Illness is common in trail runners during training: a prospective cohort study

Area of Science:

• Sports Medicine
• Exercise Physiology
• Public Health

Background:

• Trail running is a popular endurance sport, but athletes often face illness during demanding training periods.
• Understanding illness patterns and risk factors in trail runners is crucial for optimizing performance and health.

Purpose of the Study:

• To prospectively determine the prevalence, incidence, clinical characteristics, and severity of illness in South African recreational trail runners over 30 weeks.
• To identify potential risk factors associated with illness in this population.

Main Methods:

• A prospective cohort study involving 152 recreational trail runners (120 males, 32 females) over a 30-week period.
• Bi-weekly data collection using the updated OSTRC-H questionnaire to record illness and training details.
• Analysis of illness prevalence, incidence, incidence ratio (IR), time-loss, illness burden (IB), and risk factors using statistical methods, including Poisson regression.

Main Results:

• 52% of runners reported illness during the 30-week study period, with a mean two-week prevalence of 10.1%.
• Overall illness incidence was 7.2 per 1000 exposure-days, with higher incidence observed in females (9.7) compared to males (6.6).
• Respiratory illnesses were most prevalent (64.3%), followed by digestive (15.9%) and musculoskeletal (5.7%) issues. A BMI ≥25 kg/m² was associated with increased illness risk.

Conclusions:

• Trail runners experience significant illness during training, particularly affecting the respiratory system, with females exhibiting higher incidence rates.
• Moderate to severe illness (over one week of time-loss) affected one in three runners.
• While a higher BMI was associated with illness, further research is required to elucidate specific risk factors and develop targeted prevention strategies for trail runners.