Front. Endocrinol., 2019; 10:833: , PMID: 31827461

Differences in the Cortical Structure of the Whole Fibula and Tibia Between Long-Distance Runners and Untrained Controls. Toward a Wider Conception of the Biomechanical Regulation of Cortical Bone Structure

Year: 2019

Sergio H. Lüscher , Laura M. Nocciolino Nicolás Pilot , Leonardo Pisani, Alex Ireland Jörn Rittweger , José L. Ferretti Gustavo R. Cointry and Ricardo F. Capozza
School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom

Abstract

The cortical structure of human fibula varies widely throughout the bone suggesting
a more selective adaptation to different mechanical environments with respect to the
adjacent tibia. To test this hypothesis, serial-pQCT scans of the dominant fibulae and
tibiae of 15/15 men/women chronically trained in long-distance running were compared
with those of 15/15 untrained controls. When compared to controls, the fibulae of trained
individuals had similar (distally) or lower (proximally) cortical area, similar moments of
inertia (MI) for anterior-posterior bending (xMI) and lower for lateral bending (yMI) with
a lower “shape-index” (yMI/xMI ratio) throughout, and higher resistance to buckling
distally. These group differences were more evident in men and independent of group
differences in bone mass. These results contrast with those observed in the tibia, where,
as expected, structural indicators of bone strength were greater in trained than untrained
individuals. Proximally, the larger lateral flexibility of runners’ fibulae could improve the
ability to store energy, and thereby contribute to fast-running optimization. Distally, the
greater lateral fibular flexibility could reduce bending strength. The latter appears to have
been compensated by a higher buckling strength. Assuming that these differences could
be ascribed to training effects, this suggests that usage-derived strains in some bones
may modify their relative structural resistance to different kinds of deformation in different
regions, not only regarding strength, but also concerning other physiological roles of
the skeleton.

Keywords: fibula, bone biomechanics, pQCT, running, bone mechanostat, exercise and bone
GID: 4998; Last update: 28.11.2019