Dynamic intramuscular pressure measurement during gait

Intramuscular pressure is useful for quantifying muscle function during dynamic activities. Currently, theintegrated electromyogram (EMG) is used to indicate the timing and intensity of muscle contraction in gait.However, the relationship between EMG and muscle tension is unclear. There is a need for a reliable measure of muscle tension under dynamic conditions. This need may be filled through the measurement of intramuscular pressure.Intramuscular pressure can be measured with either fluid-filled or fiber optic transducers. The fluid-filled transducers can be used only when the limb position does not change relative to the horizontal plane. This type of transducer is not suitable for gait studies. In contrast, fiber optic transducers are not sensitive to hydrostatic artifacts and can be used effectively during gait. Current fiber optic transducers for measurement of intramuscular pressure are large (1.35-mm diameter) and thus the procedure is not typically used for clinical applications. However, a microsensor is being designed that is small (0.18-mm diameter) and will have direct clinical applications. The intramuscular pressure during walking parallels the electromyographic activity, but also accounts for passive stretch of the muscle. Interpretation of the intramuscular pressure does not require integration, which is necessary for EMG. The information gained from the measurement of intramuscular pressure can be used to treat patients who suffer from neuromuscular disorders.