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Recreational mountain biking injuries
  1. S A Aitken,
  2. L C Biant,
  3. Charles M Court-Brown
  1. Department of Trauma and Orthopaedics, Royal Infirmary Edinburgh, Edinburgh, UK
  1. Correspondence to Stuart A Aitken, Department of Trauma and Orthopaedics, Royal Infirmary Edinburgh, Little France, Edinburgh EH16 4SU, UK; stuart.aitken{at}nhs.net

Abstract

Mountain biking is increasing in popularity worldwide. The injury patterns associated with elite level and competitive mountain biking are known. This study analysed the incidence, spectrum and risk factors for injuries sustained during recreational mountain biking.

The injury rate was 1.54 injuries per 1000 biker exposures. Men were more commonly injured than women, with those aged 30–39 years at highest risk. The commonest types of injury were wounding, skeletal fracture and musculoskeletal soft tissue injury. Joint dislocations occurred more commonly in older mountain bikers. The limbs were more commonly injured than the axial skeleton. The highest hospital admission rates were observed with head, neck and torso injuries. Protective body armour, clip-in pedals and the use of a full-suspension bicycle may confer a protective effect.

  • Mountain biking
  • cycling
  • epidemiology
  • injury
  • musculo-skeletal
  • soft tissue injury
  • trauma

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The popularity of the sport of mountain biking (MTBing) has increased steadily since its inception in the late 1970s, and various disciplines now exist. Cross-country MTBing achieved Olympic status at Atlanta in 1996. The development of Downhill MTBing allows participants to travel much faster as they aim to reach the bottom of the course in the shortest possible time. Despite the use of protective clothing and equipment—for example, helmet, gloves, body armour, the risk of injury is ever present, and there have been concerns regarding the safety of the sport.

The Forestry Commission (FC) in the United Kingdom adopted MTBing as a key recreational activity in 1996 and is now responsible for managing and maintaining many of the countries MTBing centres.1 One of the largest and most visited is Glentress MTBing Centre, situated in the Scottish Borders.

Early MTBing injury research carried out in the United States analysed injury patterns in competitive mountain bikers at race meetings.2 3 A multi-centre Canadian study analysed injuries requiring Trauma Centre admission but excluded injuries managed on an outpatient basis.4

Epidemiological injury data from recreational MTBing has proven difficult to obtain. One prospective, single-centre study of competitive and recreational MTBing was conducted in the United Kingdom almost 10 years ago.5

The aim of this study was to describe the epidemiology of acute mountain biking injuries in recreational participants, using Glentress MTBing Centre as a population base. The secondary aim was to examine patterns of protective clothing and equipment use.

Methods

The study was conducted following approval from the local research and ethics committee, and with the assistance of FC Scotland.

The Glentress MTBing centre in Scotland has 130 900 visitors a year.1 Five medical facilities serve the local area surrounding Glentress (figure 1); three Accident and Emergency departments (one trauma centre), one Minor Injuries Unit and the on-site First Aid Station.

Figure 1

The location of Glentress MTBing Centre in the Scottish Borders. (A) Glentress MTBing Centre and First Aid Station. (B) Minor Injuries Unit, Peebles. (C) Borders General Hospital, Melrose. (D) Royal Infirmary, Edinburgh (designated Trauma Centre). (E) St John's Hospital, Livingston.

Mountain bikers seeking medical care at one of these five facilities, between 1st July 2007 and 30th June 2008, were prospectively identified from triage data. Those bikers sustaining acute injury, while MTBing at Glentress, were included in the study. Verbal consent was gained at triage, and contact details for each biker were recorded on the data collection sheet. Bikers whose injuries were sustained in areas outside of Glentress were excluded from analysis. Bikers sustaining injuries while not in the process of actively biking were similarly excluded. The first author (SA) then made contact with each injured biker, within 2 weeks of injury. Consent was obtained for study participation. Data relating to the accident and resultant injury(s) were recorded. The injury type and site were classified according to the criteria outlined in table 1.

Table 1

Classification of MTBing injury type and site

FC Scotland have been monitoring visitor numbers at Glentress MTBing centre since 1994,1 and the most up-to-date figures were made available to the authors by the Information and Statistics Division at the completion of the study period. The latest visitor survey suggested 93% of visitors arrived by car (with a mean of 2.4 visitors in each vehicle). The remaining 7% travelled to Glentress by bus or bicycle.6 Demographical information and details of biking patterns and preferences, relating to the study population, were gathered in two ways:

  1. Analysis of the latest visitor field survey of 143 bikers at Glentress in Sept 2007. This survey was conducted by a private marketing firm, on behalf of FC Scotland. The full results were obtained from the FC Scotland website.6

  2. Analysis of data from four additional field surveys. Data were obtained from 100 mountain bikers (28% of the mean daily total) on four separate occasions (400 bikers in total). The information was gathered by the first author (SA) over a 14-week period in 2008 and included details relating to biker demographics, use of helmet/gloves/body armour, bicycle design, suspension type, pedal type, grade of trail used and level of MTBing experience. Questionnaires were completed on different days of the week, from different sites within Glentress and in varying weather conditions, in order to obtain a random population sample. A copy of the questionnaire can be found online in appendix 1.

Statistical analysis

Statistical calculations and resultant graphical illustrations were created using Microsoft Excel worksheet (Microsoft Inc. 2003). Groups were compared using chi-squared tests for non-continuous variables and two-sample t tests for continuous variables. A p value threshold of 0.05 was used to determine significance.

Results

There were 187 000 visitors to Glentress during the study period, of which 130 900 were mountain bikers. The mean number of biker visits per day was 359. The results of each of the five mountain biker surveys were similar, suggesting that a random sample had been obtained on each occasion. The demographical details of the uninjured biker sample are shown in figure 2. Men accounted for 83% (108 647) of the MTBing population, with women accounting for 17% (22 253). The mean age was 32 years for all bikers; 32 (10–66) years for men, 33 (11–63) years for women. Men aged 30–39 years represented the largest age group.

Figure 2

Recreational mountain biking population field survey results by age group and sex.

Two hundred and two injured mountain bikers presented to one of the five recruiting medical facilities during the 12-month study period. Eighty-eight per cent (178) of injured bikers were men, while 12% (24) were women (p=0.12). A “biker exposure” was defined as one person MTBing at Glentress for all or any part of a day or night. The overall injury rate was 1.54 injuries per 1000 biker exposures. The rate was higher in men (1.64 per 1000 biker exposures) than in women (1.08 per 1000 biker exposures). The mean age for all injured bikers was 31.5 years: 31.5 (11–58) years for men, 32.0 (10–49) years for women. Men in the 30–39 years age group were most commonly injured (figure 3). Sixteen per cent of injured bikers required hospital admission.

Figure 3

Injured recreational mountain bikers by age group and sex.

One hundred and sixty-eight (83%) of the 202 injured bikers were able to be contacted for further telephone interview. Demographical information was obtained from these individuals. Further detailed information was recorded, with reference to the injury(s) sustained, the requirement for hospital admission or follow-up, the use of protective biking equipment (gloves, body armour), the use of a helmet and any helmet damage, the bicycle pedal and suspension system, the level of mountain biking experience and the circumstances surrounding the accident. Of the remaining 34 bikers, additional details were obtained from medical notes in 14 cases: these notes gave injury type and site details but no data about accident circumstances or equipment use. No additional information was available for 20 bikers. Therefore, analysis of injury type and site was possible in 182 (90%) of the 202 injured bikers (figure 4).

Figure 4

Flow diagram for the injured recreational mountain bikers.

One hundred and eighty-two mountain bikers sustained a total of 289 injuries (mean 1.6 injuries per biker). Eighty-seven bikers sustained a single injury type, 84 reported two distinct types, 10 reported three types and one biker reported four. The mean age and sex ratio was calculated for each injury type (table 2).

Table 2

Demographical details of injured bikers by injury type

Two thirds of bikers seeking medical attention had suffered wounding. The prevalence was similar in men and women, and the upper limbs were affected as commonly as the lower limbs. The admission rate was low in this group of patients, with only six bikers (5%) requiring admission for reasons attributed to wounding. Five of these individuals required operative debridement of contaminated wounds.

One third of attendees had suffered one or more soft tissue injury(s). Male and female bikers were similarly affected. Injuries to the upper limb accounted for 50% of this group (shoulder, elbow, wrist), lower limb injuries 25% (hip, knee), with the remainder affecting the axial skeleton (neck, chest, abdomen, perineum). Only one patient required admission for inpatient treatment of a muscular hip injury. There was one case of blunt abdominal trauma causing occult haematuria. This patient required outpatient follow-up.

One third of injured bikers had suffered from one or more fracture(s). Eighty distinct fractures were seen in this group of 68 bikers (table 3). Skeletal fractures were seen more commonly in men than in women (p=0.019). Upper limb fractures occurred ten times more commonly than lower limb fractures, with clavicle and distal radius injuries predominating. Nine bikers required admission for reasons relating to their fracture(s). A similar number required admission for neurological observations due to the presence of a co-existing head injury.

Table 3

A list of all fractures sustained during the study period

Thirteen per cent of injured bikers reported suffering head injury. A higher incidence was seen in women (p=0.33). Two thirds of this group reported loss of consciousness at the time of their accident. The highest admission rate (33%) was seen in this group; eight bikers were admitted for neurological observations, and each of these individuals had also sustained fracture(s). All head-injured individuals had been wearing a helmet at the time of injury. Modern helmets are designed to absorb kinetic energy and shatter on impact; this occurred in 71% of cases.

Dislocations were relatively uncommon, but a significant correlation was seen between incidence of dislocation and advancing age (p=0.001). All dislocations occurred in male bikers. Three bikers admitted from the dislocation group required surgical stabilisation (two elbow injuries, one acromioclavicular injury).

Ninety-nine bikers suffered injury to a single site, 70 reported involvement of two distinct sites and 13 bikers reported three (table 4). Injury to the limbs was common, particularly the upper limb. Almost one third of bikers described injury to the head and neck.

Table 4

Demographical details of injured bikers by injury site

MTBing trails are given a coloured grading, mirroring the system in use at most ski resorts. The grading system is designed to reflect the length, gradient, technical difficulty and surface condition of the trail (table 5). In addition, many centres have a Freeride Park, containing numerous jumps and technical hazards.

Table 5

The trail grading system in use at Glentress, with the length of each trail shown

Almost half (45%) of the injuries reported during the study period were sustained on the Freeride Park. The Red route accounted for 30% of injuries, with the Black (11%), Blue (11%) and then Green (1%) accounting for the remainder. As part of the authors' field survey, mountain bikers were asked which trails they used most often. Answers were categorised as “Every time”, “Usually”, “Seldom” or “Never”, and this allowed for the calculation of injury incidence for each grade of trail (table 6).

Table 6

The pattern of use and injury incidence for each trail grade

The effect of protective equipment

Helmet usage data were available for 173 injured bikers. All but one of these individuals had been wearing a helmet at the time of injury. Several designs of mountain bike helmet were used. The simple “Cross-Country (XC)” style helmet aims to protect the top of the head and was used by 84%. The robust “Full Face” downhill MTBing helmet affords additional protection to the face and mandible (11%), as does the “XC with Face” variant (3%). The “Skater” style helmet falls in-between these two broad categories; it has no face protection but covers the back and sides of the head. Despite 6% of field survey respondents reporting use of a Skater helmet, only 1% of injured bikers were wearing this type (p=0.03). The prevalence of different helmet designs was compared between those bikers who had sustained a head injury and those who had not. No difference was seen. Of those individuals whose helmet had shattered, 68% reported no head injury.

Thirty-one per cent of injured bikers were wearing some form of body armour at the time of injury (figure 5). The use of lower limb body armour was associated with fewer lower limb wounding injuries (p=0.04), but there was a tendency towards a greater number of lower limb fractures (p=0.2). No trend was identified with soft tissue injuries. The use of upper limb body armour did not have a significant effect on the pattern of upper limb injury.

Figure 5

The proportion and type of body armour used within the injured biker group.

The majority of injured bikers (82%) were wearing gloves at the time of injury. The use of gloves was associated with fewer wounding injuries (p=0.05); this association was not solely restricted to wounding of the hands.

Field survey data suggested approximately half of recreational mountain bikers used a standard “Flat” pedal design. Half used a binding mechanism, similar to the quick-release mechanism used in skiing. When analysing injured biker data, 123 (73%) individuals were using flat pedals at the time of their injury, and only 45 (27%) were using quick-release (p<0.001).

The two commonly available types of MTB suspension set-up are “Full suspension” and “Hardtail”. Hardtail MTBs have suspension over the front wheel. Full-suspension MTBs are fitted with additional rear wheel shock absorption and are thought to make it easier to ride on increasingly technical terrain. The field survey results showed an equal number of bikers used one of these two types. However, 96 injuries were seen in bikers using Hardtail MTBs with 62 injuries occurring in those using Full suspension (p=0.03).

Discussion

The mountain bike emerged on the West coast of the United States in the early 1970s. It was not until 1982 that MTBs started to appear in significant numbers in the United Kingdom, but by 1986, MTB sales had overtaken the sales of the popular BMX and Road bike models. In 1993, Chow et al conducted a retrospective questionnaire survey in California describing patterns of injury within the sport.7 Pfeiffer, in 1994, presented a study of prospectively collected data from Elite level competitive events in the US.3 In 1995, Pfeiffer and Kronisch described the incidence of different injury types, using predominantly retrospective data.8 They concluded that future research should attempt to determine the relationships between bicycle design, terrain and safety equipment.

The first substantial prospective study of competitive bikers was conducted by Kronisch, Pfeiffer and Chow in 1996.2 They looked at injury rates, types, mechanisms and severity across the two popular disciplines of Cross-country and Downhill MTBing. They concluded that the risk of injury is similar in each discipline but uncovered a possible difference in injury patterns between men and women. Jeys et al conducted a study of recreational and competitive bikers who required Orthopaedic referral.5 Our study has highlighted that 62% of recreational mountain biking injuries recorded during our study period did not require orthopaedic review. Kronisch and Chow examined mechanisms of injury in competitive MTBing in 20029 and showed that falling forward over the handlebars was associated with a greater severity of injury. The same group further examined sex differences in MTB racing injuries and concluded that the risk of injury was greater in women10; a finding that has not been replicated in our study of recreational bikers.

Kronisch and Pfeiffer in 2002 stated that little had been learned about the demographics and injury epidemiology of non-competitive mountain bikers.11 A multi-centre study from Canada examined 10 years of mountain biking injuries.4 Like the survey by Jeys et al, this large study included only patients requiring trauma centre admission and, therefore, described the more serious injuries encountered within the sport. Quigley and Boyce reported on a prospectively collected case series of recreational and competitive MTBing injuries in 2005, but there was no control group.12

Men aged 30–39 years accounted for 30% of mountain bikers in the study. As a consequence, injury was most commonly seen in this group. Men aged 20–29 years were somewhat over-represented. It may be that this group ride more aggressively and are willing to take greater risks. The overall injury rate of 1.54 injuries per 1000 biker exposures suggests that recreational mountain biking compares favourably with many other popular sports. Studies looking at indoor and outdoor soccer have found injury rates of between 4.0 and 18.0 injuries per 1000 player exposures,13–15 while rates in competitive rugby union often exceed 100.0 per 1000 player games.16 Even the injury rate in competitive Downhill MTBing (43.4/1000 biker hours) compares favourably with the injury rate found in competitive BMX cycling (1190/1000 biker hours) at the peak of its popularity.2 17

Catastrophic head injury was not seen during the study period, but 30% of bikers reported injury to the head and neck region. This is twice the proportion reported in the early MTBing literature7 and is three times the amount seen in soccer injuries.18 A reported LOC/Concussion rate of 13% (or 0.2 per 1000 biker exposures) is similar to that reported by competitive MTBing studies.2 3 When comparing this head injury rate with other popular sports, it is similar to that seen in rugby union training but is 60 times less than that seen during professional rugby union.19 A helmet usage rate of 99% within the injured group suggests that recreational mountain bikers are aware of the risks of injury to the head and neck region. Of those whose helmet shattered on impact, 68% suffered no head injury, suggesting that modern helmets afford the wearer good protection.

Despite the modest overall injury rate seen during the study period, the reported prevalence of skeletal fracture in mountain biking is higher than in soccer and rugby union and may be similar to other road cycling disciplines.20 In contrast to competitive MTBing injury data,10 fractures were much more common in male recreational participants than in women.

The high rate of helmet use among injured bikers precluded any comparison of helmet users and non-users. The results presented here cannot confirm or refute any association between the larger “Full face” helmet design and an increased risk of cervical spine injury. The potentially protective effect of “Skater” helmets cannot easily be explained and warrants further study.

The results of this study suggest a potential protective effect of body armour. In our cohort, lower limb armour protected against lower limb wounding, but this effect was not replicated with upper limb armour use. The use of gloves offered additional protection.

Despite the popularity of a flat pedal system among younger MTBing enthusiasts, it was the quick-release system that was associated with fewer injuries. This may reflect the particular riding style of each group. Bikers using flat pedals are often said to favour them in order to attempt more tricks and jumps, while quick-release has traditionally been reserved for the cross-country enthusiast.

Improvements in mountain bike design and technology have led to more sophisticated and effective suspension system options on modern frames. The results of this study demonstrated a protective effect of the full-suspension set-up, despite this design reportedly allowing the biker to tackle steeper and more technically demanding terrain.

This study has limitations. We have had to rely on the accuracy of FC Scotland data when determining details on visitor numbers to mountain biking sites. The analysis of risk factors is dependent on a random sample being obtained by the field surveys. While every effort was made to ensure this was the case (questioning 30% of the daily number of bikers, on four separate occasions), it is accepted that our sample group may not be entirely representative of the population at risk as a whole. Some attendances at the named medical facilities may have been missed at triage, and there may have been a number of injured individuals attending for treatment out with the study area. Telephone interviews may introduce a further source of bias, but using this method of data capture, we were able to achieve an 83% response rate, with the information obtained directly from the injured bikers.

This is the first large prospective study of recreational mountain biking injury. We report clear associations between protective equipment, bicycle design and the patterns of injury encountered. Previous studies have reported a trend towards serious and debilitating injury, but these results suggest that recreational MTBing compares favourably with many other popular sports.

References

View Abstract

Footnotes

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Borders General Hospital Ethics Committee, Borders General Hospital, Melrose, Roxburghshire, TD6 9BS.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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