Parker, L (2024) Assessing the prevalence and factors affecting low energy availability in Women’s Super League soccer players. Doctoral thesis, Liverpool John Moores University.

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Abstract

The growth of female soccer in England has been substantial since the Football Association (FA) lifted its ban on female players using accredited facilities in 1971. The establishment of the Women’s Super League (WSL) in 2010 marked a significant milestone in this growth, evolving into a fully professional league with 12 teams, known as WSL 1. Despite this progress, research in the field of female soccer, particularly concerning nutritional and menstrual health, remains relatively underdeveloped. For female soccer players it is imperative that their energy intake is aligned with their total energy requirements. If this does not occur players could suffer from low energy availability (LEA), which is the failure to provide the body with adequate energy to sustain homeostasis. Low energy availability has been shown to have detrimental health and performance outcomes including, but not limited to, altered menstrual function and poor bone health. With this in mind the aim of this thesis was to assess hormonal contraceptive use, menstrual function, energy intake, energy expenditure, blood biomarkers and body composition with a view to ascertain the prevalence and factors contributing to LEA among elite female soccer players in WSL 1. Study 1 (Chapter 4) investigated the prevalence of hormonal contraceptive and non-hormonal contraceptive use and associated symptomatology among multiple squads in WSL 1 (N = 75). Results revealed that 28% of players reported current hormonal contraceptive use, with non-users experiencing more negative symptoms (74%) such as cramps (70%) during menstruation. Fourteen players (26%) reported menstrual dysfunction, though only one had been clinically diagnosed. These findings highlight that naturally menstruating female soccer players suffer from more negative symptoms associated with the menstrual cycle and that menstrual dysfunction could be a league wide issue. Having quantified that 26% of players suffered from menstrual dysfunction in Study 1 (Chapter 4), Study 2 (Chapter 6) assessed resting metabolic rate (RMR), exercise energy expenditure (EEE), energy intake (EI), menstrual function (Low Energy Availability in Females Questionnaire (LEAF-Q)), blood biomarkers, and body composition during pre-season in a WSL 1 team. Despite the LEAF-Q classifying 32% of the squad being at risk of LEA, actual measurements of LEA did not support the presence of this or menstrual dysfunction. Additionally, players did not adjust their energy or carbohydrate intake based on the intensity of training or the match schedule, with all of the squad under consuming carbohydrates on match day (3.7 ± 1.1g·kg·day-1). Most of the squad were within normal clinical ranges for micronutrient markers, suggesting that players dietary intakes were providing sufficient nutrients. Though none of the squad appeared to suffer from LEA or menstrual dysfunction in Study 2 (Chapter 5), this was only one time point in the season, therefore, the aim of Study 3 (Chapter 6) was a longitudinal assessment of RMR, EEE, EI, menstrual function, blood biomarkers, and body composition among elite female soccer players participating in a WSL 1 team throughout an entire season. Over the 10-month season where players were measured over four equally spaced time points, LEAF-Q continued to overestimate players at risk of LEA. Two players reported menstrual dysfunction over the season, with one player presenting with symptoms (menstrual dysfunction) and markers of suffering from LEA (energy availability of 34 kcal·kg FFM-1·day-1, decrease in FM, BF%, BM and RMR ratio). Players significantly periodised their energy and carbohydrate intake around training and match days, however, still under consumed carbohydrates on match days (4.5 g·kg·day-1). Body composition notably changed over the season with a significant decrease in fat mass and increase in fat free mass, while bone health remained within normal clinical ranges throughout the season. Vitamin D concentrations significantly declined during the season, with 70% of the squad having insufficient concentrations (<75 nmol·L-1) mid-season. Although remaining within clinical norms, ferritin concentrations dropped in 50% of players during the season, classifying them as stage 1 iron deficient according to athletic classifications (Peeling et al., 2007).
Although there was an absence of major issues related to LEA and menstrual dysfunction within the team in Studies 2 and 3 (Chapters 5 and 6), the aim of Study 4 (Chapter 7) was to provide a detailed two-year examination of one elite female soccer player suffering from secondary amenorrhea and anovulatory menstrual cycles. The player reported eight months without menstruation after suffering a serious injury and having surgical intervention. Initial indications suggested the possibility of LEA, with the player scoring 13 on the LEAF-Q. However, thorough investigations involving RMR, energy expenditure, energy intake, and biomarker analyses concluded that LEA was unlikely the cause of the player's condition. Unfortunately, due to the onset of the COVID-19 pandemic and the player relocating abroad, an official diagnosis could not be obtained. Subsequent follow-ups revealed that the player's menstrual function returned to normal, and she later became pregnant. As a result, it was concluded that despite initial suspicions of LEA, further investigation suggested other psychological and stress-related factors contributed to the menstrual dysfunction, highlighting the importance of practitioners considering multifactorial causes.
In summary, the findings of this thesis challenge previous estimations of LEA in elite female soccer players and underscores the need for a comprehensive, multidisciplinary approach to address menstrual disturbances. Moreover, it highlights the importance of education required to better fuel female soccer players for match day. Meanwhile, individualised supplement protocols are required to help achieve optimal nutritional status throughout the season, with continuous monitoring allowing for early identification and intervention to mitigate potential issues before they impact players' health and performance.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Energy availability; Women's soccer; Menstrual function
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine G Geography. Anthropology. Recreation > GV Recreation Leisure > GV561 Sports
Divisions:	Sport and Exercise Sciences
SWORD Depositor:	A Symplectic
Date Deposited:	26 Sep 2024 09:59
Last Modified:	26 Sep 2024 09:59
DOI or ID number:	10.24377/LJMU.t.00024102
Supervisors:	Close, G, Morton, J and Elliot-Sale, K
URI:	https://researchonline.ljmu.ac.uk/id/eprint/24102

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