Introduction

Cycling is a very popular sport and leisure activity with many health and environmental benefits, including improved cardiovascular fitness, muscle strength and mental well-being. It also offers significant environmental advantages, such as reducing air pollution and traffic congestion1,2. According to the Spanish General Direction of Traffic (DGT), more than half of Spaniards between the ages of 12 and 79 (50.7%) use bicycles with some frequency, reaching to approximately 4.5 million users in recent years3. However, as cycling gains popularity, it also presents growing concerns related to safety and injury prevention, with bicycle-related injuries contributing to a noticeable increase in emergency department visits and Hospital admissions. These injuries represent a public health challenge that requires attention from the healthcare providers as well as the cycling community4.

The sport of cycling is very broad and, although the different types appear similar, they harbor some differences and singularities. Mountain biking and road cycling are two of the most widely practiced and distinct disciplines within cycling5. On the one hand, mountain biking takes place mainly on unpaved roads and trails and often involves more technical complexity due to obstacles like rocks, roots and sharp turns. These routes are frequently shared with pedestrians and hikers, making safety a critical concern6. This type of cycling generally involves short, explosive routes with low speed and high technical complexity. On the other hand, road cycling takes place on paved roads and shares the route, alongside motor vehicles, requiring cyclists to contend with traffic and potentially hazardous road conditions. This type of cycling involves long itineraries that imply longer effort and higher speeds7.

While cycling is beneficial for health, it can also lead to chronic injuries, particularly due to prolonged and repetitive postures, that can increase the risk of injuries over time. For instance, Patti et al.8 have explored how adopting a specific cycling posture may impact the spine and found that sustained cycling postures, especially in professional riders, could lead to spinal alignment issues and discomfort, which may increase the risk of musculoskeletal injuries. Over time, these effects can accumulate, contributing to long-term discomfort and a higher likelihood of injury if not managed properly through posture adjustments and regular body care.

Previous literature generally indicates similar injury patterns across cycling styles, such as strains, sprains and fractures, but it lacks a detailed exploration of how these injuries may differ in frequency, severity and location between mountain biking and road cycling. Given the growing number of cycling participants, understanding the volume, nature and risk factors associated with cycling-related injuries is vital for improving medical response9.

The aim of the study was to analyze the frequency, severity and some risk factors associated to road and mountain cycling. Analyzing the incidence and characteristics of injured cyclists is paramount to preparing medical assistance for these increasingly frequent users. Consequently, this lays the foundation for implementing measures to improve the diagnosis and treatment of this patient profile and the endorsement of effective and reliable approaches for these patients. Furthermore, examining the most frequently encountered injuries can help prevent them.

Methods

This was a single-center prospective observational and descriptive study. The study followed the ethical principles of biomedical research. Methods were performed in accordance with de Declaration of Helsinki and relevant guidelines and regulations. The approval of the Ethics Committee of Parc Taulí was obtained and documented (2020/737) and provided consent before enrolling participants in the study.

Parc Tauli Hospital is located in Sabadell, Barcelona, with about half a million inhabitants of reference population, in an urban area near several mountains. It is a tertiary trauma center hospital, the only one in the reference area and receives about 20,000 emergencies for trauma patients annually.

Patients

We recruited patients during the emergency care visit from November 1, 2020, to October 31, 2021. The informed consent process was completed, and consent was obtained from all participants.

We defined inclusion and exclusion criteria as listed:

Inclusion Criteria:

  1. 1.

    Adult population (≥ 18 years of age).

  2. 2.

    Attended to Emergency Trauma Department at any time of the day.

  3. 3.

    Reported cycling-related injuries.

  4. 4.

    Patients with the ability to understand the study and provide informed consent.

Exclusion criteria.

  1. 1.

    Patients who did not provide information regarding the mechanism of injury.

Variables

For this study, data collection involved gathering both patient and accident-related information through interviews conducted during visits to the emergency department. Additionally, clinical data were prospectively retrieved from medical records. All collected data were meticulously organized into a tailored form designed specifically for statistical analysis. In the emergency room, injury severity was assessed for all patients using the Injury Severity Score (ISS), a scale that ranges from 0 (indicating a healthy state) to 75 (indicating a fatal injury). This scoring system was derived from the Abbreviated Injury Scale (AIS) scores, which categorize injuries using a six-point scale based on affected body regions such as the head, face, neck, chest, abdomen, spine, upper extremity, and lower extremity. The ISS was calculated by summing the squares of the highest AIS code from each of the three most severely injured body regions10.

During the emergency care visit, comprehensive data were collected on several relevant factors related to cycling accidents. These included details of the type of cycling involved (mountain or road), the specific type of bicycle used (mountain, road or urban) and the use of safety equipment (helmet and lights) at the time of the incident (morning, afternoon, night). Information was also collected on previous alcohol consumption (yes or not), prevailing weather conditions (sunny, cloudy, rainy) and various characteristics of the accident itself, including its mechanism (collision with another motor vehicle, another bicyclist, pedestrian, object, or loss of control of the bicycle), geographical location (nature or road), and speed (< 30 km/h or ≥ 30 km/h). Demographic details such as age and sex were also recorded, as well as injury-related factors such as diagnosis, need for surgery, triage level and length of stay in the emergency department.

Statistical analysis

Statistical analyses were performed following the principles specified in the International Conference on Harmonisation (ICH) Topic E9 (CPMP/ICH/363/96). Descriptive statistical methods were used to summarize quantitative variables, including the number of valid and missing values, observed range, median, mean, standard deviation and 95% confidence interval for the mean.

For qualitative variables, the number of valid and missing values, along with the frequency and percentage for each category, were reported. Differences between groups were analyzed using the Chi-square test. To identify the risk factors associated with the severity of the injuries, a multivariate logistic regression model was applied. The percentage of explained variance (or R2) in a univariate analysis reflects how much variability in the dependent variable is explained by a single independent variable, providing a measure of the impact that variable has on the dependent one. In contrast, in a multivariate analysis, R2 measures the total amount of variability in the dependent variable that is explained by all the independent variables combined. While in the univariate case, R2 varies depending on the independent variable being analyzed, in the multivariate case, this value reflects the combined predictive power of all variables and does not change for each individual one. We selected what we considered the ten most relevant variables for the study (Head and neck, column, lower extremities, upper extremities, helmet, mechanism of injury, helmet, mechanism of the accident, age and surgical treatment required), along with the dependent variable ISS Score. Table 1 shows the results of the multivariate analysis.

Table 1 Univariate and multivariate analysis. A p value of 0.05 was considered significant, but for the multivariate analysis all values < 0.1 and considered clinically relevant were analyzed. Data is presented as Beta coefficient (CI 95%) and p value.
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A p value of < 0.05 was considered statistically significant for all analyses. Statistical computations were carried out using IBM® SPSS® software v.29.0.

Results

The study included a total of 149 cyclists, including 129 men and 18 women (12%), with an average age of 44.8 years. Participants ranged in age from [18] to [77] years. In the same period, mountain bike accidents (100, 67.1%) were treated more than twice as often as road bike accidents (49, 32.8%).

Cycling experience showed no significant difference between the two groups. The use of safety equipment such as helmets and lights showed high compliance in both groups, with no significant difference observed. In addition, factors such as alcohol consumption, time of day and weather conditions showed no discernible effect between mountain and road cycling. The mechanism of injury revealed significant differences between the two groups, with motor vehicle accidents being more common among road cyclists11 compared to mountain cyclists2, p < 0.05. Furthermore, speed did not emerge as a differentiating factor between the two groups. No differences in terms of severity or mortality of accidents according to sex were found in this study. All this information is displayed in Tables 2 and 3.

Table 2 Demographic variables.
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Table 3 Cycling characteristics.
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Table 2 shows a summary of the main demographic variables. The variables described the total number of patients who reported having suffered mountain or road cycling accidents.

Table 3 shows a summary of the main cycling characteristics. The variables described the total number of patients who reported having suffered mountain or road cycling accidents. There were no differences in the level of triage, need for surgical treatment or length of hospital stay between the two groups.

Table 4 shows findings on injury severity scores (ISS) across different body regions according to the type of cycling. The total ISS score was 5 (3–9 Q3-Q1), and, road cycling related accidents showed to be statistically significant more severe than mountain cycling accidents. In terms of head injuries, mountain cyclists demonstrated a lower proportion of serious and severe lesions compared to road cyclists (p = 0.029). However, no statistically significant differences were observed in the severity of injuries to the face, neck, chest, abdomen, spine, lower extremities, and upper extremities between the two cycling groups. To note, the patient who died from the road cycling group suffered a head injury.

Table 4 Variables related to the severity of injuries.
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As depicted in Fig. 1, the most prevalent injury locations were the upper extremity, followed by lower extremity, face, thorax, head, spine, neck and abdomen. Road cycling-related accidents recorded a higher percentage of the type of injuries in all anatomical regions except the upper extremity.

Fig. 1
figure 1

Prevalence of injury locations for different types of cycling.

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Lastly, when looking for risk factors in cycling related accidents and injury severity, we found a positive correlation of ISS with age, meaning that as the age of the cyclist increases, the ISS tends to increase as well; as shown in Fig. 2 (which excluded the patient who died) for each additional year of age of the cyclist, the ISS increases by 0.09 units for mountain cyclists and by 0.20 units for road cyclists. These results show that age is a risk factor, especially for road cyclists. The difference of the two slopes, according to the linear analysis of the regression lines, is statistically significant (p value = 0.025). This means that the observed difference in the relationship between age and ISS for the two groups is unlikely to have occurred by chance.

Fig. 2
figure 2

Relationship between ISS and age for both types of cycling.

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Discussion

This study evidences significant higher several injuries in road cycling-related accidents compared to the mountain bike ones.

The ISS value obtained in the present work was similar to that reported in the Australian study by Meuleners et al.12 which registered an ISS value of 8.7, but it was lower than that found in studies from other countries which registered a 13.6 ISS score in The Netherlands and an ISS score of 10 in Ireland7,13. Significant differences in injury severity were observed between road and mountain bikers, with road cyclists showing more serious injuries and therefore higher ISS values. These results are consistent with those of a study assessing cycling crashes in Denmark14. This could be explained by the high incidence of head injuries observed in the road cyclists which are also statistically different from those of the mountain bikers. There seems to be an accordance between present results and literature. In the Netherlands, indeed, traumatic brain injuries are the leading cause of mortality in cycling accidents15.

We observed that mountain cyclists had higher emergency care attendance rates for injuries compared to road cyclists. This could be primarily due to the geographical location and the larger proportion of people in those areas who practice mountain cycling.

Our results evidenced that both road and mountain cyclists suffered more injuries to the extremities. In contrast de Guerre7 or de Foley13 found that the most affected anatomical region was the head. One of the possible reasons for these differences lies in the fact that the de Guerre or Foley’s studies analyze patients from other countries, the Netherlands and Ireland, respectively, which might influence the type of falls and the consequent location of injuries. Regarding the involvement of the extremities and in agreement with other studies, the upper extremities were more frequently affected in both groups13,16,17 .

As possible causes of the difference in injury severity, we consider that the mechanism of injury is a key factor that determines both the severity and location of injuries. In our study, in both groups the main cause of fall and therefore the mechanism of injury was loss of control. However, different results can be found in the literature. Some studies reported collision with another vehicle as the main cause of the accident, either with a car or another bicycle11,12,18,19,20 , others, as our study, outline that the main cause was loss of control8,21,22 and other studies found no differences between the two groups23. The high percentage of accidents involving motor vehicles in the road cycling group may be one of the main causes for the increased severity of injuries in this group. Nevertheless, in the present study we found no differences in this parameter.

We also looked for other risk factors that may explain the differences in severity evidenced in both groups, such as the use of helmets. It has been shown that head injuries can be one of the main causes of morbidity and mortality in cyclists15. On the other hand, helmets, which are effective in preventing head and facial injuries7,24,25 , are related to a decrease in ISS26. In our study, no differences were found in the use of the helmet between the two groups; however, road cyclists suffered more severe head injuries than mountain bikers. Further studies on the use of the helmet should be conducted, particularly due to the fact that other studies11 related the use of this safety device to cyclist age, which might have been interesting to evaluate, as we encountered a correlation between age and ISS.

Another factor evaluated in this study was sex. Conversely to what has been reported in other studies, which observed that most accident victims are men12,14,26,27 no differences in terms of severity or mortality of accidents according to sex were found in this study.

In addition, the level of triage or the length of stay in hospital were analyzed. These variables, unlike the ISS Score, did not provide significant differences when comparing the two groups. Structured triage systems with five levels of priority are used in our center. It allows patients to be classified according to “degree of urgency”, so that the most urgent patients are seen first, and the rest are reassessed until being seen by the doctor28. These levels are based on the concept of urgency rather than severity, and possibly due to the fact that urgent is not always severe and severe is not always urgent, the differences between triage and ISS Score results may have been observed.

Alcohol is a factor associated with an increased risk of crashes and more serious injuries in the event of a crash29,30,31. No statistically significant differences were found between the severity of injuries related to the alcohol consumption in the two groups. The patients were questioned by the professionals during the interview with the patient. We observed lower rates of alcohol consumption (7.4%) than those reported in the literature (14.6%, 15.1% and 12%, respectively)11,25,28 probably because not all patients were tested for alcohol consumption or simply because certain drinks, such as a beer, are not considered as alcohol consumption.

Finally, our results highlighted the association between the patients age and the injuries severity, especially in road cyclists. The older the patient, the more serious the injury was. Thus, the age can be considered an important risk factor in road cycling accidents. These findings are in line with other studies reporting a positive correlation between age and the severity of injuries7,23,26,32,33,34 or the type of injuries32. Ekman et al.33 observed that the risk of dying from a cycling-related injury was 3.5 times higher in older people (65 or older) and the risk of suffering a serious injury was 7.5 times higher. Some characteristics related to the age are, a longer reaction time, that makes it more difficult to avoid obstacles, bone fragility, acoustic or visual loss or higher presence of pathologies, which can determine the association between age and severe injuries.

Furthermore, biomechanical and physiological factors, including muscle fatigue, altered gait patterns, reaction time variability, and neuromuscular control, have been previously discussed in the context of sports injuries35,36,37. These factors may also play a crucial role in influencing injury mechanisms and severity among cyclists. In particular, issues related to posture control and delayed motor responses, often affected by repetitive strain or inadequate posture adaptation38, have the potential to exacerbate the risk of injury during cycling falls or collisions. Additionally, the acquisition of technical skills and motor learning, which have been demonstrated to be contingent on early development and expertise39, may also influence cyclists’ capacity to respond effectively in high-risk situations, potentially affecting injury outcomes. These aspects warrant further investigation in future research on cycling-related trauma.

We would like to emphasize that the findings presented in our study represent associations and do not imply causal relationships. Due to the observational nature of the data, causal inferences cannot be drawn.

One limitation of this study is that the patient group represents only a small subset of all bicycle-related injuries. As a regional study, the findings may not be generalizable to other areas with different cycling infrastructure, traffic regulations or cycling popularity. Additionally, the study lacks injury rates for comparison, offering only absolute numbers of injured cyclers. Another limitation is the absence of objective speed measurements, which could have provided more insights into the circumstances surrounding the injuries. We acknowledge that the absence of detailed cycling exposure data (such as hours of cycling per week or frequency) represents a limitation of our study. This lack of exposure metrics restricts our ability to accurately assess relative risk and to fully contextualize injury rates. Finally, a key limitation is the relatively small sample size, which may reduce statistical power to detect significant associations, so some true associations may not have reached statistical significance and findings should be interpreted with caution, although a priori sample size calculations were conducted. We suggest that future studies incorporate exposure data to provide a more comprehensive risk assessment.

However, the trauma center involved is one of the largest in Catalonia, which increases the likelihood that the results reflect a representative sample of bicycle-related injuries in the region. A critical limitation is that patients who died at the scene of the accident did not reach the hospital and were therefore excluded from the present study. This exclusion may affect all variables related to injury severity, the frequency of patients in each injury group, and the lack of differences observed in triage levels.

Moreover, the study was carried out during 2021, when some mobility restrictions related to the COVID-19 pandemic were still in place. These restrictions could have influenced the sample size, particularly due to confinement periods that may have limited cycling activity. A further limitation is the gender disparityin the sample, with 129 men and only 18 women included, which hinders the ability to draw generalizable conclusions and introduces gender bias.

Additionally, this was a prospective study that required patient consent during recruitment, there is the possibility of selection bias, as some patients chose not to participate, resulting in a loss of data.

Lastly, while electric bicycles are gaining popularity and are associated with higher injury rates, particularly multiple fractures, they were not yet widely used in the study’s setting at the time of the research, unlike in other countries30,40. This limited the ability to fully assess the impact of electric bicycles on injury patterns.

Conclusions

This research shows that injuries from road cycling accidents are less frequent but more severe than those from mountain biking accidents. This study shows that road cycling patients experience more serious head injuries. It is very important to consider the type of cycling to assess the patient’s triage; specific codes such as polytrauma (which is associated with earlier and more complete management) should be assessed in this patient profile. Even more so if the patient has suffered a traumatic brain injury. The results show a correlation between the age of the patient and the severity of the injury, with older people typically suffering more severe injuries. Therefore, age appears to be a significant risk factor in cycling accidents, particularly among road cyclists.