Muscle Mechanics Projects

Microsensor for intramuscular pressure

The overall objective of this project is to develop and test a fiber-optic microsensor that can be used for routine clinical measurement of muscle function.

No practical method exists for direct measurement of force production from individual muscles. Manual muscle tests do not give an accurate estimate of muscle strength. Measurements of joint torque are inadequate because several muscles often contribute to torque development. Implantation of a buckle transducer on a tendon is highly invasive and impractical for regular use.

The integrated electromyogram is customarily used to provide quantification of muscle contraction. However, the problem remains that the electromyographic activity cannot provide a quantitative measure of muscle tension under dynamic conditions.

An alternative measurable parameter related to muscle force is intramuscular pressure. Commercially available intramuscular pressure transducers are too large for optimum comfort. Microsensor technology is now available to construct transducers that are approximately the same size as the fine wires used for electromyographic analysis.

The association of genetic polymorphisms with statin-induced side effects

This study will develop a cohort of participants for comparison, collecting data such as age, sex, duration of statin use, and type of statin both with and without myopathic side effects. Investigators will evaluate the association of genetic variants with myopathic symptoms.

Statin use is associated with beneficial reduction of lipidemia, but is also associated with side effects such as achy muscles (myopathies). For patients who develop myopathies, the assumption is that either strength is not affected or if affected, it will return to baseline following cessation of the statin medications.

In this study, muscle strength of affected muscles is quantified in the Motion Analysis Laboratory on the Humac system, which provides detailed information about isometric and isokinetic strength as well as the ability of the muscle groups to sustain activities over a period of time.

Medication trial for amyotrophic lateral sclerosis patients

Mayo Clinic researchers are participating in a worldwide multicenter study to determine the efficacy of a medication, dexpramipexole, to slow the deterioration of motor neurons in people with amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig's disease, ALS is a progressive disease of nerve cells in the brain and spinal cord.

The Motion Analysis Laboratory is responsible for quantifying the strength of the subjects during the 18-month-long study.

This is a randomized, double-blind, placebo-controlled study, which means that some patients are randomly assigned to receive the medication while some receive a placebo. None of the participants, the physicians caring for them or the study personnel measuring strength know into which group each participant has been assigned.

Nerves that control voluntary muscle movement are called motor neurons. They reach down the spinal cord from the brain and also run from the spinal cord to muscles. In ALS, the motor neurons deteriorate. When motor neurons can no longer transmit command signals to the muscles, voluntary muscle action is lost in the muscles supplied by those motor neurons.

When the muscles no longer contract, they become thinner (atrophied), and limbs begin to look smaller as muscle bulk diminishes. ALS often is discovered when a patient notices weakness in muscles of the arms, legs or face that is interfering with a common activity.

Evaluation of McArdle's sign and its response to dalfampridine in multiple sclerosis patients

Many people with multiple sclerosis (MS) exhibit a neck position-dependent weakness known as McArdle's sign. Neck flexion causes a deterioration of strength in the extremities that is reversed when the neck is placed in extension.

The purpose of this study is to evaluate McArdle's sign and its response to dalfampridine in MS patients through objective strength measurement in the Motion Analysis Laboratory.

Muscular dystrophy collaboration

  • Principal investigator: Duygu Selcen, M.D.
  • Co-investigator: Sherilyn W. Driscoll, M.D.
  • Coordinator: Krista A. Coleman Wood, P.T., Ph.D.

Mayo Clinic is participating in a longitudinal study of the relationship among impairment, activity limitation, participation and quality of life in children with Duchenne muscular dystrophy. Children visit the Motion Analysis Laboratory every six to 12 months for quantification of strength and range of motion and assessment of functional activities.

This study is being conducted through the Cooperative International Neuromuscular Research Group, a consortium of medical and scientific investigators from academic and research centers. The group has created a global network of researchers and study personnel who perform the same assessments on their local population of neuromuscular disease patients and pool all of the data for analysis.

Through the cooperative group, researchers are able to gather a sufficient number of participants for a valid statistical evaluation. This is difficult at a single medical center because people with neuromuscular diseases represent a small number of patients.