Effects of low level and severe dietary restriction on age-related sarcopenia

Aging is associated with a progressive loss of muscle mass and strength, a condition also known as sarcopenia of aging. Progressive muscle wasting has been observed in rodents, non human primates and humans. Caloric restriction is a very robust anti-aging intervention, whose effect may depend on level and duration. A severe caloric restriction was said to attenuate the loss of muscle mass and function with age. We have evaluated the effects of age and mild (one day of fasting every week) or severe caloric restriction (3 days fasting every week) on the weight of different muscles (extensor digitorum longus, soleus, tibialis anterior and diaphragm) of male rats. Our data show that sarcopenia of aging does not necessarily occur in all muscles (diaphragm appears to be immune) and that only a severe caloric restriction counteracts sarcopenia of aging. Functioning of diaphragm is related to energy consumption and may not decrease significantly per unit of weight with age. Thus our findings are in line with the hypothesis that both severe dietary anti-aging intervention and uninterrupted exercise in the physiological range, may counteract sarcopenia of aging.