Here is the answers to the post.

Thanks to all.

-----------------------------------------------------------------------

Original message:

Dear coleagues.

I've seen in many articles expressions like average rectified value, mean

power frequency, but I've not found math expressions for this algorithms.

There is information available in this topic?

Thanks in advace.

PD: I'll post a summary if i receive replies

----------------------------------------------------------------------------

Jaime,

These articles should adress your questions. These equations are also in

the Basmajian & DeLuca book.

a.. Basmajian, J.V. and C.J. DeLuca. Muscles alive: Their functions

revealed by electromyography. 5th rev. ed., Baltimore, MD: Williams &

Wilkins, 1985, pp. 60-64.

b.. Bilodeau, M., Arsenault, A., Gravel, D. and Bourbonnais, D.: EMG power

spectrum of elbow extensors: a reliability study. Electromyogr. Clin.

Neurophysiol., 34: 149-158, 1994.

c.. Heinonen, A., Sievänen, Viitasalo, J., Pasanen, P., Oja, P. and Vuori,

I.: Reproducibility of computer measurement of maximal isometric strength

and electromyography in sedentary middle-aged women. Eur. J. Appl. Physiol.,

68: 310-314, 1994.

Best Wishes,

-d.g.

David A. Gabriel, Ph.D.

Assistant Professor

Biomechanics

Physical Education Department

Brock University

St. Catharines, Ontario, CANADA

L2S 3A1

Phone: 905-688-5550 ext.4362

Fax: 905-688-5550 ext. 4104

e-mail: dgabriel@arnie.pec.brocku.ca

----------------------------------------------------------------------------

--

Dear Jaime:

Rectification means to take the absolute value of the EMG signal. A

Fourier transformation is required to look at the EMG power spectrum. Any

basic textbook on signal processing (or talk to someone in electrical

engineering) should have the information on how these quantities are

calculated.

Sincerely,

John

At 10:48 AM 6/7/00 -0400, you wrote:

>Dear coleagues.

>

>I've seen in many articles expressions like average rectified value, mean

>power frequency, but I've not found math expressions for this algorithms.

>

>There is information available in this topic?

>

>Thanks in advace.

>

>PD: I'll post a summary if i receive replies.

>

>Jaime B. Zamora S.

>Laboratorio DAMAC.

>Departamento de Ingeniería Mecánica.

>Pontificia Universidad Católica de Chile.

>http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

>

>Attachment Converted: "E:\Attach\Jaime B. Zamora S..vcf"

>

John M. Barden, M.Sc. & Rehabilitation Technology Dept.

Ph.D. Candidate Glenrose Rehabilitation Hospital

Surgical-Medical Research Institute 10230-111 Ave.

Department of Surgery Edmonton, Alberta

Faculty of Medicine & Dentistry T5G 0B7

University of Alberta Work phone: (780)471-2262 ext. 2688

Edmonton, Alberta Fax: (780)471-7972

Canada T6G 2E2 e-mail: jbarden@ualberta.ca &

rara@dlcwest.com

---------------------------------------------------------------------------

Dear Jaime:

Rectification means to take the absolute value of the EMG signal. A

Fourier transformation is required to look at the EMG power spectrum. Any

basic textbook on signal processing (or talk to someone in electrical

engineering) should have the information on how these quantities are

calculated.

Sincerely,

John

At 10:48 AM 6/7/00 -0400, you wrote:

>Dear coleagues.

>

>I've seen in many articles expressions like average rectified value, mean

>power frequency, but I've not found math expressions for this algorithms.

>

>There is information available in this topic?

>

>Thanks in advace.

>

>PD: I'll post a summary if i receive replies.

>

>Jaime B. Zamora S.

>Laboratorio DAMAC.

>Departamento de Ingeniería Mecánica.

>Pontificia Universidad Católica de Chile.

>http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

>

>Attachment Converted: "E:\Attach\Jaime B. Zamora S..vcf"

>

John M. Barden, M.Sc. & Rehabilitation Technology Dept.

Ph.D. Candidate Glenrose Rehabilitation Hospital

Surgical-Medical Research Institute 10230-111 Ave.

Department of Surgery Edmonton, Alberta

Faculty of Medicine & Dentistry T5G 0B7

University of Alberta Work phone: (780)471-2262 ext. 2688

Edmonton, Alberta Fax: (780)471-7972

Canada T6G 2E2 e-mail: jbarden@ualberta.ca &

rara@dlcwest.com

----------------------------------------------------------------------------

---

Dear Jaime, you are right, these formulae are usally assumed

familiar. A good text is in the (very recent) book : SENIAM

recommendations for surface electromyography, Ch 3

published by Roessingh RRD ISBN 90-75452-15-2

see also a webpage at

http://www.delsys.com/emg_articles/EMG.shtml#processing

But this page does not give formulae either. so I give them:

It is a bit awkward without the right symbols.

average rectified:

-filter(abs(raw emg))

filter can be moving average, Butterworth etc. low pass

for dynamical movements I would recommend a cut-off frequency of 20

Hz

mean power frequency

- make power spectrum S(f) by FFT over some epoch T

- MPF = int( f*S(f))/int(S(f) with int from 0 - inf

- Median freq = fm

, so that int from 0-fm (S(f)) = 0.5* int from 0-inf (S(f))

if you really want formulae on frequency parameters (an awfull lot in

fact) , consult my paper in IEEE trans BME 38:1077-1088 (1991).

Good luck

At Hof

Department of Medical Physiology &

Laboratory of Human Movement Analysis AZG

University of Groningen

A. Deusinglaan 1

room 769

PO Box 196

NL-9700 AD GRONINGEN

THE NETHERLANDS

Tel: (31) 50 3632645

Fax: (31) 50 3632751

e-mail: a.l.hof@med.rug.nl

----------------------------------------------------------------------------

--

Regards,

http://www.ing.puc.cl/icmtesis/magister/jzamora/index_esp.html

Jaime B. Zamora S.

Laboratorio DAMAC.

Departamento de Ingeniería Mecánica y Metalúrgica.

Pontificia Universidad Católica de Chile.

BEGIN:VCARD

VERSION:2.1

N:Zamora S.;Jaime;B.

FN:Jaime B. Zamora S.

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TITLE:M. Sc. student

TEL;WORK;VOICE:56-2-6864409

TEL;CELL;VOICE:56-09-4296556

TEL;WORK;FAX:56-2-6865828

ADR;WORK:;DAMAC Lab.;Vicuña Mackenna 4860;Santiago;Santiago;;CHILE

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X-WAB-GENDER:2

URL:http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

EMAIL;PREF;INTERNET:jzamoras@ing.puc.cl

EMAIL;INTERNET:jzamoras@puc.cl

REV:20000709T224042Z

END:VCARD

Thanks to all.

-----------------------------------------------------------------------

Original message:

Dear coleagues.

I've seen in many articles expressions like average rectified value, mean

power frequency, but I've not found math expressions for this algorithms.

There is information available in this topic?

Thanks in advace.

PD: I'll post a summary if i receive replies

----------------------------------------------------------------------------

Jaime,

These articles should adress your questions. These equations are also in

the Basmajian & DeLuca book.

a.. Basmajian, J.V. and C.J. DeLuca. Muscles alive: Their functions

revealed by electromyography. 5th rev. ed., Baltimore, MD: Williams &

Wilkins, 1985, pp. 60-64.

b.. Bilodeau, M., Arsenault, A., Gravel, D. and Bourbonnais, D.: EMG power

spectrum of elbow extensors: a reliability study. Electromyogr. Clin.

Neurophysiol., 34: 149-158, 1994.

c.. Heinonen, A., Sievänen, Viitasalo, J., Pasanen, P., Oja, P. and Vuori,

I.: Reproducibility of computer measurement of maximal isometric strength

and electromyography in sedentary middle-aged women. Eur. J. Appl. Physiol.,

68: 310-314, 1994.

Best Wishes,

-d.g.

David A. Gabriel, Ph.D.

Assistant Professor

Biomechanics

Physical Education Department

Brock University

St. Catharines, Ontario, CANADA

L2S 3A1

Phone: 905-688-5550 ext.4362

Fax: 905-688-5550 ext. 4104

e-mail: dgabriel@arnie.pec.brocku.ca

----------------------------------------------------------------------------

--

Dear Jaime:

Rectification means to take the absolute value of the EMG signal. A

Fourier transformation is required to look at the EMG power spectrum. Any

basic textbook on signal processing (or talk to someone in electrical

engineering) should have the information on how these quantities are

calculated.

Sincerely,

John

At 10:48 AM 6/7/00 -0400, you wrote:

>Dear coleagues.

>

>I've seen in many articles expressions like average rectified value, mean

>power frequency, but I've not found math expressions for this algorithms.

>

>There is information available in this topic?

>

>Thanks in advace.

>

>PD: I'll post a summary if i receive replies.

>

>Jaime B. Zamora S.

>Laboratorio DAMAC.

>Departamento de Ingeniería Mecánica.

>Pontificia Universidad Católica de Chile.

>http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

>

>Attachment Converted: "E:\Attach\Jaime B. Zamora S..vcf"

>

John M. Barden, M.Sc. & Rehabilitation Technology Dept.

Ph.D. Candidate Glenrose Rehabilitation Hospital

Surgical-Medical Research Institute 10230-111 Ave.

Department of Surgery Edmonton, Alberta

Faculty of Medicine & Dentistry T5G 0B7

University of Alberta Work phone: (780)471-2262 ext. 2688

Edmonton, Alberta Fax: (780)471-7972

Canada T6G 2E2 e-mail: jbarden@ualberta.ca &

rara@dlcwest.com

---------------------------------------------------------------------------

Dear Jaime:

Rectification means to take the absolute value of the EMG signal. A

Fourier transformation is required to look at the EMG power spectrum. Any

basic textbook on signal processing (or talk to someone in electrical

engineering) should have the information on how these quantities are

calculated.

Sincerely,

John

At 10:48 AM 6/7/00 -0400, you wrote:

>Dear coleagues.

>

>I've seen in many articles expressions like average rectified value, mean

>power frequency, but I've not found math expressions for this algorithms.

>

>There is information available in this topic?

>

>Thanks in advace.

>

>PD: I'll post a summary if i receive replies.

>

>Jaime B. Zamora S.

>Laboratorio DAMAC.

>Departamento de Ingeniería Mecánica.

>Pontificia Universidad Católica de Chile.

>http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

>

>Attachment Converted: "E:\Attach\Jaime B. Zamora S..vcf"

>

John M. Barden, M.Sc. & Rehabilitation Technology Dept.

Ph.D. Candidate Glenrose Rehabilitation Hospital

Surgical-Medical Research Institute 10230-111 Ave.

Department of Surgery Edmonton, Alberta

Faculty of Medicine & Dentistry T5G 0B7

University of Alberta Work phone: (780)471-2262 ext. 2688

Edmonton, Alberta Fax: (780)471-7972

Canada T6G 2E2 e-mail: jbarden@ualberta.ca &

rara@dlcwest.com

----------------------------------------------------------------------------

---

Dear Jaime, you are right, these formulae are usally assumed

familiar. A good text is in the (very recent) book : SENIAM

recommendations for surface electromyography, Ch 3

published by Roessingh RRD ISBN 90-75452-15-2

see also a webpage at

http://www.delsys.com/emg_articles/EMG.shtml#processing

But this page does not give formulae either. so I give them:

It is a bit awkward without the right symbols.

average rectified:

-filter(abs(raw emg))

filter can be moving average, Butterworth etc. low pass

for dynamical movements I would recommend a cut-off frequency of 20

Hz

mean power frequency

- make power spectrum S(f) by FFT over some epoch T

- MPF = int( f*S(f))/int(S(f) with int from 0 - inf

- Median freq = fm

, so that int from 0-fm (S(f)) = 0.5* int from 0-inf (S(f))

if you really want formulae on frequency parameters (an awfull lot in

fact) , consult my paper in IEEE trans BME 38:1077-1088 (1991).

Good luck

At Hof

Department of Medical Physiology &

Laboratory of Human Movement Analysis AZG

University of Groningen

A. Deusinglaan 1

room 769

PO Box 196

NL-9700 AD GRONINGEN

THE NETHERLANDS

Tel: (31) 50 3632645

Fax: (31) 50 3632751

e-mail: a.l.hof@med.rug.nl

----------------------------------------------------------------------------

--

Regards,

http://www.ing.puc.cl/icmtesis/magister/jzamora/index_esp.html

Jaime B. Zamora S.

Laboratorio DAMAC.

Departamento de Ingeniería Mecánica y Metalúrgica.

Pontificia Universidad Católica de Chile.

BEGIN:VCARD

VERSION:2.1

N:Zamora S.;Jaime;B.

FN:Jaime B. Zamora S.

ORG:PUC;DAMAC Lab.

TITLE:M. Sc. student

TEL;WORK;VOICE:56-2-6864409

TEL;CELL;VOICE:56-09-4296556

TEL;WORK;FAX:56-2-6865828

ADR;WORK:;DAMAC Lab.;Vicuña Mackenna 4860;Santiago;Santiago;;CHILE

LABEL;WORK;ENCODING=QUOTED-PRINTABLEAMAC Lab.=0D=0AVicu=F1a Mackenna 4860=0D=0ASantiago, Santiago=0D=0ACHILE

ADR;HOME:;;;;;;CHILE

LABEL;HOME:CHILE

X-WAB-GENDER:2

URL:http://www.ing.puc.cl/icmtesis/magister/jzamora/jzamora.htm

EMAIL;PREF;INTERNET:jzamoras@ing.puc.cl

EMAIL;INTERNET:jzamoras@puc.cl

REV:20000709T224042Z

END:VCARD