An Integrated Low-Volume Nutritional Countermeasure to Maintain Muscle Mass and Function During Space Exploration
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 40
- 试验地点
- 2
- 主要终点
- Lean Leg Mass
研究概览
简要总结
The investigators will test the following hypotheses:
- Bedrest will blunt the anabolic response to a mixed nutrient meal, facilitating a loss of muscle mass and functional capacity that is only partially restored during rehabilitation.
- Enriching daily meals with leucine will promote protein synthesis and maintain the anabolic response to mixed nutrient meal ingestion. This will preserve lean muscle mass and function during bedrest and facilitate the recovery of functional and metabolic capacity during rehabilitation.
详细描述
Our long-term goal is to identify, prevent and remedy defects in the metabolic pathway that contribute to the loss of muscle mass and function during exposure to microgravity. Demographic data indicate that the average age of shuttle crew members has increased from 40.7 yrs in 1995 to 46.7 yrs in 2007 with an increasing number of astronauts over 50 yrs of age. We contend that the loss of muscle mass and function during spaceflight is facilitated by an age-associated, progressive impairment in the ability to mount an anabolic response to standard mixed nutrient meals. We propose that enriching daily meals with a low-volume leucine supplement will reduce the deleterious effects of microgravity on skeletal muscle and facilitate recovery during rehabilitation.
We will employ our established 14 day bed rest protocol to model the skeletal muscle unloading that occurs during microgravity. We will also examine recovery of muscle mass and functional capacity during a 7 day rehabilitation period. We will study 2 groups: CON (Bedrest/Recovery + Placebo; n=15), LEU (Bedrest/Recovery + Leucine; n=15). We will assess a) markers of translation initiation, b) muscle protein synthesis, c) muscle mass and body composition and d) strength and aerobic capacity.
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
- Double (Participant, Investigator)
入排标准
- 年龄范围
- 45 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Age between 45-60
- •Ability to sign informed consent
排除标准
- •Subjects with cardiac abnormalities considered exclusionary by the study physicians
- •Subjects with uncontrolled metabolic disease
- •A GFR <65 mL/min/1.73m2 or evidence of kidney disease or failure
- •Subjects with vascular disease or risk factors of peripheral atherosclerosis
- •Any history of hypo- or hyper-coagulation disorders. (e.g., Coumadin use or history of DVT or PE)
- •Subjects with chronically elevated systolic pressure >150 or a diastolic blood pressure > 100
- •Subjects with implanted electronic devices (e.g., pacemakers, electronic infusion pumps, stimulators)
- •Subjects with recently (6 months) treated cancer other than basal cell carcinoma
- •Any subject currently on a weight-loss diet or a body mass index > 30 kg/m2
- •Inability to abstain from smoking for duration of study
- •A history of > 20 pack per year smoking
- •Any subject that is HIV-seropositive or has active hepatitis
- •Recent anabolic or corticosteroids use (within 3 months)
- •Subjects with hemoglobin or hematocrit lower than accepted lab values
- •Agitation/aggression disorder
- •History of stroke with motor disability
- •A recent history (<12 months) of GI bleed
- •Any other condition or event considered exclusionary by the PI and faculty physician
研究组 & 干预措施
Leucine
3-4 g Leucine added to daily meals during bed rest
干预措施: Leucine (Dietary Supplement)
Placebo
3-4 g Alanine added to daily meals during bed rest
干预措施: Alanine (Dietary Supplement)
结局指标
主要结局
Lean Leg Mass
时间窗: At baseline prior to beginning bed rest and after 14 days of bed rest
DEXA scan of both legs pre/post bed rest
次要结局
未报告次要终点