reach too long Raise handlebars No Aero-position Use upright bars No Riding in the drop position Move saddle closer to handlebars No Facet compression Same as encroachment Same as encroachment No Myofascial pain Same as encroachment Same as encroachment No Hand/wrist Ulnar nerve compression Handlebar reach too long Raise handlebars No Supporting too much body Reduce stem length No weight with arms Not enough padding on bars Change hand position often No Wear padded gloves No Reduce weight supported by arms No Median nerve compression Same as ulnar nerve Same as ulnar nerve No Buttock Saddle soreness Narrow saddle Wider saddle No Chafing Not enough padding on saddle Stand to cycle periodically No Padded shorts/saddle No Same as saddle soreness Same as saddle soreness No Ulceration Same as saddle soreness Same as saddle soreness No Sweating Powder, antiperspirant No Continued next page 14 Dettori & Norvell

9 Table II. Contd Site of injury Possible condition Possible mechanisms Prevention strategies advocated in the literature Strategies tested? suggested in the literature Perineum Numbness Narrow saddle Wider saddle Yes [43,44]a Not enough padding on saddle Padded shorts/saddle No Stand to cycle periodically Saddle nose tilted up Tilt saddle nose down No Handlebars higher than saddle Use cut-out saddle No ED Same as numbness Same as numbness Same as numbness Use of cut-out saddle for some Don t use cut-out saddle if previously numb No cyclists Back Lumbar strain Improper stem/top tube length Proper adjustment of the cyclist fore-aft position No Leg length discrepancy Correct leg length discrepancy with shim No Yes [19]b Riding in the drop position Tilt saddle anterior Yes [18]c Upper leg/hip Trochanteric tendonitis/bursitis Saddle too high Adjust saddle to prevent fascia lata against No trochanter Iliopsoas tendonitis Saddle too high Adjust saddle height No Lower leg/foot Achilles tendonitis Saddle too low Adjust saddle to prevent excessive ankle No dorsiflexion a b c Foot too low on pedal Move foot forward on pedal No Saddle too low Same as Achilles tendonitis No Plantar fascitis Saddle too low Adjust saddle to prevent excessive ankle No dorsiflexion Metatarsalgia Shoes too tight Proper shoe fit No Narrow saddle associated with reduced blood flow. Standing to cycle associated with pre-cycling blood flow. Anterior saddle tilt of reduced low back pain in before-after study design. ED = erectile dysfunction. Use floating pedal system No Non-Traumatic Bicycle Injuries 15

10 16 Dettori & Norvell He claims that both result in painful pressure on the posterior elements of the lumbar spine. Ischaemic pain originating in the lumbar disc [50] or arising from constant isometric contraction of the support mus- cles of the back [41] are two additional potential causes of low back pain while bicycling. One study, an uncontrolled case series, evaluated saddle angle as a possible cause of low back pain. They lowered the tip of the saddle 10 15º from horizontal in a group of cyclists with low back pain. After 6 months individual may result in a side-to-side rocking motion, and this, combined with accumulation of sweat, can cause chafing to occur in the buttock area. [14,31,42] Prolonged friction in the presence of moisture could result in skin breakdown, which may cause a cyclist to discontinue a bicycle riding event. [31,42,48] More data are needed to determine the effectiveness of prevention strategies for reducing buttock pain. 5.5 Genital Numbness and of continued bicycle riding, 93% reported no pain or Erectile Dysfunction marked reduction in occurrence and magnitude of pain. [18] Controlled trials are needed to evaluate the Erection is a complex neurovascular mechanism prevention strategies advocated for reducing low incorporating sympathetic and parasympathetic back injuries. pathways. [49] Pressure on the dorsal branch of the pudendal nerve or the perineal artery either at the symphysis pubis or at Alcock s canal is thought to 5.7 Upper and Lower Leg Injuries be the mechanism for both genital numbness and When the saddle is too high, some cyclists may ED. [19,43,44] Reducing the pressure on the perineum develop iliopsoas tendinitis. Others may develop hip appears to be the solution. In two studies, a smaller pain from the repetitive sliding of the fascia lata over decrease in penile perfusion was found in cyclists the greater trochanter. [42] Foot pain on the plantar using a wider saddle compared with a more narrow surface (plantar fasciitis or metatarsalgia) is thought saddle. [43,44] Frequent breaks and standing on the to be a result of constant pressure on the pedals or pedals periodically while bicycle riding also is rec- ill-fitting shoes. [13] Achilles tendonitis occurred earommended to take pressure off the genital area. [43] ly during a mountain phase in a tour across Oregon, While experimental evidence using physiological USA, in some individuals. [13] This led the authors to outcomes suggests better penile perfusion with re- attribute this condition to poor conditioning prior to duced saddle pressure, clinical trials testing the as- the tour. Generally, non-traumatic injuries of the sociation between different methods of reducing lower leg and foot do not prevent individuals from pressure and ED are needed. Other prevention strat- bicycle riding. [13,14] The problem is thought to occur egies mentioned to reduce the risk of genital numb- when the saddle is too high. Although some advoness and ED include riding a road bicycle instead of cate that cyclists should perform stretching exera mountain bicycle, keeping the handlebar height cises to treat and prevent lower extremity injuries, lower than the saddle, and switching to a saddle no association between stretching and injury was without a cut-out if perineal numbness is exper- found in the study by Dannenberg et al. [16] ienced while using a saddle with a cut-out. [21] Trials evaluating the effectiveness of these prevention 6. Limitations of the Literature strategies are needed. It is difficult to estimate the incidence or prevalence 5.6 Back Injuries of non-traumatic bicycle injuries without knowing the underlying bicycle riding exposure in Complaints of low back pain have been attributed the general population. Worldwide numbers of cyto various causative factors. Mellion [41] claims that a clists are not known; however, a 1991 survey by the top tube that is too long extends the cyclist s lordotic US Consumer Product Safety Commission estilumbar posture. Similarly, if the handlebars are in an mates 67 million bicycle riders in the US alone. [51] extremely low position, the lordosis is exaggerated. This has led investigators to focus their research of

11 Non-Traumatic Bicycle Injuries 17 non-traumatic injuries to a subpopulation of cyclists interest that are directly relevant to the content of this manu- who participate in organised bicycle rides, a subpopulation that allows investigators to determine a script. denominator for calculating exposure. Even though References this population is convenient to study, readers must 1. Paffenbarger RJ, Hyde R, Wing A, et al. Physical activity, all- cause mortality, and longevity of college alumni. N Engl J be careful not to generalise the distribution and Med 1986; 314: frequency of injuries obtained from these studies to 2. Paffenbarger RJ, Lee I. Physical activity and fitness for health and longevity. Res Q Exerc Sport 1996; 67 (3 Suppl.): S11-28 the general population of bicycle riders who do not 3. Siscovick D, LaPorte R, Newman J. The disease-specific beneenter organised endurance rides. Population-based fits and risks of physical activity and exercise. 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Impotence and genital Non-traumatic injury research in the sport of bicycle riding is a young field. The number of individuals who cycle for recreation, fitness and transportation makes this an area of public health concern. While many recommendations to reduce non-traumatic bicycle riding injuries are available, few have been tested for effectiveness. Two categories of injuries that may have some impact on disability include ulnar and median nerve palsy, and ED. More information on the incidence of these injuries numbness in cyclists. Int J Sports Med 2001; 22 (6): is needed in order to develop and evaluate intervention strategies. Acknowledgements No sources of funding were used to assist in the preparation of this manuscript. The authors have no conflicts of 20. Patterson JM, Jaggars MM, Boyer MI, et al. Ulnar and median nerve palsy in long-distance cyclists: a prospective study. Am J Sports Med 2003; 31 (4): Dettori JR, Koepsell TD, Cummings P, et al. 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