See how they run: Characteristics of 114,324 runs from 227 runners with and without a history of knee surgery

This study aimed to describe and compare the characteristics of runs performed by a cohort of male and female runners, with and without a history of knee surgery. Data on frequency, distance, pace and cadence were collected from 227 runners (45% females, 48% knee surgery) using smartwatches over 4 years (n = 114,324 runs). Generalised mixed models compared running characteristics between sex and knee surgery strata. Runners typically performed 2-5 runs per week between 3.5-20 km in length, 4-7 min/km pace, at 160-180 steps/min cadence. Comparing group averages, males ran faster (0.78 fewer min/km, 95% CI 0.55 to 1.0), and further distances (13% longer, [4% to 22%]). Average run frequency and cadence did not differ between males and females. Surgical group ran less frequently on average (66% longer gaps, [14% to 142%]), shorter distances (10% shorter, [17% to 2% shorter]), at slower pace (0.29 more min/km, [0.06 to 0.52]), with lower cadence (4.32 fewer steps/min, [0.73 to 7.91 fewer]). Despite group-level differences, sex and surgical history had limited ability to explain variations in running behaviours, with the majority of variance attributed to participant-level effects (29-53%). Runners within sex and knee surgery sub-groups should not be considered homogenous cohorts.