# MUSCLE FUNCTION DURING LOCOMOTION

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 1992 · $189,514

## Abstract

The long term goal of my research program is to understand the design of
the muscular system.  This involves integrating information from cellular
studies and whole animal studies.  This approach is unusual and important
because scientists generally work either on cells or whole animals but
not on both.  This approach is crucial because there are large gaps in
our knowledge of the integrative principles by which animals use their
muscles.  Further, I believe that elucidation of the principles of how a
healthy motor system works may be useful in 1) diagnosing diseases and
injuries of the motor system, 2) understanding function basis of improved
performance (training) and 3) designing computer systems for aiding
movement in the handicapped.

The first goal of this proposal is to test in additional (but
functionally different) locomotory systems, the importance of two design
constraints we have previously discovered (muscle works at optimal points
on the sarcomere length-tension curve and on the force-velocity curve).
Then we will evaluate the importance of the kinetics of activation and
relaxation in muscle function and design.  To do this we must measure the
sarcomere length changes, and the duration and phase of the stimulation
the muscle undergoes during locomotion and then impose these on isolated
muscle.  Although our main interest is in understanding muscle function
in mammals and man, in this study we use frog and fish as experimental
models because their locomotor behavior and muscular anatomies are far
simpler allowing us to develop greater insights than we could working
directly on mammals.  For each of the animals, the sarcomere length
changes of the muscle fibers during locomotion will be measured by a
combination of high-speed motion picture and anatomical analysis.  The
duration and phase (with respect to length changes) of the muscle
stimulation will be recorded using electromyography.  We will then remove
the muscle from the animals and impose on it the exact length changes and
stimulation pattern that the muscle undergoes in vivo and measure how
much work the muscle can perform under these conditions.  To determine
the relative importance of maximum velocity of shortening (V-max) and
rate of relaxation in muscle function, we will pharmacologically slow
relaxation (while keeping V-max the same) and then see how well the
muscle can still perform its tasks.  These approaches will give us new
insights into how muscle is designed and the functional importance of the
observed variation seen in different fiber types.

## Key facts

- **NIH application ID:** 3158541
- **Project number:** 2R01AR038404-07
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **SAM.gov UEI:** GM1XX56LEP58
- **Principal Investigator:** Lawrence Craig Rome
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $189,514
- **Award type:** 2
- **Project period:** 1989-01-01 → 1996-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3158541

## Citation

> US National Institutes of Health, RePORTER application 3158541, MUSCLE FUNCTION DURING LOCOMOTION (2R01AR038404-07). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3158541. Licensed CC0.

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