NUTRITION-LEUCINE-BED REST or INACTIVITY-AGING


PROTECTING SKELETAL MUSCLE PROTEIN & AMINO ACID DURING PERIODS OF DISUSE – 2016

Elfego Galvan 1, Emily Arentson-Lantz 1,2, Séverine Lamon 3 and Douglas Paddon-Jones
INTRODUCTION
– Leucine protects skeletal muscle by mitigating the loss of muscle mass, strength, and endurance associated with disuse

LEUCINE PARTIALLY PROTECTS MUSCLE MASS & FUNCTION DURING BED REST IN MIDDLE-AGED ADULTS – 2015

Kirk L English, Douglas Paddon-Jones et al
OBJECTIVE:
– Determine whether leucine can protect skeletal muscle health during bed rest
DESIGN:
– Adults (n = 19; age: 52 ± 1 y)
(a) leucine supplementation (LEU group: 0.06 g ∙ kg(-1) ∙ meal(-1))
(b) an alanine control (CON group)
– during 14 d of bed rest
CONCLUSIONS:
(1) Bed rest has a negative effect on muscle metabolism, mass, and function in middle-aged adults
(2) Leucine supplementation may partially protect muscle health during relatively brief periods of physical inactivity


DEFINING ANABOLIC RESISTANCE – Implications for delivery of clinical care nutrition – 2018


Morton, Phillips et al
RECENT FINDINGS
1. Anabolic resistance is responsible, in part, for skeletal muscle atrophy with aging, muscle disuse, and during disease states
2. Anabolic resistance describes the reduced stimulation of muscle protein synthesis to a given dose of protein/amino acids and contributes to declines in skeletal muscle mass
3. Physical inactivity induces: anabolic resistance (that is likely exacerbated with aging), insulin resistance, systemic inflammation, decreased satellite cell content, and decreased capillary density
3. Critical illness results in rapid skeletal muscle atrophy that is a result of both anabolic resistance and enhanced skeletal muscle breakdown.
SUMMARY
1. Insofar as atrophic loss of skeletal muscle mass is concerned, anabolic resistance is a principal determinant of age-induced losses and appears to be a contributor to critical illness-induced skeletal muscle atrophy
2. Older individuals should perform exercise using both heavy and light loads 3x/wk, ingest at least 1.2 g of protein/kg/day, evenly distribute their meals into protein boluses of 0.40 g/kg, and consume protein within 2 h of retiring for sleep
3. During critical care, early, frequent, and multimodal physical therapies in combination with early, enteral, hypocaloric energy (∼10-15 kcal/kg/day), and high-protein (>1.2 g/kg/day) provision is recommended.


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