Exercise science researchers at University of Galway have revealed how careful consideration of the timing and intensity of training will benefit muscle health.

The study examined the effects of exercise on muscle, and in particular whether shorter bursts of very intensive exercise or longer periods of less intensive exercise were more effective at improving muscle health.

Dr Enda Murphy, an exercise scientist working at CÚRAM – the Research Ireland Centre for Medical Devices based at University of Galway, led the international collaboration, with scientists from Dublin City University and Toulouse University in France.

In order to fully assess the impact of exercise on muscle health, the researchers took muscle biopsy samples from participants before and after exercise. They also took very precise measures of metabolic health, including “insulin sensitivity” – a measure of how well insulin can control the flow of glucose and other fuels around the body. This made it possible to analyse very precisely the effects of exercise on metabolism within the muscle itself.

Dr Enda Murphy said: “The findings were interesting and unexpected. There were much bigger improvements in muscle function after the short, intensive exercise bouts compared to the longer bout of less intensive exercise, even though the overall workload with the short intensive bout was much lower.

“Our analysis also showed improvements in insulin sensitivity – which relates to how effectively the body’s cells respond to insulin in order to absorb glucose from the bloodstream and regulate blood sugar levels.”

The research involved young, healthy, active men involved in training or exercising at least twice a week. In order to assess how their bodies responded to the exercise, they were assessed 24 hours after sprint intervals (7x30 second high intensity sprints over 40 minutes), cycling over 1 hour (continuous moderate intensity), and while not exercising.

The full research can be read in the American Journal of Physiology - Endocrinology and Metabolism.

Dr Cedric Moro, part of the research team based in the Institute of Metabolic and Cardiovascular Diseases (I2MC) INSERM/Toulouse University France, said: “Whether the findings apply to other groups such as women, older people or those with chronic medical conditions like obesity, needs further study. However, the fact that we were able to quantify very precisely the changes in insulin sensitivity, as well as the changes in muscle at a molecular and microscopic level with the biopsy samples makes us confident that what we are seeing is real.”

Professor Francis Finucane, part of the research team and Consultant Endocrinologist, Galway University Hospitals and University of Galway, said: “This study shows the power of collaboration between specialists in metabolism, muscle function and exercise science. We know that exercise is really important for metabolic health, and making exercise interventions as effective as possible will help our patients with obesity and related disorders. This study is a small but important step on that journey.”

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