Assessment of Skeletal Muscle Contractile Properties by Radial Displacement: The Case for Tensiomyography

Abstract

Skeletal muscle operates as a near-constant volume system; as such muscle shortening during contraction is transversely linked to radial deformation. Therefore, to assess contractile properties of skeletal muscle, radial displacement can be evoked and measured. Mechanomyography measures muscle radial displacement and during the last 20 years, tensiomyography has become the most commonly used and widely reported technique among the various methodologies of mechanomyography. Tensiomyography has been demonstrated to reliably measure peak radial displacement during evoked muscle twitch, as well as muscle twitch speed. A number of parameters can be extracted from the tensiomyography displacement/time curve and the most commonly used and reliable appear to be peak radial displacement and contraction time. The latter has been described as a valid non-invasive means of characterising skeletal muscle, based on fibre-type composition. Over recent years, applications of tensiomyography measurement within sport and exercise have appeared, with applications relating to injury, recovery and performance. Within the present review, we evaluate the perceived strengths and weaknesses of tensiomyography with regard to its efficacy within applied sports medicine settings. We also highlight future tensiomyography areas that require further investigation. Therefore, the purpose of this review is to critically examine the existing evidence surrounding tensiomyography as a tool within the field of sports medicine.

Fig. 1

Typical incremental progression of displacement curves. The increase in curve magnitude is induced by an increase in stimulation amplitude (typically up to 60–100 mA). Peak displacement (Dm) is identified by a plateau in displacement curves, despite increased stimulation amplitude. Peak radial displacement signifies the absolute spatial transverse deformation of the muscle

Fig. 2

Parameters extracted from a typical displacement curve; displacement (Dm), contraction time (Tc), delay time (Td), contraction velocity (Vc) [Vc = (90%Dm − 10%Dm)/Tc], sustain time (Ts) and half-relaxation time (Tr)