New research to understand muscle response to exercise in people with obesity

A new study from Manchester Metropolitan University will look at why people with obesity may be unable to increase their muscle size even by weightlifting and eating protein.

Muscles in people with obesity do not respond in the same way as those of lean people to nutrition or exercise. Anabolic resistance, as it is known, refers to the diminished ability of muscle tissue to build new protein in response to protein intake or resistance exercise. This can lead to muscle atrophy, weakness, and a reduced ability to recover from injury or stress.

The muscles of people living with obesity contain more fat, which prevents processes in their cells from working properly. One of these is muscle protein turnover (the balance between muscle growth and loss), which controls muscle size.

Understanding the complex relationship between obesity and anabolic resistance is crucial for developing effective interventions to improve muscle health and overall metabolic function in people with obesity and could reduce the risk of conditions such as diabetes and heart disease.

Dr Nathan Hodson, a Senior Lecturer in Musculoskeletal Physiology at Manchester Met’s Institute of Sport, who led the research, said: “Our research will focus on the activity of an important regulator of muscle size which is reduced in people with obesity, compared to lean individuals, when they lift weights or eat protein. We currently do not know why this happens.

Dr Hodson has recently discovered a way that this regulator is switched on, causing it to move to other regions of the muscle where it has a positive effect on muscle growth.

He adds:“We want to know if this process occurs less in obese skeletal muscle, which could explain anabolic resistance. If we find that it does, we can find ways to overcome the problem and increase muscle size/quality in people with obesity, which reduces their risk of suffering from other problems like diabetes or heart disease as their muscles can manage greater amounts of sugar/fat.”

The two-year study, which is due to get underway later this year, will take small muscle samples– a 20-minute procedure - in both lean and obese people and compare the movement and activity of this important regulator. Participants will also undergo an MRI scan to visualise the amount of fat within their thigh muscles.

Dr Hodson has been awarded a £125,000 Springboard Award by the Academy of Medical Sciences to conduct the study.