594
Soundmyogram Analysis during Sustained Maximal Voluntary Contraction in Sprinters and Long Distance Runners C. Orizio, A. Veicsteinas
Abstract C. Orizio and A. Veicsteinas, Soundmyogram Analysis during Sustained Maximal Voluntary Contraction in Sprinters and Long Distance Runners. mt i Sports Med, Vol 13, No 8, pp 594—599, 1992.
Accepted after revision: August 12, 1992
The aim of this study was to describe the influence of the different fiber type composition of the vastus Tateralis muscle on the soundmyogram (SMG) time and frequency domain characteristics. The SMG was recorded from the vastus lateralis belly during exhausting maximal voluntary contraction (MVC) of the leg extensors in 7 sprinters (SPR) and 7 long distance runners (LDR). Seven sedentary males (SED) were investigated in the same experimental conditions. In the SPR the effort time was shorter and the MVC was greater while the SMG root mean square and the SMG frequency content, at the onset of contraction, were higher than in the SED and LDR, respectively. Throughout exertion the SMG RMS showed clear reduction for SPR and SED only and the SMG power spectra presented a compression towards the lower frequencies. The reported phenomena
were less pronounced in the LDR than in SPR and SED.
stimulation of the isolated and of the in vivo muscle. Besides these aspects of muscle mechanics, information about the motor units (MUs) activity were suggested to be reflected in the SMG properties from experiments carried out during voluntary contraction. Gordon & Holbourn (16) already demonstrated that the SMG can be considered as the "mechanical counterpart" of the motor unit electrical activity recording a sound spike per each MU compound action potential. More recently it has been reported that the MUs recruitment level and their mean firing rate influence the amplitude and the power spectrum of the signal (29,31,34,38). Moreover the changes of the MUs activity due to fatigue strongly influence the SMG amplitude (1,30, 38).
It is well known that vastus lateralis muscle of elite athletes differs widely in fiber and MUs type composition in relation to their sport practice (24,33,35).
As the muscular sound is generated by the lateral expansion of the muscle fibers of the recruited motor units (10, 16), this work was aimed to describe the characteristics of the SMG, recorded from vastus lateralis muscle, in
sprinters and long distance runners during an exhausting isometric maximal voluntary contraction of the knee extensors.
Material and Methods
These results can be explained when the differences in the %
of fast twitch fibers area, belonging to stronger and more fatiguing F motor units, in the three groups of subjects are considered and suggest that SMG characteristics reflect the muscle fiber typing.
Key words Muscle sound, fiber typing, maximal voluntary contraction, muscle fatigue
The study was carried out on two groups of athletes. Seven sprinters (SPR) and 7 long distance runners (LDR). Seven sedentary (SED) subjects were studied as control group. The age ranged from 18 to 22, from 25 to 30, and from 20 to 24 years for SPR, LDR and SED, respectively. The time of performance was less than 11 s over the lOOm dash (SPR) and less than 2 hours and 30minutes over the marathon distance (LDR). The sedentary subjects performed recreational physical activity twice a week. Subcutaneous fat over the vastus lateralis
muscle, measured by a skinfold caliper, was 1 .2mm (mean
SE), 2.5 .6mm and 4.5 1.5mm for LDR, SPR and SED, Introduction The analysis of the soundmyogram (SMG) detected at the muscle surface indicates that information of different nature are contained in the signal. Data on muscular stiffness (3,14) and the characteristics of the elastic tissue in paral-
lel to the contractile muscle component (9) can be retrieved from the analysis of the SMG recorded during the electrical mt. J. Sports Med. 13 (1992) 594—599 Georg Thieme Verlag Stuttgart New York
respectively (when allowance is made for 2 mm skin thickness). After the explanation of the experimental procedure the subject
gave his informed consent, as required by the local Research Ethics Committee, and he was asked to perform a maximal isometric contraction of his knee extensors. The joint segments were kept at 9O. The ergometer used was designed in order to allow the contraction of the knee extensors while the subject was in a sitting position, as previously suggested (7). The output
force was recorded by a load cell (Interface S-M 2000, linear from 0 to 2000 N) strapped perpendicularly to the ankle. The applied force was displayed on a monitor for the visual feedback. The SMG was detected by a piezoelectric crystal contact sensor (Hewlett-Packard 21050 A) fixed orthogonally to the
Downloaded by: National University of Singapore. Copyrighted material.
Istituto di Fisiologia Umana, Dipartimento di Scienze Biomediche e Biotecnologie, Universitá di Brescia, Brescia, Italy
mt. J Sports Med. 13 (1992) 595
Soundmyogram Analysis during Sustained Maximal Voluntary Contraction
passband (± 3 dB) was from few Hz (between 5 and 10, depending on the specific contact sensor investigated) to 500 Hz. After the analog to digital conversion (Cambridge Electronic Design
Linear regression was used for the interpolation of the best fit functions for the time course of MF and HF%. As previously described (30) the parameters of the functions were obtained using mean square minimization and a grid search method, as e will be indicated the average residual between the experimental values and the best fit functions calcu-
lated. The results are given as mean±SE. When required the Student's t-test was performed. The differences were considered significant for p
Soundmyogram Analysis during Sustained Maximal Voluntary Contraction in Sprinters and Long Distance Runners C. Orizio, A. Veicsteinas
Abstract C. Orizio and A. Veicsteinas, Soundmyogram Analysis during Sustained Maximal Voluntary Contraction in Sprinters and Long Distance Runners. mt i Sports Med, Vol 13, No 8, pp 594—599, 1992.
Accepted after revision: August 12, 1992
The aim of this study was to describe the influence of the different fiber type composition of the vastus Tateralis muscle on the soundmyogram (SMG) time and frequency domain characteristics. The SMG was recorded from the vastus lateralis belly during exhausting maximal voluntary contraction (MVC) of the leg extensors in 7 sprinters (SPR) and 7 long distance runners (LDR). Seven sedentary males (SED) were investigated in the same experimental conditions. In the SPR the effort time was shorter and the MVC was greater while the SMG root mean square and the SMG frequency content, at the onset of contraction, were higher than in the SED and LDR, respectively. Throughout exertion the SMG RMS showed clear reduction for SPR and SED only and the SMG power spectra presented a compression towards the lower frequencies. The reported phenomena
were less pronounced in the LDR than in SPR and SED.
stimulation of the isolated and of the in vivo muscle. Besides these aspects of muscle mechanics, information about the motor units (MUs) activity were suggested to be reflected in the SMG properties from experiments carried out during voluntary contraction. Gordon & Holbourn (16) already demonstrated that the SMG can be considered as the "mechanical counterpart" of the motor unit electrical activity recording a sound spike per each MU compound action potential. More recently it has been reported that the MUs recruitment level and their mean firing rate influence the amplitude and the power spectrum of the signal (29,31,34,38). Moreover the changes of the MUs activity due to fatigue strongly influence the SMG amplitude (1,30, 38).
It is well known that vastus lateralis muscle of elite athletes differs widely in fiber and MUs type composition in relation to their sport practice (24,33,35).
As the muscular sound is generated by the lateral expansion of the muscle fibers of the recruited motor units (10, 16), this work was aimed to describe the characteristics of the SMG, recorded from vastus lateralis muscle, in
sprinters and long distance runners during an exhausting isometric maximal voluntary contraction of the knee extensors.
Material and Methods
These results can be explained when the differences in the %
of fast twitch fibers area, belonging to stronger and more fatiguing F motor units, in the three groups of subjects are considered and suggest that SMG characteristics reflect the muscle fiber typing.
Key words Muscle sound, fiber typing, maximal voluntary contraction, muscle fatigue
The study was carried out on two groups of athletes. Seven sprinters (SPR) and 7 long distance runners (LDR). Seven sedentary (SED) subjects were studied as control group. The age ranged from 18 to 22, from 25 to 30, and from 20 to 24 years for SPR, LDR and SED, respectively. The time of performance was less than 11 s over the lOOm dash (SPR) and less than 2 hours and 30minutes over the marathon distance (LDR). The sedentary subjects performed recreational physical activity twice a week. Subcutaneous fat over the vastus lateralis
muscle, measured by a skinfold caliper, was 1 .2mm (mean
SE), 2.5 .6mm and 4.5 1.5mm for LDR, SPR and SED, Introduction The analysis of the soundmyogram (SMG) detected at the muscle surface indicates that information of different nature are contained in the signal. Data on muscular stiffness (3,14) and the characteristics of the elastic tissue in paral-
lel to the contractile muscle component (9) can be retrieved from the analysis of the SMG recorded during the electrical mt. J. Sports Med. 13 (1992) 594—599 Georg Thieme Verlag Stuttgart New York
respectively (when allowance is made for 2 mm skin thickness). After the explanation of the experimental procedure the subject
gave his informed consent, as required by the local Research Ethics Committee, and he was asked to perform a maximal isometric contraction of his knee extensors. The joint segments were kept at 9O. The ergometer used was designed in order to allow the contraction of the knee extensors while the subject was in a sitting position, as previously suggested (7). The output
force was recorded by a load cell (Interface S-M 2000, linear from 0 to 2000 N) strapped perpendicularly to the ankle. The applied force was displayed on a monitor for the visual feedback. The SMG was detected by a piezoelectric crystal contact sensor (Hewlett-Packard 21050 A) fixed orthogonally to the
Downloaded by: National University of Singapore. Copyrighted material.
Istituto di Fisiologia Umana, Dipartimento di Scienze Biomediche e Biotecnologie, Universitá di Brescia, Brescia, Italy
mt. J Sports Med. 13 (1992) 595
Soundmyogram Analysis during Sustained Maximal Voluntary Contraction
passband (± 3 dB) was from few Hz (between 5 and 10, depending on the specific contact sensor investigated) to 500 Hz. After the analog to digital conversion (Cambridge Electronic Design
Linear regression was used for the interpolation of the best fit functions for the time course of MF and HF%. As previously described (30) the parameters of the functions were obtained using mean square minimization and a grid search method, as e will be indicated the average residual between the experimental values and the best fit functions calcu-
lated. The results are given as mean±SE. When required the Student's t-test was performed. The differences were considered significant for p
