Research

PACE Director, Professor in the Department of Kinesiology, Tier 1 Canada Research Chair  

• Bachelor of Science, McMaster University  
• Master of Science, McMaster University  
• Doctor of Philosophy, University of Waterloo  

My research program focuses on the following research question: what factors serve to maintain, increase, or decrease skeletal muscle mass?

In addition, my research does not only address the absolute mass of skeletal muscle, but also its quality as assessed by the quantity of force it can generate, but also by the metabolic activity of various enzymes and energy consuming pathways. In my lab, we use a human model of resistance or aerobic exercise, immobilization, or aging to study the processes that govern: muscle accretion, in the case of resistance exercise; atrophy, in the case of immobilization; and sarcopenia, in the case of aging. In addition, my research group has studied the interaction of feeding different protein composition and varied meal timing on the processes regulating hypertrophy and disuse atrophy. We employ stable isotope tracers of amino acids to metabolically trace the fate of ingested proteins. Muscle biopsies provide us with mechanistic information regarding processes that regulate protein accretion and degradation. We use Western blotting, RT-PCR, histological, and immunohistochemical methods to examine these mechanisms. I am also very interested in conditions in which muscle wasting occurs, particularly in the elderly.

My research activities in the PACE are centred on projects that look at how nutrition and exercise interact to affect strength and muscle mass in older people or in persons with chronic disease such as type 2 diabetes or obesity. For example, one study examines the effects of short-term training among people with pre-diabetes consuming a diet with or without dairy. Another training study involving older adults, has examined the effects of post-workout dairy consumption.

My research examines social-cognitive factors that influence and are influenced by participation in physical activity. Current interests include self-perceptions such as self-efficacy, perceived control, self-regulation, and self-determination.

My research examines social-cognitive factors that influence and are influenced by participation in physical activity. Current interests include self-perceptions such as self-efficacy, perceived control, self-regulation, and self-determination. I also investigate people’s perceptions about influential others who interact with them (proxy agents) in their pursuit of behavioural objectives. Understanding relationships between these perceptions and behaviour involves laboratory and field-based research. Challenges faced by people navigating life transitions such as moving away from home to attend college or university, rehabilitating from illness, and becoming a parent are of particular interest.

My current research activities in the PACE include a collaborative project—The “HOPP” (Health Outcomes and Physical activity in Preschoolers) Study—in which we are investigating health risk factors associated with physical activity in young children as well as parents’ perceptions of benefits and barriers to providing physical activity opportunities for their preschoolers. I am also involved in a collaborative study investigating the effects of a telephone-delivered counseling intervention to promote physical activity among children and youth with epilepsy.

My research examines the regulation of skeletal muscle energy provision. I am particularly interested in the potential for exercise and/or nutrition to induce metabolic adaptations at the molecular and cellular levels in humans.

In addition to basic, mechanistic studies, I also conduct applied research that examines the impact of exercise training and dietary manipulation on sport performance. Recent work in my laboratory has focused on two main areas:

1. Metabolic adaptations to low-volume, high-intensity interval training, with an emphasis on the regulation of oxidative energy provision.
2. The potential for alterations in nutrient availability to impact the acute or chronic adaptations to exercise training.

Working within the PACE facilities, we plan to conduct larger-scale, randomized controlled trials in order to comprehensively examine the physiological and health-related benefits of low-volume HIT versus traditional high-volume endurance training. We are interested in the potential for high-intensity interval training (HIT) to improve health-related indices in various populations including those at risk for chronic diseases. Preliminary work from small proof-of-principle studies suggests that HIT is a time-efficient strategy to improve insulin sensitivity and reduce blood sugar levels in people at risk for, or afflicted by, type 2 diabetes

My research program examines the interplay between brain and body fitness in the promotion of health.

I use brain-imaging methods to explore how neural network dynamics are affected by physical exercise and cognitive interventions for young adults, healthy older adults, and older adults with mild cognitive impairment (MCI). A key question is whether cognitive-physical interventions target a particular cognitive ability or generalize to everyday functioning.  An important clinical application of my work is to establish neural biomarkers as screening protocols for the early detection of neurodegenerative disorders such as Alzheimer’s disease and other dementias.

By conducting research among exercisers in PACE community programs—such as the MacSeniors—I am able to study the long-term effects of regular physical exercise on cognitive health. Specifically, my research in PACE focuses on understanding the long-term benefits of exercise on measures of cognitive health, by assessing exercisers’ cognitive performance at regular intervals. This research will help to determine the optimal dose and type of exercise that mitigates cognitive decline in healthy older adults and individuals with mild cognitive impairment. The ultimate goal of my research program is to understand how lifestyle choices such as exercise can be used for disease prevention.

My research focus is on exercise rehabilitation, with a specific focus on people with mobility impairments resulting from either spinal cord injury or multiple sclerosis,

I am interested in examining the assorted health and rehabilitative benefits of engaging in regular exercise, as well as developing best practice physical activity guidelines for special populations. At a more basic level, I also study characteristics of muscle, fatigue properties, and activation at the neuromuscular level.

I am also the founder and Director of the MacWheelers program, which is a community-based exercise program for people with spinal cord injury living in the Hamilton area.

My current research activities in the PACE focus on validating the physical activity guidelines for adults with SCI, comparing muscle activation and metabolic demand between different modes of assisted ambulation, and determining optimal and preferred modes of exercise training for people with SCI.

Our laboratory investigates mechanisms of neuromuscular maintenance and remodelling with an emphasis on identifying therapeutic targets for neuromuscular system disorders.

Neuromuscular plasticity refers to the remodeling of the neuromuscular system in response to genetic or environmental cues. Neuromuscular disorders, including the neuromuscular alterations that are hallmarks of advanced aging, are more common in Canada then generally appreciated. The central experimental questions that form the foundation of our research program are: 1) What roles do phenotype-modifying proteins play in the maintenance and remodeling of the peripheral neuromuscular system, and 2) Are these molecules efficacious therapeutic targets for neuromuscular disorders? To address these questions, we design investigations around rational lifestyle- and pharmacological-based strategies focused on the manipulation of powerful phenotype-bending molecules in the neuromuscular system. Furthermore, we employ an integrative and rigorous cell-to-animal experimental approach, as well as an innovative combination of molecular physiological solutions.

The long-term goals of our research activities in the PACE are to expand fundamental understanding of the mechanisms governing neuromuscular plasticity, as well as to identify novel, evidence-based therapeutic strategies to improve the lives of those with compromised neuromuscular systems. In our efforts to attain these goals, we design studies that examine the presence, location, and activity of specific proteins in neural and skeletal muscle tissues. We manipulate their molecular and cellular characteristics by employing lifestyle, drug, or genetic interventions in order to better define the function of these proteins, as well as to facilitate their identification as potential therapeutic targets. In collaboration with our colleagues in the PACE, as well as with partners in the Faculty of Health Sciences at McMaster University, we advance studies through basic, pre-clinical, and clinical phases of inquiry

Our blood vessels play an important role in transporting blood to and from all of the tissues of our body. My research focuses on the role that physical activity plays in altering arterial structure and function.

Two important features of our arteries are how flexible they are and how much they can expand when they need to accommodate more blood flow. In my lab, we are using new ultrasound methods to look directly at the walls of the arteries and blood flow inside muscles. Our ongoing studies will focus on the use of cutting edge ultrasound technology to view blood vessels. The information gained from these studies will assist in advancing the current basic knowledge of human physiology and help in developing effective exercise programs.

My work in the PACE includes several studies looking at blood vessels in different populations including healthy individuals and those at increased risk for cardiovascular disease. Some current research questions include:

• Is arm or whole body exercise training better to decrease cardiovascular risk in individuals with a chronic spinal cord injury?
• Are activity patterns predictive of arterial health in pre-school aged children?
• Will sprint interval exercise improve the function of arteries for people in a cardiac rehabilitation program?
• Do adults with cerebral palsy have increased cardiovascular risk?
• Does Tai Chi increase exercise capacity for people with cardiac disease?
• How do different exercise programs regulate changes in blood vessel health?

The purpose of my research is to develop fundamental understanding of the cortical control of the human hand and upper limb.

My research program is focused on the somatosensory contributions to motor control; human hand control is profoundly dependent on the integrity of somatosensory input that arises from touch and muscle receptors. Multiple cortical areas receive and process somatosensory input yet little is known about the role of these areas in the control of human hand movement. My research program is primarily focused on investigating the role of somatosensory loci in the control of hand movement in healthy and clinical populations such as individuals with spinal cord injury. Students in my lab use a combination of neurophysiology techniques including transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging.

One of the long-term goals of my research in the PACE is to improve hand and arm control in individuals with incomplete spinal cord injury. To achieve this goal, we are initiating several studies that aim to combine positive plasticity-inducing effects of TMS with positive plasticity-inducing effects of exercise. Our initial studies in SCI will examine the neural output of the motor cortex to the muscles of the hand. These studies will determine the extent of the remaining connections between the neurons in the motor cortex and spinal cord with the muscles that control finger and hand movements. Further, we are measuring how the remaining motor connections are modified by remaining sensory connections. These studies will tell us whether the motor connections can be modified, an essential element of inducing neural plasticity.

My research focuses on skeletal muscle growth and adaptation that requires the contribution of a unique population of cells known as muscle stems (or satellite cells).

In response to damage or stress, muscle stem cells become activated, proliferate, and fuse with muscle fibers to repair damaged tissue. These cells are controlled by a series of transcriptional networks, collectively referred to as the myogenic regulatory factors that govern the induction of these cells from quiescence through proliferation and into terminal differentiation. What remains poorly understood is precisely what environmental cues, released in the hours and days following exercise-induced muscle damage, and how these cues interact with satellite cells.

A related question, that is a focus of my laboratory, is what are the intracellular events that act downstream of these signals leading to the activation of the myogenic regulatory factors? My research activities in the PACE link with a second major focus of my laboratory—revealing the mechanism(s) underlying the progressive loss of muscle mass associated with aging. It has been shown that muscle growth (hypertrophy) is not possible without the contribution of a functional muscle stem cell population. By extension, it stands to reason that a loss of muscle mass with aging, and a blunted hypertrophic response to chronic exercise in older adults, is likely a result of age-related muscle stem cell dysnfunction and/or age-related loss of muscle stem cell number. My research program aims to examine potential age-related impairment of muscle stem cells, as well as the molecular and cellular events that lead to dysregulation of muscle stem cells in advanced age.

My research is focused on exercise and cardiovascular health among people with stroke and other neurological conditions, particularly as these relate to cardiovascular risk factors and prevention of cardiovascular disease.

In Canada, there are 50,000 new cases of stroke each year, or about 1 stroke every 10 minutes. Stroke affects different people in different ways. Many people continue to live with physical and cognitive effects of stroke, which can contribute to limited mobility, physical inactivity, and sedentary behaviours. This can lead to higher risk for developing cardiovascular disease or having another stroke.

Exercise and regular physical activity has the potential to mediate many cardiovascular risk factors and may be effective for primary and secondary prevention of stroke and cardiovascular disease.

Our research examines the physiological effects of exercise and physical activity after stroke, refining protocols for exercise testing and training, investigating the effects of broader, holistic health promotion approach to improving cardiovascular health, and examining the effects of physical activity on primary and secondary events. This work contributes to our knowledge regarding effective strategies to improve the health and lives of people at risk for stroke and those living with the effects of stroke.