5.1 Study of Velocity of Muscle Contraction Using the …
375
5.1 Study of Velocity of Muscle Contraction Using
the Speckle-Counting Method
The development of muscular physiology is essentially connected with the progress in
experimental equipment: appearing of methods of irritation, holographic registration,
calorimetry, etc. Microoptical visual observations gave the possibility to single out
the main structural elements of muscle fibers. Observation of contraction of the
muscle fiber and the whole muscle is complicated as it shifts beyond the limits of
depth of field of the microscope.
The muscle tissue has a great number of diffusers, and at illumination with
coherent radiation behind it a developed speckle-field is formed, the contrast of
which is close to unit. Muscle contraction causes forward shift of all the diffusers
as well as change of their relative location. In turn, this leads to the movement of
separate spots–speckles and their decorrelation [136]. Also, the velocity of movement of the scattering object can be calculated after determining the time of speckle
correlation. The velocity of muscle shortening is its main independent characteristic. Besides, it gives the possibility to calculate mechanical power of the muscle
and to investigate the energy escape velocity [137]. We used the speckle-counting
method for study of the dependence of velocity of muscle shortening during isotonic
contraction [39, 138].
The device is offered for measurement of velocity of muscle tissue contraction,
which is an important physiological parameter, which gives the possibility to ascertain power of muscle contraction and energy escape velocity. The device is based
on counting the number of intensity fluctuations of dynamic speckle-field formed
by diffusely moving scattering tissue. Also, the device can be used for investigation
of biomechanical parameters of muscles, for determination of velocities of movement of diffusive objects with different types of scattering surfaces. The range of
the measured velocities is from 1 to 100 cm/s. The spatial resolution is 10 mm
2 .
It is possible to measure time distribution of velocities in real time with temporal
resolution of 10 ms.
This device has the following advantages in comparison with myograph traditionally applied for studying muscle contraction:
• The speckle-counting method is contactless and gives the possibility to study a
muscle without isolating it.
• Horizontal position of the muscle gives the possibility to put it into physiological solution and stimulate it electrolytically without inserting electrodes, without
cutting the preparation.
• It is possible to investigate different small areas of muscles.
• Zero lag,
• namely the contraction velocity of a certain area, but not changes of the total
length of the muscle, is measured. The transition from velocity to dependence of
the length on time, which is measured in direct myography, is connected with integration and reduction of test errors, while the reverse operation—differentiation
greatly increases measurement errors.
375
5.1 Study of Velocity of Muscle Contraction Using
the Speckle-Counting Method
The development of muscular physiology is essentially connected with the progress in
experimental equipment: appearing of methods of irritation, holographic registration,
calorimetry, etc. Microoptical visual observations gave the possibility to single out
the main structural elements of muscle fibers. Observation of contraction of the
muscle fiber and the whole muscle is complicated as it shifts beyond the limits of
depth of field of the microscope.
The muscle tissue has a great number of diffusers, and at illumination with
coherent radiation behind it a developed speckle-field is formed, the contrast of
which is close to unit. Muscle contraction causes forward shift of all the diffusers
as well as change of their relative location. In turn, this leads to the movement of
separate spots–speckles and their decorrelation [136]. Also, the velocity of movement of the scattering object can be calculated after determining the time of speckle
correlation. The velocity of muscle shortening is its main independent characteristic. Besides, it gives the possibility to calculate mechanical power of the muscle
and to investigate the energy escape velocity [137]. We used the speckle-counting
method for study of the dependence of velocity of muscle shortening during isotonic
contraction [39, 138].
The device is offered for measurement of velocity of muscle tissue contraction,
which is an important physiological parameter, which gives the possibility to ascertain power of muscle contraction and energy escape velocity. The device is based
on counting the number of intensity fluctuations of dynamic speckle-field formed
by diffusely moving scattering tissue. Also, the device can be used for investigation
of biomechanical parameters of muscles, for determination of velocities of movement of diffusive objects with different types of scattering surfaces. The range of
the measured velocities is from 1 to 100 cm/s. The spatial resolution is 10 mm
2 .
It is possible to measure time distribution of velocities in real time with temporal
resolution of 10 ms.
This device has the following advantages in comparison with myograph traditionally applied for studying muscle contraction:
• The speckle-counting method is contactless and gives the possibility to study a
muscle without isolating it.
• Horizontal position of the muscle gives the possibility to put it into physiological solution and stimulate it electrolytically without inserting electrodes, without
cutting the preparation.
• It is possible to investigate different small areas of muscles.
• Zero lag,
• namely the contraction velocity of a certain area, but not changes of the total
length of the muscle, is measured. The transition from velocity to dependence of
the length on time, which is measured in direct myography, is connected with integration and reduction of test errors, while the reverse operation—differentiation
greatly increases measurement errors.