It may not be the fountain of youth, but researchers at York University have discovered that regular exercise can effectively turn back the clock for aging skeletal muscle.
The study, “Molecular basis for an attenuated mitochondrial adaptive plasticity in aged skeletal muscle,” was recently published in the journal Aging. The results indicate that the elderly are able to rebuild muscle mass, and while they will not achieve the abs of a 20-year-old, they can reverse significant damage and loss of muscle function caused by inactivity and old age.
The research team led by Professor David Hood, Canada Research Chair in Cell Physiology and a professor in the School of Kinesiology & Health Sciences in York’s Faculty of Health, carried out the study as part of an ongoing series of investigations into the benefits of exercise (see YFile, May 11, 2007 & March 2, 2009). This most recent study demonstrates that even in the elderly (individuals of 70 or 80 human years of age), regular exercise has the effect of rejuvenating muscle health, and these benefits are demonstrated by 
reduced fatigue and enhanced cellular function. The study adds weight to a growing body of findings by Hood and his research team that exercise plays a key role in achieving long-term health, even into advanced age.
Right: David Hood
“We found that muscle does adapt, but it takes a longer time for that adaptation to take place,” says Hood. “It is not a question anymore that regular exercise offers little benefit for elderly individuals because their muscles won’t adapt. That is not the case. The muscles of older individuals do adapt, they just don’t adapt as robustly or as quickly as younger individuals.”
Hood says the study showed that elderly muscle will continue to improve in its responsiveness as long as the exercise continues. "It may take more time but the benefits are definitely there," he says.
"To prove this, we used a well-established animal model of aging, the Fisher Brown Norway rat at young and very old ages. To avoid any differences in exercise behaviour between ages, we used a chronic stimulation model of muscle contraction in which the muscles of one leg were made to contract for three hours a day for seven consecutive days. This represents a standardized high exercise workload which can be imposed on one leg of both the young and old animals while the opposite leg remains at rest," explains Hood.
| In cell biology, mitochondria are membrane-enclosed organelles found in most cells of complex organisms. Mitochondria are sometimes described as the powerplants of cells because of their role in generating most of the cell’s chemical energy. Mitochondria are involved in a variety of other processes, such as signaling, cellular differentiation into tissues, cell death, as well as the control of the cell cycle and cell growth. |
At the end of the seven-day period, the adaptability of the muscle with respect to its ability to withstand fatigue was assessed. Specifically, Hood’s research team looked at key components of muscle cell health, including the production of mitochondria and proteins which are known regulators of mitochondrial synthesis. "While the older muscle fatigued more rapidly than the young muscle, this fatigue was reduced by the exercise and the muscle was ‘rescued’, allowing it to perform similarly to that of the young muscle," says Hood. In the younger muscle, regular exercise increased the mitochondrial content to a greater degree than in the old muscle, but old muscle did experience an increase and there was reduced apoptosis (cell death) in the old muscle.
Hood says the findings mean that exercise carries huge benefits for all ages, and muscle, no matter what its age, can adapt regardless of how old a person is. “People should be encouraged to exercise continually throughout their life,” says Hood. “Don’t expect that as you get older, the adaptations will happen as quickly, but an ongoing lifestyle choice to exercise is very important.”
The benefits, says Hood, are many for the elderly include and include stronger muscles, greater resistance to injury and bone breakage, and enhanced metabolism. “Regular exercise means being less tired doing normal daily activities, improved metabolism which helps you break down fat making you more sensitive to insulin, which is important in preventing pre-diabetic conditions. Better metabolism improves whole body function and wellness.”
Muscle Health Research Centre
Hood’s lab is part of York’s new Muscle Health Research Centre (MHRC), which is the first of its kind in Canada. The centre will celebrate its official opening on Wednesday, Jan. 20, at 10:30am.
“This centre is unique in that we’re zeroing in on skeletal muscle and its relationship to health, with a strong focus on what exercise can do,” says Hood, who will serve as the centre’s director. “We’re looking for new discoveries on how exercise can benefit Canadians through adaptations in the metabolism and structure of muscle.”
The MHRC conducts collaborative research with scientists from the School of Kinesiology & Health Science and the Department of Biology.
“Like all research centres at York, the MHRC has an interdisciplinary mandate – that is, enabling researchers from different departments and disciplines to work together towards a common goal,” says Hood.
Scientists from the MHRC are investigating topics such as muscle metabolism, muscle development and muscle adaptations to exercise, metabolic disease and cancer. Professor Tara Haas and colleagues in the MHRC recently identified a cell-signalling process that stimulates blood vessel growth and may help individuals with diabetes to exercise and thereby improve their health (see YFile, Nov. 17, 2009).
“As a leading research institution, we’re concerned with bringing the work of our scientists to bear on the real world and improving the health and well-being of Canadians,” says Harvey Skinner, dean of York’s Faculty of Health. The centre will serve as an innovative hub for the life sciences within York’s Faculty of Health, generating new knowledge and disseminating research findings to the public and the health system.
The opening ceremony will feature guest speakers, including Olympic figure skater Barbara Underhill; Philip Gardiner, director of the Health, Leisure & Human Performance Research Institute at the University of Manitoba; and Jane Aubin, scientific director of the Canadian Institutes of Health Reserach Institute of Musculoskeletal Health and Arthritis.
The opening will take place Jan. 20, from 10:30am to 1pm, in the Execultive Learning Centre located in X106 Seymour Schulich Building on York’s Keele campus. For more information, contact Kathy Thomas at thomask@yorku.ca. To learn more about muscle health research at York University, visit the MHRC Web site or contact Hood at dhood@yorku.ca.
By Jenny Pitt-Clark, YFile editor