Advancing the research for muscle health

Skeletal muscle is the largest tissue within the body, occupying about 40 per cent of body mass in lean individuals. Good muscle health is vital for everyday locomotion and physical activity. In addition, because of its size within the body, muscle contributes substantially to whole body metabolism. This has an impact on how we store the calories we take in, as well as how we burn those calories during physical activity. Inadequate caloric expenditure, or excess caloric intake can lead to metabolic diseases such as type 2 diabetes and obesity.

Skeletal muscle has an important role to play in a variety of different conditions, including some of the most common diseases of our time:

1) Metabolic diseases such as obesity and Type 2 Diabetes;
2) Cancer and muscle wasting (cancer cachexia);
3) Inactivity and muscle disuse conditions (eg. immobilization, nerve damage);
4) Muscle degeneration diseases (eg. muscular dystrophy).

Compounding this is the fact that during the aging process, muscles become weaker and lose their endurance capabilities. This is because of the progressive loss of muscle cells and the drop in mitochondrial content within each cell. Mitochondria are the organelles which provide the energy (by burning fat and carbohydrate) for muscle function and endurance capabilities. Type 2 diabetes and obesity are also characterized by poor muscle metabolism, and these conditions currently afflict over 2 million people in Canada. In addition, the muscle wasting evident during the progression of cancer is responsible for approximately 30% of all cancer deaths. Thus, research in the area of skeletal muscle health should be at the forefront of our understanding of how to improve the quality of life of individuals affected by these conditions.

Recent findings by York researchers

Recent findings have also indicated that exercise, or regular physical activity, can serve an important role in attenuating the loss of muscle function evident in these conditions. Exercise is therefore a vital intervention which can be used to help improve the quality of life of millions of people.

At York University, there are currently 15 researchers within both Kinesiology and Health Science and Biology that are studying and researching in the area of muscle health and disease. Topics include the study of muscle metabolism, muscle development, and muscle adaptations to exercise, metabolic disease and cancer. This probably represents the greatest focus of research on skeletal muscle health in the entire country. Under the direction of Professor David A. Hood, York University’s Canada Research Chair in Cell Physiology, York has established a unique biomedical research centre focused on skeletal muscle, called the Muscle Health Research Center. It is devoted to skeletal muscle health and disease, metabolism, adaptation and the role of various forms of exercise in improving muscle function. The purpose of the proposed Center is to facilitate the integrated study and understanding of muscle biology in the broadest terms, with implications for whole body health and the prevention of disease. A greater understanding of skeletal muscle function in health and disease is one of the key components of maintaining a good quality of life with functional independence.

Investigating critical questions:

• What is the fundamental link between exercise, the creation of more cellular mitochondria, and corresponding increase in energy levels?
• How can muscle tissue be healed much more quickly after damage, at the cellular level?
• What is the relationship between muscle carbohydrate and fat metabolism, and how can we prevent Type 2 Diabetes and obesity using exercise interventions?
• What is the link between our genetic make-up and the adaptation and evolution of our differing muscle fiber types (i.e. fast-twitch and slow-twitch muscles)?
• What is the cellular basis for muscle protein breakdown in disease states, and with advancing age? Can exercise prevent this?
• How does oxidative stress (i.e. free radicals) damage muscle? Is exercise helpful or harmful?
• How does exercise promote better blood flow and nutrient supply to muscles?

Specialized Laboratory Equipment available within the MHRC which helps us answer these questions.

Under current development is the Clinical Evaluation Unit, which will allow an increasing number of studies to be conducted in humans in the near future, in addition to our current research using animal models and muscle cells in culture. This will permit the research to be interdisciplinary and highly collaborative.

The Muscle Health Research Center at York University is unique in North America. The work of this Centre will continue to provide new and unique knowledge which should have a dramatic impact on the health of Canadians.