Impaired muscle function can such as weakness is a reduction in muscle quality or quantity. Muscle weakness is debilitating conditions which can result from neuromuscular diseases and conditions such as multiple sclerosis, muscular dystrophy, stroke, injury, and aging. Impaired muscle function leads to disability, risk of injury, decreases in quality of life, and even death. Early disease detection, rehabilitation efforts, surgical techniques, and drug delivery can all be improved with the ability to identify muscle weakness by determining individual muscle force in vivo. Current clinical methods fail to measure individual muscle force as they are either inaccurate for individual muscle estimations (torque measurements) or are too invasive (buckle transducer insertion). Electromyography (EMG) is commonly used to diagnose improper muscle function, yet it is only a measurement of electrical activity. Thus, there is no minimally invasive clinical method which currently evaluates muscle force in vivo, which makes identifying and treating impaired muscle a challenge.

Pressure of interstitial fluid within muscle (i.e. Intramuscular Pressure, IMP) is the direct result of active muscle contraction or passive stretch. A low profile pressure microsensor can be used to measure IMP and thus evaluate force of individual muscles in vivo. Accurate microsensor use however, is reliant upon developing a relationship between IMP and force, which is currently incomplete. Specifically, while force and IMP are correlated, the variability of IMP in vivo makes muscle force estimates from IMP measurements a challenge. Additionally, the distribution of IMP throughout muscle is variable and poorly understood. The goal of this work is to develop a computational model which can be used to better understand the behavior of intramuscular pressure. However, a lack of mechanical experimental analysis of skeletal muscle makes developing a robust model a challenge. Thus, two specific aims are proposed:​

1. Experimentally investigate the passive properties of skeletal muscle and identify proper modeling assumptions to make in developing a constitutive approach.
2. Develop and implement a finite element approach for skeletal muscle which is capable of simulating muscle force and intramuscular pressure under passive stretch and active contraction conditions

Implementation of this model will provide insight into the potential causes of variability of intramuscular pressure measurements in vivo and future clinical approaches.