STRENGTH | MUSCLE – ANABOLIC RESISTANCE – AGING


3 RESEARCH ARTICLES


2 WKS REDUCED ACTIVITY INDUCES “ANABOLIC RESISTANCE” IN HEALTHY ELDERLY – 2013


Breen L1, Stokes KA, Churchward-Venne TA, Moore DR, Baker SK, Smith K, Atherton PJ, Phillips SM
STUDY
– investigate impact of 14 days of reduced daily steps on fasted and fed-state rates of myofibrillar protein synthesis (MPS)
– 10 healthy adults (72 ± 1 y)
RESULTS
(1) Daily step-count was reduced by approximately 76% to 1413 ± 110 steps per day
(2) Leg fat-free mass was reduced by approximately 3.9%
(3) Post-absorptive insulin resistance increased approx 12%
(4) Postprandial insulin sensitivity reduced by approx 43% after step reduction

(5) Postprandial rates of MPS reduced by approx 26% after intervention with no difference in post-absorptive rates
STOP MOVING FOR AS LITTLE AS 14 DAYS → DETERIORATION
– 14 days of reduced steps induced small but measurable reductions in muscle mass
– They appear to be underpinned by:
1. reductions in postfeeding MPS
2. impairments in insulin sensitivity
3. systemic inflammatory markers


4 DAYS OF MUSCLE DISUSE IMPAIRS FUNCTION IN YOUNG AND OLD – 2012


– Need effective preventive and rehabilitative approaches for old individuals exposed to as little as 4 days of disuse


EFFECTS OF AGING ON MUSCLE AFTER IMMOBILIZATION & RETRAINING – 2009


DESIGN
(a) 9 old (61-74 yr) men
(b) 11 young men (21-27 yr)
– after 2 wk of immobilization and 4 wk of retraining.

RESULTS
(1) Both young and old experienced:
– decreases in maximal muscle strength
– resting twitch peak torque and twitch rate of force development
– quadriceps muscle volume, pennation angle, and specific force after 2 wk of immobilization

(2) Only the old men experienced a decrease in quadriceps activation
(3) After retraining, both young and old regained their initial muscle strength, but old had smaller gains in quadriceps volume compared with young


 

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