Progressive Loads in the Tibia During Exercise Related Activity

Abstract

Introduction: Bone stress injuries represent ~10% of injuries associated with sports and exercise and typically result in prolonged periods of recovery, costly diagnostic medical imaging, and exercise participation attrition. While the initial management of bone stress injury involves a phase of reduced physical activity to limit injury progression, an ensuing progressive exposure of bone to mechanical loads during rehabilitation is required to condition bone for a safe return to activity and decrease the risk of re-injury.

Objective: The purpose of this study is to quantify bone specific loads across a spectrum of exercise-related activities. Specifically, bone stress will be estimated in silico at the distal 1/3 tibia, one of the most common sites of BSI in physically active populations.

Methods: As part of an ongoing study, lower extremity joint motion and ground reaction forces of 39 healthy adults (19 male, 20 female) have been collected during walking, running, sprinting, cutting, double leg take-off and landing, and single leg take-off and landing using 3D motion capture and force plate data. 3D kinematics and kinetics during these tasks were input to a series of musculoskeletal models, including a cross-sectional finite element model (FEM) of the tibia to estimate tibia stress. Peak tibia compression (COMP), tension (TENS), and shear stress were extracted for comparison across activities for preliminary analysis using repeated measures analysis of variance (=0.05).

Results: Males and females differed in height, mass, and condition jump height (p≤0.05). In general, peak bone stress increased when progressing from walking, to double leg (DL) activities, to push off activities including single limb (SL) take off, running, cutting and sprinting. The greatest peak stress was observed in SL landing. While females tended to display greater bone stress during walking and running, males displayed greater bone stress during jumping activities.

Conclusions: Understanding loading associated with exercise-related activity may help in sequencing exercise progression for safe return to activity. Activities involving double leg stance may be more suitable in early rehabilitation. Unilateral activities and cutting maneuvers were associated with the greatest stress and therefore may be more beneficial later in exercise progressions.