X-Message-Number: 26593
Date: Tue, 12 Jul 2005 20:02:09 -0700 (PDT)
From: Doug Skrecky <>
Subject: exercise stops muscle aging

[Curiously, exercise does not increase maximum lifespan in rodents.
This implies that maximum lifespan is not determined by muscle tissue in
these animals. By contrast, in nematodes muscle tissue does appear to be
linked to maximum lifespan. In drosophila flies, motor neurons are the
determining factor. The critical tissue for rodent maximum longevity is
currently unknown. There is some evidence to indicate that in humans the
major lifespan determining tissue may be bone marrow.]

Habitual exercise program protects murine intestinal, skeletal, and
cardiac muscles against aging
epub June 16, 2005
  Aging and aerobic exercise are two conditions known to interfere with
health and quality of life, most likely by inducing oxidative stress to
the organism. We studied the effects of aging on the morphological and
functional properties of skeletal, cardiac, and intestinal muscles, and
their corresponding oxidative status, in C57BL/6 mice, and investigated
whether a lifelong moderate exercise program would exert a protective
effect against some deleterious effects of aging. As expected, aged
animals presented a significant reduction of physical performance,
accompanied by a decrease of gastrocnemius cross-sectional area, and
cardiac hypertrophy. However, the most interesting was that aging
dramatically interfered with the intestinal structure, causing a
significant thickening of the ileum muscular layer. Senescent intestinal
myocytes displayed many mitochondria with disorganized
cristae, and the presence of cytosolic lamellar corpuscules. Lipid
peroxidation of ileum and gastrocnemius muscle, but not of the heart,
increased in aged mice, thus suggesting enhanced oxidative stress. With
exception of the intestinal muscle responsiveness, animals submitted to a
daily session of 60 min, 5 days/week, at 13 up to 21m/min of moderate
running in treadmill during animal life span exhibited a reversion of all
the observed aging effects on intestinal, skeletal, and heart muscles.
The introduction of this lifelong exercise protocol prevented the
enhancement of lipid peroxidation and sarcopenia, and also preserved
cellular and ultra-cellular structures of the ileum. This is the first
time that the protective effect of a lifelong regular aerobic physical
activity against the deleterious effects of aging on intestinal muscle
was demonstrated.

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