A
CASE REPORT –
abstract
Transversal
and Longitudinal Twitch Response of Biceps Brachii Boštjan
Šimunič1,2,
Dejan Križaj2,
Rado Pišot1
1University
of Primorska, Scientific Research Centre Koper, Institute of
Kinesiology Research, Slovenia
2University
of Ljubljana, Faculty of Electrical Engineering, Slovenia
Abstract.
Isometric
transversal displacement (TD) and torque responses were
simultaneously recorded during graded electrically elicited isometric
twitch contractions on the human biceps
brachii muscle. The
amplitude of electrical stimulation was increased in 5 mA steps from
a threshold up to a supramaximal response. Muscles’ belly
transversal displacement was measured by a high precision mechanical
displacement sensor using a slight pre-tension to the muscle belly.
The results were compared to simultaneously measured muscle torque on
a distal limb. The results indicate parabolic relation between the TD
and the torque twitch peak amplitudes. Significantly shorter
contraction time was found for the TD response than for the torque
response. Variation of the contraction time measured from threshold
to supramaximal stimulation was notably different for the TD response
and the torque response. This suggests that different mechanisms
affect longitudinal (torque) and transversal (TD) deformations during
contraction. Delay time was similar at submaximal and supramaximal
responses but much larger in TD at just above threshold contractions.
Half relaxation time has a similar linear trend in both responses,
however, the magnitude is much larger in the TD than in the torque
responses. Parameters extracted from the transversal displacement of
the muscle belly on a twitch could serve as an appropriate predictor
of the muscle contraction velocity and of the muscle composition.
Key
words: tensiomyography,
mechanomyography, transversal displacement, skeletal muscle, joint
torque |
