Motor Learning in Individuals With Lower Limb Loss and Chronic Diabetes

Inadequate rehabilitation training after amputation can result in poor patient outcomes, injuries, and wasted healthcare resources. This is a serious public health problem due to an aging population and rising prevalence of diabetes (main cause of amputation in the U.S.). In this study, the investigators will examine the effects of external vs. internal attentional focus instruction on learning of a balance task in individuals with existing amputation and those at risk of amputation (older adults with diabetes). With the proposed research, the investigators aim to expand the understanding of motor learning in individuals with and at risk of lower limb loss to provide knowledge that will lead to more effective and efficient rehabilitation.

Study Overview

• Status: Recruiting
• Conditions: Diabetes Mellitus; Amputation; Neuropathy, Diabetic
• Intervention / Treatment: Behavioral: Instructions to perform a motor task (external vs. internal focus instructions)

Detailed Description

1. Prior to participation in the study, the purpose and procedures of the study, including possible image and video recordings, will be explained to the subjects.
2. Subjects will then be required to give written consent for their participation and will receive a copy of their consent form.
3. The following 2-part research protocol uses a similar experimental protocol (learning a balance task) on individuals with leg amputation (Part 1), and individuals with chronic diabetes (Part 2).

Part 1:

The experiment will take place over a 3-day period including screening and baseline testing (Visit 1), balance training (Visits 2), and retention testing (Visit 3; at least 24 hours after Visit 2). On Visit 1, the investigators will assess aspects of health and functional capacity to assess participation eligibility and establish baseline characteristics of the participants. In addition to medical history and anthropometric measurements, the assessment will consist of clinical surveys of quality of life, physical activity level, balance confidence, and fear of falling. Ambulatory performance will be quantified. Additional amputee-specific measures will be used to assess functional characteristics unique to the population.

The balance training involves standing and maintaining balance on a stabilometer, which consists of a platform (1.3m long by 1.4m wide) connected to a single axis that allows bi-directional sway (Lafayette Instrument Co.; Figure 1). The maximum angular deviation of the platform is 18°. A safety harness is provided to prevent falls but does not provide support during the performance of the task. The load on the harness will be monitored with an S-type strain gauge (Delsys Inc., Massachusetts, USA) connected in series to the harness tether. Participants are required to maintain balance with feet in a medial-lateral orientation while standing on the balance board and looking straight ahead. A potentiometer monitors the sway angle of the platform. An integrated timer measures time in balance, which is defined as when the platform angle is within ± 5° of horizontal.[52] The primary outcome measure is time in balance (sec.) for each 30s trial. The secondary outcome measure is platform angular deviation from horizontal (RMSE; degree).

Participants will be assigned to receive the 2 attentional focus conditions in random order. Depending on the condition, participants will receive either internal or the external focus instruction on where to direct their attention while training to perform the balance task. During training, the assigned instruction will be reinforced at the beginning and after every 5 practice trials. After they complete training with the first condition, they will go through a washout period (at least 4 weeks) before receiving training under the other condition. Participants will be blinded to the purpose of the intervention and study design until debriefing at the end of the study.

The training will take place over a 2-day period (Visits 1 and 2), the investigators will monitor the changes in balance task performance over 40 total practice trials (20 trials each visit). The balance training consists of thirty 30s trials with a 90s rest interval between trials. During the rest interval, the platform will be locked to provide a stable surface or the participant can choose to step off the platform to sit down and rest when needed. After each 5 trials, participants will be given feedback regarding their performance (time in balance). No additional feedback will be provided. This protocol has been validated in the older adult population (mean age 69.4 years) in a previous study (Chiviacowsky et al. 2010). After each training block of 5 trials, the participant's self-perceived direction of attentional focus and spontaneous comments during the practice will be checked. The retention test will be performed at least 24 hours after the 2nd training day (Visit 3). The retention test will consist of performing 10 trials of the same balance task during which the participant will not receive any instructions, reminders, or feedback. An additional 10 trials of skill transfer task will be performed with an added cognitive task (counting numbers backward).

Part 2 (individuals with diabetes):

The procedure of Part 2 of this research is identical to Part 1. The main differences, in addition to the different participant population are described below.

In addition to the baseline health and functional capacity assessments as described in Part 1, the investigators will assess all participants' sensorimotor function using an established knee joint reposition sense test on a Cybex Norm dynamometer (Computer Sports Medicine Inc., Stoughton, MA, USA). This test assesses participant's ability to reproduce a joint angle using only proprioception. The test performance will be measured as the absolute error in degrees between the reproduced and target angles. This specific test was chosen to quantify the lower limb sensorimotor function because previous studies have shown it to be predictive of mobility outcomes in older adults in general and in those with diabetes. The investigators will determine individuals with diabetes-related sensorimotor impairment if the error is greater than 3.65°.

Individuals will be randomly assigned to receive either internal or external focus instructions conditions during the balance training. The experimental protocols and procedures will be the same as in Aim 1, including the screening (Visit 1), balance training (Visits 2), and retention and skill transfer testing (Visit 3; at least 24 hours after Visit 2).

• Study Type: Interventional
• Enrollment (Anticipated): 55
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Szu-Ping Lee, PhD; Phone Number: 7028953086; Email: szu-ping.lee@unlv.edu
• Study Contact Backup: Name: Szu-Ping Lee, PhD; Phone Number: 3528704767; Email: szupinglee@gmail.com

Study Locations

• United States
  • Nevada
    • Las Vegas, Nevada, United States, 89154
      • Recruiting
      • University of Nevada, Las Vegas
      • Contact: Szu-Ping Lee, PhD; Phone Number: 702-895-3086; Email: szu-ping.lee@unlv.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria (amputees):

1. Have unilateral transtibial or transfemoral amputation,
2. Age >18 years,
3. Are fitted with a walking prosthesis and use it regularly and proficiently (K-level of 2 or above, further defined as scoring higher than 50 percentile on the Prosthetic Limb Users Survey of Mobility),
4. Able to stand for at least 5 minutes without using an assistive device or experiencing excessive fatigue
5. Willing to travel to UNLV 6 times for training and testing.

The inclusion criteria (non-amputee older adults with and without chronic diabetes):

1. Age >18 years,
2. With or without a current diagnosis of type II diabetes
3. Able to walk for at least 50 meters without assistance from other people,
4. Able to stand for at least 5 minutes without using an assistive device or experiencing excessive fatigue
5. Willing to travel to UNLV 6 times for training and testing. -

Exclusion Criteria:

1. Have other concurrent central nervous system diseases that influence motor functions and balance.
2. Have leg/foot ulcer or other conditions that cause pain during weight-bearing.

3. Have cardiovascular, respiratory or other critical health conditions that preclude moderate physical activity.

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Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Amputees (External Focus); Participants in this group will receive the external focus instruction on where to direct their attention while training to perform the balance task. During training, the assigned instruction will be reinforced at the beginning and after every 5 practice trials.	Behavioral: Instructions to perform a motor task (external vs. internal focus instructions); During the balance task, the participants will receive instructions to focus on external targets (external focus group) vs. movement of the body (internal focus group).
Active Comparator: Amputees (Internal Focus); Participants in this group will receive the internal focus instruction on where to direct their attention while training to perform the balance task. During training, the assigned instruction will be reinforced at the beginning and after every 5 practice trials.	Behavioral: Instructions to perform a motor task (external vs. internal focus instructions); During the balance task, the participants will receive instructions to focus on external targets (external focus group) vs. movement of the body (internal focus group).
Experimental: Diabetes (External Focus); Participants in this group will receive the external focus instruction on where to direct their attention while training to perform the balance task. During training, the assigned instruction will be reinforced at the beginning and after every 5 practice trials.	Behavioral: Instructions to perform a motor task (external vs. internal focus instructions); During the balance task, the participants will receive instructions to focus on external targets (external focus group) vs. movement of the body (internal focus group).
Active Comparator: Diabetes (Internal Focus); Participants in this group will receive the internal focus instruction on where to direct their attention while training to perform the balance task. During training, the assigned instruction will be reinforced at the beginning and after every 5 practice trials.	Behavioral: Instructions to perform a motor task (external vs. internal focus instructions); During the balance task, the participants will receive instructions to focus on external targets (external focus group) vs. movement of the body (internal focus group).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in balance performance	During each 30-second balance practice trial, time in balance which is defined as when the balance platform is within 5 degrees from horizontal will be measured in seconds. A longer time in balance (up to 30 seconds) indicates better balance performance.	Throughout the training period (2 days, up to 40 trials) and during the post-training tests
Change in balance performance	During each balance practice trial, average deviation of balance platform angle from horizontal will be measured in degrees. Smaller deviation from horizontal indicates better balance performance.	Throughout the balance training period (2 days, up to 40 trials) and during the post-training tests

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fall recovery performance	Rate of successful recovery from 10 trials of simulated tripping/slipping perturbation during walking on a treadmill will be measured in percentage. Higher percentage of successful recovery indicates better fall recovery performance.	Before and after balance training. The after training assessment will be conducted 2-10 days after the conclusion of the balance training.
Change in fall recovery performance	Trunk flexion angle during slipping/tripping (degrees). Previous studies have shown that smaller trunk angle during simulated tripping/slipping is associated with successful fall recovery. Smaller trunk flexion angle indicates better fall recovery performance.	Before and after the 2-day balance training. The after training assessment will be conducted 2-10 days after the conclusion of the balance training.
Change in fall recovery performance	Trunk angular velocity during slipping/tripping (degree/second). Previous studies have shown that slower trunk angle change (i.e. lower trunk angular velocity) during simulated tripping/slipping is associated with successful fall recovery. Slower trunk angular velocity indicates better fall recovery performance.	Before and after the 2-day balance training. The after training assessment will be conducted 2-10 days after the conclusion of the balance training.
Change in patient's self-reported outcomes	Self-efficacy regarding the performance of the balance task is assessed using a 4-question survey. An example question is: "How confident are you that you can keep yourself in balance for 15 out of 30 seconds?". Participant's response to each question is measured using a 0-10 scale. Higher confidence indicates greater self-efficacy.	Throughout the balance training period (2 days, assessed every 5 practice trials).

Collaborators and Investigators

• Sponsor: University of Nevada, Las Vegas
• Collaborators: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
• Investigators: Principal Investigator: Szu-Ping Lee, PhD, University of Nevada, Las Vegas

Publications and helpful links

General Publications

• Chiviacowsky S, Wulf G, Wally R. An external focus of attention enhances balance learning in older adults. Gait Posture. 2010 Oct;32(4):572-5. doi: 10.1016/j.gaitpost.2010.08.004. Epub 2010 Sep 17.

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2019
• Primary Completion (Anticipated): December 31, 2023
• Study Completion (Anticipated): June 30, 2024

Study Registration Dates

• First Submitted: June 4, 2019
• First Submitted That Met QC Criteria: June 17, 2019
• First Posted (Actual): June 18, 2019

Study Record Updates

• Last Update Posted (Actual): July 28, 2022
• Last Update Submitted That Met QC Criteria: July 27, 2022
• Last Verified: July 1, 2022

More Information

Terms related to this study

• Keywords: Diabetes; Balance; Attentional Focus; Motor Learning; Limb Loss
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Nervous System Diseases; Endocrine System Diseases; Diabetes Complications; Neuromuscular Diseases; Peripheral Nervous System Diseases; Diabetes Mellitus; Diabetic Neuropathies
• Other Study ID Numbers: 1299365; 1K01HD091449-01A1 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No
• IPD Plan Description: The individual participant data (IPD) collected in this study is specific to the study protocol only. Sharing of the IPD to other researchers would pose a risk to participant privacy, and is not scientifically merited.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No