Energy expenditure, intake and availability in female soccer players via doubly labelled water: Are we misrepresenting low energy availability?

Female soccer players have been identified as presenting with low energy availability (LEA), though the prevalence of LEA may be overestimated given inaccuracies associated with self-reporting dietary intakes. Accordingly, we aimed to quantify total daily energy expenditure (TDEE) via the doubly labelled water (DLW) method, energy intake (EI) and energy availability (EA). Adolescent female soccer players (n = 45; 16 ± 1 years) completed a 9-10 day 'training camp' representing their national team. Absolute and relative TDEE was 2683 ± 324 and 60 ± 7 kcal kg-1 fat free mass (FFM), respectively. Mean daily EI was lower (P < 0.01) when players self-reported using the remote food photography method (RFPM) (2047 ± 383 kcal day-1) over a 3-day period versus DLW derived EI estimates accounting for body mass (BM) changes (2545 ± 518 kcal day-1) over 7-8 days, representing a mean daily Δ of 499 ± 526 kcal day-1 and 22% error when using the RFPM. Estimated EA was different (P < 0.01) between methods (DLW: 48 ± 14 kcal kg-1 FFM, range: 22-82; RFPM: 37 ± 8 kcal kg-1 FFM, range: 22-54), such that prevalence of LEA (<30 kcal kg-1 FFM) was lower in DLW compared with RFPM (5% vs. 15%, respectively). Data demonstrate the potential to significantly underestimate EI when using self-report methods. This approach can therefore cause a misrepresentation and an over-prevalence of LEA, which is the underlying aetiology of 'relative energy deficiency in sport' (REDs). HIGHLIGHTS: What is the central question of this study? Do self-reported dietary intakes (via remote food photography method, RFPM) overestimate low energy availability (LEA) prevalence in female soccer players compared with energy intake evaluation from the doubly labelled water (DLW) method? What is the main finding and its importance? Estimated energy availability is greater with the DLW method compared with RFPM, such that the prevalence of LEA is greater when self-reporting dietary intakes. Accordingly, data demonstrate the potential to misrepresent the prevalence of LEA, an underlying factor in the aetiology of 'relative energy deficiency in sport' (REDs).

Case Study: The Effect of Nutritional Intervention on Body Composition and Physical Performance of a Female Squash Player.

The body composition of a squash player may affect athletic performance as carrying excessive body fat may increase injury risk and impair agility and speed. This case study outlines the effect of a nutritional intervention on body composition, vitamin D status, and physical performance of a female squash player. A structured, 6-week, moderate energy-restricted diet (70-78% of estimated energy requirement of 2,300 kcal) was implemented with weekly support. A daily supplement of vitamin D, omega-3 fatty acids, and a multivitamin and whey protein was used. Full blood count, vitamin D status, body composition, and physical performance assessments were carried out at baseline and Week 6 of intervention. Body composition changes were measured using the BOD POD™ and skinfold calipers. Body fat was 23% at baseline and 22% at Week 6. Mean sum of eight skinfolds was 127.4 ± 2.2 mm at baseline and 107.3 ± 0.4 mm at Week 6. Lean body mass-to-fat mass ratio improved from 3.4 at baseline to 3.7 at Week 6. The greatest increments compared with baseline in serum markers were 25-hydroxyvitamin D3 (68%), ferritin (31%), eosinophils (20%), and triglycerides (16%). All physical performance measures improved, with reactive strength index (4.8%), and on-court repeated speed (6.0%) showing the greatest improvements from baseline. This intervention demonstrates that structured energy restriction alongside appropriately structured strength and conditioning training is an effective way to gradually reduce the body fat and improve the body composition of a female athlete.

Under-Fuelling for the Work Required? Assessment of Dietary Practices and Physical Loading of Adolescent Female Soccer Players during an Intensive International Training and Game Schedule.

Previous studies demonstrate that "under-fuelling" (i.e., reduced carbohydrate (CHO) and energy intake (EI) in relation to recommended guidelines) is prevalent within adult female soccer players, the consequence of which may have acute performance and chronic health implications. However, the dietary practices of adolescent female soccer players, a population who may be particularly at risk for the negative aspects of low energy availability (LEA), are not well documented. Accordingly, we aimed to quantify EI and CHO intake, physical loading and estimated energy availability (EA) in elite national team adolescent female soccer players (n = twenty-three; age, 17.9 ± 0.5 years) during a 10-day training and game schedule comprising two match days on day six (MDa) and nine (MDb). The players self-reported their EI via the remote food photography method, whilst the physical loading and associated exercise energy expenditure were assessed via GPS technology. The relative CHO intake was significantly greater (all p < 0.05) on the day before the first match (MD-1a) (4.1 ± 0.8 g·kg-1), on the day before the second match (MD-1b) (4.3 ± 1.1 g·kg-1), MDa (4.8 ± 1.2 g·kg-1) and MDb (4.8 ± 1.4 g·kg-1) in comparison to most other days (<4 g·kg-1). The mean daily measured EA over the 10-day period was 34 ± 12 kcal·kg FFM-1·day-1 (with six players, i.e., 34%, presenting LEA), though, when adjusting the energy intake for potential under-reporting, these values changed substantially (44 ± 14 kcal·kg FFM-1·day-1, only one player was classed as presenting LEA). Such data suggest that the prevalence of LEA amongst female team sport athletes may be over-estimated. Nonetheless, players are still likely under-fuelling for the work required in relation to the daily CHO recommendations (i.e., >6 g·kg-1) for intensive training and game schedules. These data provide further evidence for the requirement to create and deliver targeted player and stakeholder education and behaviour change interventions (especially for younger athletes) that aim to promote increased daily CHO intake in female soccer players.

Energy Expenditure of Female International Standard Soccer Players: A Doubly Labeled Water Investigation.

PURPOSE: The purpose of this study is to quantify total daily energy expenditure (TEE) of international adult female soccer players. METHODS: Twenty-four professional players were studied during a 12-d period where they participated in an international training camp (also inclusive of two competitive games) representing the English national team. The TEE was assessed via the doubly labeled water method during the full 12 d as well as the initial 4-d period before game one. Energy intake was also assessed (via weighed food analysis) during the initial 4-d period to permit estimation of energy availability (EA). RESULTS: Mean TEE did not differ (P = 0.31) between the 12-d (2693 ± 432 kcal·d-1; range, 2105-3507 kcal·d-1; 54 ± 6 kcal·kg-1 fat-free mass [FFM]) versus the 4-d assessment period (2753 ± 359 kcal·d-1; range, 1942-3280 kcal·d-1; 56 ± 8 kcal·kg-1 FFM). Mean 4-d energy intake was 1923 ± 357 kcal·d-1 (range, 1639-2172 kcal·d-1) and mean activity energy expenditure was 1069 ± 278 kcal·d-1 (range, 155-1549 kcal·d-1). When assessed for estimated EA, 88% of players were categorized with low EA status according to the threshold of <30 kcal·kg-1 FFM. Mean daily carbohydrate intake equated to 3.3 ± 0.7 g·kg-1 body mass. CONCLUSIONS: When compared with previously published data from adult male players, we demonstrate that the relative daily energetic requirements of engaging in professional soccer training and match play are comparable between sexes. From a practical perspective, data suggest that practitioners should likely focus education and behavior change strategies on "fuelling" for match play and training to optimize both player health and performance.

Carbohydrate fear, skinfold targets and body image issues: a qualitative analysis of player and stakeholder perceptions of the nutrition culture within elite female soccer.

PURPOSE: This qualitative study explores player and stakeholder perceptions of the role of nutrition in supporting player development and performance in elite female soccer. METHODS: Semi-structured interviews (36 ± 18 mins in length) were conducted with 47 participants, including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). Via thematic analysis, data provided an insight into the nutrition culture within elite women's soccer. RESULTS AND CONCLUSIONS: Data demonstrate that considerable confusion and misconceptions exist amongst players and stakeholders regarding the theoretical underpinning and practical application of meeting energy requirements. As such, it is perceived that players 'under-fuel', which is likely caused by misunderstandings about the impact of carbohydrate intake on body composition, a fear of weight gain and the associated impacts upon body image. The 'carbohydrate fear' that is experienced by players is exacerbated by external pressures arising from social media, key stakeholders (e.g., coaches) and the skinfold culture surrounding measurement of body composition. Such cultural issues are amplified by the lack of full-time professionally accredited nutritionists overseeing the provision of nutrition support. Indeed, the infrastructure supporting the women's game (e.g. staffing resource, on-site food provision, player education programmes, etc.) was considered incomparable to the men's game.When taken together, our data provide a platform for which to develop organisational, stakeholder and player centred education and behaviour change interventions that strive to promote a positive performance nutrition culture within the women's game.

Normalising the conversation: a qualitative analysis of player and stakeholder perceptions of menstrual health support within elite female soccer.

PURPOSE: This qualitative study explores player and stakeholder perceptions of menstrual health support in elite female soccer. METHODS: Semi-structured interviews were conducted with 47 participants including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). RESULTS: Via thematic analysis, data demonstrate that elite female soccer players experience a range of physical and psychological symptoms primarily at the onset of and during menses (as also perceived by stakeholders), with most participants perceiving these symptoms to impact performance. Nonetheless, menstrual health support is perceived as minimal and although players have their menstrual status tracked, they report little understanding as to why or how this information is used. This confusion was also present among stakeholders, often as a result of uncertainty about the evidence supporting the need for menstrual health support. The perceived lack of support may also be reflective of a culture where conversations about the menstrual cycle are not normalised. Overall, this may result in failure to identify and treat menstrual irregularities despite non-coaching staff members perceiving them to be common amongst players. CONCLUSION: These data support the need for individualised support based on the lived experiences of individual players and support staff. Furthermore, our research identifies the need for organisational, stakeholder, and player centred education programmes (led by experts in female athlete health) that create an environment where players receive personalised menstrual health support.