A group of sedentary and overweight older people placed on a four-month exercise program not only became more fit, but burned off more fat, compared to older sedentary people who were placed on a diet but did not exercise.
The new study also showed that when older people diet without exercising, they lose more lean muscle compared to those who exercise, said senior researcher Bret H. Goodpaster. When they combined weight loss with exercise, it nearly completely prevented the loss of lean muscle mass. The results are important because older people tend to lose muscle mass as they age and too much muscle loss may interfere with activities of daily living.
The study, “Separate and combined effects of exercise training and weight loss on exercise efficiency and substrate oxidation,” appears in the current issue of the Journal of Applied Physiology, published by The American Physiological Society. Francesca Amati, John J. Dube, Chris Shay and Goodpaster, all of the University of Pittsburgh, carried out the study.
Exercise while losing weight is probably good advice at any age. However, the elderly in particular have a problem with a loss of muscle mass called sarcopenia. While some see it mainly as a consequence of decreased exercise with age a number of age-related changes might contribute to sarcopenia.
Thus, in humans between 20 and 80 years of age, muscle mass decreases about 40%, with negative effects on mobility, strength production, metabolic rate and respiratory function. A continuous reparative process is also present in skeletal muscle due to the presence of quiescent adult stem cells, called satellite cells, which are able to change their phenotype when appropriate conditions are present. Sarcopenia is considered an event with a multifactorial etiology: (1) mitochondrial deletion, i.e., replication errors in mitochondrial DNA that lead to an energetic deficit and fiber atrophy; (2) protein synthesis alterations, with an imbalance between protein degradation and the ability of the fibers to synthesize protein; (3) loss of repair ability of the satellite cells, caused by an alteration in the proteic growth factors (mainly IGF–1, mIGF–1, HGF) and hormones (growth hormone, testosterone and estrogens), or by an imbalance of the antioxidant system.
We need stem cell therapies and gene therapies to do repairs on aged muscle tissues. But while we wait for those therapies we should get lots of exercise to minimize the muscle mass loss.
|Share |||Randall Parker, 2008 September 21 07:40 PM Aging Diet Weight Studies|