Is testosterone really the key to a female’s athletic performance?

This research project aimed to discover whether testosterone, the major male hormone that is also found in females, is a direct determinant of muscle adaptation and athletic performance in females.

Associate Professor Severine Lamon said certain females naturally presenting ‘higher than normal’ testosterone concentrations were currently excluded from international competitions in certain disciplines.

“This is because there is an assumption that natural high testosterone levels provide them with an unfair advantage over other competitors. This assumption has however not been verified and we wanted to demonstrate that it is too simplistic,” she said.

“This work fights for the right of naturally gifted female athletes to compete in their discipline of choice regardless of their natural testosterone level. This will make female sport fairer.”

The research, funded by the International Olympic Committee, sought to prove the hypothesis that testosterone levels do not correlate with female muscle mass, strength and performance. The research aligned with Associate Professor Lamon’s focus on the lack of scientific research specifically in female physiology, despite females comprising 50 per cent of the population.

Associate Professor Lamon recruited 35 pre-menopausal females presenting a broad range of natural testosterone concentrations.

The participants performed a 12-week resistance exercise program designed to maximise gains in muscle mass and strength. The research team used this process to determine the role of testosterone and establish whether testosterone levels were a reliable predictor of their gains in muscle mass, strength and power.

The 12-week intervention elicited a strong anabolic response with increased body weight, BMI, total body lean mass, muscle strength, thigh muscle cross-sectional area (CSA), muscle power, average myofiber size, and molecular markers of anabolic stimulation.

Despite the increased strength, the plasma levels of testosterone remained unchanged. There was no evidence of a relationship between baseline total testosterone and pre-training muscle strength. In contrast, free but not total testosterone was positively associated with muscle mass and function and with the muscle anabolic response in pre-menopausal females.

This fundamental research has shed light on the very understudied area of female muscle physiology and will improve understanding of how the female muscle grows and adapts.

“Importantly, this research has the very practical consequence to inform or change the female eligibility rules surrounding naturally high testosterone levels in athletics competitions,” Associate Professor Lamon said.

Associate Professor Lamon said that future interventions (exercise, nutritional, hormonal) should consider how free testosterone may be a more valid biomarker when maintaining muscle mass and function in health and disease conditions.