Goubel F. In vivo force-velocity relation of human muscle: A modelling from sinusoidal oscillation behaviour

Abstract Isokinetic tests performed on human muscle in vivo during plantar flexion contractions lead to torque-angular velocity relationships usually fitted by Hill's equation expressed in angular terms. However, such tests can lead to discrepant results since they require maximal voluntary contractions performed in dynamic conditions. In the present study, another way to approach mechanical behaviour of a musculo-articular structure was used, i.e. sinusoidal oscillations during sub-maximal contractions. This led to the expression of (i) Bode diagrams allowing the determination of a damping coefficient (B bode ); and (ii) a viscous parameter (B sin ) using an adaptation of Hill's equation to sinusoidal oscillations. Then torque-angular velocity relationships were predicted from a model based on the interrelation between B bode and B sin and on the determination of optimal conditions of contraction. This offers the possibility of characterizing muscle dynamic properties by avoiding the use of isokinetic maximal contractions.

Muscle physiology

The Topical Team for Muscle Physiology has identified and discussed the basic parameters and functions in relation to the change of loading and activity pattern seen during simulated and actual spaceflight. A significant overlap with similar situations on Earth can be identified, with clinical application as a direct benefit. It is pointed that human skeletal muscle samples should be analyzed after long-duration spaceflight and bed rest. Resistance training has been proved to be effective in preventing muscle wasting during various simulated microgravity models carried out over 14-110 days