The Effect of Ischemic Conditioning on Strength and Ambulation in Subjects with PAD

Not Applicable

Completed

• Conditions: Peripheral Arterial Disease; Peripheral Vascular Disease; Lower Limb Amputation Knee; Amputation; Lower Limb Amputation Above Knee (Injury); Lower Limb Amputation Below Knee (Injury)
• Interventions: Procedure: Ischemic Conditioning High - Active Comparator; Procedure: Ischemic Conditioning Low - Sham Comparator

• Registration Number: NCT04937179
• Lead Sponsor: University of Illinois at Chicago

Brief Summary

Lower limb amputation is common in the United States, with approximately 150,000 amputations annually. Most individuals walking with a prosthesis demonstrate asymmetrical loading-i.e., they favor the amputated side by placing more weight and increased ground reaction forces through the intact limb-which likely contributes to increased metabolic cost of walking. Lack of adequate muscular strength in the lower limb to attenuate these forces places increased stress on the joints, which may be displaced proximally, and may play a role in reported knee and hip pain in the intact limb.

Lower limb muscle weakness following amputation has been well documented. Increasing quadriceps strength is important after an amputation because it is positively correlated with gait speed. Gait speed may also be associated with successful community mobility, which leads to improved quality of life following amputation. Individuals with amputation who resume an active lifestyle are able to maintain strength. However, these individuals represent a minority of persons with lower limb amputation; most individuals report more barriers than motivators to adopt an active lifestyle.

Ischemic conditioning (IC) may strengthen leg muscles and reduce the metabolic cost of activity after amputation. In IC, the limb is exposed to brief, repeated bouts of ischemia (reduced blood flow) immediately followed by reperfusion. IC has been shown to improve muscle performance in healthy and diseased populations. IC has also been used more recently in patients with peripheral artery disease (PAD) as an intervention to improve function, such as walking ability. Acute exposure to IC increases muscle strength and activation, both in healthy, active individuals and in those with severe neuromuscular dysfunction, such as stroke survivors. IC also attenuates muscular fatigue. Increased fatigue resistance at submaximal contraction levels following IC may be due to increased neural activation of skeletal muscle. Changes in neural activation of muscle may be particularly beneficial during cortical reorganization after amputation. Reduced quadriceps fatigue during submaximal activities may also drive changes in gait kinematics, such as increased knee flexion during loading and mid-stance. Exposure to IC may also increase the oxidative properties of skeletal muscle, offering a direct pathway to reduce metabolic cost. Therefore, IC may lead to cellular changes that lower the metabolic cost of activity.

The primary aim of this study is to quantify the benefits of acute and chronic IC on quadriceps strength and walking economy in individuals with PAD and history of lower limb amputation.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2021-05-27
• Study First Submitted QC: 2021-06-14
• Study First Posted: 2021-06-23
• Study Start: 2022-07-01
• Primary Completion: 2024-12-31
• Study Completion: 2024-12-31
• Status Verified: 2025-02
• Last Update Submitted: 2025-02-25
• Last Update Posted: 2025-02-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 21

Inclusion Criteria

• 18 years or older
• Able to ambulate independently without the use of aids (i.e., walking cane)
• Able to walk at least 10 minutes continuously without stopping
• History of diagnosed peripheral artery disease.
• For Amputees: History lower limb unilateral transtibial or transfemoral amputation.

Exclusion Criteria

• Inability to give informed consent
• neurological disorder that affects gait
• two or more falls within the previous 12 months
• currently pregnant (or intend to become pregnant while participating in study)
• history of any condition where fatiguing contractions or resisted leg contractions are contraindicated
• blood clots in the leg, or any condition in which compression of the thigh or transient ischemia is contraindicated (e.g. open wounds in the leg).
• history of hypertension
• history of heart failure
• Head injury within the previous 6 months
• Seizure disorder
• Adverse reaction to ultrasound gel
• History of thrombosis
• History of sickle cell trait

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Ischemic Conditioning High	Ischemic Conditioning High - Active Comparator	Blood flow restriction with high compression
Ischemic Conditioning Low	Ischemic Conditioning Low - Sham Comparator	Blood flow restriction with low compression

Primary Outcome Measures

Name	Time	Method
Change in quadriceps strength	through study completion, an average of 6 weeks	Quadriceps strength assessed by a Biodex dynamometer
Change in gait kinematics	through study completion, an average of 6 weeks	Gait mechanics assessed by joint angles using Vicon cameras and reflective markers
Change in gait metabolics	through study completion, an average of 6 weeks	Assessment of oxygen consumption during walking using a metabolic cart
Change in gait kinetics	through study completion, an average of 6 weeks	Gait mechanics assessed by joint forces using a Bertec instrumented treadmill in combination with gait kinematics

Secondary Outcome Measures

Name	Time	Method
Six-minute walk test	through study completion, an average of 6 weeks	Measurement of distance walked in six minutes

Trial Locations

Locations (1)

UIC Physical Therapy Faculty Practice; 🇺🇸 Chicago, Illinois, United States