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Completed

NCT Number: NCT03617185

Effect of Exercise and Surgical Weight Loss on Polyneuropathy

The purpose of this research study is to evaluate how exercise and surgical weight loss affect how likely an individual is to develop peripheral neuropathy and other neurologic complications.

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Key information

About this study

The length of this study, including screening is approximately 24 months. Patients at Bariatric Surgery Clinics will be recruited for this study. Both patients that decide to undergo bariatric surgery, and those that do not undergo surgery will be enrolled. Patients will be randomized to either a high intensity interval training (HIIT) or standard exercise regimen after eligibility is confirmed and the baseline visit is complete. All patients will complete follow-up appointments at 3 month, 12 months and 24 months. Patients that are randomized to the HIIT program will compete 2 supervised and 1 unsupervised training sessions a week for 24 months.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Attending a bariatric surgery clinic
  • BMI > 35 with one comorbid condition present or BMI > 40 without comorbid conditions present
  • Willing and capable to sign the Institutional Review Board (IRB) approved consent form and cooperate with the medical procedures for the study duration
  • Willing to accept random treatment assignment to HIIT or routine exercise counseling

Exclusion criteria

  • History of distal symmetric polyneuropathy (DSP) from causes other than diabetes and/or the metabolic syndrome as determined through medical history, family history, history of medications, occupational history, history of exposure to toxins, physical and neurological examinations;
  • Use of warfarin, heparin, or other anticoagulants, which would increase the risk of complications from skin biopsy
  • Contraindication to HIIT participation including a failed exercise stress test
  • Participation in an experimental medication trial within 3 months of starting the study
  • Undergoing therapy for malignant disease other than basal-cell or squamous-cell skin cancer
  • Medical or psychiatric reason for not being a surgical candidate
  • Requiring a walking assist device;
  • Currently smoking

Treatment and study plan

High Intensity Interval Training (HIIT)

Other

Patients will complete a HIIT training protocol of a total of 10 x 1 min intervals at 90% heart rate (HR) max. They will continue this training protocol, 3 sessions a week (2 supervised and 1 unsupervised), for 24 months.

Routine Exercise

Other

Patients will receive counseling regarding exercise as a routine part of their participation in the bariatric surgery clinic. Specifically, they are counseled to participate in 60 min of aerobic exercise daily in addition to 2-3 non-consecutive days of strength training workouts every wk. Patients are encouraged to contact the bariatric conditioning program, obtain a gym membership, purchase exercise equipment, join a walking group, and/or sign up for fitness classes (employer or city parks and recreation).

bariatric surgery

Procedure

Patients will undergo bariatric surgery as part of their routine care

Primary outcomes

  1. Intraepidermal Nerve Fiber Density (IENFD) at the Proximal Thigh

    Time frame: Baseline, 3 months, 12 months and 24 months

    Intraepidermal Nerve Fiber Density (IENFD) as assessed by 3mm skin biopsies at the proximal thigh.

Secondary outcomes

  1. Intraepidermal Nerve Fiber Density (IENFD) at Distal Leg.

    Time frame: Baseline, 3 months, 12 months and 24 months

    Intraepidermal Nerve Fiber Density (IENFD) as assessed by 3mm skin biopsies at the distal leg.

  2. Corneal Confocal Microscopy (CCM) - Fiber Density

    Time frame: Baseline, 3 month, 12 months and 24 months

    Non-invasive imaging technique of the corneal nerves to quantify nerve density and morphology.

    Corneal Nerve Fiber Density are quantified by fibers/mm2, a higher number represents a higher density of fibers. Lower numbers indicate worse neuropathy.

  3. Corneal Confocal Microscopy (CCM) - Branch Density

    Time frame: Baseline, 3 month, 12 months and 24 months

    Non-invasive imaging technique of the corneal nerves to quantify nerve density and morphology.

    Corneal Nerve Branch Density are quantified by branches/mm2, a higher number represents a higher density of branches. Lower numbers indicate worse neuropathy.

  4. Corneal Confocal Microscopy (CCM) - Fiber Length

    Time frame: Baseline, 3 month, 12 months and 24 months

    Non-invasive imaging technique of the corneal nerves to quantify nerve density and morphology.

    Corneal Nerve Fiber Length are quantified by mm/mm2, a higher number represents a higher total length of fibers. Lower numbers indicate worse neuropathy .

  5. Corneal Confocal Microscopy (CCM) - Tortuosity Coefficient

    Time frame: Baseline, 3 month, 12 months and 24 months

    Non-invasive imaging technique of the corneal nerves to quantify nerve density and morphology.

    Tortuosity Coefficient represents the total tortuosity (twisting/bending of nerves). As a coefficient the value is unitless, a higher value represents greater tortuosity. Lower numbers indicate worse neuropathy.

  6. 24-2 Frequency Doubling Technology (FDT) - Mean Deviation

    Time frame: Baseline, 3 month, 12 months and 24 months

    24-2 FDT was used to evaluate retinopathy using visual field deficits. Mean Deviation is presented below.

    Mean deviation is the average difference from normal expected value in the patients' particular age group. Lower values indicate more visual deficit. Higher values indicate fewer visual deficit.

  7. 24-2 Frequency Doubling Technology (FDT) - Foveal Sensitivity dB

    Time frame: Baseline, 3 month, 12 months and 24 months

    24-2 FDT was used to evaluate retinopathy using visual field deficits. Foveal sensitivity is presented below.

    Foveal sensitivity is the measurement of the fovea's light detection ability. Lower values suggest visual field deficits.

  8. 24-2 Frequency Doubling Technology (FDT) - Pattern SD

    Time frame: Baseline, 3 month, 12 months and 24 months

    24-2 FDT was used to evaluate retinopathy using visual field deficits. Pattern SD (PSD) is presented below.

    PSD provides information about localized loss. A higher PSD indicates a non-uniform sensitivity loss and visual field deficit.

  9. Retinal Fundus Photography

    Time frame: Baseline, 3 month, 12 months and 24 months

    As assessed by fundus photographs, participants were identified as either having retinopathy or not having retinopathy. Data is shown as number of people with retinopathy at a particular study visit.

  10. Nerve Conduction Study (NCS) - Latency

    Time frame: Baseline and 24 months

    Latency measures the time in millisecond between stimulation and the recording electrode. Was performed on sural, peroneal, and tibial nerves. No response and abnormal values indicate neuropathy.

    • Peroneal: 0 - No response, >6.5 - Abnormal
    • Sural: 0 - No response, >4.5 - Abnormal
    • Tibial: 0 - No response, >6.1 - Abnormal
  11. Nerve Conduction Study (NCS) - Motor Amplitude

    Time frame: Baseline and 24 months

    Amplitude measures the height of electrical signal (waveform) in millivolts produced by the stimulated motor nerve. Was performed on peroneal, and tibial nerves. No response and abnormal values indicate neuropathy.

    • Peroneal: 0 - No response, < 1.1 - Abnormal
    • Tibial: 0 - No response, <1.1 - Abnormal
  12. Nerve Conduction Study (NCS) - Sensory Amplitude

    Time frame: Baseline and 24 months

    Amplitude measures the height of electrical signal (waveform) in microvolts produced by the stimulated sensory nerve. Was performed on sural nerve. No response and abnormal values indicate neuropathy.

    • Sural: 0 - No response, <4 - Abnormal
  13. Nerve Conduction Study (NCS) - CV

    Time frame: Baseline and 24 months

    Conduction velocity (V) measures the speed (m/s) at which the electrical impulse travels along the nerve. Was performed on peroneal nerves. No response and abnormal values indicate neuropathy. Abnormal values are <36 or 39, depending on whether certain criteria applied to the participant. Data was not analyzed separately.

  14. Nerve Conduction Study (NCS) - F Wave Index

    Time frame: Baseline and 24 months

    F wave index measures the time in millisecond between stimulation at a distal (near the muscle) point and for the stimulus to travel to the spinal cord and back, allowing to assess the entire length of the nerve.

    Was performed on peroneal, and tibial nerves. No response and abnormal values indicate neuropathy.

    • Peroneal: 0 - No response, >55 - Abnormal
    • Tibial: 0 - No response, >55 - Abnormal
  15. Cardiac Autonomic Neuropathy Testing-Deep Breathing/Exhalation to Inhalation (E:I) Ratio

    Time frame: Baseline and 24 months

    Deep breathing/exhalation to inhalation (E:I) ratio were evaluated using PS monitor software. Values < 1 are abnormal, indicative of cardiovascular autonomic neuropathy

  16. Cardiac Autonomic Neuropathy Testing (30:15 Ratio)

    Time frame: Baseline and 24 months

    Postural change-30:15 ratio was evaluated using PS monitor software. Values < 1 are abnormal, indicative of cardiovascular autonomic neuropathy

  17. Cardiac Autonomic Neuropathy Testing (Valsalva Ratio)

    Time frame: Baseline and 24 months

    Valsalva ratio was evaluated using PS monitor software. Values <= 1.10 are abnormal, indicative of cardiovascular autonomic neuropathy

  18. Participants With Probable Polyneuropathy as Defined by the Toronto Definition of Probable Neuropathy

    Time frame: 24 months

    Toronto definition of probable neuropathy is having at least 2 out of 3 of the following: abnormal sensory examination, reflexes, and patient-reported symptoms. Data is reported as number of participants who, under the Toronto definition, were identified as having probable polyneuropathy.

  19. Michigan Neuropathy Screening Instrument (MNSI)

    Time frame: Baseline, 3 month, 12 months and 24 months

    MNSI questionnaire is scored from 0-15, score > 4 indicate neuropathy, higher scores indicate worse neuropathy.

    A score of 1 point is given for answers of "yes" for questions 1-6, 8-12, 14, and 15 and "no" for questions 7 and 13.

  20. Michigan Neuropathy Screening Instrument (MNSI) - Exam

    Time frame: Baseline, 3 month, 12 months and 24 months

    MNSI exam is scored from 0-8, score >= 2.5 indicate neuropathy. Higher scores indicate worse neuropathy.

  21. Michigan Neuropathy Screening Instrument (MNSI) - Index

    Time frame: Baseline, 3 month, 12 months and 24 months

    The Michigan Neuropathy Screening Instrument (MNSI) index is a weighted composite score computed using the sum of the b-coefficients for all items within the MNSI questionnaire (15 questions) and MNSI exam (4 physical/visual exam).

    Range: -0.93, 7.39 Values > 2.5407 are indicative of clinical neuropathy

  22. Utah Early Neuropathy Score (UENS)

    Time frame: Baseline, 3 month, 12 months and 24 months

    UENS is a composite score with five sections measuring multiple clinical measures of nerve injury. Sections are scored separately for each side (Right vs Left), and the total score is the sum across everything. Range: 0-42, higher score represents more severe polyneuropathy.

  23. Modified Toronto Neuropathy Score (mTNS)

    Time frame: Baseline, 3 month, 12 months and 24 months

    mTNS is a scale of 0-33 that measures neuropathy symptoms and exam findings. Higher scores indicate more severe polyneuropathy.

  24. Survey of Autonomic Symptoms (SAS)

    Time frame: Baseline, 3 month, 12 months and 24 months

    SAS evaluates the presence and magnitude of autonomic symptoms. Total impact score ranges from 0-60 (or up to 55 for participants to whom certain criteria did not apply). Higher score indicates worse autonomic neuropathy

  25. Diabetic Neuropathy Score (DNS)

    Time frame: Baseline, 3 month, 12 months and 24 months

    DNS is a questionnaire of neuropathy symptoms. Score ranges 0-4, >/=1 indicates polyneuropathy. 0 indicates no polyneuropathy.

  26. Short Form McGill Pain Questionnaire

    Time frame: Baseline, 3 months, 12 months, 24 months

    Sum of the sensory score (0-30) and affective score (0-15) for a total score of 0-45. A higher score represents greater pain present.

  27. Numerical Rating Scale for Pain

    Time frame: Baseline, 3 months, 12 months, 24 months

    Participant reported pain scale with range 0-10, higher score indicates more pain.

  28. Neuropathy Quality of Life (NeuroQOL)

    Time frame: Baseline, 3 months, 12 months, and 24 months

    Neuropathy Quality of Life (NeuroQOL) evaluates symptoms and function in regard to quality of life over the past four weeks. Range 1-15, higher score indicates neuropathy having a greater impact on quality of life.

  29. 8 Foot Get Up and Go Test

    Time frame: Baseline, 3 months, 12 months, and 24 months

    This test measures in seconds how long it takes the participant to stand up from a seated position, walk around a cone places 8 feet away, and return to the chair and sit down. Less time indicates better speed, agility, and balance when moving.

  30. Berg Balance Scale

    Time frame: Baseline, 3 months, 12 months, and 24 months

    Berg Balance Scale measures participants' ability to balance and avoid falls. Scores range from 0-56, higher score indicates less likely to fall.

  31. Modified Falls Efficacy Scale - Fall Evaluation

    Time frame: Baseline, 3 months, 12 months, and 24 months

    Patient response indicating if they have fallen in the last year. Data is shown as number of people who have fallen in the last year.

  32. Neurothesiometer

    Time frame: Baseline, 3 months, 12 months, and 24 months

    Neurothesiometer is placed on the bottom of the great toe, and slowly increased until participant reports they can feel the vibration. The greater the microns, the less feeling the participant has, suggestive of worse sensory function.

    Value > 25 Microns is indicative of neuropathy. There is no known maximum range. Lower values indicate better sensory function.

  33. NIH Toolbox Cognitive Battery

    Time frame: Baseline and at 24 months

    NIH Toolbox Cognition Fluid (Range: 0-100) - Composite score derived as an average across five cognitive domains.

    It's a fully adjusted T-score comparing the participant to a nationally representative sample, stratified by age and other demographics.

    Individual domain scores are fully adjusted T score with range 0-100 and measures the following-

    • Inhibitory Control and Attention - executive function, attention .
    • Dimensional Change Card Sort - executive function
    • Picture Sequence Memory - episodic memory
    • List Sorting Working Memory - working memory
    • Pattern Comparison - processing speed

    A T-score of 50 represents the population mean. A score of 60 indicates that the participant is 1 SD above the national average for individuals with similar demographic characteristics

    Higher scores reflect better cognitive functionality. No set clinical threshold, scores above mean indicate above average cognition for a given age group.

  34. Rey Auditory Verbal Learning Test

    Time frame: Baseline and at 24 months

    Used to evaluate verbal learning and memory using a list of 15 unrelated words presented to the participant over repeat trial.

    Includes 3 independent scales:

    • Auditory Learning (Total recall) - Measures memory and learning ability. Raw score range (0- 75)
    • Delayed Recall - Measures long term memory retention. Raw score range (0-15)
    • Recognition - Measures ability to recognize previously learned information. Raw score range (0-15).
    • Raw scores were converted to age-standardized Z-scores using 10-year age bands (e.g., 20-29, 30-39, 40-49, etc.), with a mean of 0 and standard deviation of 1.
    • A Z-score of 0 represents the population mean
    • For each scale, scores above 0 are better. Standard deviations above the mean indicates a better learning and memory ability for a given age group.

    No set clinical threshold, scores above mean indicate above average cognition for a given age group.

Sponsors and collaborators

Lead sponsor

University of Michigan

Other

Collaborators

  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Registry information

Official study title

The Effect of High Intensity Interval Training and Surgical Weight Loss on Distal Symmetric Polyneuropathy Outcomes

Important dates

Study start
2018
Primary completion
2024
Study completion
2024
First posted
Aug 6, 2018
Registry last updated
Feb 24, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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