Summary

Aim of the project
The aim of the project is to improve basic knowledge of muscle ageing in relation with biomechanical and functional data, and thus ameliorate the remobilisation of elderly people after traumatic or surgical immobilisation and also orient their future physiotherapy in certain cases. The main questions asked are:
- Is it possible to use biomarkers of muscle ageing to evaluate the physiological state and regeneration capacity of the muscles of elderly people?
- Can the levels of these biomarkers be correlated with the results of a functional evaluation of motricity
- Can the effects of functional physiotherapy be predicted from the analysis of these biomarkers in sports-trained subjects?

 

Pre-operative as well as several phases of post-operative non-invasive evaluations are carried out. The measurement protocols are adapted according to muscles type assessed (vastus lateralis of the thigh, and neck muscles).
This part of the project will require the design and validation of measurement systems adaptable to an isokinetic dynamometer to quantify muscle strength. At present, the team is working on the development of a similar system for the cervical muscles. These protocols should take into account the specificity of the movements generated by the different muscle groups evaluated.
The functional evaluation will include electromyographic surface measurements (temporal and spectrum parameters, propagation speed of motor unit action potential) as well as biomechanical measurements (strength torque, pair-angular speed relation, viscosity etc).
Finally, the architecture of the vastus lateralis muscle will be studied by echography. This will allow the modifications of the pennation of muscle fibres to be highlighted as well as their length variations in function of contraction intensity of degree of stretch, also to the establishment of a link  between the architectural modifications, mechanics and muscle cell properties of these elderly patients.
Concerning the thigh, classic morphological parameters (transversal section surfaces) is also be measured by echography.
For the spine, muscle morphology is studied using MRI. The data obtained will allow the realisation of a 3D reconstruction of the cervical musculature as well as participation in the design of a predictive model of the behaviour of the muscle mechanics of the cervical spine developed at the Laboratory of Biomechanics of ENSAM (UMR CNRS 8005).

 

Analysis of muscle regeneration capacity
The classic characteristics of muscle fibre (size, type capillary density) will be determined by biopsy analyses, as will be the number of satellite cells available, identified on sections by specific markers (in collaboration with Prof Lars-Eric Thornell, University of Umeå, Sweden). This experimental phase will provide information about the history of muscle regeneration. The experimental approaches described above will be used to compare muscles and the isolated cells of these muscles from both patients and controls as well as from sports-trained subjects.