The Catabolic Effects of Prolonged Inactivity and Acute Hypercortisolemia Are Offset by Dietary Supplementation

Paddon‐Jones, Douglas; Sheffield‐Moore, Melinda; Urban, Randall J.; Aarsland, Asle; Wolfe, Robert R.; Ferrando, Arny A.

doi:10.1210/jc.2004-1702

Cited by 47 publications

(71 citation statements)

References 46 publications

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“…These investigators showed that the catabolic effects of prolonged bed rest with or without acute hypercortisolemia could be ameliorated by an essential amino acid and carbohydrate (AA/CHO) supplement through the maintenance of muscle protein synthesis. In contrast, the ingestion of a typical mixed clinical meal had minimal or no effect on protein synthesis (14).…”

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confidence: 88%

“…Muscle wasting, whether induced by spaceflight or clinically mandated BR, results from an imbalance between protein synthesis and breakdown (4), and it is also generally associated with elevated plasma concentrations of the stress hormone cortisol (6,14). With prolonged space flights on MIR (Ͼ3 mo), astronauts and cosmonauts showed a 45% drop in whole body protein synthesis rates, and a reduced protein breakdown of a somewhat lesser magnitude (16).…”

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confidence: 99%

“…Ferrando et al (4) observed a 50% drop in protein synthesis with no change in protein breakdown in the vastus lateralis (VL) of subjects following a 14-day BR. In many space crew members and patients confined to BR, the extent of muscle protein breakdown was exacerbated by an inadequate energy intake, which resulted in a negative caloric balance (14,16,17). In patients, the incidence of undernutrition during hospitalization has been estimated to be as high as 50% (1).…”

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“…In patients, the incidence of undernutrition during hospitalization has been estimated to be as high as 50% (1). The importance of proper nutrition in the maintenance of muscle mass was recently demonstrated by Paddon-Jones et al (14). These investigators showed that the catabolic effects of prolonged bed rest with or without acute hypercortisolemia could be ameliorated by an essential amino acid and carbohydrate (AA/CHO) supplement through the maintenance of muscle protein synthesis.…”

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The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

Fitts¹,

Romatowski²,

Peters³

et al. 2007

American Journal of Physiology-Cell Physiology

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The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

Fitts¹,

Romatowski²,

Peters³

et al. 2007

American Journal of Physiology-Cell Physiology

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“…In addition, essential amino acid and carbohydrate supplementation during prolonged inactivity (28 d of bed rest) could prevent loss of lean leg mass and stimulate net muscle protein synthesis (178,179). Moreover, dietary intake supplementation with 30 mmol/d each of the three branched-chain amino acids (BCAAs) during bed rest has been reported to improve nitrogen retention by increasing the accretion of amino acids in the tissue free amino acid pool, however with no significant influence on protein kinetics (60).…”

Section: 2) Dietary Supplementationmentioning

confidence: 99%

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

Bajotto

Shimomura

2006

J Nutr Sci Vitaminol

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Summary Muscle atrophy results from a variety of conditions such as disease states, neuromuscular injuries, disuse, and aging. Absence of gravitational loading during spaceflight or long-term bed rest predisposes humans to undergo substantial loss of muscle mass and, consequently, become unfit and/or unhealthy. Disuse-or inactivity-induced skeletal muscle protein loss takes place by differential modulation of proteolytic and synthetic systems. Transcriptional, translational, and posttranslational events are involved in the regulation of protein synthesis and degradation in myofibers, and these regulatory events are known to be responsive to contractile activity. However, regardless of the numerous studies which have been performed, the intracellular signals that mediate skeletal muscle wasting due to muscular disuse are not completely comprehended. Understanding the triggers of atrophy and the mechanisms that regulate protein loss in unloaded muscles may lead to the development of effective countermeasures such as exercise and dietary intervention. The objective of the present review is to provide a window into the molecular processes that underlie skeletal muscle remodeling and to examine what we know about exercise and nutrition countermeasures designed to minimize muscle atrophy. Key Words Skeletal muscle disuse atrophy, microgravity, hindlimb suspension, protein synthesis and degradation, exercise and nutrition countermeasures Because skeletal muscle is the most abundant tissue of the human body, we may hypothesize that decreases in its mass possibly will profoundly impact the wholebody metabolism and ultimately lead to the development of lifestyle-related diseases. In addition, muscle deconditioning (reduced strength, abnormal reflex patterns, increased fatigability) could limit the ability of astronauts to work in space and/or to rapidly egress the spacecraft in an emergency landing ( 1 ). Even though various functional and morphological alterations are noticeable in inactive muscles, decreased protein content has been regarded as the hallmark of skeletal muscle atrophy. Muscle protein can be either gained or lost by relative changes in protein synthesis and degradation rates, which are known to be modulated by contractile activity. Thus, understanding about the molecular regulators of protein turnover during different mechanical loading conditions and their response to specific treatments leads to the likelihood of developing effective countermeasures for preventing disuseinduced muscle wasting.This article provides a review of muscular adaptations to disuse, with emphasis on protein kinetics. We describe first the general aspects of muscle wasting with regard to exposure to actual or ground-based, simulated microgravity and some of the most significant findings that provide evidence for a close connection between skeletal muscle plasticity and protein metabolism. Next, we present a review of the literature in which results of measurements of protein synthesis/ degradation rates during unloading are avail...

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Low‐volume resistance exercise attenuates the decline in strength and muscle mass associated with immobilization

et al. 2010

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We determined the effectiveness of low-volume resistance exercise (EX) for the attenuation of loss of muscle mass and strength during leg immobilization. Men (N = 5) and women (N = 12, age 24 ± 5 years, body mass index 25.4 ± 3.6 kg/m(2)) were divided into two groups: exercise (EX; n = 12) and control (CON; n = 5). Subjects wore a knee brace on one leg that prevented weight bearing for 14 days. Resistance exercise (EX; 80% of maximal) was performed by the immobilized limb every other day. Immobilization induced a significant reduction (P < 0.05) in muscle fiber and thigh cross-sectional area (CSA), isometric knee extensor, and plantarflexor strength in the CON (P < 0.01) but not in the EX group. There were significant losses in triceps surae CSA in the CON and EX groups (P < 0.05), but the losses were greater in CON subjects (P < 0.01). A minimal volume (140 contractions in 14 days) of resistive exercise is an effective countermeasure against immobilization-induced atrophy of the quadriceps femoris but is only partially effective for the triceps surae.

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The Catabolic Effects of Prolonged Inactivity and Acute Hypercortisolemia Are Offset by Dietary Supplementation

Abstract: We compared the anabolic stimulus provided by an essential amino acid and carbohydrate (AA/CHO) supplement to a mixed clinical meal during bed rest (BR) and episodic hypercortisolemia (ϳ24 g⅐dl

Cited by 47 publications

References 46 publications

The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

Low‐volume resistance exercise attenuates the decline in strength and muscle mass associated with immobilization

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