Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo

Niels Rahe-Meyer¹ , Matthias Pawlak²^,3 , Christian Weilbach⁴ , Wilhelm Alexander Osthaus¹ , Hainer Ruhschulte¹ , Cristina Solomon¹ , Siegfried Piepenbrock¹ and Michael Winterhalter¹

¹Department of Anaesthesiology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625, Hannover, Germany

²Department of Physiology, Biochemistry and Hygiene, University School of Physical Education, ul. Krolowej Jadwigi 27/39, Poznañ, Poland

³Institute of Physiology, University of Wuerzburg, Roentgenring 9, D-97070, Wuerzburg, Germany

⁴Department of Anaesthesiology, St. Josefs Stift Cloppenburg, Krankenhausstr. 13, D-49661, Cloppenburg, Germany

author email corresponding author email

BioMedical Engineering OnLine 2008, 7:20doi:10.1186/1475-925X-7-20


Published:	10 July 2008

Abstract

Background

The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible.

Methods

The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions.

Results

The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant – uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions.

Conclusion

With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed.