# Elastic mechanisms in locomotion

> **NIH NIH R01** · BROWN UNIVERSITY · 2024 · $432,246

## Abstract

Project Summary
 All movements involve dynamic interactions between passive elastic structures and muscle
contractile elements, but our understanding of the consequences of this interaction for both
normal and pathological muscle function is limited. Our long-term goal is to define the mechanical
influence of elastic elements on muscle force production and gait. This project aims to understand
how the mechanical interaction between internal muscle elastic elements, fluid pressure, and
contractile elements define muscle force, speed and power output. Previous work shows that this
interaction is highly three-dimensional and significantly influences muscle performance. A
dominant paradigm of muscle force production as a one-dimensional process determined
primarily by contractile element properties has limited our understanding. The project aims to use
a combination of modeling and experiment to test novel hypotheses about how multi-scale, three-
dimensional interactions influence muscle mechanical output. A combination of direct
measurement of contractile behavior of muscles in different animal systems and physical models
is used to test mechanistic hypotheses about how structures at multiple scales interact to
influence mechanical output. The specific aims of the project are: 1) to test the hypothesis that
fluid forces contribute to muscle force output, 2) to determine whether stiffened connective tissue
in older muscle reduces force and work output, 3) to test the hypothesis that muscle fluid volume
influences passive muscle stiffness, and 4) to test the hypothesis that dynamic changes in muscle
architecture provide a mechanism for intramuscular elastic energy storage and recovery.
 In most cases the mechanistic link between structural pathologies in muscle and functional
deficits is poorly developed. We will test novel hypothesized mechanisms for how changes in
extracellular matrix and muscle fluid content can alter muscle mechanical output with the aim of
determining structure-function relationships that may underpin functional deficits in a range of
conditions, including dystrophies, cerebral palsy, aging, and secondary to stroke and spinal cord
injury. These models will inform the design of rehabilitative strategies and interventions to improve
muscle-tendon function. An improved understanding of how muscle elastic elements influence
the mechanical behavior of healthy muscle-tendon units may also aid in the design of prosthetic
devices.

## Key facts

- **NIH application ID:** 10769849
- **Project number:** 5R01AR055295-14
- **Recipient organization:** BROWN UNIVERSITY
- **Principal Investigator:** EMANUEL AZIZI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $432,246
- **Award type:** 5
- **Project period:** 2008-08-01 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10769849

## Citation

> US National Institutes of Health, RePORTER application 10769849, Elastic mechanisms in locomotion (5R01AR055295-14). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10769849. Licensed CC0.

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