Parameters describing the contractility of the urinary bladder can be calculated from both isometric contractions and pressure-flow studies. The first method has the advantage of making very little demand either on the patient or on the urodynamicist, and the disadvantage of yielding a parameter that is not clearly related to muscle physiology. The second method demands more from both patient and experimenter but yields straightforward parameters. For a group of 86 patients with mixed pathologic findings, a correlation between the two types of parameters was demonstrated, showing that both methods test, at least partly, the same mechanism.,
Erasmus MC: University Medical Center Rotterdam

van Mastrigt, R., & Griffiths, D. (1987). Clinical comparison of bladder contractility parameters calculated from isometric contractions and pressure-flow studies. Urology, 102–106. doi:10.1016/0090-4295(87)90615-7