Oxygen-guided Supervised Exercise Therapy in Peripheral Artery Disease
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 12
- 试验地点
- 1
- 主要终点
- Distance walked
研究概览
简要总结
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.
详细描述
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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Basic Science
- 盲法
- None
入排标准
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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
排除标准
- •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
研究组 & 干预措施
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.
干预措施: Supervised exercise therapy (Behavioral)
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.
干预措施: Supervised exercise therapy (Behavioral)
结局指标
主要结局
Distance walked
时间窗: Before and after 12 week exercise program
Total distance walked during the exercise session (standard or M-SET) will be determined using the total time of walking multiplied by the walking speed.
Reactive oxygen species
时间窗: Before exercise, immediately after exercise, 30 minutes after exercise, and 1 hour after exercise
Quantification of reactive oxygen species (ROS) related markers and free radicals: Electron paramagnetic resonance (EPR), which has been known as a gold standard for free radical assessment, will be used to quantify free radicals such as superoxide as we have previously performed (1-3). Plasma samples will be used for measuring ROS-related markers such as TAC, SOD, GSH:GSSG, ONOO- and MDA with commercially available and previously validated ELISA Assay Kits (CAT#s ab65329, ab65354, ab138881, ab233469, and ab233471 Abcam, UK) according to the manufacturer's instructions60. The average intra-assay variability measured as the coefficient of variation for each sample was 2.9%, 3.8%, and 3.3% for SOD, TAC, and MDA, respectively.
Initial and absolute walking distances
时间窗: Before and after 12 week supervised exercise program
Initial and absolute walking distances will be determined from the progressive-load treadmill test. Subjects will walk on a treadmill that starts at 0% grade and 2.0 mph. Every two minutes, the grade will be increased by 2% up to a maximum of 15% grade, and the speed held constant throughout the test. Initial claudication distance is the distance walked prior to claudication pain onset. Absolute claudication distance is the total distance walked before subjects had to stop walking due to claudication pain.
Energy expenditure
时间窗: Before and after 12 weeks after the exercise program
Energy expenditure57 will be assessed via oxygen consumption as measured by a metabolic cart (K5, Cosmed USA, Inc., Chicago, IL). Subjects will stand quietly for five minutes to collect resting energy expenditure. Standing steady state energy expenditure will be calculated for each subject by plotting VO2 and assigning a sliding best fit line over a two-minute window. Steady-state oxygen consumption in ml/kg/min will be calculated during the exercise session. Energy cost of transport will be calculated by subtracting the energy consumption values at standing from walking to achieve net metabolic cost for each bout of exercise.
Protein expression of ROS-related enzymes
时间窗: Before exercise, immediately after exercise, 30 minutes after exercise, and 1 hour after exercise
Protein expression of ROS-related enzymes: Enzymes related to ROS will be quantified with western blots of isolated PBMCs analyzed for catalase, 4 hydroxynonenal (4HNE), and glutathione peroxidase 1 (GPX) (4). All samples will be homogenized in RIPA buffer (Boston Bioproducts) and 100X protease inhibitor (Sigma Aldrich). A 150-volt electrical potential will be applied to the gel for 1 hr to separate proteins based on mass. A 250-volt electrical potential will then be applied to the gel for 7 min to transfer protein bands to transfer paper with TurboTransfer (Biorad). Primary antibodies for catalase, 4HNE, and GPX will be recombinant anti-catalase antibody (ab209211), anti-4 hyroxynonenal antibody (ab243070), and recombinant anti-glutathione peroxidase 1 antibody (ab108429), respectively.
Markers of systemic inflammation
时间窗: Before exercise, immediately after exercise, 30 minutes after exercise, and 1 hour after exercise
Markers of systemic inflammation: Standard ELISA kits will be used to test blood samples for interleukin 6, tumor necrosis factor-a, vascular cell adhesion protein 1, and vascular endothelial growth factor-a (Cat#s, ab178013, ab285312, ab223591, ab119566). Oxidized low density lipoproteins (LDL) will be measured with an oxidized LDL assay kit (ab242302). All measurements will be made per validated manufacturer specifications.
Mitochondrial reactive oxygen species production
时间窗: Before and after 12 week supervised exercise program
Mitochondrial reactive oxygen species production will be assessed with fluorescent imaging of skeletal muscle biopsy samples treated with H2DCFDA (D399, ThermoFisher), which is validated to detect ROS within cells. The validated mitochondrial targeted antioxidant MitoTempo (SML0737, Sigma-Aldrich) will be used to confirm the presence of mitochondrial ROS. EPR will be used to quantify free radicals such as superoxide.
Comprehensive mitochondrial respiratory complex function
时间窗: Before and after 12 week supervised exercise program
Comprehensive mitochondrial respiratory complex function (complex I, II, III, IV, and V) will be completed with previously validated high resolution respirometry with complex agonists/antagonists. Skeletal muscle tissue will be manually teased and permeabilized with 15 l of digitonin for 30 min. Samples will then be rinsed twice in 2 ml of MIRO5 for 10-min. 3-5 mg (dry weight) of tissue will then be isolated and placed in the high-resolution respirometer with 2 ml of MIRO5 solution. The order and quantity of each agonist and antagonist will be applied as follows: 5 l malate and 10 l glutamate (complex I agonist), 20 l adenosine diphosphate (complex V agonist), 20 l succinate (complex II agonist), 1 l rotenone (complex I antagonist), 1 l oligomycin (complex V antagonist), 1 l antimycin A (complex III antagonist), and 5 l ascorbate + 5 l TMPD (complex IV agonist).
Mitochondrial dynamics
时间窗: Before and after 12 week supervised exercise program
Specific proteins we will assess are Fis-1 and DRP-1 (fission), Mfn-1, Mfn-2 and OPA-1 (fusion), and UPC-1 and UCP-2 (dynamics). We will perform the same Western Blot technique mentioned in Aim #262. Primary antibodies for Fis-1, DRP-1, Mfn-1, Mfn-2, OPA-1, UPC-1, and UCP-2 will be recombinant anti- TTC11/FIS1 (ab156865), recombinant anti-DRP1 (ab184247), anti-mitofusin 1 antibody-N-terminal (ab191853), recombinant anti-mitofusin 2 (ab205236), recombinant anti-OPA1 (ab157457), anti-UCP1 (ab155117), and anti-UCP2 (ab247184), respectively.
次要结局
- Metabolic equivalents of task(Immediate)
- Maximum cadence/day(Before and after 12 week supervised exercise program)
- Physical activity enjoyment scale(Immediate)
- Acceptability(Before and after 12 week supervised exercise program)
- Rating of perceived exertion(Immediate)
- Physical activity average steps/day(Before and after 12 week supervised exercise program)
- Muscle strength(Before and after 12 week supervised exercise program)
- Muscle endurance(Before and after 12 weeks supervised exercise program.)