Estimating Tibial Forces While Running: All We Need Is A Wrist-watch?

Tibial bone stress injuries are common in runners and develop due to factors including mechanical loading, training load errors, and tissue maladaptation. Tibial loading can be quantified using lab-based instruments, but availability of wearable devices now makes it easier to quantify tibial loading for daily monitoring. PURPOSE: To assess the validity and reliability of four estimates of peak tibial compressive force (TCF) using wearable devices. METHODS: 11 runners (6 women) completed running bouts at 3.0, 3.5, and 4.0 m/s on two separate days. The “gold” standard (GS) approach computed TCF (peak axial tibial force) from 3D kinematics and ground reaction forces, and individual Achilles tendon (AT) moment arm. Four TCF estimation methods from wearable devices were used: 1) a foot-mounted IMU and vertical force insoles (FOOT+VRF), 2) a foot-mounted IMU only (FOOT), 3) a wrist-mounted IMU only (WRIST), and 4) a pelvis-mounted IMU only (PELVIS). Calculations included individual AT moment arms and ground reaction force moment arms. Validity (vs GS) and inter-day reliability were assessed using Bland-Altman offsets and ICC. RESULTS: FOOT+VRF, FOOT, and WRIST showed strong to moderate ICC with GS and excellent day-to-day reliability across speeds, while PELVIS showed weak ICC (Table 1). Based on Bland-Altman offsets, FOOT+VRF and FOOT slightly underestimated TCF across all speeds. The quotient of the average TCF value from the GS and the estimated TCF value for WATCH across all speeds was used as the multiplier (1.62). Adjusted WRIST data slightly overestimated TCF across all speeds but agreement was excellent. PELVIS greatly overestimated TCF indicating poor agreement with GS. CONCLUSION: Findings from this study suggests that methods using wearable devices, including a wrist-worn IMU only, can yield valid and reliable estimations of tibial compressive forces in runners, raising the potential for simple and practical in-field prospective tibial load monitoring. Supported by: American Athletic Conference Academic Consortium; ACSM Foundation World Athletics Research Grant