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Pelvis stabilizing muscles activity and forces In hip flexion resistance training AnyBody modeling

Publication

Introduction

One of the most common scheme observed in low back pain and posture defects is hip flexors shortening and hypertension together with hip extensors elongation. The main reason for using hip flexion resistance training in those conditions is to cause a hypertrophy (muscle growth) of hip flexors and the reduction in their default activity. The idea is based on typical morphological and physiological adaptation mechanisms that describe how a muscle responds to resistance training.

 
Fig. 1. Training device used in the study equipped with strain gauges placed under the platforms for the forefoot and backfoot and in the bindings for the back of the foot.

Method

The exercise was recorded with a BTS Smart motion capture system. Equipment used in the exercise was a free weight machine constructed according to the patent P.435615. Strain gauges were placed under the feet platforms (separately for the front foot and the back foot) and in the bindings (placed on the back of the feet). The inverse dynamics study was conducted with the use of human motion capture driven model in AnyBody Modeling System (AnyBody Technology A/S, Denmark) with the measured forces applied as boundary conditions.

Fig. 2a, 2b Course of activity (2a) and forces (2b) of main hip flexors and extensors of the right side of the body during the training cycle of resistance hip flexion.

Results

The study provides information on crucial pelvis stabilizing muscles activity and forces. It shows that all targeted muscles were highly active during the training, even though the training was performed with the weight of the device only and no additional weight applied  (about 100 N of applied force). What’s more, the muscle activity of hip flexors is disproportionally high in relation to generated force what proves a potential for hypertrophy.

Financing

This research was partially funded by polish Ministry of Education and Science as part of the Excellence Initiative – Research University program. Funding was awarded as a grant in an internal pro-quality competition for funding ground-breaking research.

This study results were presented at the International Society of Biomechanics Congress 2023 in Fukuoka, Japan (XXIX ISB Congress, links below).

References

[1] Geisser ME et al. J. Pain 6:711-26, 2005.
[2] Hrysomallis C et al. J. Strength Cond. Res 15:385-90, 2001.
[3] Joanisse S et al. F1000Res 24, 2020.
[4] Jones DA et al. Q. J. Exp. Physiol 74:233-56, 1989.
[5] Lim C et al. Med Sci Sports Exerc 54:1546-59, 2022.