REF-783 · Viljoen et al., 2022 · British Journal of Sports Medicine, Vol. · Paper · PubMed

Trail running injury risk factors: a living systematic review

B+moderate evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

A living systematic review (searches of eight databases to 18 March 2021, to be updated every 6 months for at least 5 years) included nineteen studies on trail running injury, 10 of which examined injury risk factors in 2 785 participants. It identified eight intrinsic and nine extrinsic risk factors.

Injury was associated with more running experience, being a level A runner and a higher PAD-22 (propensity to sports accident) score, and with neglecting warm-up, having no specialised running plan, training on asphalt, double training sessions per day and physical labour occupations.

Reported injury incidence ranged from 0.7 to 61.2 injuries per 1000 hours of running and prevalence from 1.3% to 90%; the lower limb, specifically blisters of the foot/toe, was the most reported injury.

Participants

Nineteen eligible studies; 10 investigated injury risk factors among 2 785 trail-running participants. Individual study designs and populations are not given in the abstract.

Protocol

Living systematic review, updated searches every 6 months for a minimum of 5 years.
Eight electronic databases searched from inception to 18 March 2021.
Eligibility: studies of injury risk factors and/or injury epidemiology in trail running.
PROSPERO registration CRD42021240832.

Key Results

OutcomeIntrinsic factors associatedExtrinsic factors associated
Injurymore running experience; level A runner; higher PAD-22 scoreneglecting warm-up; no specialised running plan; training on asphalt; double training sessions per day; physical labour occupations
Crampingprevious history of cramping; post-race biomarkers of muscle damageslower race finishing time
Sunburnyounger age; low skin phototypesmore than 3 hours of training per day; shade as the primary mode of sun protection; being single
Injury incidence: 0.7-61.2 injuries/1000 hours of running. Prevalence: 1.3% to 90%.
Site: the lower limb was the most reported region, specifically blisters of the foot/toe.
The authors conclude that few studies have investigated trail running injury risk factors.

Practical Application

Across nineteen studies (10 on risk factors, 2 785 participants), trail running injury was associated with neglecting the warm-up, having no specialised running plan, training on asphalt, doing two sessions a day and a physically demanding job, as well as with more running experience, being a level A runner and a higher accident-propensity score; the most reported injuries were foot and toe blisters (living systematic review of observational studies). Warm up, follow a plan built for trail racing, and treat double days as a load to earn; more experience did not protect these runners.
Blisters of the foot/toe were the most reported injury: shoes, socks and foot care belong in race preparation, not only muscles and tendons.
Cramping was associated with a history of cramping, muscle-damage biomarkers after the race and slower finishing times. Inference, not tested here: this fits cramping as a fatigue and muscle-damage problem more than a salt problem; see REF-233.
Sunburn was associated with more than 3 hours of training per day and relying on shade for sun protection; long trail days need active sun protection.
The incidence range (0.7-61.2 injuries per 1000 hours) is too wide to give an athlete a single risk number. Inference, not tested here: the spread likely reflects few, varied studies with different injury definitions.
Inference, not tested here: "more experience" and "level A runner" as risk factors likely reflect more exposure and harder racing rather than experience itself being harmful; the abstract does not say how these were adjusted.

Limitations

Few risk-factor studies (10) of varied design and injury definition; the abstract reports associations without effect sizes.
The review reports "more running experience" as a risk factor for injury, which runs against the ultrarunner cohort in REF-779 (less experience = more injury); definitions and populations differ, and the abstract does not resolve it.
The abstract does not state how the included studies were quality-rated or whether any factors were adjusted for exposure.
Living review: later updates may change the list; this entry reflects the version published in 2022 with searches to 18 March 2021.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

systematic review of few, heterogeneous observational studies (injury incidence 0.7-61.2 per 1000 h, prevalence 1.3% to 90%)

Content correction 2026-09-27
2026-10-01: independent check against the abstract — wording brought back to what the abstract states.