Bladder dysfunction is a common pathology in elderly individuals, with complete urodynamics being the gold standard for diagnosis. The method involves urethral catheters, not reflecting the natural circumstances of urinary flow. Urethral catheters can determine the occurrence of premature muscle fatigue in hypocontractile detrusors, compromising the analysis of bladder emptying efficiency. Uroflowmetry is a non-invasive urodynamic test used in the initial assessment of lower urinary tract dysfunctions, purposed to identify bladder outlet obstruction. However, it is inconclusive in identifying muscle contractility dysfunction. Aiming to improve the diagnostic quality of uroflowmetry and assuming the bladder with a sphere, we used a mathematical model to quantify the speed of shortening of the detrusor fiber, a parameter of function independent of urethral distensibility. They tested this model to uroflowmetry performed on individuals with lower urinary tract complaints. The speed of muscle shortening for maximum urinary flow was related to bladder emptying efficiency, reflecting a pattern of muscle contractility. Additionally, the average speed of muscle shortening and the duration of urinary flow were related to prostate enlargement. In conclusion, the results suggest that this approach is promising, but application to a broader range of individuals is needed to confirm its effectiveness.