title: On the relationship between tibia torsional deformation and regional muscle contractions in habitual human exercises in vivo.
abstract: The mechanical relationship between bone and muscle has been long recognized. However, it still remains unclear how muscles exactly load on bone. In this study, utilizing an optical segment tracking technique, the in vivo tibia loading regimes in terms of tibia segment deformation in humans were investigated during walking, forefoot and rear foot stair ascent and running and isometric plantar flexion. Results suggested that the proximal tibia primarily bends to the posterior aspect and twists to the external aspect with respect to the distal tibia. During walking, peak posterior bending and peak torsion occurred in the first half (22%) and second half (76%) of the stance phase, respectively. During stair ascent, two noticeable peaks of torsion were found with forefoot strike (38% and 82% of stance phase), but only one peak of torsion was found with rear foot strike (78% of stance phase). The torsional deformation angle during both stair ascent and running was larger with forefoot strike than rear foot strike. During isometric plantar flexion, the tibia deformation regimes were characterized more by torsion (maximum 1.35°) than bending (maximum 0.52°). To conclude, bending and torsion predominated the tibia loading regimes during the investigated activities. Tibia torsional deformation is closely related to calf muscle contractions, which further confirm the notion of the muscle-bone mechanical link and shift the focus from loading magnitude to loading regimes in bone mechanobiology. It thus is speculated that torsion is another, yet under-rated factor, besides the compression and tension, to drive long bone mechano-adaptation.
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environment Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi׳an, China; Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany; Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Germany. Electronic address: yangpf@nwpu.edu.cn.
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Yang
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kriechbaumer
authors.affiliation: Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Germany.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Albracht
authors.affiliation: Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Sanno
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.
authors.forename: Bergita
authors.initials: B
authors.lastname: Ganse
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Cologne, Germany.
authors.forename: Timmo
authors.initials: T
authors.lastname: Koy
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environment Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi׳an, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Shang
authors.affiliation: Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Germany.
authors.forename: Gert-Peter
authors.initials: GP
authors.lastname: Brüggemann
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Cologne, Germany.
authors.forename: Lars Peter
authors.initials: LP
authors.lastname: Müller
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Rittweger
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013977:Tibia / Q000502:physiology*; D016138:Walking / Q000502:physiology*
keywords: Bone–muscle interactions; In vivo; Optical approach; Tibia deformation; Torsion