Background Rates of injury among endurance sporting participants are high, as are subjective health complaints (SHCs - e.g. poor sleep, low mood). However, there is limited prospective data evaluating the relationship between SHCs and rates of new injury.
Objective To examine longitudinal associations between SHCs, sleep quantity and new injury within an endurance sport population.
Design Prospective cohort study.
Setting Competitive, sub-elite, endurance sports.
Patients (or Participants) Ninety-five endurance sporting participants recruited from running, triathlon, swimming, cycling and rowing disciplines. 92.6% of 95 participants submitted data for all 52 weeks, with the remainder completing ≥ 30 weeks.
Main Outcome Measurements Participants submitted weekly data regarding SHCs (cardiorespiratory, gastrointestinal and psychological/lifestyle), sleep quantity, training load and new injury episodes. Applying a 7- and 14-day lag period, a shared frailty model was used to explore new injury risk associations with total SHCs and sleep quantity, as planned a-priori.
Results Seven-day lag psychological/lifestyle SHCs were significantly associated with new injury risk (Hazard ratio (HR)=1.32; CI 95%=1.01–1.72, p<0.04). Whilst cardiorespiratory (HR=1.15; CI 95%=0.99–1.36, p=0.07) and gastrointestinal (HR=0.77; CI 95%=0.56–1.05, p=0.09) SHCs were not significantly associated. New injury risk had a significant increased association with 14-day lag <7hrs/day sleep quantity (HR=1.51; CI 95%=2.02–1.13, p<0.01) and a significant decreased association with >7hrs/day sleep quantity (HR=0.63, CI 95%=0.45–0.87, p<0.01. A secondary regression analysis demonstrated no significant association with total SHCs and training load factors (Relative Risk (RR)=0.08, CI 95%=0.04–0.21, p=0.20).
Conclusions To minimise an increased risk of new injuries within an endurance sporting population, this study demonstrates that psychological/lifestyle SHCs and sleep quantity should be considered. The study also highlights a lag period between low sleep quantity and its subsequent impact on new injury risk. No association was demonstrated between subjective health complaints, sleep quantity and training load factors.