Oxygen-guided Supervised Exercise Therapy

NCT ID: NCT06003855

Last Updated: 2026-01-13

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 12 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-10-01
• Study Completion Date: 2026-12-30

Brief Summary

Peripheral artery disease (PAD) is a cardiovascular disease manifesting from systemic atherosclerosis, which blocks the leg arteries and results in insufficient blood flow to the lower extremities. Limb ischemia from PAD is the most common disorder treated within the vascular surgery service at the Omaha Veterans' Affairs Medical Center. PAD also accounts for one-third of the operations performed in the VA Medical Centers nationwide. This project aims to establish the feasibility and acceptability of a muscle oxygen-guided supervised exercise program for patients with PAD. The investigators will determine the potential benefits of using this intervention over standard supervised exercise therapy. This modified intervention may enable patients to increase overall physical activity without the negative impacts on muscle structure and function. Increasing physical activity will decrease cardiovascular morbidity and mortality. If proven beneficial, the findings will lead to an improved exercise program that directly benefits veterans nationwide.

Detailed Description

The long-term goal of this research is to improve mobility, functional independence, and quality of life in patients with peripheral artery disease (PAD) by developing conservative interventions. PAD is a manifestation of atherosclerosis, which produces blockages in the leg arteries, and results in insufficient blood flow to the legs. PAD results in significant gait deficits and an overall sedentary lifestyle. The investigators' prior work showed that the biochemical (oxidative stress and mitochondrial dysfunction) and histological (myofiber degeneration and fibrosis) characteristics of PAD muscles are altered compared to controls. These myopathic changes are due to cycles of ischemia and reperfusion, and they correlate to functional limitations (walking distance and calf muscle strength). Limb ischemia from PAD is the most common disorder treated within the vascular surgery service of the Omaha Veterans Affairs Medical Center. The most effective treatment for increasing the distances that patients with PAD can walk is supervised exercise therapy (SET). However, SET uses pain onset to guide exercise intensity and rest cycles. These repeated bouts of ischemia/reperfusion could cause further pathological damage to muscle myofibers and oxidative processes. Such adverse effects of ischemia may explain why not all patients improve with SET. Preventing cycles of ischemia-reperfusion during SET can improve walking performance without further muscle biochemistry damage in patients with PAD. The investigators propose using hemodynamic responses to modulate exercise intensity and prevent ischemia during SET. Muscle oxygen-guided supervised exercise therapy (M-SET) can prevent ischemia onset and thus preserve muscle mass and function during exercise therapy in patients with PAD. The aims are:

Aim 1: To determine the exercise outcomes of an M-SET versus a standard SET session in patients with PAD. Aim 2: To determine the acute effect of M-SET versus standard SET on oxidative stress and inflammation in patients with PAD. Aim 3: To determine the effect of 12 weeks of M-SET versus standard SET on exercise outcomes, muscle biochemistry, and subject-reported preference in patients with PAD.

The investigators will measure exercise outcomes during one session each of M-SET (using StO2 on the calf to modulate exercise) and SET, in 12 patients with PAD using a cross-over design. Exercise outcomes will be assessed by the total distance patients walked during the session, metabolic cost, metabolic equivalents of the task, physical activity enjoyment, and rate of perceived exertion. In Aim 2, oxidative stress will be measured using peripheral blood mononuclear cells before and after each exercise session (SET and M-SET) in all patients. During the standard SET session, subjects will walk until claudication pain becomes severe and the participant needs to stop. Then subjects will rest until claudication pain subsides. Afterward, subjects will walk again, repeating the cycle for up to 50 minutes. M-SET will use an StO2 threshold that is 15% lower level than baseline StO2 levels. Subjects will stop walking once they reach the threshold and rest until StO2 levels return to baseline. Then, subjects will begin walking again, repeating this cycle for 50 total minutes (including walking and rest). Patients from Aims 1 and 2 will be randomly assigned to either a 12-week M-SET or standard SET (6 per group) program. Training will be performed three times weekly as described above. Subjects will be evaluated before and after the intervention to capture initial and absolute walking distances and 7-day physical activity. Muscle biochemistry will be quantified using mitochondrial function, mitochondrial oxidative dynamics, and reactive oxygen species production before and after training. Results will support a full clinical trial and rehabilitation recommendations.

Conditions

Peripheral Artery Disease

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Oxygen guided supervised exercise

Modified-SET parameters will be determined from resting StO2 during 10 minutes of sitting. The StO2 threshold will be set at 15% lower than baseline StO2 levels. After warm-up, the subjects will walk until they reach the StO2 threshold. The subjects will be instructed to stop walking once they reach the threshold and to rest until the StO2 level returns to the baseline level. Then, subjects will be instructed to begin walking again and this cycle will be repeated for 50 total minutes. The threshold was selected to be above the 31% drop associated with claudication onset time. If subjects experience pain earlier than the 15% drop, the threshold will be progressively decreased by 5%, as needed. Subjects will repeat this for up to 50 minutes (including walking and rest). Walking speed and treadmill incline will be adjusted to allow for 5-10 minutes of walking before reaching the threshold. Subjects will complete 3 sessions/week for 12 weeks.

Group Type: EXPERIMENTAL

Supervised exercise therapy

Intervention Type: BEHAVIORAL

Subjects will be enrolled in a 12-week intervention program of either modified supervised exercise therapy or standard supervised exercise therapy. The program will be 3 sessions/week for 12 weeks. Each session will consist of 50 minutes plus 5 minutes warm up and cool down.

Standard supervised exercise

After the warmup, subjects will walk until claudication pain becomes severe and needs to stop. Then subjects will rest until claudication pain subsides. Afterwards, subjects will walk again, repeating the cycle for up to 50 minutes (including walking and rest). Walking speed and treadmill incline will be adjusted during the SET session to allow individuals with PAD to walk for 5-10 minutes before claudication symptoms arise. Time at each speed and incline, along with rest times will be recorded during each exercise session. Subjects will complete 3 sessions/week for 12 weeks.

Group Type: ACTIVE_COMPARATOR

Supervised exercise therapy

Intervention Type: BEHAVIORAL

Subjects will be enrolled in a 12-week intervention program of either modified supervised exercise therapy or standard supervised exercise therapy. The program will be 3 sessions/week for 12 weeks. Each session will consist of 50 minutes plus 5 minutes warm up and cool down.

Interventions

Supervised exercise therapy

Subjects will be enrolled in a 12-week intervention program of either modified supervised exercise therapy or standard supervised exercise therapy. The program will be 3 sessions/week for 12 weeks. Each session will consist of 50 minutes plus 5 minutes warm up and cool down.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

At entry into the study, all subjects must:

• Be able to give written, informed consent
• Have documented lower extremity arterial occlusive disease based on ankle/brachial index measurements and/or arterial imaging
• Demonstrate positive history of chronic claudication
• Have a stable blood pressure regimen, stable lipid regimen, stable diabetes regimen and risk factor control for 6 weeks

Exclusion Criteria

Any potential subjects will be excluded if they have:

• Rest pain or tissue loss due to PAD (Fontaine stage III and IV)
• Acute lower extremity ischemic event secondary to thromboembolic disease or acute trauma
• Walking capacity limited by conditions other than claudication including leg (joint/musculoskeletal, neurologic) and systemic (heart, lung disease) pathology

• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

University of Nebraska

OTHER

Sponsor Role: collaborator

VA Office of Research and Development

FED

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Iraklis I Pipinos, MD

Role: PRINCIPAL_INVESTIGATOR

Omaha VA Nebraska-Western Iowa Health Care System, Omaha, NE

Locations

Omaha VA Nebraska-Western Iowa Health Care System, Omaha, NE

Omaha, Nebraska, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Farahnaz Fallahtafti, PhD

Role: CONTACT

ffallahtafti@unomaha.edu

(402) 995-3542

Sara A Myers, PhD

Role: CONTACT

Sara.Myers2@va.gov

(402) 554-3246

Facility Contacts

Frederick G Hamel, PhD

Role: primary

Frederick.Hamel@va.gov

402-995-3540

Amy M Patten

Role: backup

amy.patten@va.gov

(402) 995-3541

Other Identifiers

E4632-P

Identifier Type: -

Identifier Source: org_study_id