Evaluating Wearable Robotic Assistance on Gait Mechanics and Energetics in Individuals With Neurological Impairment
Phase: EARLY_PHASE1
Conditions: Cerebral Palsy
Sponsor: Northern Arizona University

NCT04119063 
 
Document date: 12/16/2023 (Date of latest IRB ac?on: Yearly Con?nuing Review) 
 
Zach Lerner, PhD 
Associate Professor 
Department of Mechanical Engineering 
Northern Arizona University 
 
 

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1) Investigator 
 
Zachary Lerner, Ph.D. 
 
2) Protocol Title  
 
Evaluating wearable assistance on gait biomechanics 
 
3) Objectives 
 
The overarching goal of this study is to improve mobility in individuals with movement disorders 
through advances in wearable assistance (i.e. powered orthoses). This goal will be accomplished 
by focusing on two specific research aims. The first aim is to quantify how the magnitude of 
powered plantar-flexor assistance affects the energetics and mechanics of walking at self-selected 
(over-ground) and set (treadmill) speeds, and stair ascent in cerebral palsy (CP). The second aim is 
to evaluate how training frequency and patient characteristics affect clinical and biomechanical 
gait outcomes across repeated over-ground walking sessions with powered ankle assistance in CP.  
 
 
4) Background 
 
Neurological deficits, such as those caused by stroke, spinal cord injury, and cerebral palsy, often 
lead to reduced walking ability and pathological gait patterns that limit quality of life [1-3]. 
Achieving and maintaining independent mobility for the estimated 17 million individuals with 
walking disabilities in the US is an essential rehabilitation challenge [4]. Currently, standard-of-care 
treatments are not fully effective in restoring gait function. Physical therapy, treadmill-based gait 
training, and intensive muscle strengthening programs have demonstrated variable and 
inadequate success for gait rehabilitation [5-7]. Research suggests that the type and dosage of 
standard therapy programs are insufficient for large sustainable gains [8].  
 
Wearable assistive devices (i.e. powered orthoses) offer a promising new means to improve gait 
rehabilitation outcomes and meet the increasing demand for therapy from our aging population 
[9]. By administering appropriately timed assistance to lower-extremity joints, powered orthoses 
can augment weak or deficient muscles to improve walking capacity. Importantly, powered 
orthoses offer the ability to increase the dosage of gait therapy by providing daily assistance at 
home and in the community.  
 
The PI (Dr. Lerner) and his colleagues at the National Institutes of Health (NIH) led an exploratory 
clinical study that sought to evaluate the potential for a powered knee orthosis to treat walking 
deficits in children and adolescents (ages 5-19) caused by cerebral palsy. The results from the 6-
visit 12-week study were very promising with the participants exhibiting significantly improved gait 
function with the aid of a powered knee orthosis [10, 11]. The success of this previous investigation 
provides the rationale for continued research that will lead to the effective implementation of 
wearable assistive devices for use as a long-term rehabilitation strategy at home and in the 

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community. Working towards this longer-term goal, the study proposed under this protocol is 
designed to resolve remaining challenges that must be addressed, including:  
 
1) Improving walking performance: Pathological gait patterns drastically increase the metabolic 
requirements for locomotion [18], leading to a barrier to physical activity and downward spiral 
that results in a deterioration of walking ability with age, ultimately leading to a loss of 
ambulation in a large portion of the affected population [19]. This study seeks to meet the 
need to evaluate the use of wearable assistive devices for improving mobility in individuals 
with movement disorders.  
5) Lay Summary (approximately 400 words) 
 
Many individuals with physical disabilities exhibit abnormal walking patterns that limit quality of 
life and lead to long-term health consequences. Reduced physical activity from gait dysfunction 
can lead to a downward spiral that results in a deterioration of walking ability with age, ultimately 
leading to a loss of ambulation in a large portion of the affected population. 
 
The goal of this research protocol is to improve mobility in these individuals with gait disorders 
through advances in wearable assistive devices. We seek to improve independent walking ability 
and increase daily physical activity for individuals with cerebral palsy. To meet this goal, our 
proposal aims to evaluate the novel use of powered ankle assistance from a wearable exoskeleton 
to improve walking economy across varied terrain.  
 
The knowledge gained from this protocol will enhance our ability to optimize the prescription of 
powered orthoses for rehabilitation of pediatric and adult gait disorders. Further, this proposal 
was designed to lay the foundation for our future, long-term research objectives, which is to 
conduct longitudinal studies (12-36 months) to implement assistive-device interventions to treat 
neuromuscular gait disorders at home and in the community.  
 
6) Setting of the Human Research 
 
The proposed research will take place at NAU’s Flagstaff and Phoenix Biomedical Campuses. At the 
Flagstaff location, the research will be conducted at or around the new state-of-the-art human 
performance lab, a 2700 sq. ft. interdisciplinary facility located in the Learning Resource Center 
(Building 61). At the Phoenix Biomedical campus, the research will be conducted at or around the 
motion capture facility in NAU’s Phoenix Physical Therapy Department.  
 
7) Resources available to conduct the Human Research  
 
NAU's Disability Resources office will assist in participant recruitment. Investigators on this 
protocol in NAU’s department of physical therapy (e.g. Dr. Tarang Jain) will assist Dr. Lerner in the 
consenting and evaluation of participants with disabilities. Investigators in physical therapy (e.g. 
Dr. Andrea Lerner) will also assist in patient monitoring during the study visits. Graduate students 
in Dr. Lerner’s Biomechatronics Lab will provide technical assistance and conduct data analysis. All 
persons assisting with this study will be undergo CITI human subjects and CPR training.  

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The Flagstaff and Phoenix motion analysis labs contain all of the biomechanics equipment 
necessary for the experimental measurements. This equipment includes a 10 camera Vicon motion 
capture system, Bertec instrumented treadmill. Wearable assistive technology, EEG and metabolic 
measurement equipment will be made available from Dr. Lerner’s faculty start-up package. 
 
8) Study Population 
a) Inclusion and Exclusion Criteria 
 
Subject population will include: 
• 10 individuals with a neurologically-based walking disorder due to cerebral 
palsy. We will recruit 11 individuals anticipating a 10% withdrawal rate to 
obtain the target sample size. 
 
Inclusion criteria: 
• Age between 5 and 35 years old, inclusive. 
• An individual with a diagnosis of a neurologically-based walking disorder due 
to cerebral palsy. 
• Must be able to understand and follow simple directions based on parent 
report and clinical observation during the history and physical examination. 
• Able to provide verbal assent, if appropriate. If the participant is non-verbal, 
parental interpretation of gesticulation for assent will be used.  
• The ability to read and understand English. 
• Able to walk at least 30 feet with or without a walking aid (GMFCS Level I-III for 
individuals with cerebral palsy)  
• Able to safely fit into a device configuration and tolerate assistance without knee 
hyperextension while walking 
 
Exclusion criteria: 
• Any neurological, musculoskeletal or cardiorespiratory injury, health condition ( 
including pregnancy), or diagnosis other than cerebral palsy that would affect the 
ability to walk as directed for short periods of time.   
• Participant or parent report that the perspective participant’s physician has 
recommended that they not engage in moderate intensity walking exercise. 
 
Note: No exclusions will be made on the basis of race, gender or ethnic background and 
efforts will be made to recruit underrepresented minorities.  
b) Vulnerable populations 
The Human Subjects research includes children and adults with neurological disorders. 
Several safeguards are included in our protocol to protect their rights and welfare. A 

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licensed physical therapist or trained safety advocate will be present during all walking 
trials; the primary purpose of this individual is to ensure participant safety and to be 
the participant advocate. Walking trials will be immediately stopped upon request of 
the participant or therapist. Children will be supervised at all times during the test 
procedures. 
 
A participant’s risk for falling during the walking trails will be assessed by a physical 
therapist; participants who are at risk of falls will be protected by a gait belt or safety 
harness. Note: the risk of falling from the potential participants as a result of their 
motor deficits does not represent an elevation of risk beyond those during their daily 
lives.  
 
Dr. Lerner has over 9 years of experience and training in conducting biomechanical 
evaluations of gait disorders in individuals of all ages, including children as young as 5 
years old. Additionally, he has successfully led multiple pediatric gait analysis studies. 
The most relevant (and recent) experience includes a clinical study evaluating powered 
assistance for children with cerebral palsy at the National Institutes of Health. This 
study was conducted with 7 individuals ages 5-19, and included 6 study visits; the study 
results were overwhelmingly positive.  
 
9) COVID-19 Mitigation Strategy 
 
COVID-19 may be spreading within our communities for some time. To maximize the safety 
and health of our participants and research team, the following mitigation techniques will be 
in place: 
a) We will minimize face to face contact by conducting the consent process, when applicable and 
any possible screening/history questionnaires over the phone. We will also offer the option 
for participants to complete walking exercises (without the orthosis) at home.  
b) The research team will follow CDC guidelines, including wearing face coverings and gloves, 
when recommended.  
c) We will offer face coverings and gloves to visitors (participants and/or their families). 
d) We will increase our rigorous sanitation procedure to include wiping down every surface 
touched by visits to the lab.  
 
 
10) Recruitment Methods and Consenting Process 
a) Recruitment Process:  
 
Participants with gait disorders: We will contact NAU’s Disability Resources office by phone 
or email to discuss our recruitment efforts for participants with stroke, spinal cord injury, 
Parkinson’s disease and cerebral palsy. We will ask them to display our recruitment flyer. We 
will also provide them with our email/phone recruitment script, that they may use if they 
choose to contact individuals who they believe may be eligible for participation in our study. 
Additionally, we will contact clinical care providers, biomedical researchers, physicians or 
physical therapists by phone or email to discuss our recruitment efforts for this study. If they 

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are willing to help our efforts, we will mail or email a flyer that they can provide to potential 
participants. The flyer briefly describes the study, the inclusion and exclusion criteria, and 
whom to contact for more information. A copy of this flyer is included in the appendix 1. The 
information on the flyer will also be made available on our laboratory’s website.  A link to the 
website has been provided in the recruitment appendix for IRB reference, but the website 
will not be made available to the public until IRB approval has been obtained. We may also 
display the flyer throughout hospitals, physician offices, rehabilitation settings, in the 
community (i.e., schools, churches, local support groups), or posted in print and online 
newsletters and newspapers after permission for posting is obtained. 
 
Timeline: Recruitment will be staggered so that less than 10 participants will be enrolled at 
any one time. Therefore, recruitment will take place throughout the duration of the protocol.  
Pre-screening: Inclusion/exclusion criteria will be reviewed with each prospective participant 
(or the parent/guardian in the case of a child) using the pre-screening email or phone scripts 
(a copy can be found in the appendix 1). Data will not be recorded during the pre-screening 
process; therefore, pre-screening data cannot and will not be used in the research for either 
successful enrollees or for screen failures.  
b) Informed Consent:  
 
The consent process will take place in person or over the phone in a private, soundproof room 
by a member of the research team. Consent will be obtained before any study procedures are 
done. If eligibility criteria are met, the participant, legally authorized individual (LAR), or a 
legal guardian in the case of minors will be verbally taken through and be provided an 
electronic (if phone consenting) or hard copy of the consent form and assent form (for minors) 
to review. For the case of a subject being represented by a LAR, both the subject and the LAR 
will be present while the consent process. If the subject indicates a willingness to participate via 
verbal or gesticulated assent, the LAR will sign the consent form on their behalf. Any questions 
will be answered. The consent form will be provided in English. Once consent and assent 
are obtained in writing and prior to undergoing any research assessments, all enrolled patients 
will have their relevant medical history recorded and physical examination completed (“history 
and physical”, Appendix 2). The medical history may be recorded over the phone as well if the 
participant or guardian is willing to share that information over the phone. The physical will be 
performed by a licensed physical therapist and relevant medical information such as having a 
seizure disorder, other current medications, presence of any communicable diseases and allergy 
history will be documented. Each participant will be screened for any cardiorespiratory, 
neurological or musculoskeletal contraindications to short exercise bouts of walking or moving 
lower limbs. 
Minor assent will be obtained after parental consent has been provided.  The minor assent 
process is detailed in Appendix A, Children. 
 
11) Procedures involved in the Human Research 
 

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Overview: Participants with gait deficits will be asked to complete up to 18 visits (they may agree 
to fewer visits or withdraw at any point). We may terminate a subject’s participation if they no 
longer meet eligibility requirements or if there are safety concerns that cannot be addressed. The 
experimental conditions allocated during each visit (defined below) will be customized for each 
participant using the “Visit Allocation” table provided in the consent form and will depend on their 
specific neurological deficit and walking ability.  
 
Powered Orthosis: Wearable assistance will be provided from powered orthoses that are tailored 
to the specific gait deficits of each participant (e.g. Fig. 4). The devices provide a small amount of 
motorized assistance that is intended to 
augment existing muscle activity to elicit 
function changes at the ankle joints. This and 
other similar investigational devices have been 
classified by the Food and Drug Administration 
(FDA) as a nonsignificant risk because they do 
not meet the definition of a significant risk 
under 812.3(m) of the investigational device 
exceptions regulation (21 CFR 812) (letter from 
FDA outlining exemption from Dr. Lerner’s 
prior work at NIH, Appendix 3). This 
information has been provided to assist the 
IRB in its determination for this study.  Several 
safety precautions will be implemented to 
ensure patient safety, including mechanical 
“stops” to prevent hyperextension of joints, an 
emergency stop button that shuts off power to the device, and embedded software mechanisms 
that shut off power if the user were to fall.  
 
Unpowered Orthosis: Wearable assistance will be provided from passive orthoses that are tailored 
to the specific gait deficits of each participant (e.g., ankle-foot orthosis or AFO). These devices are 
considered less risk than that of powered orthoses. 
 
Experimental conditions: Several powered orthosis conditions will be tested during several modes 
of walking throughout the course of the study. Trials will take place over-ground and/or on a 
treadmill. Balance trials will take place on a treadmill. Participants with gait deficits will walk for 
up to 40 minutes. Frequent breaks will be provided between trials and conditions to avoid fatigue; 
a maximum of 15 minutes of continuous walking will take place between breaks.  
 
1) Level walking over ground 
2) Level walking on a treadmill 
3) Walking at a mild incline/decline (0°-15°) on the treadmill  
4) “Walking” on a stepmill machine 
5) Walking on stairs 
6) Balance on a treadmill 
7) All terrain walking over ground 
Figure 1. Picture and schematic of a powered orthosis, designed and 
implemented by Dr. Lerner and the Biomechatronics Lab at NAU. 

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8) Mobility analysis 
 
 
Orthosis Conditions: 
1) Walking without assistance: We will obtain the normal/representative walking pattern of each 
participant. This condition will be used to compare the effectiveness of the assistive conditions. 
2) Walking with powered orthosis assistance: We will provide on/off assistance during walking, 
depending on the individual’s specific gait deficits.  
3) Walking with adaptable powered orthosis assistance: We will provide assistance that changes 
magnitude based on measures of gait performance.  
4) Walking with passive (unpowered) orthosis assistance.  
 
In Laboratory Mobility analysis: 
To assess mobility, participants will undergo the following tests, with or without a powered 
orthosis, under direct supervision by a research team member, who will be available to spot 
for safety (heart rate and metabolic cost may be collected): 
1) Timed up and go: participants will walk as quickly as possible in a safe and controller manner 
to a cone 3 meters away, turn around, walk back to the chair and sit down; 3 – 6 trials will be 
collected. 
2) 6 minute walk test: participants will walk as quickly as possible in a safe and controlled manner 
for 6 minutes to test walking endurance; 1 – 3 trials will be collected. 
3) Stair test: participants will climb 1 – 4 flights of stairs (with hand rails for support) as quickly as 
possible in a safe and controlled manner; 1 – 4 trials will be collected. 
 
All terrain walking over ground: 
Participants will be monitored and accompanied at all times by the trained safety advocate and 
study staff during indoor or outdoor all terrain walking trials that may take place on campus in 
controlled environments. Trials will include ambulation with and without wearable assistance. On-
campus locations will include the Engineering, Business, and Learning resource Center buildings, 
the north and south quads, and campus walkways and urban trails.  
 
Data Collection: Experimental data collection will include motion capture (movement and force 
gait analysis), measurement of muscle activity (electromyography, EMG), and measurement of 
oxygen consumption/c02 production (metabolic rate).  
 
Physical activity questionnaire: The Physical Activity Questionnaire for Older Children (PAQ-C) and 
Adolescents (PAQ-A), two questionnaires that have been validated for children and young adults, 
may be given to participants with the help of a parent/guardian if necessary. 
 
Description of visits for Participants:  
Pre-visit phone call: Optional phone call prior to first in-person visit (but after consent) to 
collect relevant medical history and physical activity questionnaire. 
 
Visit 
1: 
Participants 
will 
undergo 
consent 
(if 
not 
done 
over 
the 
phone), 
history/physical/activity questionnaire, and orthotic device fitting. Following device fitting, 

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the participants will undergo baseline gait and mobility analysis, and then practice walking 
with powered assistance. The expected duration is 3-4 hours.  
 
Visits 2 through (up to a maximum of) 17: On each visit, participants will complete two to 
four of the experimental powered orthosis conditions and one to six of the experimental 
conditions, depending on their customized experimental plan and walking ability. The 
expected durations are 2-3 hours. 
 
Final visit: On the final visit (maximum number of visits = 18) participants will complete a 
follow-up gait and mobility analysis, and evaluation of the experimental conditions. The 
expected duration is 2 – 3 hours. 
 
Timeline: The participants will be asked to complete 1-4 visits per week for 3-12 weeks. To 
quantify how high frequency gait training affects walking performance, participants will 
complete four 20-30 minute ankle exoskeleton assisted walking sessions in one week. To 
quantify how high frequency gait training affects walking performance, participants will 
complete two 20-30 minute ankle exoskeleton assisted walking sessions each week for two 
weeks. To accommodate illness, travel, and scheduling conflicts, the maximum time that a 
participant can be enrolled in the study is 16 weeks.   
 
12) Cost to subjects  
 
The only cost to the participants is a time commitment for which remuneration will be provided. 
There will be a maximum number of seventeen visits for volunteers with neuromuscular deficits, 
and a maximum number of four visits for healthy volunteers. Each visit will be a maximum of 4 
hours. Any parking costs will be paid for up front, or reimbursed. 
 
13) Risks to subjects 
 
a. Gait Analysis: There is a slight risk of falls during ambulatory activities performed during this 
protocol, but this risk is not greater than during normal daily life. This risk will be minimized by 
supervision from a licensed physical therapist or trained safety advocate. If the subject appears 
unstable, a safety harness will be used to arrest any falls that may occur. Therefore, the risk 
should be no greater than that of normal daily activities. The safety harness will always be used 
during the incline/decline treadmill walking, stepmill walking, and stair ascent/decent walking.  
b. Walking with wearable Assistance: The powered and unpowered wearable assistive devices 
have been evaluated by the FDA as non-significant risks to human subjects (Appendix 3). There 
is a mild risk of falling when subjects are walking with motorized assistance; subjects may feel 
a slight perturbation from the orthotic device. The device is not designed or able to over-power 
the user. Safety measures are integrated within the control algorithms used to control the 
wearable device such that it automatically deactivates during gait disturbances. During 
laboratory testing, a physical therapist or trained safety advocate will closely monitor each 
subject while walking with assistance. If the subject appears unstable, a safety harness will be 
used to arrest any falls that may occur. Additionally, a therapist or researcher may hold an 

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emergency switch so the wearable assistance can be immediately deactivated, if needed. For 
any home/community testing, the participant and parent/guardian (if applicable) will complete 
extensive training on operation and use of the device. 
There is a small risk of pressure by the orthotic braces causing skin irritation. A physical 
therapist or trained safety advocate will be with the subject throughout the tests, and 
continuously monitor subject tolerance and inquire about presence of pain, pressure or other 
complaints to detect any discomfort during testing. If the subject experiences anything beyond 
minimal discomfort (extra inertia and resistance against movement), we will stop the testing 
and readjust the device as needed until the problem is resolved. Redness or any other skin 
problem due to the brace will be inspected at the end of every visit.  
c. Balance with/without Assistance: There is a small risk of falling during the balance test, but 
no greater than that of during the walking test. A safety harness will be used to arrest any falls 
that may occur. A physical therapist or trained safety advocate will stand by the side of the 
participant and “spot” them.  
 
d. Muscle Activity Measurement (EMG): There is minimal risk associated with EMG recording. 
Small, matchbox sized boxes will be place on various leg muscles to measure when they are 
active using an electromyography (EMG) device that measures the electrical activity that can 
be recorded during muscle contractions. 
e. Metabolic Testing: There is minimal risk associated with heart-rate monitoring or open-circuit 
respirometer recording. A facemask covering the nose and mouth that is connected to a 
respirometer will capture breath inhalation/exhalation.  
14) Potential benefits to subjects and/or society 
 
Benefits to Subjects: Walking remains prohibitively challenging for the target population. Properly 
implemented wearable assistance has a strong potential to improve their ambulatory ability and 
balance. These studies will determine if wearable assistance is a viable treatment strategy for each 
of our participants, which can be used to guide future treatment and therapy.  
 
Benefits to Society: Achieving and maintaining independent mobility for the estimated 17 million 
individuals with walking disabilities in the US is an essential rehabilitation challenge. The proposed 
studies have the potential to improve gait rehabilitation outcomes and meet the increasing 
demand for therapy from our aging population. Our findings will provide generalizable knowledge 
about the optimal assistance for a range of neurological walking disorders. Additionally, our 
objectives will advance knowledge regarding muscle and brain activation patterns during assisted 
locomotion, which can advance their use for clinical and research applications.  
 
15) Provisions to protect the privacy of subjects and the confidentiality of data 
 
a) Protection of subject privacy:  
Only IRB approved methods and documents will be used for subject recruitment and consent.  
 

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b) Protection of data confidentiality:  
Samples and data will be stored using codes that Dr. Lerner will assign. Only Dr. Lerner will 
have the code, which will be recorded in a secure password protected document that will be 
destroyed 5 years after the completion of the study. Data will be kept in password-protected 
computers. Hard copies of data will be kept in locked storage on NAU’s campus. Only study 
investigators will have access to the data. Digital pictures and videos will be recorded of 
participants in this study in conjugation with motion analysis of gait. Participants can choose 
to sign an Authorization for Recording, Filming, and/or Photographing of Patients (included in 
the consent form) to give permission to use these videos for publications and public 
presentations of this work, with or without obscuring identifying features. After the 
recommended 5 year minimum time frame, all identifying information will be destroyed by 
erasing files and shredding documents.  
16) Subject compensation 
 
Subjects will receive monetary compensation for their participation in the study. All participants 
will be compensated $30 per hour for lab visits; payment will be made to the parents/legal 
guardians of minor participants. The minimum compensation for each visit is $30, should the 
participant or investigator choose to stop the study within the first hour, and the maximum is $120. 
For those with gait deficits who complete all visits, the maximum possible compensation would be 
$2160 if they complete all data collection and the visit durations all last 4 hours. Impaired 
participants will be provided $10 of travel compensation for every 25 miles traveled to the facility 
where the study will take place, with a maximum of $60 per visit. Impaired participants may be 
reimbursed up to $120/night of hotel or Airbnb accommodations if an overnight stay is necessary 
for participation.  
 
All participants can elect on the timing (payment at the end of the study or after each visit) and 
method of compensation, either a check in the mail or an Amazon gift card. 
 
17) Monitoring the data for subject safety  
 
A therapist will assess the areas on each participant’s lower-limbs under the orthoses for skin 
irritation and redness. Any discomfort following the removal of the orthoses will be addressed 
and monitored via phone or email for 24-48 hours.   
 
18) Withdrawal of subjects 
 
Subjects or their parents, if applicable, may withdraw from the protocol at any time. There is no 
elevated risk for withdrawal. If a participant withdraws from this research project before it is 
complete, results obtained prior to the subject’s withdrawal from the study will be maintained and 
their privacy will be preserved.  
 
Refusal to participate will involve no penalty or loss of benefits to which the subject is otherwise 
entitled. 

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All participants may discontinue participation at any time without penalty or loss of benefits to 
which the subject is otherwise entitled. 
A subject's participation may be stopped by the investigator if the investigator assesses that the 
participant is at a safety risk or if they are non-compliant with the research protocol; termination 
will involve no penalty or loss of benefits to which the subject is otherwise entitled. 
There is no consequences of a subject's decision to withdraw from the research. Orderly 
withdrawal will occur by talking with the principal investigator.  
 
 
19) Sharing of results with subjects  
 
The adult subjects or the parents of child participants may request a report of the individual’s 
motion analysis results. Copies of any manuscripts reporting on the study’s full results will also be 
provided, when available, upon request.  
 
20) Future use and long-term storage of data or specimens 
 
De-identifiable motion and gait data may be kept for future research. Following publication of our 
findings, these de-identifiable data will be made available upon request. Dr. Lerner will hold and 
maintain the repository. 
 
21) Information management  
 
Dr. Lerner is responsible for data management.  
 
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Sta$s$cal Analysis Plan (SAP) 
 
Protocol Overview 
Following the informed consent process, all par?cipants completed a high frequency gait 
training protocol followed by a washout period and a low frequency gait training protocol. For 
each gait training protocol, par?cipants completed a shod (shoes only)  pre and post 
interven?on assessment that included walking for at least 6 minutes while we measured speed, 
energy cost, cadence, step length, and muscle ac?vity. 
 
For the high frequency gait training por?on, par?cipants completed four 20-30 minute ankle 
exoskeleton assisted walking sessions in one week. For the low frequency gait training por?on, 
par?cipants completed two 20-30 minute ankle exoskeleton assisted walking sessions each 
week for two weeks. During the walking sessions, plantar ﬂexor exoskeleton assistance was 
ini?ally set to 0.35 Nm/kg and adjusted as need to prevent knee hyper extension. A small 
amount of dorsiﬂexor assistance was provided to address drop foot (1-2 Nm), as needed. 
 
Outcome Measures 
Our primary outcome measures are the metabolic energy required to walk and walking speed. 
Our secondary outcome measures are stride length, cadence, and muscle ac?vity variance ra?o. 
 
Sta$s$cal Analyses 
 
• We calculated the percent change in each outcome measure pre and post each ankle 
exoskeleton assisted gait training frequency (high frequency and low frequency) for each 
par?cipant.  
• We computed the group mean and standard devia?on for each outcome measure.  
• We then calculated the diﬀerence in the percent changes between the two frequencies.  
• We then tested whether these data were normally distributed using the Shapiro-Wilk 
normality test. We found that all data were normally distributed.  
• We used paired two-tailed Student’s t-tests to compare the outcome measures between 
high frequency and low frequency gait training.