Neurourology and Urodynamics 26:404 (2007)

EDITORIAL COMMENT

Re: Morin M, Dumoulin C, Gravel D, Bourbonnais D,Lemieux MC. 2007. Reliability of Speed of Contraction

and Endurance Dynamometric Measurements of the PelvicFloor Musculature in Stress Incontinent Parous Women.

Neurourol Urodynam 26:397–403

This study assessed the test-retest reliability of twodifferent aspects of pelvic floor muscle voluntary function;the speed of the contraction and the endurance. Establishingthe reliability of a measurement is mandatory as it is theprerequisite to judge whether a method can be used as aresearch tool to measure real, and not erroneous, findings. Theauthors of this study have used sound scientific andstatistical methodology to test the stability of dynamometricspeculum measuring pelvic floor muscle endurance and speedin stress urinary incontinent women. They found that the test-retest reliability was good (F> 0.75) and conclude correctlythat these parameters can be used in assessment of changes inpelvic floor muscle function within the framework of inter-vention studies, for example, randomized controlled trials(RCTs). Former studies have also demonstrated that themeasurement of maximum voluntary contractions using thesame instrument was reliable.

Validity is the degree to which a test or instrumentmeasures what it purports to measure. A method can neverbe valid if it is not reliable. Hence, it is important to establishreliability first. However, the method can be reliable withoutbeing valid. In former studies the dynamometer has shown toseparate women with and without SUI measured as passiveforces, speed of the contraction, and endurance. However, thisis only one aspect of validity. The main question concerningvalidity of measurement of VOLUNTARY contractions of thepelvic floor muscles is whether this reflects the AUTOMATICfunction of the muscles during cough, lifting, running, anddancing. Is there any connection at all between the voluntary

contraction and the automatic one? This important questionremains to be investigated, and until we know the answer, thewhole idea of testing different aspects of voluntary contrac-tions related to incontinence may be questioned. However, areliable measurement tool to measure a possible change inpelvic floor function and strength in a pelvic floor muscletraining study is important for other reasons. When we startto train women with untrained pelvic floor muscles we mustexpect the strength or other functions of the muscles toimprove after an adequate training period. If it is notimproving compared to untrained controls, this is most likelydue to an inadequate training dosage. Hence, measurement ofdifferent aspects of pelvic floor muscle function and strengthis mandatory in pelvic floor muscle training interventions.

The authors of the present study should be congratulatedon a well-conducted study and for combining thoroughknowledge of measurement methodology with obviouscomprehensive practical skills in the area. They also basetheir studies on thorough knowledge from previous studies inthe area. The researchers have invented an important newmeasurement tool that is well accepted by women. Hopefully,they will also continue to investigate the other importantareas of validity of assessment of pelvic floor muscle function.Unfortunately this measurement tool is not yet availablecommercially to be taken into use by other research groups,and we look forward to it being available.

Kari Bø*Norwegian School of Sport Sciences

Oslo, Norway

No conflict of interest reported by author(s).*Correspondence to: Kari Bø, Norwegian School of Sport Sciences, P.O. Box 4014Ulleval Stadion, 0806 Oslo, Norway.Published online 29 January 2007 in Wiley InterScience(www.interscience.wiley.com)DOI 10.1002/nau.20388

� 2007 Wiley-Liss, Inc.