Exercise training in ad libitum and food-restricted old rats: effects on metabolic and physiological parameters.

Aging is accompanied by a decline in the healthy function of multiple organs, leading to increased incidence and mortality from diseases such as cancer and inflammatory, cardiovascular and neurodegenerative diseases. Dietary restriction is the most effective experimental intervention known to consistently slow the aging process and with positive effects on health span in different organisms, from invertebrates to mammals. Age is also associated with progressive decline in physical activity levels in a wide range of animal species: therefore, regular physical exercise could represent a safe intervention to antagonize aging. In this research we explore the effects of exercise training initiated in late middle aged rats fed with different lifelong dietary regimens: one group was fed ad libitum and the second group was subjected to every-other-day fasting. These two groups might represent examples of "normal" aging and "successful" aging. The study shows the effects of exercise and food restriction and their interaction on plasma levels of total antioxidant capacity, lactate, amino acids, and on products of protein oxidation in soleus and tibialis anterior muscles. In addition, we evaluated body composition measurement by bioelectrical impedance analysis and muscle strength by grasping test. Results show that late-onset exercise training has the potential to improve some metabolic and physiological parameters in rats with the same "chronological age" but different "biological age", without negative effects, and highlight the relevance of a personalised and selected exercise protocol, since the responsiveness to exercise may depend on the individual's "biological age".