Novel Molecular Mechanisms of Skeletal Muscle Insulin, Resistance if Physically Inactive Older Adults
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 9
- 试验地点
- 2
- 主要终点
- Steady state glucose infusion rate
研究概览
简要总结
The over-65 population is not only increasing at an alarming rate, but because six out of 10 will be managing more than one chronic condition by 2030, they will make up a much greater proportion of hospitalizations than ever before. Hospitalizations for disease, injury, and/or surgery in this group are likely to impair physical mobility and, therefore, the older adults capacity to be physically active both during hospitalization and beyond. The resulting sedentary lifestyle is likely to be accepted as the "new normal", ultimately increasing the risk of skeletal muscle and metabolic dysfunction (e.g. impaired glucose disposal, insulin resistance). These devastating outcomes are neither inevitable nor necessary if prevented with an appropriate mechanism-based intervention.
A novel mechanism that may contribute to physical inactivity-induced insulin resistance is accumulation of inflammation and ceramide within skeletal muscle. Of interest, increased skeletal muscle inflammation and ceramide has been tied to various metabolic disturbances such as diabetes and insulin resistance. However, it is currently unknown if skeletal muscle inflammation and ceramide are a key mechanism associated with insulin resistance due to physical inactivity in older adults.
详细描述
The investigator team will recruit younger and older (N=8; 18-35y and 60-85 yrs) male and female adults recruited in the Salt Lake City area.
The investigator team will then schedule separate visits for Strength, Power and Physical Function and the separate visits for Lean Mass and OGTT measurements (see description below).
- Lean Mass, oral glucose tolerance test , Strength, Power, Exercise Testing and Physical Function Measurements. Lean mass assessment via dual-energy X-ray absorptiometry (DXA), ultra sound and peripheral quantitative computed tomography (pQCT) will be assessed in the center for clinical and translational sciences (CCTS) while knee extensor isometric strength, power and physical function testing will be conducted in the Skeletal muscle exercise research facility (SMERF) laboratory (520 Wakara Way). These endpoints will be considered secondary objectives to determine relationships with insulin sensitivity and muscle cell signaling events. These tests will occur within one week before the reduced activity experiment and will be repeated after completing the reduced activity period and after exercise training. For lean mass assessment, subjects will be tested in the morning after an overnight fast prior to the DXA scan. Isometric strength will be assessed in both legs with a maximal voluntary isometric contraction effort (at a 600 knee angle) developed by the knee extensors (quadriceps) and plantar/dorsi flexor muscles on a dynamometer. For lower extremity extension power testing a Nottingham power rig will be used. The following battery of functional performance tests will be used: Stair ascent/descent time, six-minute walk distance, 50 foot walk time, and the timed up and go test. All tests are tests that we frequently and safely perform in older individuals.
Maximal oxygen consumption (exercise testing) will be measured by a metabolic cart during a graded maximal exercise test on a stationary cycle ergometer. This test will be performed in the CCTS under direct supervision of an exercise physiologist. 2. Physical Activity Monitoring, Dietary Record. Subjects will be fitted with an ankle Step Activity Monitor in order to determine their daily level of physical activity over 7 days period preceding the reduced physical activity study. Additionally, a 3-day daily dietary record will be self-reported before this period. The participant will be properly instructed by a research team member on how to conduct this reporting and how to wear the ankle activity monitor. 3. Insulin Clamp Study, Metabolic Rate and Muscle Biopsies. On a separate day, participants will arrive at the CCTS fasted in the morning on Day 1 and a euglycemic-hyperinsulinemic clamp study will be performed as we have done previously. The research team physician will oversee the clamp procedure as he is very experienced using this method.
Metabolic rate will be determined 30 minutes before the initiation of the insulin infusion and 30 minutes at the end of the insulin infusion period. Metabolic rate will be determined using a indirect calorimeter housed at the CCTS. To do so, the participant will be fitted with a canopy hood. The participant with breathe normally for 30 minutes during the procedure. The canopy will be removed then the first muscle biopsy will occur.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Treatment
- 盲法
- None
入排标准
- 年龄范围
- 60 Years 至 85 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Age between 60-85 yrs
- •Ability to sign informed consent
- •Free-living, prior to admission
排除标准
- •The participant must not have participated in any previous research studies utilizing ionizing radiation (either radioisotopes or diagnostic x-rays) during the past 12 months in order to participate in this study. Cardiac abnormalities considered exclusionary by the study physician
- •Uncontrolled endocrine or metabolic disease (e.g., hypo/hyperthyroidism, diabetes)
- •History of kidney disease or failure
- •Vascular disease or risk factors of peripheral atherosclerosis. (e.g., uncontrolled hypertension, obesity, diabetes, hypercholesterolemia > 250 mg/dl, claudication or evidence of venous or arterial insufficiency upon palpitation of femoral, popliteal and pedal arteries)
- •Risk of deep vein thrombosis (DVT) including family history of thrombophilia, DVT, pulmonary emboli, myeloproliferative diseases including polycythemia (Hb>18 g/dL) or thrombocytosis (platelets>400x103/mL), and connective tissue diseases (positive lupus anticoagulant), hyperhomocysteinemia, deficiencies of factor V Leiden, proteins S and C, and antithrombin III
- •Use of anticoagulant therapy (e.g., Coumadin, heparin)
- •Elevated systolic pressure >150 or a diastolic blood pressure > 100
- •Implanted electronic devices (e.g., pacemakers, electronic infusion pumps, stimulators)
- •Cancer or history of successfully treated cancer (less than 1 year) other than basal cell carcinoma
- •Currently on a weight-loss diet or body mass index > 30 kg/m2
- •Recent anabolic or corticosteroids use (within 3 months)
- •History of stroke with motor disability
- •A recent history (<12 months) of GI bleed
- •Exercise training (>2 session of moderate to high intensity aerobic or resistance exercise/week)
- •History of liver disease
- •History of respiratory disease (acute upper respiratory infection, history of chronic lung disease)
- •Prior history of Heparin-Induced Thrombocytopenia (HIT)
- •Any other condition or event considered exclusionary by the PI and faculty physician
- •An HbA1c value at or greater than 6.5%
- •Subjects may not participate if they have utilized ionizing radiation (either radioisotopes or diagnostic x-rays) during the past 12 months
结局指标
主要结局
Steady state glucose infusion rate
时间窗: percent change from baseline at 14 days
Glucose infusion rate will be determined by a hyperinsulinemic-euglycemic clamp
次要结局
- lean mass(percent change from baseline at 14 days)