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Wolf C.1, Sanno M.1,2, Goldmann J.-P.1,2
1Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany, 2German Research Centre of Elite Sport, German Sport University Cologne, Cologne, Germany
Background: Nowadays the foot is a largely neglected part of the body during athletic training. This is surprising in that the toes and their basic joints represent the last link of the energy transfer between the human body and the subsoil. It is now assumed that the medial longitudinal arch (MLA) is also supported by the intrinsic plantar foot muscles. Jumping creates higher forces and torsional moments than walking and running, whether this also has an influence on the stability of the MLA, has not been investigated so far. Foot deformation could be related to energy absorption or energy release. New findings on the deformation of the foot during different movements, such as running and jumping, could be interesting to draw conclusions about an optimal deformation. The intrinsic foot muscles are more innervated with increasing load and the arch of the foot gets more stabilised.
Purpose: 1. Description of the longitudinal arch deformation while running and jumping.
2. To study the possibility to manipulate the deformation with heavy resistance strength training of toe-plantarflexor muscles.
2. To study the possibility to manipulate the deformation with heavy resistance strength training of toe-plantarflexor muscles.
Methods: 28 male sport students with untrained toe-plantarflexor muscles were randomly separated into two groups: the experimental group (EG, n = 15; 24 ± 4 years; 77 ± 9 kg; 185 ± 7 cm) and the control group (CG, n = 13; 26 ± 2 years; 77 ± 5 kg; 181 ± 6 cm). Participants of the EG executed a seven-week long isometric strength training (4/week, 4 x 5 repetitions, 3-3 s contraction-relaxation, 90 % maximal voluntary isometric contraction (MVIC), break 3 min). Longitudinal arch deformation was measured by using a 3D-movement analysis PRAE and POST intervention while running, long and high jumping. Three markers were positioned onto the foot (Os calcaneus, Tuberositas Os naviculare, Caput Os metatarsale I) to analyse the angular change of the MLA. The analysis of variance (ANOVA) for repeated measures was used to identify significant effects between the measurements before and after training (Bonferroni post-hoc test) (MatLab 8.5.0 and SPSS 19).
Results: Further studies figured out that metatarsophalangeal joint plantar flexion moments significantly increased by 6070% in EG. During jumping, the deformation was significantly larger compared to running (Range of Motion: running 19,2° ± 3,5° to Counter Movement Jump (CMJ) 24,2° ± 5,2° and to Standing Long Jump (SLJ) 25,1° ± 5,4°, each p = 0,000; re-erection: running 10,8° ± 3,0°; to CMJ 14,9° ± 3,5°, to SLJ 15,3° ± 3,7°, each p = 0,000); strength training did not influence arch deformation.
Conclusion(s): The large deformation while re-erection was a result of more energy-storing and -release in muscle-tendon-unit and passive structures (ligaments, fascia, etc.) of the foot while jumping. POST intervention higher torsional moments were generated; this should have led to a larger deformation, which was probably prevented by increased muscle power.
Implications: If increased muscle power led to a stiffer foot, the intrinsic muscles could discharge passive structures while flattening. This could be interesting for patients with Plantar Fasciitis or flattening MLA.
Funding acknowledgements: None
Topic: Sport & sports injuries
Ethics approval: The ethics committee of the German Sport University Cologne approved this study.
All authors, affiliations and abstracts have been published as submitted.
