Objective To investigate the effects of a moderate increase in serum testosterone on physical performance in young, physically active, healthy women.
Methods A double blind, randomised, placebo controlled trial was conducted between May 2017 and June 2018 (ClinicalTrials.gov ID: NCT03210558). 48 healthy, physically active women aged 18–35 years were randomised to 10 weeks of treatment with 10 mg of testosterone cream daily or placebo (1:1). All participants completed the study. The primary outcome measure was aerobic performance measured by running time to exhaustion (TTE). Secondary outcomes were anaerobic performance (Wingate test) and muscle strength (squat jump (SJ), counter movement jump (CMJ) and knee extension peak torque). Hormone levels were analysed and body composition assessed by dual energy X-ray absorptiometry.
Results Serum levels of testosterone increased from 0.9 (0.4) nmol/L to 4.3 (2.8) nmol/L in the testosterone supplemented group. TTE increased significantly by 21.17 s (8.5%) in the testosterone group compared with the placebo group (mean difference 15.5 s; P=0.045). Wingate average power, which increased by 15.2 W in the testosterone group compared with 3.2 W in the placebo group, was not significantly different between the groups (P=0.084). There were no significant changes in CMJ, SJ and knee extension. Mean change from baseline in total lean mass was 923 g for the testosterone group and 135 g for the placebo group (P=0.040). Mean change in lean mass in the lower limbs was 398 g and 91 g, respectively (P=0.041).
Conclusion The study supports a causal effect of testosterone in the increase in aerobic running time as well as lean mass in young, physically active women.
- female athletes
- physical performance
- body composition
- randomised controlled trial
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Contributors All authors listed met the conditions required for full authorship. Concept and study design: ALH, SB and BE. Acquisition of the data, data analysis and interpretation of the data: all authors. Drafting of the manuscript: ALH. Critical revision and approval of the manuscript for important intellectual content: all authors.
Funding The study was financed by grants from the International Athletics Foundation, the Swedish Research Council (2017-02051), the Swedish Research Council for Sport Science, the Karolinska Institutet and the Swedish Military Forceś Research Authorities (#AF9220914). Lawley Pharmaceuticals provided the treatment of testosterone and placebo.
Competing interests ALH is a medical and scientific consultant for the Swedish Olympic Committee and a member of the International Association of Athletics Federation (IAAF) and the International Olympic Committee (IOC) working groups on hyperandrogenic female athletes and transgender athletes. SB is a medical and scientific consultant for the IAAF and a member of the IAAF and IOC working groups on hyperandrogenic female athletes and transgender athletes. The authors have no other involvement with any entity having a financial interest in the material discussed in the manuscript.
Patient consent for publication Not required.
Ethics approval The study was approved by the regional ethics committee in Stockholm (2016/1485-32, amendment 2017/779-32). All women gave written informed consent.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement The trial is registered at ClinicalTrials.gov ID: NCT03210558. De-identified data from the trial are available on reasonable request from the corresponding author.
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