Optimizing Ankle Exoskeleton Assistance for Walking Across the Life Span

January 23, 2024 updated by: Georgia Institute of Technology
The investigators seek to 1) determine why older adults expend more metabolic energy during walking than young adults, and 2) reduce the older adult's metabolic energy expenditure during walking using an ankle exoskeleton.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Older adults walk with greater metabolic rates than young adults. Growing evidence suggests that the greater older adult metabolic rates are related to the structural properties of their lower leg tissues. The tendons of the leg of older adults are more compliant than that of young adults. Accordingly, older adult leg tendons stretch more under a given load, such as walking and running, causing their muscles to operate at shorter, less optimal lengths, and higher activations than that of young adults. Using shorter muscles lengths and more muscle activation offers less economical force production. Thus, the investigators seek to alter the passive stiffness acting about the ankle, using an ankle exoskeleton in-parallel to the ankle, thereby enabling muscles to operate at relatively longer lengths. Generally, muscles produce force more economically when they are at operating lengths greater than that exhibited during normal walking. By adding an exoskeleton in-parallel to the ankle, the investigators hypothesize that older adults will walk with longer plantar flexor muscle lengths, thereby lessening their muscle activation, and consequently, reducing whole-body metabolic rate during walking.

In this study, the investigators will have young and older adults perform isolated calf muscle contractions while the investigators capture the behavior of their leg muscles and tendons using a non-invasive ultrasound probe that sits flush to the participant's skin. The investigators will also have participants walk on a treadmill with the ankle exoskeleton set at multiple assistance values. During these trials, the investigators will take many physiological and biomechanical measurements to assess why the optimal ankle exoskeleton profile minimizes the metabolic cost of walking in young and older adults.

Study Type

Interventional

Enrollment (Actual)

28

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • Georgia
      • Atlanta, Georgia, United States, 30332
        • Physiology of Wearable Robotics Laboratory (Georgia Tech)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Subjects must be able to walk for 60 minutes in a 90-minute time frame.
  • Subjects are apparently free of cardiovascular, metabolic, and renal disease, which includes no signs or symptoms suggestive of cardiovascular, metabolic or renal disease.
  • Subjects have no current musculoskeletal injury.
  • Subjects need to be either 18-45 or 65+ years old.

These criteria meet the American College of Sports Medicine's 2015 guidelines for participant health screening prior to joining a moderate or moderate-to-vigorous exercise protocol. (Riebe et al., 2015).

Exclusion Criteria:

  • Have dementia or an inability to give informed consent
  • Have a musculoskeletal injury or feel pain while walking
  • Have a history of dizziness and/or balance problems
  • Have cardiovascular, heart, metabolic, or renal disease, or respiratory problems
  • Smoke cigarettes
  • Asthma
  • Feel pain or discomfort in the chest, neck, jaw, arms during rest or exercise
  • Have orthopnea or paroxysmal nocturnal dyspnea
  • Have ankle edema
  • Have palpitations or tachycardia
  • Have a heart murmur
  • Have had a heart attack
  • Have diabetes
  • Have a pace maker
  • Have unusual shortness of breath with usual activities
  • Are <18 or 46-64 years of age
  • Do not speak or understand English

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Economical muscle dynamics
The investigators are trying to figure out how to optimize muscle contractile conditions for mobility. To do this, the investigators are systematically altering muscle contraction conditions for all participants.
Device: Strengthening muscle contractions during walking
The investigators will use ankle-exoskeletons to systematically alter the behavior of participant muscle contractions. For example, participants will walk in a robotic device that adds a spring in parallel with their lower limb that will help the participants generate a stronger propulsive push-off and may reduce the effort of walking.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Metabolic rate (watts)
Time Frame: 1 year
The rate of metabolic energy that subjects expend during walking.
1 year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Preferred walking speed (m/s)
Time Frame: 1 year
Measurements will be taken on how fast subjects prefer to walk with each exoskeleton.condition
1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Georgia Institute of Technology

Collaborators

National Institute on Aging (NIA)

Investigators

  • Principal Investigator: Gregory S Sawicki, Ph.D., Georgia Institute of Technology

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 4, 2020

Primary Completion (Actual)

May 23, 2023

Study Completion (Actual)

May 23, 2023

Study Registration Dates

First Submitted

July 23, 2019

First Submitted That Met QC Criteria

July 23, 2019

First Posted (Actual)

July 25, 2019

Study Record Updates

Last Update Posted (Estimated)

January 25, 2024

Last Update Submitted That Met QC Criteria

January 23, 2024

Last Verified

January 1, 2024

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • H18208
  • F32AG063460 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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