TRAIL RUNNING INJURY RISK FACTORS: A LIVING SYSTEMATIC REVIEW
This page aims to provide clinicians and trail runners with an up-to-date summary of evidence regarding associated injury risk factors and the epidemiology (incidence, prevalence, clinical characteristics) of injury in trail running that is currently available. It further aims to provide an overview of how we will update the findings in future.
BACKGROUND
Trail running is a popular outdoor sport requiring runners to contend with varying off-road terrains and substantial elevation changes, including distances from only a few kilometres to more than 200km. Even though most trail running injuries are minor, rare cases of fatal injuries have been reported. Trail runners usually participate in remote natural environments where medical access can be challenging. To help guide the development of injury risk management strategies, the need exists to understand the injury risk in trail running and the most common injuries.
Therefore, we are conducting a living systematic review that summarise the current evidence regarding associated injury risk factors and injury epidemiology in trail running. The first summary of evidence was published in a peer-reviewed journal (article link). Search updates are performed twice per year until 2025. After that the update strategy will be re-defined. Updated review findings are presented as a plain-language summary on this webpage. If the findings result in substantial changes to the conclusion or recommendations of the initial peer-reviewed publication, an updated review will be submitted for publication
Our current conclusion are:
· There is a shortage of studies investigating injury risk factors in trail running.
· These studies predominantly focus on the reductionist paradigm, identifying linear relationships of isolated factors associated with injury using univariate analyses.
· Thirteen intrinsic and 18 extrinsic risk factors associated with a significant higher risk for injury in trail running were identified.
· The lower limb is the most injured anatomical region, specifically the foot/toe, ankle, hip/groin and lower leg.
· The specific pathology types most reported are joint sprains, tendinopathies, and skin blisters.
· Advances in trail running injury research focusing on injury risk factors associated with specific injury profiles will assist in designing and implementing future injury risk management strategies for safer trail running participation.
CURRENT REVIEW STATUS
The initial literature search was completed in 2021, and the findings were published in a peer-reviewed journal (article). We will continue to update the review every six months until July 2025.
January 2022: Published review in a peer reviewed journal (article).
July 2022: Published the 1st updated search results (up to January 2022) on this webpage.
January 2023: Published the 2nd updated search results (up to July 2022) on this webpage.
July 2023: Published the 3rd updated search results (up to Jan 2023) on this webpage.
January 2024: Published the 4th updated search results (up to July 2023) on this webpage
July 2024: Published the 5th updated search results (up to Jan 2024) on this webpage
The 6th updated search is completed and the updated findings will be publicly available on this website before Jan 2025.
WHICH STUDIES WERE INCLUDED IN THE REVIEW?
We searched for studies in eight relevant databases. Our initial search produced 2 755 results, with an additional 1 717 studies identified by our combined updated searches up to Jan 2024 (Figure 1). We included studies in this review that investigated associated injury risk factors or injury epidemiology in trail running. Trail running was defined according to the International Trail Running Association (ITRA). We included race participation and training-related studies. Medical attention, clinical assessment and self-reported injuries were included. Twenty-eigth studies met our inclusion criteria.
New studies included:
July 2024 (5th update)
Viljoen C, du Toit E, van Niekerk T, et al. Training for shorter ultra-trail races results in a higher injury rate, a more diverse injury profile, and more severe injuries: 2022 Mac ultra races. Phys Ther Sport 2024;65:7-13. doi: 10.1016/j.ptsp.2023.10.004
Jooste M, Janse van Rensburg DC, Scheer V, et al. One in Five Trail Running Race Entrants Sustained an Injury in the 12 Months Training Period before the 2021 Mac Mac Ultra Race. Applied Sciences 2023;13(17):9586.
January 2024 (4th update)
Armento AM, VanBaak KD, Seehusen CN, Howell DR. Differences in Training and Health Characteristics Between Trail Ultrarunners and Shorter Distance Runners. Wilderness Environ Med. 2023;34(2):182-186. doi:10.1016/j.wem.2022.12.002
Damoisy JB, Destombes V, Savina Y, Pröpper CJ, Braun C, Tanné C. Epidemiology, prevention methods, and risk factors of foot blisters in French trail ultramarathons. The Journal of Sports Medicine and Physical Fitness. 2023 May 11.
Zapata-Rodrigo R, Ramírez Parenteau C, Escribano-Rodríguez M, Vicente-Romero J. Musculoeskeletal injuries and illnesses in the Spanish team the month prior to the WMTRC 2022. Apunts Sports Medicine. 2023;58(217):100405.
July 2023 (3rd update)
No new study included.
January 2023 (2nd update)
Hamill J, Hercksen J, Salzano M, et al. The prevalence of injuries in trail running: influence of trails, terrains and footwear. Footwear Science 2022:1-9Gajardo-Burgos R, Monrroy-Uarac M, Barría-Pailaquilén RM, et al. Frequency of Injury and Illness in the Final 4 Weeks before a Trail Running Competition. Int J Environ Res Public Health 2021;18(10)
July 2022 (1st update)
Viljoen CT, Janse van Rensburg DC, Verhagen E, et al. Epidemiology, Clinical Characteristics, and Risk Factors for Running-Related Injuries among South African Trail Runners. Int J Environ Res Public Health2021;18(23):12620
Viljoen CT, Sewry N, Schwellnus MP, et al. Independent Risk Factors Predicting Gradual Onset Injury in 2824 Trail Running Race Entrants: SAFER XVIII Study. Wilderness & Environmental Medicine 2021.
Sanchez-Garcia LF, Penichet-Tomas A, Pueo B, et al. Injury Incidence and Pattern in Elite Young Male and Female Trail Runners. Applied Sciences 2022;12(3):1155.
Hutson MJ, O'Donnell E, Petherick E, et al. Incidence of bone stress injury is greater in competitive female distance runners with menstrual disturbances independent of participation in plyometric training. J Sports Sci2021;39(22):2558-66 [published Online First: 20210716]
Figure 1: Preferred reporting items for systematic review and meta-analysis (PRISMA) 2020 flow diagram
WHAT ARE THE FINDINGS?
Injury risk factors
The associated injury risk factors reported in trail running literature should be considered in the context of the limitations of the included studies. Risk factors were mainly reported in single studies (similar factors’ associations with injury are not reproduced in multiple studies). These associated injury risk factors must be reproduced across various trail running settings to enhance the robustness of the results. Most studies applied a univariate analysis (only considering the association of a single factor with injury) to investigate risk factors. Sports injuries have a multifactorial origin, and therefore it is unlikely that addressing a single factor will be sufficient in a successful injury risk management strategy. We identified the following associated risk factors with a higher risk for:
Any injury:
· Runners with more running experience.
· Being a level A runner. This classification was based on a mathematical algorithm that classifies runners based on their sex, age, previous races' difficulty, and running performance. Level A is the highest classification.
· Having a higher propensity to a sports accident questionnaire (PAD-22) score. This means that the runners scored higher for sensation-seeking psychological factors, assumption of risk, perceived competence, perception of risk, and competitiveness.
· Neglecting warm-up before running participation.
· Not adhering to a specialised running plan.
· Training more on asphalt compared to mountainous terrains or tartan surfaces.
· Performing two training sessions per day.
· Runners who worked in physical labour occupations.
· History of running-related injury in the past 12 months.
· History of any allergies.
· History of chronic disease.
· Higher weekly running distance.
· Being entered for a longer race distance (10 km vs 22 km).
· Running on certain trail types: back-country, alpine mountain, desert trails
· Running on certain trail terrains: moderate to highly technical, sandy, muddy, and slick
Bone stress injuries:
· Menstrual dysfunction (oligomenorrheic or amenorrhoeic).
Skin injuries (sunburn specifically):
· Younger age.
· Having low skin phototypes.
· More than three hours of training per day.
· Using shade as the primary mode of sun protection.
· Being single (marital status).
Skin injuries (blisters):
A history of having previous blisters
Muscle cramping:
· Having a previous history of muscle cramping.
· Having higher levels of post-race blood urea nitrogen.
· Having higher levels of post-race creatine kinase.
· Finishing a race in a slower running time.
Epidemiology of injury
· The findings need to be considered in the context of mainly ultramarathon race participation studies included in this review.
· The injury incidence (0.7–61.2 injuries/1000 hours of running) and prevalence (1.3% to 90%) presented with a wide range and high upper limits.
· The lower limb is the most injured body part, specifically the foot/toe, followed by the ankle, hip/groin and lower leg body regions.
· Superficial tissue/skin injuries were the most injured tissue type, followed by muscle/tendon and ligament/joint capsule injuries.
· The most common reported pathology was joint sprains, followed by tendinopathies and skin blisters.
CLINICAL RECOMMENDATIONS
· Injuries among trail runners are common.
· Considering the poor quality of evidence currently available, it is inappropriate to make strong recommendations regarding injury risk management in trail running.
· As this review matures over the next few years, it is expected to include more studies using more extended follow-up periods and more inclusive of female participants and shorter distance races.
· In the presence of better quality evidence, more robust clinical recommendations will be presented in future.
DO YOU HAVE ANY QUESTIONS?
Please email the corresponding author at: carel.viljoen@up.ac.za
CURRENT AUTHORS
Carel Viljoen, Christa Janse van Rensburg, Willem van Mechelen, Evert Verhagen, Bruno Silva, Volker Scheer, Manuela Besomi, Rubén Gajardo-Burgos, Sérgio Matos, Marlene Schoeman, Audrey Jansen van Rensburg, Nicol van Dyk, Susan Scheepers, Tanita Botha.