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This project aims to determine whether a novel strength training rehabilitation protocol can diminish the negative consequences of limb immobilization and expedite the restoration of muscle function during retraining in healthy individuals.
Individuals who sustain musculoskeletal injuries (MSKI) can experience a rapid loss of muscle mass due to declines in muscle loading and activation that occur post-injury (i.e., disuse atrophy). Loss of muscle under these conditions is attributed to a persistent negative net muscle protein balance (muscle protein synthesis \[MPS\] \< muscle protein breakdown) that results, in part, from declines in postprandial MPS (i.e., anabolic resistance). Nutritional interventions that enhance postprandial MPS may be used to overcome disuse-induced anabolic resistance and preserve muscle mass to accelerate recovery and improve recovery outcomes. While supplemental protein has been explored as a potential countermeasure to disuse-induce anabolic resistance, the observed efficacy of such interventions has been mixed. Equivocal findings across studies may be attributed, in part, to an insufficient understanding of what constitutes an effective protein-based intervention. Importantly, no study to date has determined an optimal protein dose for overcoming disuse-induce anabolic resistance, or if there is a threshold for maximally stimulating postprandial MPS under disuse conditions. Therefore, the objective of this work is to determine rates of MPS at rest and in response to standard (20 g) or high (40 g) doses of whey protein during knee immobilization (DISUSE) compared with standard activity (ACTIVE)
The primary objective of this study is to determine whether muscle atrophy induced by immobilization of the lower limb can be attenuated by BIIB023 in healthy male volunteers. The secondary objectives of this study in this study population are: * To determine whether muscle weakness induced by immobilization of the lower limb can be attenuated by BIIB023 * To assess the effect of BIIB023 on the recovery of muscle mass and strength after immobilization * To assess the effect of BIIB023 on histological markers of muscle atrophy and regeneration * To assess the effect of BIIB023 on muscle bioenergetics based on oxidative metabolism recovery kinetics * To evaluate the safety and tolerability of BIIB023
Diminished use of skeletal muscle, such as occurs with many chronic diseases (e.g., heart failure or cancer cachexia), denervation, bedrest, immobilization (e.g., limb casting or bracing), etc., is a common clinical condition affecting untold millions of individuals each year. Such disuse leads to a rapid decline in muscle fiber area and hence whole muscle size, contributing to a decrease in strength, speed, and power as well as alterations in energy metabolism. Collectively, these changes lead to reduced physical function and contribute to the seriousness of any disease, illness (e.g., pneumonia), surgery (e.g., joint replacement), or injury (e.g., broken bone) accompanied by decreased muscular activity. Currently, there are no effective pharmacological treatments to prevent disuse-associated muscle wasting in humans. The above-described effects of disuse appear to be due, at least in part, to a decrease in nitric oxide (NO) bioavailability. Reduced synthesis of NO and/or increased NO destruction (due to increased production of oxygen free radicals) likely contributes to the mitochondrial changes, energetic abnormalities, and muscle atrophy resulting from immobilization. The objective of this study is to investigate the potential benefits of dietary nitrate supplementation on immobilization-induced changes in muscle contractile function and mitochondrial respiratory capacity in young healthy men. Our disuse-induced muscle atrophy model will involve wearing a knee brace for a period of 14 d.
This study will characterize intramuscular molecular mechanisms underlying anabolic resistance to protein ingestion during muscle disuse. Adults (n=12) will be studied using a unilateral leg immobilization model in which one leg will be randomly assigned to immobilization and the contralateral, active leg used as a within-subjects control. Immobilization will be implemented for five days using a rigid knee brace, during which time participants will ambulate using crutches. Integrated ribonucleic acid (RNA) synthesis will be determined during immobilization in the immobilized and non-immobilized legs using ingested deuterium oxide, salivary and blood sampling, and muscle biopsies. Immediately after immobilization, muscle biopsies will be collected before and 90 mins after consuming 25 g of whey protein from the immobilized and non-immobilized legs to characterize the intramuscular molecular response to protein feeding. Serial blood samples will be collected during that time to characterize the circulating metabolic response to protein ingestion. Knowledge generated from this effort will inform the development of targeted interventions for mitigating anabolic resistance to protein ingestion that develops during periods of muscle disuse.
Following orthopedic surgery and/or injury, a significant loss of muscle mass is generally observed. While this loss of muscle mass appears to be the norm, it causes significant problems in both the athletic and general population. Athletes struggle to regain their performance because of the decrease in muscle mass and also have a greater potential for reinjury while they are in a depleted state. In the general population, and particularly among the elderly, this loss in muscle mass can be even more devastating because as people age, it is more difficult to regain muscle after it is lost. In elderly individuals, this loss in muscle mass can lead to significant disability, diminished quality of life along with an increased risk of falls. In addition to the muscle mass lost during the post-operative period, the strength of the muscle also decreases. This has obvious performance implications in athletes, as well as having the potential to extend recovery time. In the elderly, decreased strength may result in reduced independence and inability to perform activities of daily living. Many previous bed rest studies have reported that significant bone loss also occurs during times of decreased mechanical loading. The post-operative period generally results in decreased mechanical loading; however, some muscle loading will still occur during the rehabilitation process. The dynamic relation between muscle activity/loading and bone density changes in the post-operative state has not been fully described and requires further study. With this knowledge of the importance of nutrition to the musculoskeletal system, applying the principles of increased protein intake through the addition of a dietary supplement to a population preparing for orthopedic surgery and subsequent muscle disuse is a logical next step. The investigators hypothesize that through the consumption of a protein-based dietary supplement three times per day (75g protein), along with educating patients on the importance of consuming foods that are high in protein, there will be an attenuation of decreases in muscle mass and strength as well as losses in bone that occur with orthopedic injury and disuse. The investigators long-term goal is to identify a nutritional protocol that can be implemented prior to and following orthopedic surgery to diminish the deleterious effects of the subsequent disuse on muscle and bone.
This study aims to determine how flywheel-based inertial training (FIT) implemented according to principles of velocity-based training (VBT) and High-Intensity Interval Training (HIIT) affects disuse-induced physical de-conditioning including loss of voluntary muscle strength, aerobic capacity, and balance regulation.
This project is a 2-phase, randomized clinical trial that includes 7 days of unilateral leg disuse (Phase 1), immediately followed by 1 week of bilateral leg rehabilitation (Phase 2). The investigators will recruit cohorts of healthy middle-aged men and women to address their aims: * Demonstrate the sex-specific effects of skeletal muscle disuse (Phase 1) * Identify key molecular determinates of susceptibility of skeletal muscle atrophy (Phase 1) * Map the early, sex-specific molecular time-course of rehabilitation (Phase 2) * Determine if disused and healthy muscle respond similarly to exercise (Phase 2) Healthy, middle-age men and post-menopausal women (50-65 years) will be recruited from the greater Houston/Galveston area. This under-represented research demographic demonstrate few negative metabolic or phenotypic signs of advanced age, but are at increased risk of being hospitalized and experiencing accelerated loss of lean mass and muscle function that parallels a much older population. The goal of this study is to characterize phenotypic and molecular skeletal muscle changes in middle-aged men and women during critical periods of disuse and rehabilitation and ultimately direct the development of targeted and effective prevention and treatment strategies.
Patients who are forced to rest or reduce activity as a result of illness, injury, or surgery often experience resulting muscle weakness. This study will evaluate muscle features and muscle strength in patients who are recovering from surgery for broken ankles. The goal of this study is to improve the recovery of muscle function and overall ability after prolonged periods of ankle inactivity due to surgery.
The primary objective of this study is to test the hypothesis that appendicular lean body mass (aLBM) will increase after 12 weeks of LY2495655 treatment versus placebo in older participants undergoing elective total hip arthroplasty (eTHA).