Evaluating Changes in Skeletal Muscle Proteins Following Resistance Exercise and Single-Leg Disuse

Last updated: October 15, 2024
Sponsor: Queen's University
Overall Status: Active - Recruiting

Phase

N/A

Condition

Muscular Dystrophy

Myasthenia Gravis (Chronic Weakness)

Treatment

Resistance training

Immobilization

Clinical Study ID

NCT06350591
6038674
  • Ages 18-30
  • Female
  • Accepts Healthy Volunteers

Study Summary

Skeletal muscle plays a critical role in supporting human health. Beyond its role in providing the force to move, skeletal muscle accounts for a large proportion of metabolic rate, glucose disposal, and amino acid storage. Skeletal muscle is dynamically regulated by environmental stimuli, such as loading (i.e., resistance training]) and unloading (i.e., disuse atrophy) as well as the intake of essential amino acids (EAAs). However, the precise mechanisms that regulate skeletal muscle mass in response to various conditions (e.g., EAA supplementation, resistance training, and unloading) are not completely understood. Therefore, concerted efforts to better understand the mechanisms regulating skeletal muscle size are needed that aid in the development of therapeutic interventions to combat age, disease, and disuse related muscular atrophy.

Eligibility Criteria

Inclusion

Inclusion Criteria:

  • Females 18-30 years

  • BMI between 18-28 kg/m2

  • ≥2 days per week of structured exercise

  • Generally healthy as assessed by medical and physical activity questionnaires

  • Participants not currently pregnant

Exclusion

Exclusion Criteria:

  • Any muscular, neurological, respiratory, or metabolic disease including diabetes

  • Any form of cancer currently or in the last 5 years

  • Bleeding disorders or antiplatelet / anticoagulation therapy

  • Currently taking fish oils or within the last 6 months

  • Currently taking any form of steroid or within the last 3 months

  • Inability to attain magnetic resonance imaging scans

  • Known irregular responses to physical activity (e.g., shortness of breath, chestpain, dizziness, etc.)

  • Any current illness

  • Currently smoking or smoking within the last 6 months

  • Currently pregnant

  • Any concurrent medical, psychiatric, or orthopedic condition that, subject toinvestigators' discernment, would negatively affect the subject's ability to complywith the study requirements

Study Design

Total Participants: 14
Treatment Group(s): 2
Primary Treatment: Resistance training
Phase:
Study Start date:
April 01, 2024
Estimated Completion Date:
September 30, 2025

Study Description

Skeletal muscle is a highly plastic tissue capable of modifying its phenotype (i.e., structural, contractile, and metabolic properties) in response to alterations in mechanical loading. Mechanistically underpinning skeletal muscle plasticity are changes in skeletal muscle protein turnover. Skeletal muscle size is dictated by changes in rates of muscle protein synthesis (MPS) and rates of muscle protein breakdown (MPB) with changes in rates of MPS being the primary determinant of human skeletal muscle mass. Both MPS and MPB are highly sensitive to contractile and nutritional cues. In response to EAA ingestion, there is a rise in rates of MPS and a mild suppression of MPB rates resulting in a positive state of protein balance. Similarly, when an individual performs a bout of resistance exercise, there is an increase in rates of MPS that is potentiated by EAA feeding; It is for this reason that when repeated bouts of resistance exercise are coupled with EAA intake over time, there is a gradual increase in skeletal muscle mass termed hypertrophy. In contrast, when an individual undergoes a reduction in levels of contractile activity (e.g., immobilization due to injury or surgery), there is a reduction in both fed and fasted rates of MPS leading to the loss of skeletal muscle mass and size termed muscle atrophy.

Although it is well known that both nutrition and contractile activity affect rates of muscle protein turnover and skeletal muscle mass, our current knowledge is limited by most studies reporting rates of MPS and MPB that are averages of thousands of proteins in the whole muscle, or subcellular protein fractions, such as myofibrillar, sarcoplasmic, and mitochondrial. Further, individual protein MPS and MPB rates might span a broad range and there may be selective changes to the turnover of individual proteins under different skeletal muscle loading scenarios. Dynamic proteomic profiling (DPP) is an emerging methodology that combines quantitative proteomic abundance measurements with individual protein MPS and MPB rates, to deliver unprecedented insight into the molecular regulation of individual protein turnover. Another major consideration is that nearly all studies in this field have been conducted in males, with limited data in females. The lack of data in females is a major knowledge gap and of major concern particularly given there is evidence that women may display different molecular responses to exercise, nutrition, and disuse compared to men.

The purpose of this investigation is to gain a better understanding of the acute and short-term effects of an EAA supplement and an acute bout of resistance exercise on rates of muscle protein turnover. Further, the investigators aim to measure the dynamic proteome during 10 days of unilateral leg immobilization, and following several bouts of resistance exercise in the contralateral leg, in young healthy women. The present investigation will characterize skeletal muscle mass, strength, protein expression, and protein synthesis rates (individual [i.e., DPP] and average). The study may inform potential future novel interventions to attenuate losses in skeletal muscle mass owing to disuse, aging, or injury.

Connect with a study center

  • School of Kinesiology and Health Studies

    Kingston, Ontario K7L 3N6
    Canada

    Active - Recruiting

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