Mechanisms of Improving Fecal Continence Muscles Motor Function in Health and Disease

To achieve the specific aim, the investigators will use state-of the-art available techniques and recording modalities, as well as a novel device that provides pre-determined different levels of resistance against contraction of continence muscles to induce measurable fatigue. The investigators will determine and characterize the fatigue characteristics of the striated continence muscles across adult age spectrum and sex. The investigators will determine and compare the effect of 6-weeks daily fatigue on continence musculature motor function and its effect on incontinence severity and related patient quality of life.

Aim1A: the investigators will determine and characterize the fatigue characteristics of the continence muscles induced by repetitive isotonic contractions using various loads, intervals, and repetitions in a. Continence muscle complex (comprised of external anal sphincter muscle group and puborectalis muscle) , and b. puborectalis muscle alone recorded intra-vaginally

Technique to induce fatigue: To apply resistance against contraction of continence muscles and to induce fatigue, the investigators developed a hand-made device in our laboratory; continence muscles resistance device; c-RED . The c-RED consists of a 6 cm x 2 cm noncompliant cylindrical balloon (intra-anal balloon) that is connected to a small compliant balloon (external balloon, about 1.5 x 2 cm) by a 2 mm diameter tube and a stopcock to allow for air to be filled and sealed in the system. To ensure consistent resistance provided by the anal balloon in the study, a commercially available noncompliant valvuloplasty balloon (Z-Med) is chosen to serve as the intra-anal balloon in the c-RED. The system is prefilled with air to determine the amount of air needed for a given internal pressure, or desired resistance of the intra-anal balloon. This is determined using a sphygmomanometer gauge in a sealed system. The intra-anal balloon, while providing resistance, is compressed by the anal contraction (exceeding the internal pressure) due to displacement of its air to the external distensible balloon. The compressibility of the anal balloon allows for the muscle shortening necessary for isotonic exercise. Air displacement into the external balloon results in its expansion allowing to maintain the predetermined intra-anal balloon pressure and serves as an externally visible indicator that an anal contraction has occurred. Using this device, the investigators can choose different level of resistance load on the continence muscles complex (external anal sphincters (EAS) and puborectalis muscle (PRM)).

High-resolution anorectal manometry: Anorectal manometric pressures will be monitored using a high-resolution anorectal manometry catheter (Medical Measurements Systems, Laborie) positioned across the anal canal with the distal end in the rectum. A computerized recording and analysis system stores pressure data from 8 sensor rows (23 pressure sensors total) spaced 1 cm apart along the probe.

High-resolution vaginal manometry: Vaginal pressure recording is a method to record contractile function of the puborectalis muscle. Reliable measurement of the pressure generated by PRM contraction from vaginal cavity has been challenging. However, using a combined technique of Barostat technology and high-resolution Manometry, the investigators have overcome this challenge.