Peripheral Arterial DiseaseNCT06389149
Leg Exercise Assistive Paddling (LEAP) Therapy for Peripheral Artery Disease
A study testing LEAP therapy and no LEAP therapy in people with Peripheral Arterial Disease and Peripheral Vascular Disease, run by University of Nebraska at 1 site in United States.
Trial summary
The purpose of this study is to test the effects of leg exercise assistive paddling (LEAP) therapy during prolonged sitting (PS) on vascular and functional performance in those with peripheral artery disease (PAD) and age-matched controls. Read more about this study
- Who is it for?
- Ages 55 to 85 yearsHealthy volunteers can take part
- Conditions the study is for
- Peripheral Arterial Disease, Peripheral Vascular Disease, Peripheral Artery Occlusive Disease
- What is being tested?
- LEAP therapy and no LEAP therapy
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 0 participants
- Where
- 1 siteUnited States
- Study dates
- 16 Aug 2024to Aug 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 55 to 85 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- PAD subjects:
- Able to provide written informed consent
- 50-85 years of age
- Diagnosed with Peripheral Arterial Disease (PAD) Fontaine stage II-III
- Women must be postmenopausal (cessation of menses for > 24 months)
- History of exercise-induced claudication
Show all 12Show fewer
- Free of ulcers, gangrene, or necrosis of the foot, Fontaine stage IV PAD
- Age-matched control subjects:
- Able to provide written informed consent
- 50-85 years of age
- No evidence of peripheral occlusive disease, ankle-brachial index > 0.90
- Women must be postmenopausal (cessation of menses for > 24 months)
Who cannot join
- PAD subjects:
- Pain at rest and/or tissue loss from Peripheral Arterial Disease (PAD), Fontaine stage IV PAD
- Acute lower extremity ischemic event secondary to thromboembolic disease or acute trauma
- Limited walking capacity from conditions other than PAD
- Have not had a physical exam to assess exercise limitations in the past year
- Pregnant or nursing
Show all 14Show fewer
- Kidney disease or type II diabetes mellitus
- Age-matched control subjects:
- Positive diagnosis of Peripheral Arterial Disease (PAD)
- Any exercise limitations as determined at last physical exam, at least 1 year prior to study
- Have not had a physical exam to assess exercise limitations in the past year
- Limited walking capacity from musculoskeletal injury
- Pregnant or nursing
- Kidney disease or type II diabetes mellitus
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Nebraska - Omaha
Omaha, Nebraska, 68182
About this study
The purpose of this study is to test the effects of leg exercise assistive paddling (LEAP) therapy during prolonged sitting (PS) on vascular and functional performance in those with peripheral artery disease (PAD) and age-matched controls. LEAP therapy is a novel application of passive limb movement to enhance blood flow through the legs without muscular contractions. Specifically, LEAP therapy is the rotational passive movement of the lower leg about the knee from 90 to 180 degrees of rotation at a cadence of 1Hz. Previous literature has indicated that this movement pattern can produce robust increases in blood flow in the passively moved limb in healthy individuals, and passive limb movement may protect vascular function during PS. However, the impact of LEAP therapy to improve blood flow in the legs of those with PAD during PS is unknown.
Participants will participate in a randomized cross-over design study with 2 visits (LEAP therapy and no LEAP therapy). For the first visit, participants will be randomly allocated to receive LEAP therapy during 2.5 hours of PS or not. For the second visit, participants will sit for 2.5 hours and will receive the condition that they did not previously receive. Before and after PS, the following measurements will be made: flow-mediated dilation of the popliteal and brachial arteries, arterial stiffness with tonometry techniques, microvascular vasodilatory capacity and skeletal muscle metabolic rate with near-infrared spectroscopy, autonomic nervous system function, and there will be blood drawn from the antecubital vein. After PS, participants will participate in a graded exercise test to assess functional walking capacity. Finally, during PS, near-infrared spectroscopy on the calf muscles and electrocardiogram will be collected continuously to monitor muscle oxygen availability and autonomic activity, respectively.
Read the detailed description
Epidemiological studies suggest that over 200 million adults worldwide currently have peripheral artery disease (PAD), which is the buildup of atherosclerotic plaques in the arteries of the legs and is associated with high rates of morbidity and mortality. The population most suspectable to PAD is older adults, with the incidence of PAD increasing exponentially after the age of 50. This sharp age demarcation makes PAD particularly concerning for Western societies, where the proportion of older adults is steadily rising, thereby making PAD a large potential future burden to healthcare systems and economies alike. Therefore, the discovery and development of interventions to prevent and treat PAD is a top biomedical concern that has a high future return on investments.
Exercise and physical activity are known to improve functional capacity in those with PAD. In fact, exercise therapies have been reported to be as effective as revascularization surgeries at restoring functional walking capacity. However, despite the major benefits of exercise, adherence to supervised exercise therapies is low, and those with PAD report being highly sedentary, which is likely attributed to the muscle pain they experience during exercise. Elevated sedentarism among those with PAD is concerning, since the investigators and others have demonstrated that sedentarism in the form of prolonged sitting (i.e., sitting for >1 hour) can 1) increase arterial stiffness, 2) reduce the vasodilatory capacities of the macro- and micro-vasculatures, 3) reduce skeletal muscle metabolism, and 4) reduce shear stress in the large conduit arteries, all of which are known to promote atherosclerosis. Importantly, since those with PAD already demonstrate impaired vascular function, they may be more suspectable to the negative effects of prolonged sitting on vascular health. Remarkably, the investigators have shown that passive movement of the legs (i.e., limb movement without active muscle contractions) can prevent vascular decline during prolonged sitting. Therefore, passive limb movement (PLM) therapies may be an effective strategy to provide light physical activity to those with PAD and protect them against the deleterious effects of sedentarism. Importantly, since PLM does not require active skeletal muscle work, it is likely that PLM will be well-tolerated by those with PAD, and adherence to PLM therapies may be enhanced compared to traditional exercise. Therefore, developing methods that mimic exercise with PLM may be an effective front-line strategy to improve functional capacity, vascular function, and quality of life in those with PAD.
Unfortunately, there are currently no available methods that provide PLM therapy for those with PAD, and it is not known whether PLM therapies can protect the vasculature of those with PAD during PS. Therefore, the investigators have developed the Leg Exercise Assistive Paddling (LEAP) protocol to provide PLM therapy during PS. LEAP therapy is a standardized protocol for those with PAD that provides PLM by rotating the lower leg about the knee from 90-180° at a cadence of 1Hz for 1 minute every 10 minutes. These parameters have been chosen for LEAP therapy because of the robust increases in leg blood flow elicited by these parameters. The investigators hypothesize that LEAP therapy prevents vascular and functional decline in those with PAD during PS. Therefore, the development and validation of LEAP therapy is expected to promote PLM therapies as a new interventional strategy to improve vascular and functional capacities in those with PAD.
Participants will participate in a randomized cross-over design study with 2 visits (LEAP therapy and no LEAP therapy). For the first visit, participants will be randomly allocated to receive LEAP therapy during 2.5 hours of PS or not. For the second visit, participants will sit for 2.5 hours and will receive the condition that they did not previously receive. Before and after PS, the following measurements will be made: flow-mediated dilation of the popliteal and brachial arteries, arterial stiffness with tonometry techniques, microvascular vasodilatory capacity and skeletal muscle metabolic rate with near-infrared spectroscopy, autonomic nervous system function, and there will be blood drawn from the antecubital vein. After PS, participants will participate in a graded exercise test to assess functional walking capacity. Finally, during PS, near-infrared spectroscopy on the calf muscles and electrocardiogram will be collected continuously to monitor muscle oxygen availability and autonomic activity, respectively.
- Conditions
- Peripheral Arterial Disease, Peripheral Vascular Disease, Peripheral Artery Occlusive Disease, Peripheral Artery Disease
- Being tested
- LEAP therapy, no LEAP therapy
- Medical subject headings
- Peripheral Arterial Disease, Peripheral Vascular Diseases, Peripheral Arterial Occlusive Disease 1
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LEAP therapyOther
Knee bending from 90°-180° at 1Hz for 1 minute every 10 minutes during 2.5 hours of prolonged sitting
no LEAP therapyOther
2.5 hours of uninterrupted prolonged sitting (no movement)
| Study group | Role | What they receive |
|---|---|---|
| Control: LEAP therapy, then no LEAP therapy | Experimental | Participants will perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. Receives: Other: LEAP therapy; Other: no LEAP therapy |
| Control: No LEAP therapy, then LEAP therapy | Experimental | Participants will perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. Receives: Other: LEAP therapy; Other: no LEAP therapy |
| PAD: LEAP therapy, then no LEAP therapy | Experimental | Participants with peripheral artery disease will perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. Receives: Other: LEAP therapy; Other: no LEAP therapy |
| PAD: No LEAP therapy, then LEAP therapy | Experimental | Participants with peripheral artery disease will perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. Receives: Other: LEAP therapy; Other: no LEAP therapy |
What is being measured
The primary outcome is the main question the study is designed to answer.
Macrovascular Endothelial Function
Macrovascular endothelial function will be measured non-invasively using the flow-mediated dilation (FMD) technique in the brachial and popliteal arteries using a Doppler ultrasound. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Microvascular Vasodilatory Capacity
Microvascular vasodilatory capacity will be measured as the near-infrared spectroscopy (NIRS) reoxygenation rate in the medial gastrocnemius after an arterial occlusion. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Femoral and Popliteal Artery Blood Flow
Femoral and popliteal artery blood flow will be measured in both legs using Doppler ultrasound. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Walking capacity
Physical walking capacity will be measured during the Gardner treadmill protocol. Participants will walk on a treadmill at 2.0 miles per hour (mph). Grade will began at zero and will be increased by two percent every two minutes. Participants unable to walk at least 2.0 mph begin walking at 0.5 mph and their speed is increased by 0.50 mph every two minutes until the participant reaches 2.0 mph. After reaching 2.0 mph, treadmill grade is increased by two percent every two minutes. Participants are asked to continue walking without stopping until they cannot continue because of leg symptoms, exhaustion, or other symptoms. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Autonomic Function
Autonomic nervous system function will be measured non-invasively using heart rate variability via the head-up tilt test. Raw R-R interval data will be converted to time frequency domain with the wavelet transform across the frequency intervals 0.04-0.15 Hz (low-frequency, (LF)) and 0.15-0.4 Hz (high-frequency, HF). Units for both will be expressed as ms^2. Final outcome measure will be the ratio of LF/HF, which is a unitless ratio to indicate sympathetic-to-parasympathetic nervous system function. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Autonomic Activity
Autonomic activity will be measured with a 3-lead ECG system (7700 Series, IvyBiomedical Systems Inc., Branford, CT) and will be used to continuously collect heart electrical activity during prolonged sitting with LEAP therapy, and prolonged sitting without LEAP therapy. Raw R-R interval data will be converted to time frequency domain with the wavelet transform across the frequency intervals 0.04-0.15 Hz (low-frequency, (LF)) and 0.15-0.4 Hz (high-frequency, HF). Units for both will be expressed as ms^2. Final outcome measure will be the ratio of LF/HF, which is a unitless ratio to indicate sympathetic-to-parasympathetic nervous system function.
Measured: Day 1: during the condition. Day 7: during the condition
Arterial Stiffness
Peripheral and central arterial stiffness will be assessed non-invasively using pulse-wave velocity via the applanation tonometry technique. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Muscle Oxygenation
A near-infrared spectroscopy (NIRS) sensor will be adhered on the skin above the belly of the medial gastrocnemius muscle to non-invasively assess muscle oxygenation during the entire prolonged sitting bout with LEAP therapy, and the entire prolonged sitting bout without LEAP therapy.
Measured: Day 1: during the condition. Day 7: during the condition
Peripheral blood mononuclear cell mitochondrial function
Participants will have blood drawn from an antecubital vein, which will be used to isolate peripheral blood mononuclear cells (PBMCs) and assess their mitochondrial function. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Measured: Day 1: before and after condition. Day 7: before and after condition.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Apr 2024
- Study start16 Aug 2024
- Primary completionAug 2026 (estimated)
- Study completionAug 2026 (estimated)
Why it stopped: PI has left institute and study could not be continued.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (54)Papers the sponsor has linked to this study.
- Other trials for Peripheral Arterial DiseaseStudies of the same condition, open and under way.
- More trials run by University of NebraskaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- There will be a peripheral artery disease (PAD) group and an age-matched healthy control group. Within each of these groups will be a 1:1 randomized, crossover study design.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 0 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Nebraska
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Song-Young Park, PhD, Principal investigator, University of Nebraska
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06389149
- Sponsor's protocol ID
- 0165-24-FB
- Status last verified
- Aug 2026
- First submitted
- 24 Apr 2024
- Last updated
- 21 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: There is no plan to share individual participant data with other researchers.
Publications
Song P, Rudan D, Zhu Y, Fowkes FJI, Rahimi K, Fowkes FGR, Rudan I. Global, regional, and national prevalence and risk factors for peripheral artery disease in 2015: an updated systematic review and analysis. Lancet Glob Health. 2019 Aug;7(8):e1020-e1030. doi: 10.1016/S2214-109X(19)30255-4.
PubMed 31303293Golomb BA, Dang TT, Criqui MH. Peripheral arterial disease: morbidity and mortality implications. Circulation. 2006 Aug 15;114(7):688-99. doi: 10.1161/CIRCULATIONAHA.105.593442. No abstract available.
PubMed 16908785Matsushita K, Sang Y, Ning H, Ballew SH, Chow EK, Grams ME, Selvin E, Allison M, Criqui M, Coresh J, Lloyd-Jones DM, Wilkins JT. Lifetime Risk of Lower-Extremity Peripheral Artery Disease Defined by Ankle-Brachial Index in the United States. J Am Heart Assoc. 2019 Sep 17;8(18):e012177. doi: 10.1161/JAHA.119.012177. Epub 2019 Sep 10.
PubMed 31500474Allison MA, Armstrong DG, Goodney PP, Hamburg NM, Kirksey L, Lancaster KJ, Mena-Hurtado CI, Misra S, Treat-Jacobson DJ, White Solaru KT; American Heart Association Council on Peripheral Vascular Disease; Council on Hypertension; and Council on Lifestyle and Cardiometabolic Health. Health Disparities in Peripheral Artery Disease: A Scientific Statement From the American Heart Association. Circulation. 2023 Jul 18;148(3):286-296. doi: 10.1161/CIR.0000000000001153. Epub 2023 Jun 15.
PubMed 37317860Kohn CG, Alberts MJ, Peacock WF, Bunz TJ, Coleman CI. Cost and inpatient burden of peripheral artery disease: Findings from the National Inpatient Sample. Atherosclerosis. 2019 Jul;286:142-146. doi: 10.1016/j.atherosclerosis.2019.05.026. Epub 2019 May 27.
PubMed 31170647Gerhard-Herman MD, Gornik HL, Barrett C, Barshes NR, Corriere MA, Drachman DE, Fleisher LA, Fowkes FG, Hamburg NM, Kinlay S, Lookstein R, Misra S, Mureebe L, Olin JW, Patel RA, Regensteiner JG, Schanzer A, Shishehbor MH, Stewart KJ, Treat-Jacobson D, Walsh ME. 2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2017 Mar 21;135(12):e686-e725. doi: 10.1161/CIR.0000000000000470. Epub 2016 Nov 13.
PubMed 27840332Regensteiner JG, Steiner JF, Hiatt WR. Exercise training improves functional status in patients with peripheral arterial disease. J Vasc Surg. 1996 Jan;23(1):104-15. doi: 10.1016/s0741-5214(05)80040-0.
PubMed 8558725McDermott MM, Dayanidhi S, Kosmac K, Saini S, Slysz J, Leeuwenburgh C, Hartnell L, Sufit R, Ferrucci L. Walking Exercise Therapy Effects on Lower Extremity Skeletal Muscle in Peripheral Artery Disease. Circ Res. 2021 Jun 11;128(12):1851-1867. doi: 10.1161/CIRCRESAHA.121.318242. Epub 2021 Jun 10.
PubMed 34110902Fakhry F, Rouwet EV, den Hoed PT, Hunink MG, Spronk S. Long-term clinical effectiveness of supervised exercise therapy versus endovascular revascularization for intermittent claudication from a randomized clinical trial. Br J Surg. 2013 Aug;100(9):1164-71. doi: 10.1002/bjs.9207.
PubMed 23842830Dua A, Gologorsky R, Savage D, Rens N, Gandhi N, Brooke B, Corriere M, Jackson E, Aalami O. National assessment of availability, awareness, and utilization of supervised exercise therapy for peripheral artery disease patients with intermittent claudication. J Vasc Surg. 2020 May;71(5):1702-1707. doi: 10.1016/j.jvs.2019.08.238. Epub 2019 Nov 4.
PubMed 31699514Divakaran S, Carroll BJ, Chen S, Shen C, Bonaca MP, Secemsky EA. Supervised Exercise Therapy for Symptomatic Peripheral Artery Disease Among Medicare Beneficiaries Between 2017 and 2018: Participation Rates and Outcomes. Circ Cardiovasc Qual Outcomes. 2021 Aug;14(8):e007953. doi: 10.1161/CIRCOUTCOMES.121.007953. Epub 2021 Jul 23. No abstract available.
PubMed 34293930Hernandez H, Myers SA, Schieber M, Ha DM, Baker S, Koutakis P, Kim KS, Mietus C, Casale GP, Pipinos II. Quantification of Daily Physical Activity and Sedentary Behavior of Claudicating Patients. Ann Vasc Surg. 2019 Feb;55:112-121. doi: 10.1016/j.avsg.2018.06.017. Epub 2018 Aug 13.
PubMed 30114505Gerage AM, Correia MA, Oliveira PML, Palmeira AC, Domingues WJR, Zeratti AE, Puech-Leao P, Wolosker N, Ritti-Dias RM, Cucato GG. Physical Activity Levels in Peripheral Artery Disease Patients. Arq Bras Cardiol. 2019 Jul 29;113(3):410-416. doi: 10.5935/abc.20190142. eCollection 2019.
PubMed 31365605McDermott MM, Greenland P, Liu K, Guralnik JM, Celic L, Criqui MH, Chan C, Martin GJ, Schneider J, Pearce WH, Taylor LM, Clark E. The ankle brachial index is associated with leg function and physical activity: the Walking and Leg Circulation Study. Ann Intern Med. 2002 Jun 18;136(12):873-83. doi: 10.7326/0003-4819-136-12-200206180-00008.
PubMed 12069561Credeur DP, Miller SM, Jones R, Stoner L, Dolbow DR, Fryer SM, Stone K, McCoy SM. Impact of Prolonged Sitting on Peripheral and Central Vascular Health. Am J Cardiol. 2019 Jan 15;123(2):260-266. doi: 10.1016/j.amjcard.2018.10.014. Epub 2018 Oct 22.
PubMed 30409414
Study at a glance
From the registry record, last updated by the sponsor on 21 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Leg Exercise Assistive Paddling (LEAP) Therapy for Peripheral Artery Disease
- ClinicalTrials.gov ID
- NCT06389149
- Acronym / sponsor ID
- 0165-24-FB
- Conditions
- Peripheral Arterial Disease, Peripheral Vascular Disease, Peripheral Artery Occlusive Disease, Peripheral Artery Disease
- Study type
- Interventional
- Recruitment status
- WithdrawnReason stopped: PI has left institute and study could not be continued.
- Enrolment
- 0 participants (actual)
- Lead sponsor
- University of NebraskaUniversity, hospital or other
- Study start
- 16 Aug 2024 (actual)
- Primary completion
- Aug 2026 (estimated)
- Study completion
- Aug 2026 (estimated)
- First posted
- 29 Apr 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to test the effects of leg exercise assistive paddling (LEAP) therapy during prolonged sitting (PS) on vascular and functional performance in those with peripheral artery disease (PAD) and age-matched controls. LEAP therapy is a novel application of passive limb movement to enhance blood flow through the legs without muscular contractions. Specifically, LEAP therapy is the rotational passive movement of the lower leg about the knee from 90 to 180 degrees of rotation at a cadence of 1Hz. Previous literature has indicated that this movement pattern can produce robust increases in blood flow in the passively moved limb in healthy individuals, and passive limb movement may protect vascular function during PS. However, the impact of LEAP therapy to improve blood flow in the legs of those with PAD during PS is unknown.
Participants will participate in a randomized cross-over design study with 2 visits (LEAP therapy and no LEAP therapy). For the first visit, participants will be randomly allocated to receive LEAP therapy during 2.5 hours of PS or not. For the second visit, participants will sit for 2.5 hours and will receive the condition that they did not previously receive. Before and after PS, the following measurements will be made: flow-mediated dilation of the popliteal and brachial arteries, arterial stiffness with tonometry techniques, microvascular vasodilatory capacity and skeletal muscle metabolic rate with near-infrared spectroscopy, autonomic nervous system function, and there will be blood drawn from the antecubital vein. After PS, participants will participate in a graded exercise test to assess functional walking capacity. Finally, during PS, near-infrared spectroscopy on the calf muscles and electrocardiogram will be collected continuously to monitor muscle oxygen availability and autonomic activity, respectively.
Detailed description
Epidemiological studies suggest that over 200 million adults worldwide currently have peripheral artery disease (PAD), which is the buildup of atherosclerotic plaques in the arteries of the legs and is associated with high rates of morbidity and mortality. The population most suspectable to PAD is older adults, with the incidence of PAD increasing exponentially after the age of 50. This sharp age demarcation makes PAD particularly concerning for Western societies, where the proportion of older adults is steadily rising, thereby making PAD a large potential future burden to healthcare systems and economies alike. Therefore, the discovery and development of interventions to prevent and treat PAD is a top biomedical concern that has a high future return on investments.
Exercise and physical activity are known to improve functional capacity in those with PAD. In fact, exercise therapies have been reported to be as effective as revascularization surgeries at restoring functional walking capacity. However, despite the major benefits of exercise, adherence to supervised exercise therapies is low, and those with PAD report being highly sedentary, which is likely attributed to the muscle pain they experience during exercise. Elevated sedentarism among those with PAD is concerning, since the investigators and others have demonstrated that sedentarism in the form of prolonged sitting (i.e., sitting for >1 hour) can 1) increase arterial stiffness, 2) reduce the vasodilatory capacities of the macro- and micro-vasculatures, 3) reduce skeletal muscle metabolism, and 4) reduce shear stress in the large conduit arteries, all of which are known to promote atherosclerosis. Importantly, since those with PAD already demonstrate impaired vascular function, they may be more suspectable to the negative effects of prolonged sitting on vascular health. Remarkably, the investigators have shown that passive movement of the legs (i.e., limb movement without active muscle contractions) can prevent vascular decline during prolonged sitting. Therefore, passive limb movement (PLM) therapies may be an effective strategy to provide light physical activity to those with PAD and protect them against the deleterious effects of sedentarism. Importantly, since PLM does not require active skeletal muscle work, it is likely that PLM will be well-tolerated by those with PAD, and adherence to PLM therapies may be enhanced compared to traditional exercise. Therefore, developing methods that mimic exercise with PLM may be an effective front-line strategy to improve functional capacity, vascular function, and quality of life in those with PAD.
Unfortunately, there are currently no available methods that provide PLM therapy for those with PAD, and it is not known whether PLM therapies can protect the vasculature of those with PAD during PS. Therefore, the investigators have developed the Leg Exercise Assistive Paddling (LEAP) protocol to provide PLM therapy during PS. LEAP therapy is a standardized protocol for those with PAD that provides PLM by rotating the lower leg about the knee from 90-180° at a cadence of 1Hz for 1 minute every 10 minutes. These parameters have been chosen for LEAP therapy because of the robust increases in leg blood flow elicited by these parameters. The investigators hypothesize that LEAP therapy prevents vascular and functional decline in those with PAD during PS. Therefore, the development and validation of LEAP therapy is expected to promote PLM therapies as a new interventional strategy to improve vascular and functional capacities in those with PAD.
Participants will participate in a randomized cross-over design study with 2 visits (LEAP therapy and no LEAP therapy). For the first visit, participants will be randomly allocated to receive LEAP therapy during 2.5 hours of PS or not. For the second visit, participants will sit for 2.5 hours and will receive the condition that they did not previously receive. Before and after PS, the following measurements will be made: flow-mediated dilation of the popliteal and brachial arteries, arterial stiffness with tonometry techniques, microvascular vasodilatory capacity and skeletal muscle metabolic rate with near-infrared spectroscopy, autonomic nervous system function, and there will be blood drawn from the antecubital vein. After PS, participants will participate in a graded exercise test to assess functional walking capacity. Finally, during PS, near-infrared spectroscopy on the calf muscles and electrocardiogram will be collected continuously to monitor muscle oxygen availability and autonomic activity, respectively.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
- Model description
- There will be a peripheral artery disease (PAD) group and an age-matched healthy control group. Within each of these groups will be a 1:1 randomized, crossover study design.
| Arm | Type | Receives |
|---|---|---|
| Control: LEAP therapy, then no LEAP therapy | Experimental | Other: LEAP therapy, Other: no LEAP therapyParticipants will perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. |
| Control: No LEAP therapy, then LEAP therapy | Experimental | Other: LEAP therapy, Other: no LEAP therapyParticipants will perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. |
| PAD: LEAP therapy, then no LEAP therapy | Experimental | Other: LEAP therapy, Other: no LEAP therapyParticipants with peripheral artery disease will perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. |
| PAD: No LEAP therapy, then LEAP therapy | Experimental | Other: LEAP therapy, Other: no LEAP therapyParticipants with peripheral artery disease will perform a bout of 2.5 hours of prolonged sitting without LEAP therapy. After a minimum period of 7 days, they will then perform a bout of 2.5 hours of prolonged sitting with LEAP therapy. |
Who may qualify
- Ages
- 55 to 85 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (12 listed)
- Able to provide written informed consent
- 50-85 years of age
- Diagnosed with Peripheral Arterial Disease (PAD) Fontaine stage II-III
- Women must be postmenopausal (cessation of menses for > 24 months)
- History of exercise-induced claudication
Key exclusion criteria (14 listed)
- Pain at rest and/or tissue loss from Peripheral Arterial Disease (PAD), Fontaine stage IV PAD
- Acute lower extremity ischemic event secondary to thromboembolic disease or acute trauma
- Limited walking capacity from conditions other than PAD
- Have not had a physical exam to assess exercise limitations in the past year
- Pregnant or nursing
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| LEAP therapyKnee bending from 90°-180° at 1Hz for 1 minute every 10 minutes during 2.5 hours of prolonged sitting | Other | Control: LEAP therapy, then no LEAP therapy, Control: No LEAP therapy, then LEAP therapy, PAD: LEAP therapy, then no LEAP therapy, PAD: No LEAP therapy, then LEAP therapy |
| no LEAP therapy2.5 hours of uninterrupted prolonged sitting (no movement) | Other | Control: LEAP therapy, then no LEAP therapy, Control: No LEAP therapy, then LEAP therapy, PAD: LEAP therapy, then no LEAP therapy, PAD: No LEAP therapy, then LEAP therapy |
Primary outcome
Macrovascular Endothelial Function
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Macrovascular endothelial function will be measured non-invasively using the flow-mediated dilation (FMD) technique in the brachial and popliteal arteries using a Doppler ultrasound. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Microvascular Vasodilatory Capacity
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Microvascular vasodilatory capacity will be measured as the near-infrared spectroscopy (NIRS) reoxygenation rate in the medial gastrocnemius after an arterial occlusion. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Femoral and Popliteal Artery Blood Flow
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Femoral and popliteal artery blood flow will be measured in both legs using Doppler ultrasound. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Walking capacity
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Physical walking capacity will be measured during the Gardner treadmill protocol. Participants will walk on a treadmill at 2.0 miles per hour (mph). Grade will began at zero and will be increased by two percent every two minutes. Participants unable to walk at least 2.0 mph begin walking at 0.5 mph and their speed is increased by 0.50 mph every two minutes until the participant reaches 2.0 mph. After reaching 2.0 mph, treadmill grade is increased by two percent every two minutes. Participants are asked to continue walking without stopping until they cannot continue because of leg symptoms, exhaustion, or other symptoms. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Autonomic Function
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Autonomic nervous system function will be measured non-invasively using heart rate variability via the head-up tilt test. Raw R-R interval data will be converted to time frequency domain with the wavelet transform across the frequency intervals 0.04-0.15 Hz (low-frequency, (LF)) and 0.15-0.4 Hz (high-frequency, HF). Units for both will be expressed as ms^2. Final outcome measure will be the ratio of LF/HF, which is a unitless ratio to indicate sympathetic-to-parasympathetic nervous system function. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Autonomic Activity
Time frame: Day 1: during the condition. Day 7: during the condition
Autonomic activity will be measured with a 3-lead ECG system (7700 Series, IvyBiomedical Systems Inc., Branford, CT) and will be used to continuously collect heart electrical activity during prolonged sitting with LEAP therapy, and prolonged sitting without LEAP therapy. Raw R-R interval data will be converted to time frequency domain with the wavelet transform across the frequency intervals 0.04-0.15 Hz (low-frequency, (LF)) and 0.15-0.4 Hz (high-frequency, HF). Units for both will be expressed as ms^2. Final outcome measure will be the ratio of LF/HF, which is a unitless ratio to indicate sympathetic-to-parasympathetic nervous system function.
Arterial Stiffness
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Peripheral and central arterial stiffness will be assessed non-invasively using pulse-wave velocity via the applanation tonometry technique. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Muscle Oxygenation
Time frame: Day 1: during the condition. Day 7: during the condition
A near-infrared spectroscopy (NIRS) sensor will be adhered on the skin above the belly of the medial gastrocnemius muscle to non-invasively assess muscle oxygenation during the entire prolonged sitting bout with LEAP therapy, and the entire prolonged sitting bout without LEAP therapy.
Peripheral blood mononuclear cell mitochondrial function
Time frame: Day 1: before and after condition. Day 7: before and after condition.
Participants will have blood drawn from an antecubital vein, which will be used to isolate peripheral blood mononuclear cells (PBMCs) and assess their mitochondrial function. These measures will be performed before and after 2.5 hours of prolonged sitting with LEAP therapy, and before and after 2.5 hours of prolonged sitting without LEAP therapy.
Results and safety
The study was withdrawn before enrolling participants, so there are no results.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Aug 2026.
- Background: PubMed 31303293Song P, Rudan D, Zhu Y, Fowkes FJI, Rahimi K, Fowkes FGR, Rudan I. Global, regional, and national prevalence and risk factors for peripheral artery disease in 2015: an updated systematic review and analysis. Lancet Glob Health. 2019 Aug;7(8):e1020-e1030. doi: 10.1016/S2214-109X(19)30255-4.
- Background: PubMed 16908785Golomb BA, Dang TT, Criqui MH. Peripheral arterial disease: morbidity and mortality implications. Circulation. 2006 Aug 15;114(7):688-99. doi: 10.1161/CIRCULATIONAHA.105.593442. No abstract available.
- Background: PubMed 31500474Matsushita K, Sang Y, Ning H, Ballew SH, Chow EK, Grams ME, Selvin E, Allison M, Criqui M, Coresh J, Lloyd-Jones DM, Wilkins JT. Lifetime Risk of Lower-Extremity Peripheral Artery Disease Defined by Ankle-Brachial Index in the United States. J Am Heart Assoc. 2019 Sep 17;8(18):e012177. doi: 10.1161/JAHA.119.012177. Epub 2019 Sep 10.
- Background: PubMed 37317860Allison MA, Armstrong DG, Goodney PP, Hamburg NM, Kirksey L, Lancaster KJ, Mena-Hurtado CI, Misra S, Treat-Jacobson DJ, White Solaru KT; American Heart Association Council on Peripheral Vascular Disease; Council on Hypertension; and Council on Lifestyle and Cardiometabolic Health. Health Disparities in Peripheral Artery Disease: A Scientific Statement From the American Heart Association. Circulation. 2023 Jul 18;148(3):286-296. doi: 10.1161/CIR.0000000000001153. Epub 2023 Jun 15.
- Background: PubMed 31170647Kohn CG, Alberts MJ, Peacock WF, Bunz TJ, Coleman CI. Cost and inpatient burden of peripheral artery disease: Findings from the National Inpatient Sample. Atherosclerosis. 2019 Jul;286:142-146. doi: 10.1016/j.atherosclerosis.2019.05.026. Epub 2019 May 27.
- Background: PubMed 27840332Gerhard-Herman MD, Gornik HL, Barrett C, Barshes NR, Corriere MA, Drachman DE, Fleisher LA, Fowkes FG, Hamburg NM, Kinlay S, Lookstein R, Misra S, Mureebe L, Olin JW, Patel RA, Regensteiner JG, Schanzer A, Shishehbor MH, Stewart KJ, Treat-Jacobson D, Walsh ME. 2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2017 Mar 21;135(12):e686-e725. doi: 10.1161/CIR.0000000000000470. Epub 2016 Nov 13.
- Background: PubMed 8558725Regensteiner JG, Steiner JF, Hiatt WR. Exercise training improves functional status in patients with peripheral arterial disease. J Vasc Surg. 1996 Jan;23(1):104-15. doi: 10.1016/s0741-5214(05)80040-0.
- Background: PubMed 34110902McDermott MM, Dayanidhi S, Kosmac K, Saini S, Slysz J, Leeuwenburgh C, Hartnell L, Sufit R, Ferrucci L. Walking Exercise Therapy Effects on Lower Extremity Skeletal Muscle in Peripheral Artery Disease. Circ Res. 2021 Jun 11;128(12):1851-1867. doi: 10.1161/CIRCRESAHA.121.318242. Epub 2021 Jun 10.
- Background: PubMed 23842830Fakhry F, Rouwet EV, den Hoed PT, Hunink MG, Spronk S. Long-term clinical effectiveness of supervised exercise therapy versus endovascular revascularization for intermittent claudication from a randomized clinical trial. Br J Surg. 2013 Aug;100(9):1164-71. doi: 10.1002/bjs.9207.
- Background: PubMed 31699514Dua A, Gologorsky R, Savage D, Rens N, Gandhi N, Brooke B, Corriere M, Jackson E, Aalami O. National assessment of availability, awareness, and utilization of supervised exercise therapy for peripheral artery disease patients with intermittent claudication. J Vasc Surg. 2020 May;71(5):1702-1707. doi: 10.1016/j.jvs.2019.08.238. Epub 2019 Nov 4.
- Background: PubMed 34293930Divakaran S, Carroll BJ, Chen S, Shen C, Bonaca MP, Secemsky EA. Supervised Exercise Therapy for Symptomatic Peripheral Artery Disease Among Medicare Beneficiaries Between 2017 and 2018: Participation Rates and Outcomes. Circ Cardiovasc Qual Outcomes. 2021 Aug;14(8):e007953. doi: 10.1161/CIRCOUTCOMES.121.007953. Epub 2021 Jul 23. No abstract available.
- Background: PubMed 30114505Hernandez H, Myers SA, Schieber M, Ha DM, Baker S, Koutakis P, Kim KS, Mietus C, Casale GP, Pipinos II. Quantification of Daily Physical Activity and Sedentary Behavior of Claudicating Patients. Ann Vasc Surg. 2019 Feb;55:112-121. doi: 10.1016/j.avsg.2018.06.017. Epub 2018 Aug 13.
- Individual participant dataSharing planned: No. There is no plan to share individual participant data with other researchers.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Song-Young Park, PhD principal investigator
University of Nebraska
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing LEAP therapy and no LEAP therapy in people with Peripheral Arterial Disease and Peripheral Vascular Disease, run by University of Nebraska at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 12 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: withdrawn, as of the sponsor's last update on 21 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was withdrawn before enrolling participants, so there are no results.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Macrovascular Endothelial Function (time frame: Day 1: before and after condition. Day 7: before and after condition.). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06389149, which also lists 54 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Aug 2026.