Introduction. Females typically live longer than males but spend a greater proportion of their life in poor health. In addition, females have a higher frailty index score with an increasing effect size into older age. The neuromuscular system experiences age-associated declines contributing to the disparity between the biological sexes. The menopause indicates the end of a female fertile window and the dramatic reduction in the sex hormones may contribute to the exacerbated decline in neuromuscular functions in females. A reduction in firing rate of motor units from middle to older age within females is not observed in males and has the ability to influence force steadiness, a measure that can be used to identify the ability to control a force at any given level and plays an important role in stability. 

Aim. The aim of this study was to compare the force steadiness of submaximal contractions with the tibialis anterior in females across the lifespan, taking into consideration the transition through the menopause.

Methods. There were 4 groups: pre-menopause (PRE) (n= 5, age 23.2 ± 3.2 years), peri-menopause (PER) (n= 6 , age 49 ± 3.4 years), post-menopause (PO) (n= 5 , age 61.75 ± 9.5 years) and post-menopause + HRT (POH) (n = 3, age 56 ± 5.3 years) who performed  maximum voluntary contraction (MVC), and then a series of contractions at intensities of  10%, 25% and 40% of their MVC, respectively, using visual and verbal feedback. Intramuscular electromyography was used to record motor unit potentials within the tibialis anterior. A univariate ANOVA was used to compare the groups for their MVC and force steadiness (expressed as coefficient of variation (CoV)).

Results. There were no significant differences between the 4 groups for their respective MVC and CoV at all contraction intensities (10% MVC p =.083, 25% MVC p =.342, 40% MVC p =.105), but the postmenopausal group had the lowest MVC (103.67 ± 18.04 N).

Conclusion.  Whilst there are no initial significant findings within the data herein, this data forms part of a larger study and it is intended that over the forthcoming months further data will be collected to enhance our n number and ensure our sample size is large enough to draw firm conclusions. Nevertheless the data described will contribute knowledge to an area that has been lacking in regards to female physiology and in particular the menopause. Further investigations are required to explore the central and peripheral aspects of neuromuscular control and the contribution of the menopausal transition to the reduction in neuromuscular function for females in later life.