Understanding if sex hormones affect muscle differently in males and females

Sex is a fundamental biological characteristic that influences nearly all human traits – yet most scientific knowledge is inferred from males. Dr Danielle Hiam is working to better understand the role of sex hormones in regulating skeletal muscle at a molecular level.

Dr Hiam’s Deakin University Dean’s Postdoctoral Research Fellowship work directly challenges the ‘one-size-fits-all’ approach by addressing the under-representation of females in clinical and medical research.

‘We all agree that there are obvious physiological differences between males and females, however these differences extend far beyond the things we can see. Under the microscope there are a whole host of molecular differences between sexes,’ Dr Hiam said.

‘Unfortunately, most of our scientific knowledge of the human body is inferred from males, meaning that we have an incomplete picture of how things work in females.’

Skeletal muscle is one of the most important tissues to maintain a healthy body and is especially important in promoting healthy ageing.

Interestingly, research has shown that muscle loss is different between males and females.

‘However, we don’t have a good insight into the molecular regulators of skeletal muscle mass and function in females which means we don’t have enough information to differentiate between and respond to the differing needs of males and females,’ Dr Hiam said.

One of the most obvious differences between the sexes is the level of sex hormones like testosterone, which is much higher in males. Dr Hiam will research whether sex hormones could be altering important biological molecules (microRNAs) that result in changes to what the skeletal muscle looks like and how well it works.

Dr Hiam has already recruited male and female adults for part of her study and plans to recruit a second group of interest – females aged 18-45 years with Polycystic Ovary Syndrome (PCOS). PCOS is the most common hormonal disorder in females. By studying PCOS, Dr Hiam hopes to understand how hormonal imbalances can impact muscle health.

All participants will be asked to undergo fitness tests, body composition measures, and provide muscle and blood samples. She will then measure a range of microRNAs and sex hormones in participants to understand the role these play in regulating skeletal muscle mass and function.

‘I’m hoping the findings from my fellowship will eventually lead to a broader research project investigating the role sex hormones play in females across the lifespan – in particular in the context of muscle loss and associated conditions such as type 2 diabetes,’ she said.