Energy intake and energy balance in New Zealand elite female football academy players : a thesis presented in partial fulfilment of the requirements for the degree of Nutrition and Dietetics, Massey University, Albany, New Zealand

Abstract

Background: Energy is a fundamental requirement for all biological processes, making adequate dietary energy intake (EI) critical to the health and athletic performance of athletes. Playing football at the elite level is an energetically expensive activity. Research in female footballers is limited; however, due to the negative consequences of being in a state of problematic low energy availability (pLEA), further investigation is needed to assess the adequacy of female footballers’ EI in supporting physiological function and demands of training. Objectives: Determine the energy intake (EI) and energy balance (EB) of elite under 20 female Football Academy players in New Zealand and if low carbohydrate (CHO) intake is a factor that increases the risk of low EB. Methods: Twenty-four female footballers who were part of the Wellington Phoenix U20 Football Academy team in New Zealand participated in this study. Participants were asked to complete a three-day dietary record on one light training day, one heavy training day, and one pre-game rest day. Energy intake was analysed via Foodworks V.1.0 software. For training, exercise energy expenditure (EEE) was estimated using a human motion tracking device (Playermaker, Israel). Paired sample t-tests or Wilcoxon Signed Rank test (non-parametric data) were utilised for comparisons between EI, EEE and EB on different training days. Significance was determined by a p-value of < 0.05. Results: The average EI for participants on light training, heavy training, and pre-game rest days was 1758.7 ± 549.5 kcal, 1910.1 ± 611.2 kcal and 1805.8 ± 533.2 kcal respectively, with no significant differences in EI between training days. The average relative carbohydrate intake ranged between 1.4 – 6.7 g‧kg- ¹ across all training days, failing to collectively meet sports nutrition recommendations. The average EB across all training days was 297.1 ± 491.6 kcal with no significant differences between days of data collection. Across the three training days, 25.0% of female development players were in a negative EB. A very strong, significant positive correlation was found between average EI and average EB (R=0.980, n=24, P=<0.01). There was no significant correlation found between average EI and average EEE (p=0.909) or average EEE and average EB (p=0.538). Conclusion: The results of this study suggest that female footballers fail to match their EI to their EEE, and a high proportion of players at the elite development level in New Zealand are in a negative EB, which could increase their risk of pLEA.