Fuelling Gold Medals: Developing a Periodised Nutrition System for Elite Athletes and Applying it in Practice

doi:10.21203/rs.3.rs-5275222/v1

The concept of periodised nutrition is a well-established within performance nutrition support to appropriately fuel elite athletes while maximising the adaptative response from training. Despite this, there still appears to be little planning and integration of training prescription and nutrition between the nutritionist and multi-disciplinary team. Consequently, the aim of this current opinion was to (1) propose a ‘Periodised Nutrition System’ which can be utilised by nutrition practitioners when working with athletes; (2) discuss how this can be administered in practice, collaborating with the coach, multidisciplinary team and athlete; (3) present a case study of the proposed ‘nutrition periodisation system’ and its utilisation with a world class swimmer leading into the 2024 Olympic Games. The ‘Periodised Nutrition System’ presents different ‘performance plates’, quantities of different foods to fit into the ‘performance plates’ to aid recipe development, and how they may practically fit into an athlete’s periodisation alongside theoretical rationale. The case study demonstrates a ‘real world’ scenario of its utilisation with an elite swimmer, transitioning through three separate performance goals while reducing body mass by 1.9 kg, sum of eight skinfolds by 20.1mm, predicted fat mass by 2.6 kg and an increase in predicted lean mass by 0.6 kg over a six-week mesocycle. The study highlights that the ‘Periodised Nutrition System’ enables the practitioner to develop structure to their support aligning nutritional strategies with the training periodisation of the athlete, allowing for an individual approach, specific to the athlete’s performance goal(s) and the desired adaptation of a training session.

Performance nutrition

sports nutrition

periodised nutrition

Swimming

Olympics

The concept of training periodisation has been well established since the seminal work of Dr. Hans Selye in the early 1950’s [1]. This has paved the way for a mixture of different training periodisation approaches such as classical, block, pyramidal, polarised, and threshold models [2–4], with these approaches being utilised in a variety of sports such as swimming [5], and track and field [6]. The main aim of training periodisation, regardless of the approach, is to cyclically order specific training exercises and sessions, while navigating an athlete through a short (microcycle; days and within days), medium (mesocycle; weeks) and long (macrocycle; months to year(s)) term planning process, with the aim of applying the principles of progressively overloading and recovering an athlete, specific to their event, with the intention of achieving peak performance in a sporting event [2, 3].

Nutrition sits in tandem with an athlete’s training programme, ensuring that an athlete has the appropriate amount of macro-and micro-nutrients to optimise their health, physical performance, training adaptations, and body composition [7]. Over the past couple of decades, the concept of ‘periodised nutrition’ has been developed [8, 9]. It was first proposed by Stellingwerff et al., (2007) [8], who presented different energetic and macronutrient recommendations, depending on what training phase of their macrocycle an athlete was in. More recently, the concept of ‘periodised nutrition’ has been defined as “the planned, purposeful, and strategic use of specific nutritional interventions to enhance the adaptations targeted by individual exercise sessions or periodic training plans, or to obtain other effects that will enhance performance longer term” [9]. A ‘Framework for Periodisation of Nutrition’ has since been developed [10], presenting how to implement nutritional strategies on a macro-, meso- and microcycle level. It also highlights how a variety of nutrition examples such as carbohydrate, protein, iron, and creatine can be periodised on a macro-, meso- and microcycle level [10]. The advantage of adopting a periodised nutrition approach is that nutrition can be planned specific to an individual, their performance goal(s) and the desired adaptation of a training session.

During a 4 year Olympic or Paralympic cycle, over 4000 meals are consumed by an athlete, with each meal representing an opportunity to fuel a training session, or the influence adaptations from a training session. Performance nutritionists work with athletes to ensure that their diets contain optimal amounts of macro- and micronutrients. Protein intake generally remains consistent across a macrocycle at a suggested intake of 1.3–1.8 g⋅kg⋅bm^− 1 per day [11], although this may need to be increased to ~ 1.6–2.4 g⋅kg⋅bm^− 1 if the athlete’s goal is to reduce fat mass, while maintaining lean mass [12]. Fat intake is suggested to be constant at ~ 30% of total energy intake per day [13]. Consequently, the alteration of daily energy intake is suggested to come from a manipulation in carbohydrate [14]. Contemporary guidelines suggest carbohydrate intakes between 3–12 g⋅kg⋅bm^− 1 per day depending on the daily fuelling and recovery needs of the individual [14]. The concept of the ‘glycogen threshold hypothesis’ has been developed over the past decade [15]. Sherman et al., (1981) [16] first hypothesised a ‘threshold concept’ for glycogen availability to sustain the required intensity and volume of an exercise bout when they reported no differences between moderate (5 g⋅kg⋅bm^− 1) and high (8 g⋅kg⋅bm^− 1) carbohydrate intakes on half marathon performance. While high carbohydrate availability is crucial during high intensity training sessions (e.g. zone 3; > 4 mmol⋅L^− 1) [17], commencing some low intensity sessions (e.g. zone 1; <2 mmol⋅L^− 1) with low glycogen availability or fasted has been shown to activate acute cell signalling kinases (e.g. AMPK, p38) [18–26], transcription factors (e.g. p53, PPAR) [26–28], and transcriptional coactivators (e.g. PGC-1α) [29], that may augment favourable endurance adaptations such as oxidative enzyme activity [30–32, 34], mitochondrial biogenesis [27, 29], angiogenesis [35], and increased lipid oxidation [19, 22, 26, 27, 31–33, 36]. This has led to the creation of an amalgamation of targeted carbohydrate availability approaches (e.g. low, moderate, and high) throughout a microcycle [10, 15, 26], whereby glycogen is ‘cycled’ to optimise physical performance and adaptations [30].

With a growing appreciation that nutrition support could be provided on a microcycle basis, there has been a rise in the performance nutritionist. Many national governing bodies of Olympic and Paralympic sports organisations, as well as professional sports teams now employ a performance nutritionist on a part time or full-time basis, tasked with preparing and delivering athletes’ nutrition support [37]. Despite this rise, there is reported to be little planning and integration of training prescription and nutrition between the nutritionist and multi-disciplinary team [9]. Nutrition practitioners often work in isolation. However, to achieve an optimal periodised nutrition approach, nutrition practitioners should deliver nutrition support as part of an integrated multidisciplinary team, with all key stakeholders (coach, athlete, nutritionist, conditioning coach, medical) all aligned on the physiological, neuromuscular, structural and psychological demands of the athletes’ event, while understanding how the athlete can bridge any gaps to ensure success during competition [10]. Consequently, nutrition practitioners should periodise nutrition strategies on a microcycle level, ensuring that each one of the 4000 meals consumed by an athlete throughout an Olympic or Paralympic cycle is strategically placed and aligned to the coach’s training periodisation and athletes’ performance goal(s). Stellingwerff et al., (2019) [10] proposed that there needs to be better quantification of knowledge and application of nutritional periodisation approaches among athletes.

To this extent, the aim of this opinion piece is to (1) propose a ‘Periodised Nutrition System’ which can be utilised by nutrition practitioners when working with athletes; (2) discuss how this can be administered in practice, collaborating with the coach, multidisciplinary team and athlete; (3) present a case study of the proposed ‘nutrition periodisation system’ and its utilisation with a world class swimmer (as defined by McKay et al., 2022 [38]) in the build-up to the 2024 Paris Olympic games.

While previous research has proposed strategies which can be implemented to form a ‘periodised nutrition’ approach such as ‘train high’; ‘consume a pre training meal of 1–3 g⋅kg⋅bm^− 1 of carbohydrate’; ‘carbohydrate is withheld in recovery or suboptimal intakes occur’ [10], to the authors knowledge, no one has ever proposed a ‘Periodised Nutrition System’ which can be utilised to strategically plan each one of an athletes 4000 meals consumed throughout an Olympic or Paralympic cycle, specific to an athletes performance goal(s) and desired training adaptation. Table one displays the characteristics of the nutrition periodisation system, outlining the different ‘plates’, their energy and macronutrient composition, examples of each plate, how you may practically apply them in training sessions, and the theoretical rationale underpinning this.

Table 1

The ‘Periodised Nutrition System’
Name of ‘Plate’	Colour Code	Energy (Kcals)	CHO (g)	Protein (g)	Fat (g)	Food Quantity Examples**	Plate Description	Food & Drink Examples	Practical Implementation in Training sessions	Theoretical Rationale
The ‘Repair’ Plate	Green	320–580	0–50	35–50*	~ 25	CHO: Rice = ~ 25-50g Pasta = ~ 25-50g Bread = ~ 40-60g Oats = ~ 30-55g Potato = ~ 125-200g PRO: Chicken breast = ~ 130-180g Beef steak (sirloin) = ~ 130g-180g Beef mince (extra lean) = ~ 140-190g Salmon (fillet) = ~ 130-180g Salmon (smoked) = ~ 130-180g Cod = ~ 170-230g Egg = ~ 220–240 Tempeh = ~ 140-190g FAT: Avocado = ~ 80g Olive oil = ~ 13g Mixed nuts = ~ 25-30g Mixed seeds = ~ 25-30g Nut butter = ~ 25g	Predominantly protein and vegetable based	Omelette; shakshuka; chicken kebabs with vegetable salad; Turkish egg pot; yogurt, mixed nuts and berries	Zone 1 (< 2 mmol⋅L^− 1) training session; reduce non-functional mass; train low (glycogen session); recover low / sleep low strategy	Zone one (< 2 mmol⋅L^− 1) training session: Zone 1 sessions may utilise fat as a fuel and therefore less carbohydrates are required [17]. This may also augment training adaptations (see below). Reduce non-functional mass: Lower Kcal content of the ‘Repair’ plate is intended to create caloric deficit which can reduce non-functional mass (i.e. reduce fat mass of an individual) [39] Train low (glycogen session): Low muscle glycogen status, either by commencing exercise with reduced amounts or depleting throughout the duration of an exercise bout is associated with upregulated nuclear and mitochondrial genome activity through the activity of cell signalling proteins AMPK, PPAR, P38, PGC-1α [18–34]. Chronically, this may increase whole body and intramuscular lipid metabolism which could increase exercise capacity and performance [19, 22, 26, 27, 31–34, 36]
The ‘Fuel’ Plate	Amber	520–780	50–100	35–50*	~ 25	CHO: Rice = ~ 75-100g Pasta = ~ 75-100g Bread = ~ 100-150g Oats = ~ 85-110g Potato = ~ 350-400g PRO: Chicken breast = ~ 130-180g Beef steak (sirloin) = ~ 130g-180g Beef mince (extra lean) = ~ 140-190g Salmon (fillet) = ~ 130-180g Salmon (smoked) = ~ 130-180g Cod = ~ 170-230g Egg = ~ 220–240 Tempeh = ~ 140-190g FAT: Avocado = ~ 80g Olive oil = ~ 13g Mixed nuts = ~ 25-30g Mixed seeds = ~ 25-30g Nut butter = ~ 25g	Mixed meal of protein, carbohydrate and vegetables	Animal (e.g. meat, fish etc.) or plant based protein (e.g. soya, tempeh etc.) source with carbohydrate source (e.g. rice, pasta, potato etc.) and vegetables (e.g. broccoli, carrots etc.)	Zone one (< 2 mmol⋅L^− 1) training session; zone two training session (< 2–4 mmol⋅L^− 1); zone three training session (> 4 mmol⋅L^− 1); maintain current body composition	Zone one (< 2 mmol⋅L^− 1) training session: Zone 1 sessions may utilise some carbohydrates as a fuel [15]. Depending on the performance goal(s) of the athlete, it may be appropriate to ensure energy balance and carbohydrate availability [40], even during zone one training sessions. Zone two (2–4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone two training sessions and therefore the athlete needs to ensure carbohydrate availability to optimise their performance [17] Zone three (> 4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone three training sessions and therefore the athlete needs to ensure carbohydrate availability to reach the required intensities [17] Maintain current body composition: The ‘fuel’ plate represents a moderate caloric amount which can be utilised to maintain an athlete’s current body composition [39]
The ‘Perform’ Plate	Red	720–980	100–150	35–50*	~ 25	CHO: Rice = ~ 140-180g Pasta = ~ 140-170g Bread = ~ 200-250g Oats = ~ 150-200g Potato = ~ 600-700g PRO: Chicken breast = ~ 130-180g Beef steak (sirloin) = ~ 130g-180g Beef mince (extra lean) = ~ 140-190g Salmon (fillet) = ~ 130-180g Salmon (smoked) = ~ 130-180g Cod = ~ 170-230g Egg = ~ 220–240 Tempeh = ~ 140-190g FAT: Avocado = ~ 80g Olive oil = ~ 13g Mixed nuts = ~ 25-30g Mixed seeds = ~ 25-30g Nut butter = ~ 25g	Meal high in carbohydrate with moderate protein and vegetable content (similar to other plates)	Animal (e.g. meat, fish etc.) or plant based protein (e.g. soya, tempeh etc.) source with carbohydrate source (e.g. rice, pasta, potato etc.) and vegetables (e.g. broccoli, carrots etc.)	Zone two training session (< 2–4 mmol⋅L^− 1); zone three training session (> 4 mmol⋅L^− 1); increase lean mass	Zone two (2–4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone two training sessions and therefore, the athlete needs to ensure carbohydrate availability to reach the required intensities [17] Zone three (> 4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone three training sessions and therefore, the athlete needs to ensure carbohydrate availability to reach the required intensities [17] Increase lean mass: The ‘perform’ plate can increase caloric intake, promoting increases in lean mass when conducted alongside an appropriate conditioning programme [39]
‘Sustain’ Snacks	Yellow	80–370	20–60	0–10	0–10	N/A	High glycemic index carbohydrates which are lower in fibre content These are intended to be consumed either pre, during, or post exercise, or as a snack to increase glycogen content whereby this cannot be achieved through repair, fuel and perform plates	Energy ball; ripe banana; dried fruit; rice Krispies bar; sports drink; oat bar; children’s cereal (e.g. coco pops); sweets; Weetabix with honey; jam on white bread; granola with milk or yogurt	Zone 2 training session (< 2–4 mmol⋅L^− 1); zone 3 training session (> 4 mmol⋅L^− 1)	Zone two (2–4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone two training sessions and therefore the athlete needs to ensure carbohydrate availability to reach the required intensities [17] Zone three (> 4 mmol⋅L^− 1) training session: Carbohydrates are the predominant energy source during zone three training sessions and therefore the athlete needs to ensure carbohydrate availability to reach the required intensities [17]
‘Repair’ Snacks		80–255	0–10	~ 20	0–15	N/A	Protein snacks These are intended to be consumed either post exercise as a recovery strategy, or as a snack to increase protein intake whereby this cannot be achieved through repair, fuel and perform plates (e.g. individual has high lean mass)	Protein bar, protein shake, Greek yogurt and berries, seasoned meat or tempeh skewers	Zone 1 (< 2 mmol⋅L^− 1) training session; maintain lean mass while reducing non-functional mass; train low (glycogen session); recover low / sleep low strategy; increase lean mass	Zone one (< 2 mmol⋅L^− 1) training session: Zone 1 sessions may utilise fat as a fuel and therefore less carbohydrates are required [17]. By keeping protein intake consistent, through ‘repair snacks’, this helps maintain lean mass [39] Maintain lean mass while reducing non-functional mass: Extra repair snacks can increase protein intake. This has been shown to maintain lean mass while reducing non-functional mass (1.6–2.4 g⋅kg⋅bm^− 1) [12, 39]
*’Plates’ consumed at breakfast would contain ~ 20g protein rather than 30-50g protein due to typical foods consumed at breakfast such as oats, dairy, eggs being lower in protein than typical lunchtime and evening meal foods such as meat, fish, tofu
**Weights of food are raw quantities

3.1 Athlete Profile

The swimmer was a world class level female swimmer who was part of the Aquatics GB Paris 2024 Olympics Swimming Team. The swimmer had previously utilised nutrition support with the performance nutritionist since September 2022, with this continuing through to the Paris 2024 Olympic Games. Previous nutrition support (prior to switching to a ‘Periodised Nutrition System’ model) had been provided on an infrequent basis (roughly x1 nutrition consultation and x1 body composition assessment every 4–6 weeks). While nutrition support had been ongoing with the swimmer since September 2022, the athlete and performance nutritionist collaborated on a periodised nutrition approach from June 2024 to ensure that they achieved their performance goals. This was initially driven by the performance nutritionist but as the swimmer gained experience and confidence in the system, they were empowered to lead the process moving forwards.

The case study below outlines the process to establish the periodised nutrition support and presents a snapshot of the application of the ‘Periodised Nutrition System’ in action over six microcycles in the final mesocycle prior to the Olympic Games (mesocycle three = April 2024 to August 2024), between the dates of Monday 3rd June to Sunday 14th July. Previous self-reported food diaries had shown the swimmers energy balance (energy intake whereby body mass is maintained) to be roughly 2300–3000 Kcals depending on the volume and intensity of training. This is consistent with previous research quantifying the energy balance of swimmers [41]. The swimmer and coach were informed about the purpose of the support provision, and the first author answered any questions had. Written informed consent which adopted the ethical principles described by Sheffield Hallam University Ethics Committee was provided by the athlete and coach, and consequently both provided consent for the publication of this case study.

3.2 Athlete Performance Goal(s)

In September 2023, at the beginning of the 2023/24 swimming season, in collaboration with the swimmer, coach and multidisciplinary team, three performance goals were outlined for the swimmer. Table 2 displays the performance goals of the swimmer

Table 2

Swimmers’ performance goals
Goal	Goal Objective	What is Determined as Success?	Method	Measure and Monitoring
1	Increased skills around the wall	Push offs, underwater dolphin kick and breakouts improved. Speed in, around and through the breakout developed. Able to stay in the hunt in races and use clean swimming super strength	Technical analysis and regular feedback to the swimmer. Speed skill progressions bolted on to the end of sessions	Times fed back after major meets of each cycle. Physical and technical measures set by multidisciplinary team (e.g. power output by strength and conditioning coach)
2	Improve (50/100) speed and speed endurance (200) on fly and breast strokes	Technical improvements and deliver increased propulsion and reduced drag on fly and breast technique	Pool sets, kick sessions, utilisation of swim bench, land work adapted to support this goal	Technical and physical measures set by leads
3	Aquatic profile – Achieve best physical condition for the 2024 Olympic Games	Optimal strength profile (lifting and body control), flexibility profile, body composition, drag profile, technical stroke profile. Establish and then maintain throughout the season	Aligned multidisciplinary team approach – Practitioners define optimum in their areas and track throughout the season	Cross-team monitoring – Quantify drag profile through tow rig, power output using force decks, body composition via sum of 8 skinfolds, energy intake and nutritional habits via communication with the athlete and food diaries

Each performance goal had a ‘driver’ who was responsible for collating the information and feeding back to key stakeholders. The performance nutritionist was assigned as the ‘driver’ for the goal 3; Aquatic profile – Achieve best physical condition for the 2024 Olympic Games. Aquatic profile is defined as an overarching concept which relates to how a swimmer presents in the water. This can be separated into a swimmer’s technical profile in the water (cross sectional area, propulsion, drag, efficiency, buoyancy, breathing mechanics and pattern) and physical profile out of the water (stature, mass, body composition, strength, posture, limb length, flexibility, cross sectional area). One of the key strands of this performance goal was to reduce the swimmers body mass, through a reduction in non-functional mass (i.e. fat mass). It was anticipated that a reduction in non-functional mass and consequently body mass would reduce the drag profile of the swimmer. While mass is not directly involved in the drag equation (see Eq. 1), a reduction in mass was proposed to reduce the drag coefficient (C_D) and cross-sectional area of the swimmer (A), reducing their drag profile.

$$\:{F}_{D=\:\frac{1}{2}\rho\:{\upsilon\:}^{2}{C}_{D}\text{{\rm\:A}}}$$

F_D = Drag

p = Density of fluid (water in the pool)

v = Speed of the swimmer relative to the fluid

C _D = Drag coefficient

A = Cross sectional area

Equation 1. The drag equation [42]

As displayed in Table 2, goals 1 and 2 required speed and greater levels of force production to push off the wall and improve speed. Therefore, the maintenance of lean mass was an important consideration when designing any periodised nutrition intervention.

A focus on body composition can cause anxiety among athletes [43] and may be associated with body dissatisfaction and symptoms of disordered eating and eating disorders [44]. To this extent, the swimmer was screened in September 2023 by the performance nutritionist as part of the Aquatics GB National Programme Screening Strategy, to ascertain their perceptions of body composition and the body composition assessment process. This was done to ensure that the swimmer was comfortable with the process and understood why the data may be collected and how it may influence their performance (i.e. reduction in drag profile). If there were any sensitives or feeling of uncomfortableness towards the process, then the MDT team would not engage with monitoring this goal through body composition assessments, or the goal itself. The swimmer was comfortable with the process and understood the value of the data being collected. The swimmer was empowered to drive the monitoring process themselves (see section 3.5) and therefore would request body composition assessments in consultation with the performance nutritionist and consequently, body composition monitoring was not enforced upon them.

3.3 Training Periodisation

Table 3 outlines a ‘training session key’ which was provided from the coach to the nutritionist, detailing a description of all the different types of training sessions which could be included in the swimmer’s periodisation.

Table 3

Training session key
Training Session	Training Session Description
Recovery (R)	Very easy / light aerobic mix
Technical Recovery (TR)	Easy aerobic mix with technical focus
Aerobic Maintenance (AMT)	Moderate work to maintain aerobic fitness
Aerobic Development (ADEV)	Strong work to develop aerobic fitness
Aerobic > Technical (A > T)	Strong / short rest work to develop aerobic fitness
Strength Endurance (STEND)	Strong aerobic work with high resistance
Speed > Recovery (SP > R)	Session focusing on speed effort & mostly easy swimming
Speed > Aerobic Maintenance (SP > AMT)	Speed development and aerobic maintenance combination
Technical Pace (TP)	Technical, speed and pace work in preparation for key set or race
Speed > Resistance (SP > RES)	Endurance set which includes both resistance and speedwork
Speed > Endurance (SP > END)	Set starts / finishes with speed. However, the bulk of the set is endurance
Monocarboxylate Transporter 4 Race Pace ‘Tempo (MCT4 RP Tempo)	Race pace set with softer design
Monocarboxylate Transporter 4 ~ Central Fartlek (MCT4 ~ Central Fartlek)	Race pace set – Progressive and challenging pattern with strong design
Monocarboxylate Transporter 4 Race Pace Pattern (MCT4 RP ‘Pattern)	Race pace set – Progressive and challenging pattern with strong design
Monocarboxylate Transporter 4 + 1 Race Pace Combo (MCT4 + 1 RP ‘Combo’)	Race pace set & heart rate combination – Harder design
Aerobic Maintenance > Race (AMT > Race)	Aerobic block finishing with intense race / stand up swim
Monocarboxylate Transporter 4 Race Pace Simulation (MCT4 RP SIM)	Race pace work mimicking a competition
Monocarboxylate Transporter 1 (MCT1)	High intensity aerobic set which includes intensity close to race pace
Rainbow Set (RB)	Set which combines swimming at all intensities – Aerobic and anaerobic
Test Set (TS)	Either 7x200m step test or 4x [4x100 kick] best average
Kick and Pull (K + P)	Aerobic kick and pull
Gym (Gym)	Gym work as set by the strength and conditioning coach
Swim Bench (SB)	n reps at a specific watt output
Prime (P)	Land work primer in preparation for stand up swim or race effort

Table 4 outlines the training periodisation for the swimmer between the dates of Monday 3rd June to Sunday 14th July. This section of the mesocycle represented the swimmers final block of training, prior to entering the taper phase of their training on Monday 15th July. The swimmer competed in the 2024 Sette Colli swim meet in Rome during microcycle 3, racing in the three events across Friday, Saturday, and Sunday. As well as racing meters (e.g. 200m), the swimmer would typically warm up for ~ 1000-1600m and swim down for ~ 1000-1600m for each race.

Table 4

The swimmer’s training periodisation between Monday 3rd June to Sunday 14th July.
Week		Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Week One: 3rd -9th June 2024 Week distance – 57.5km	AM Session	ADEV	TR + Gym	MCT1	ADEV + Gym	SP > END	STEND	Rest
Week One: 3rd -9th June 2024 Week distance – 57.5km	PM Session	MCT1	ADEV	Rest	TR	MCT4 RP SIM	Rest	Rest
Week Two: 10th -16th June 2024 Week distance – 57.5km	AM Session	ADEV	TR + Gym	STEND	Rest	SP > END	STEND	Rest
Week Two: 10th -16th June 2024 Week distance – 57.5km	PM Session	MCT1	ADEV	Rest	Gym + ADEV	MCT4 RP SIM	Rest	Rest
Week Three: 17th June-23rd June Week distance – 52km	AM Session	SP > END	SP > END	Travel	R	Race - Heats	Race - Heats	Race - Heats
Week Three: 17th June-23rd June Week distance – 52km	PM Session	TR	MCT1	Travel	TR + RACE WARM UP	Race - Final	Race - Final	Race - Final
Week Four: 24th June-30th June Week distance – 50-55km	AM Session	Travel	R + Gym	ADEV	SP > AMT + Gym	MCT4 RP SIM	STEND	Rest
Week Four: 24th June-30th June Week distance – 50-55km	PM Session	Travel	SP > END	Rest	TR	MCT4 RP SIM	Rest	Rest
Week Five: 1st July-7th July Week distance – 60km	AM Session	AMT > SP + Gym	R	A > MT	ADEV + Gym	MCT4 RP SIM	STEND	Rest
Week Five: 1st July-7th July Week distance – 60km	PM Session	MCT4 ‘Soft’	4x200 TT	Rest	TR	MCT4 RP SIM	Rest	Rest
Week Six: 8th July-14th July Week distance – 60km	AM Session	AMT > SP + Gym	R	A > MT	ADEV	MCT4 RP SIM	STEND	Rest
Week Six: 8th July-14th July Week distance – 60km	PM Session	MCT4 RP TEMPO	MCT4 RP SIM	Rest	TR	MCT4 RP SIM	Rest	Rest

The nutritionist and coach ‘RAG rated’ each swimming session based on the glycolytic demands of the session (i.e. how much glycogen is required to complete the session) as well as the physiological goal of the session (e.g. mitochondrial biogenesis, enhance buffering capacity etc.). The nutritionist then collaborated with the swimmer to get their perceptions of ‘easy’, ‘moderate’ and ‘hard’ sessions. Table 5 displays the RAG ratings of each session. Supplementary file 1 displays the document which was created between the nutritionist and coach detailing the RAG rating of each training session.

Table 5

RAG rating of each training session
RAG Rating	Description of RAG Rating	Training Sessions Description
Green (easy)	Main set = Approx. 50 − 40 beats below max heart rate; lactate < 2mmol⋅L^− 1; low glycolytic demand	R; TR; AMT
Amber (Moderate)	Main set = Approx. 50 − 20 beats below max heart rate; speed work = lactate > 2 mmol⋅L^− 1; aerobic and recovery elements = < 2 mmol⋅L^− 1; moderate glycolytic demand Speed work programmed into these sessions is low in volume and therefore while glycogen is required to fuel the high intensity movements, this is not for a considerable period	ADev; A > T; StEnd; SP > R; SP > Amt; TP; SP > RES; SP > END; Kick and Pull K + P; Gym
Red (Hard)	Main set = Approx. 30 − 5 beats below max heart rate; lactate > 6 mmol⋅L^− 1; high glycolytic demand	MCT4 RP Tempo; MCT4 ~ Central Fartlek; MCT4 RP ‘Pattern; MCT4 + 1 RP ‘Combo’; AMT > Race; MCT4 RP SIM; MCT1; RB; TS
Other	These sessions are traditionally low in volume and ‘bolted’ onto the start (e.g. primer) or incorporated into the session (e.g. swim bench)	SB; P

3.4 Nutrition Periodisation Intervention & Plans

The nutritionist and swimmer underwent a ‘scoping’ session the week prior to starting the periodised nutrition plan, whereby the ‘Periodised Nutrition System’ was presented to the swimmer (e.g. repair plate, fuel plate, perform plate, sustain snacks, repair snacks), along with the rationale for this and how best the swimmer would like the information presented. Supplementary file 2 displays the infographics presented to the swimmer during the scoping session. The swimmer was provided with approximately, 50 repair plate recipes, 50 fuel plate recipes, 50 perform plate recipes and a variety of different sustain snack and repair snack examples. To improve adherence in the ‘Periodised Nutrition System’, the swimmer outlined the ‘types of meals’ they would consume daily and collaborated with the nutritionist to develop some recipes which they could utilise (e.g. scrambled eggs on toast, peanut butter and jam bagel, cinnamon berry porridge bowl, miso salmon with wild rice, chicken and chorizo paella). These were formulated using the nutritional analysis software Nutritics (Nutritics Ltd, Ireland). Supplementary file 3 displays an example of a recipe card sent to the swimmer.

Tables 6A-F display the periodised nutrition plan for the swimmer for each microcycle, while supplementary file 4A-F show the periodised nutrition plan infographic that was sent to the swimmer. Microcycle 1 was intentionally planned and agreed in collaboration with the swimmer to be lower in kilocalories to ‘gain momentum’ with body mass loss during the intervention period. While chronic low energy availability may have a variety of negative health and performance outcomes, leading to relative energy deficiency in sport (REDS) [40], it was ensured that carbohydrates were cycled in prior to ‘red sessions’ so that the swimmer could sustain the required volume and intensity. After microcycle one, carbohydrate and overall kilocalorie intake was increased throughout microcycles two and three to reduce the risk of any physiological or performance related consequences such as REDS [40]. A body composition assessment was undertaken on the 18th June (Tuesday of microcycle 3). After discussion with the swimmer, they stated that they were happy with their composition from a performance perspective and wanted to focus on ‘fuelling effectively’ during the upcoming swim meet (microcycle 3; Friday to Sunday), as well as the remainder of the mesocycle leading into the Olympic Games. Consequently, the focus of the intervention shifted from ‘optimising aquatic profile’ to ‘optimising adaptations from training sessions’ and the nutrition periodisation plan was adjusted accordingly.

Table 6

A. Nutrition periodisation for microcycle 1 from 3rd June 2024 to 9th June 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Fasted	Fasted	Sustain snack (40g CHO)	Fasted	Sustain snack (40g CHO)	Fasted	Repair snack
Training (AM)	ADEV	TR + Gym	MCT1 Sustain snack (20g CHO)	ADEV + Gym	SP > END	STEND
Post Swim (AM)	Repair snack	PRE GYM: x1 Repair snack & x1 sustain snack (20g CHO)	Fuel plate	PRE GYM: x1 Repair snack & x1 sustain snack (20g CHO)	Repair snack	Fuel plate
Lunch	Fuel plate	Fuel plate	Repair snack	Fuel plate	Fuel plate	Repair snack	Fuel plate
Pre-Swim (PM)	Sustain snack (40g CHO)	Sustain snack (40g CHO)			Sustain snack (60g CHO)		Repair snack
Training (PM)	MCT1 Sustain snack (20g CHO)	ADEV		TR	MCT4 RP SIM Sustain snack (20g CHO)
Dinner	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Perform plate	Fuel plate
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1450–2315	1450–2315	1450–2315	1290–2065	1530–2395	1410–2105	1515–2160
Carbohydrate (g / g⋅kg⋅bm^− 1)	160–270 / 2-3.5	160–270 / 2-3.5	160–270 / 2-3.5	120–230 / 1.5-3	180–290 / 2.3–3.8	150–260 / 1.9–3.4	100–220 / 1.3–2.9
Protein (g / g⋅kg⋅bm^− 1)	90–140 / 1.2–1.8	90–140 / 1.2–1.8	90–140 / 1.2–1.8	90–130 / 1.2–1.7	90–140 / 1.2–1.8	90–120 / 1.2–1.6	110–140 / 1.4–1.8
Fat (g / g⋅kg⋅bm^− 1)	50–75 / 0.6-1.0	50–75 / 0.6-1.0	50–75 / 0.6-1.0	50–70 / 0.6–0.9	50–75 / 0.6-1.0	50–65 / 0.6–0.8	50–80 / 0.6-1.0

Table 6

B. Nutrition periodisation for microcycle 1 from 10th June 2024 to 16th June 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Fasted	Fasted	Sustain snack (20g CHO)	Repair snack	Sustain snack (40g CHO)	Fasted	Repair snack
Training (AM)	ADEV	TR + Gym	STEND		SP > END	STEND
Post Swim (AM)	x1 Repair snack & x1 sustain snack (20g CHO)	PRE GYM x1 Repair snack & x1 sustain snack (20g CHO)	Fuel plate		x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)
Lunch	Fuel plate	Fuel plate	Repair snack	Fuel plate	Fuel plate	Fuel plate	Fuel plate
Pre-Swim (PM)	Sustain snack (60g CHO)	Sustain snack (40g CHO)		Sustain snack (60g CHO)	Sustain snack (80g CHO)	Repair snack	Repair snack
Training (PM)	MCT1 Sustain snack (20g CHO)	ADEV		Gym + ADEV	MCT4 RP SIM Sustain snack (20g CHO)
Dinner	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1810–2755	1650–2515	1490–2265	1650–2425	2050–3085	1570–2475	1490–2360
Carbohydrate (g / g⋅kg⋅bm^− 1)	250–360 / 3.2–4.7	210–320 / 2.7-4	170–280 / 2.2–3.6	210–320 / 2.7-4	310–420 / 4-5.5	170–290 / 2.2–3.7	150–270 / 1.9–3.5
Protein (g / g⋅kg⋅bm^− 1)	90–150 / 1.2–1.9	90–140 / 1.2–1.8	90–130 / 1.2–1.7	90–130 / 1.2–1.7	90–160 / 1.2–2.1	110–150 / 1.4–1.9	110–140 / 1.4–1.8
Fat (g / g⋅kg⋅bm^− 1)	50–80 / 0.6-1.0	50–75 / 0.6-1.0	50–70 / 0.6–0.9	50–70 / 0.6–0.9	50–85 / 0.6–1.1	50–80 / 0.6-1.0	50–80 / 0.6-1.0

Table 6

C. Nutrition periodisation for microcycle 1 from 17th June 2024 to 23rd June 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Sustain snack (20g CHO)	Sustain snack (20g CHO)	Fuel plate*	Fuel plate*	Sustain snack (80g CHO)	Sustain snack (80g CHO)	Sustain snack (80g CHO)
Training or Race (AM)	SP > END + GYM	SP > END		R	Race - Heats	Race - Heats	Race - Heats
Post Swim (AM)	PRE GYM x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)		x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (60g CHO)	x1 Repair snack & x1 sustain snack (60g CHO)	x1 Repair snack & x1 sustain snack (60g CHO)
Lunch	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate
Pre-Swim (PM)		Sustain snack (60g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)	Sustain snack (60g CHO)	Sustain snack (80g CHO)	Sustain snack (80g CHO)	Sustain snack (80g CHO)
Training or Race (PM)	TR	MCT1		TR	Race - Final	Race - Final	Race - Final
Post Race					x1 Repair snack & x1 sustain snack (60g CHO)	x1 Repair snack & x1 sustain snack (60g CHO)	x1 Repair snack & x1 sustain snack (60g CHO)
Dinner	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate
Pre-Bed			Sleep strategy (20g CHO)	Sleep strategy (20g CHO)	Sleep strategy (20g CHO)	Sleep strategy (20g CHO)	Sleep strategy (20g CHO)
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1570–2435	1810–2755	2075–3055	2315–3375	2690–3980	2690–3980	2690–3980
Carbohydrate (g / g⋅kg⋅bm^− 1)	190–300 / 2.5-4	250–360 / 3.3–4.8	240–400 / 3.2–5.3	300–460 / 4-6.1	450–590 / 5.8–7.6	450–590 / 5.8–7.6	450–590 / 5.8–7.6
Protein (g / g⋅kg⋅bm^− 1)	90–140 / 1.2–1.9	90–150 / 1.2-2	110–150 / 1.5-2	110–160 / 1.5–2.1	110–180 / 1.5–2.4	110–180 / 1.5–2.4	110–180 / 1.5–2.4
Fat (g / g⋅kg⋅bm^− 1)	50–75 / 0.7-1.0	50–80 / 0.7–1.1	75–95 / 1-1.3	75–100 / 1-1.3	50–100 / 0.7–1.3	50–100 / 0.7–1.3	50–100 / 0.7–1.3

Table 6

D. Nutrition periodisation for microcycle 1 from 24th June 2024 to 30th June 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Fuel plate*	Fasted	Sustain snack (20g CHO)	Sustain snack (40g CHO)	Sustain snack (60g CHO)	Sustain snack (20g CHO)	Repair snack
Training (AM)		R + Gym	ADEV	SP > AMT + Gym	MCT4 RP SIM x1 sustain snack (20g CHO)	STEND
Post Swim (AM)		x1 Repair snack & x1 sustain snack (20g CHO) pre gym	Fuel plate	x1 Repair snack	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)
Lunch	Fuel plate	Fuel plate	x1 Repair snack	Fuel plate	Fuel plate	Fuel plate	Fuel plate
Pre-Swim (PM)	x1 Repair snack	Sustain snack (60g CHO)		Sustain snack (40g CHO)	Sustain snack (80g CHO)	Repair snack	Repair snack
Training (PM)		SP > END		TR	MCT4 RP SIM x1 sustain snack (20g CHO)
Dinner	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1915–2810	1730–2595	1490–2270	1730–2595	2210–3330	1650–2645	1490–2315
Carbohydrate (g / g⋅kg⋅bm^− 1)	200–360 / 2.7–4.8	230–340 / 3.1–4.5	170–280 / 2.3–3.7	230–340 / 3.1–4.5	350–460 / 4.7–6.1	190–310 / 2.5–4.1	150–270 / 1.9–3.5
Protein (g / g⋅kg⋅bm^− 1)	110–140 / 1.5–1.9	90–140 / 1.2–1.9	90–130 / 1.2–1.7	90–140 / 1.2–1.9	90–170 / 1.2–2.3	110–160 / 1.5–2.1	110–140 / 1.4–1.8
Fat (g / g⋅kg⋅bm^− 1)	75–90 / 1-1.2	50–75 / 0.7-1.0	50–70 / 0.7–0.9	50–75 / 0.7–0.9	50–90 / 0.7–1.1.2	50–85 / 0.7–1.1	50–75 / 0.6-1.0

Table 6

E. Nutrition periodisation for microcycle 1 from 1st July 2024 to 7th July 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Sustain snack (40g CHO)	Fasted	Fasted	Sustain snack (20g CHO)	Sustain snack (60g CHO)	Sustain snack (20g CHO)	Repair snack
Training (AM)	AMT > SP + Gym	R	A > MT	ADEV + Gym	MCT4 RP SIM x1 sustain snack (20g CHO)	STEND
Post Swim (AM)	x1 Repair snack & x1 sustain snack (20g CHO) pre gym	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack	x1 Repair snack & x1 sustain snack (20g CHO) pre gym	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)
Lunch	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate
Pre-Swim (PM)	Sustain snack (60g CHO)	Sustain snack (80g CHO)			Sustain snack (80g CHO)	Repair snack	Repair snack
Training (PM)	MCT4 ‘Soft’ x1 sustain snack (20g CHO)	MCT4 RP SIM x1 sustain snack (20g CHO)		TR	MCT4 RP SIM x1 sustain snack (20g CHO)
Dinner	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1970–3005	1890–3020	1410–2105	1570–2435	2210–3290	1650–2645	1490–2315
Carbohydrate (g / g⋅kg⋅bm^− 1)	290–400 / 3.9–5.3	270–380 / 3.6–5.1	150–260 / 2-3.5	190–300 / 2.5-4	350–460 / 4.7–6.1	190–310 / 2.5–4.1	150–270 / 1.9–3.5
Protein (g / g⋅kg⋅bm^− 1)	90–160 / 1.2–2.1	90–150 / 1.2-2	90–120 / 1.2–1.6	90–140 / 1.2–1.9	90–160 / 1.2–2.1	110–160 / 1.5–2.1	110–140 / 1.4–1.8
Fat (g / g⋅kg⋅bm^− 1)	50–85 / 0.7–1.1	50–80 / 0.7–1.1	50–65 / 0.7–0.9	50–75 / 0.7-1.0	50–90 / 0.7–1.2	50–85 / 0.7–1.1	50–75 / 0.6-1.0

Table 6

F. Nutrition periodisation for microcycle 1 from 8st July 2024 to 14th July 2024
	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
Pre-Swim (AM)	Sustain snack (40g CHO)	Fasted	Fasted	Sustain snack (20g CHO)	Sustain snack (60g CHO)	Sustain snack (20g CHO)	Repair snack
Training (AM)	AMT > SP + Gym	R	A > MT	ADEV	MCT4 RP SIM x1 sustain snack (20g CHO)	STEND
Post Swim (AM)	x1 Repair snack & x1 sustain snack (20g CHO) pre gym	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)	x1 Repair snack & x1 sustain snack (20g CHO)
Lunch	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate	Fuel plate
Pre-Swim (PM)	Sustain snack (60g CHO)	Sustain snack (80g CHO)			Sustain snack (80g CHO)	Repair snack	Repair snack
Training (PM)	MCT4 RP TEMPO x1 sustain snack (20g CHO)	MCT4 RP SIM x1 sustain snack (20g CHO)		TR	MCT4 RP SIM x1 sustain snack (20g CHO)
Dinner	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate	Perform plate
Daily Kcal and Macronutrient Targets
Calories (Kcals)	1970–3005	1890–3020	1410–2105	1570–2435	2210–3290	1650–2645	1490–2315
Carbohydrate (g / g⋅kg⋅bm^− 1)	290–400 / 3.9–5.3	270–380 / 3.6–5.1	150–260 / 2-3.5	190–300 / 2.5-4	350–460 / 4.7–6.1	190–310 / 2.5–4.1	150–270 / 1.9–3.5
Protein (g / g⋅kg⋅bm^− 1)	90–160 / 1.2–2.1	90–150 / 1.2-2	90–120 / 1.2–1.6	90–140 / 1.2–1.9	90–160 / 1.2–2.1	110–160 / 1.5–2.1	110–140 / 1.4–1.8
Fat (g / g⋅kg⋅bm^− 1)	50–85 / 0.7–1.1	50–80 / 0.7–1.1	50–65 / 0.7–0.9	50–75 / 0.7-1.0	50–90 / 0.7–1.2	50–85 / 0.7–1.1	50–75 / 0.6-1.0

3.5 Monitoring & Refinement

During the scoping session, the nutritionist presented all six microcycles of the periodised nutrition plan to the swimmer. The periodised nutrition plan for a particular microcycle was then sent to the swimmer on the Friday prior to the microcycle commencing the following Monday to refresh their memory and enable them to plan and prepare their nutrition strategies for the following week. This was accompanied by a face-to-face discussion with the nutritionist to discuss the ‘flow’ of nutrition periodisation for the microcycle, as well as reflections of the current microcycle (e.g. training performance, energy levels etc.). This discussion was cross-referenced with data collected by the MDT team such as blood lactates during key sessions (e.g. MCT4 RP SIM); force plate jump metrics; rating of perceived exertion and wellness data such as energy levels, sleep quality; anecdotal feedback from the coach. This was to determine the extent to which the periodised nutrition plan needed to be adjusted based on the feedback sources. Twice-weekly meetings between the coach and MDT team were also held to discuss the performance of the swimmer and any adjustments to the training periodisation.

The swimmer was empowered to take ownership of the periodised nutrition plan and monitoring process. During the scoping session, the swimmer outlined when they wanted body composition assessments to be undertaken in agreement with the performance nutritionist (3rd June, 18th June, 16th July). Body composition was quantified through sum of 8 skinfold method. This has been shown to be a valid and reliable method when working in the field [45]. The nutritionist was an International Society for the Advancement of Kinanthropometry (ISAK) level one practitioner according to ISAK guidelines [46]. The swimmer stated that they did not value collecting body mass data on a frequent basis as this added ‘noise’ to the goal due to daily fluctuations in mass caused through glycogen, hydration status and female sex hormones such as oestrogen [47]. Therefore, body mass was only collected when quantifying body composition. At each body composition monitoring session, the swimmer was re-familiarised with the data collection process, given ample opportunity to ask any questions, or refuse the process.

Four-day self-reported food diaries were also completed by the swimmer on two separate occasions (4th to 7th June and 25th to 28th June) to ensure that the swimmer was on track, and energy intake was consistent with what was being advised in the periodised nutrition plan. Food diaries were completed through a combination of the weighed food method [48] and Snap’N’Send [49]. Food diaries were analysed using the nutrition analysis software Nutritics (Nutritics Ltd, Ireland).

3.5.1 Body Composition

Table 7 displays the body composition data collected throughout the periodised nutrition intervention. Over an 18-day period of the ‘optimising aquatic profile’ phase of the intervention, there was a 2.1 kg decrease in body mass, an 18.1 mm reduction in sum of 8 skinfolds, a 0.1 kg decrease in predicted lean mass and a 2.2 kg decrease in predicted fat mass. Over the remainder of the mesocycle and the ‘optimising adaptations from training sessions’ phase, there was a 0.2 kg increase in body mass, a 2 mm reduction in sum of 8 skinfolds, a 0.7 kg increase in predicted lean mass and 0.5 kg decrease in predicted fat mass.

Table 7

Swimmers body composition data throughout the periodised nutrition intervention
Date	Body mass (kg)	Sum of 8 Skinfolds (mm)	Predicted Lean Mass* (kg)	Predicted Fat Mass* (kg)
31/05/24	76.9	98.3	63.1	13.9
18/06/24	74.8	80.2	63.0	11.7
16/07/24	75.0	78.2	63.7	11.3
*Calculated via Van Der Ploeg et al., (2003) [50]

3.5.2 Food Diary

Table 8A displays the food diary data collected during microcycle one (Tuesday 4th June to Friday 7th June), while Table 8B shows the food diary data collected during microcycle four (Tuesday 25th June to Friday 28th June).

Table 8

A. Swimmer’s food self-reported diary data collected during microcycle one
Date	Kilocalories (Kcals)	Carbohydrate (g) / (g.kg.bm^− 1)	Protein (g) / (g.kg.bm^− 1)	Fat (g) / (g.kg.bm^− 1)
04/06/24	1783	214 / 2.8	126 / 1.6	42 / 0.5
05/06/24	2178	237 / 3.1	118 / 1.5	84 / 1.1
06/06/24	2315	243 / 3.2	137 / 1.8	91 / 1.2
07/06/24	2369	261 / 3.4	141 / 1.8	84 / 1.1

Table 8

B. Swimmer’s food self-reported diary data collected during microcycle four
Date	Kilocalories (Kcals)	Carbohydrate (g) / (g.kg.bm^− 1)	Protein (g) / (g.kg.bm^− 1)	Fat (g) / (g.kg.bm^− 1)
25/06/24	2001	246 / 3.3	103 / 1.4	67 / 0.9
26/06/24	2050	220 / 2.9	134 / 1.8	71 / 0.9
27/06/24	1746	214 / 2.9	107 / 1.4	51 / 0.7
28/06/24	2733	396 / 5.3	132 / 1.8	69 / 0.9

During microcycle one, fat intake was slightly greater than planned due to the swimmer using high amounts of olive oil while cooking. Despite olive oil having numerous health benefits [51], this was tweaked to ensure the swimmer stayed within the macronutrient guidance. During microcycle 4, the swimmer was within the planned nutrition periodisation targets for all days.

The aim of this current opinion was to (1) propose a ‘Periodised Nutrition System’ which can be utilised by nutritionists when working with athletes; (2) discuss how this can be administered in practice, collaborating with the coach, multidisciplinary team and athlete; (3) present a case study of the proposed ‘Periodised Nutrition System’ and its utilisation with a world class swimmer in the build-up to the 2024 Paris Olympic games. Stellingwerff et al., (2019) [10] stated that there needs to be better quantification of knowledge and application of nutritional periodisation approaches among athletes. While previous literature has proposed strategies of how a ‘periodised’ nutrition approach can be achieved [10], to the authors knowledge, this is the first proposed ‘Periodised Nutrition System’ in the scientific literature, conveying how different ‘performance plates’ can be utilised to sit in tandem with an athletes training periodisation in a real-world scenario. This current opinion presents the ‘Periodised Nutrition System’, proposing different ‘performance plates’, quantities of different foods to fit into the ‘performance plates’ to aid recipe development, and how they may practically fit into an athlete’s periodisation alongside theoretical rationale. This will hopefully generate some meaningful discussion among practitioners and academics to critique the proposed ‘Periodised Nutrition System’ and enable other practitioners to share their understanding and application of nutritional periodisation approaches within a variety of sports.

While the ‘Periodised Nutrition System’ provides a template for practitioners to utilise to deliver periodised nutrition support to strategically plan each of the 4000 + meals an athlete may consume over an Olympic or Paralympic cycle, simply applying a ‘copy and paste’ approach to performance nutrition support is sub optimal. This current opinion highlights an array of skills a nutritionist needs to embed a periodised approach when supporting elite athletes. A performance nutritionist must have sufficient technical knowledge to understand the underpinning physiological and technical demands of the sport as well as the intended physiological responses from different sessions (e.g. aerobic development vs. MCT4 RP SIM) to ensure that the athlete is able to work at the correct intensity, utilising the intended fuel source, maximising the adaptive response. They must also be able to accurately predict the energy expenditure of the athlete so that the recommendations of the nutrition periodisation plan are appropriate. The performance nutritionist must also possess a variety of ‘soft’ skills such as: being able to effectively communicate with the coach, MDT team, and athlete to establish performance strategies and feedback interventions to key stakeholders; time management to ensure periodisation plans are delivered on time; team work and collaborative skills to work as part of an MDT team, gaining feedback (such as lactate data) to inform the whether the nutrition periodisation needs adjusting; and creativity to package up the periodised nutrition plan in a way that is appropriate for the athlete so they can follow (such as supplementary files 3 and 4A-F).

Previous research has highlighted that there appears to be little planning and integration of training prescription and nutrition between the nutritionist and multi-disciplinary team [9]. An advantage of adopting a periodised nutrition approach with athletes on a microcycle basis is it enables practitioners to specifically plan to the individual, their performance goal(s) and the desired adaptation of a training session. Following the process of how to embed the ‘Periodised Nutrition System’ (figure one) can add structure and greater alignment of training and nutrition periodisation between key stakeholders. Anecdotally, the performance nutritionist found that they had a greater understanding of the athletes training periodisation as they were specifically programming the nutrition periodisation alongside. As the nutritionist had an awareness of the swimmers training periodisation, they were able to greater embed nutritional strategies such as the swimmer practicing their racing nutrition strategies prior to MCT4 RP SIM sessions (see microcycles 4, 5, and 6). This included refining their pre-race meal alongside the addition of racing supplements such as nitrates [52], caffeine [53] and sodium bicarbonate [54], ensuring gastrointestinal issues were minimised. By having greater awareness of the training periodisation, the performance nutritionist can be proactive in their guidance rather than being reactive, achieving a greater level of collaboration with the athlete.

While this current opinion has focused on macronutrients, the ‘Periodised Nutrition System’ is a tool to ensure that the athlete has structure and purpose to their nutrition, aligned with their training periodisation. The ‘Periodised Nutrition System’ enables an initial structure for this to develop organically between the performance nutritionist and athlete. Different performance strategies can be layered alongside such as: creating nitrate rich ‘repair’, ‘fuel’ and ‘perform’ plates to increase nitric oxide storage in the muscle [52]; the addition of creatine monohydrate to increase glycogen synthesis if the athlete is undergoing high training loads whereby high carbohydrate availability is required [55]; or the supplementation of specific micronutrients, such as iron when an athlete is training at altitude [56]. This will depend on how the performance nutritionist applies their skills and knowledge to package up the nutrition support and layer on the performance strategies.

A potential negative of embedding a periodised nutrition approach is that athletes may look at nutrition ‘mathematically’, simply looking at the nutritional value of food, how much energy and the macronutrient composition of it. This goes against the essence that food is there to be enjoyed and is a mechanism for connecting people and communities [57] and is not the intention of the ‘Periodised Nutrition System’. To this extent, the nutritionist collaborated with the athlete to ‘flex’ the periodisation to facilitate ‘social engagements’ and ‘meals out’. Feedback provided from the swimmer was that this was empowering, as there was no ‘guilt’ attached to social engagements as these were planned, and there was clarity between the nutritionist and swimmer. This does highlight a limitation of the ‘Periodised Nutrition System’, that while you can have a plan, it is impossible to be 100% sure how much energy an athlete is consuming. Similarly, across the repair, fuel, and perform plates, fat is fixed at ~ 25g. However, when consuming a ‘takeaway meal’ or ‘eating out’ this is likely to be more than this. Another limitation may be that the daily energy and macronutrient targets appear to have a high range (i.e. ~1000 Kcals; ~100-150g CHO; ~50g PRO; ~30g FAT). If an athlete was to consistently consume the lower end of this target, energy intake may not be sufficient, whereas if they were to consume the higher end this may be too much. An athlete consumes food, containing a combination of all three macronutrients, and from the authors experience, athletes tend to consume in the middle of these recommendations (see Table 8B). An example in practice may be a ‘sustain snack’ which is recommended to contain 20-60g CHO, 0-10g PRO and 0-10g FAT. However, when translated to food this could be x2 Weetabix with 150ml semi skimmed milk which contains 209 Kcals, 33g CHO, 10g PRO, and 3g FAT. It is unlikely that an athlete would ever consume at the lower end of the suggested range (e.g. 0g PRO; 0g FAT) unless they consumed high amounts of non-food products such as sports gels and protein powders which generally contain high amounts of one macronutrient but limited amounts of other macronutrients. The authors also acknowledge that the ‘Periodised Nutrition System’ is not an ‘exact science’. Indeed, there are many variables which can influence the process such as the accurately estimating of energy expenditure, while there are also discrepancies in the monitoring process such as inaccurate food diaries. Therefore, the ‘Periodised Nutrition System’ should be looked at as a tool to enable practitioners to better align their nutritional strategies with the training periodisation of an athlete and help the athlete to develop a structure to their nutrition strategies.

Future research should aim to quantify the ‘Periodised Nutrition System’ in other cohorts of athletes and sports to determine its validity. The case study demonstrates how the ‘Periodised Nutrition System’ has supported three goals of the athlete throughout the mesocycle: (1) optimising aquatic profile (microcycles 1–3); (2) racing nutrition (microcycle 3); (3) maximising training adaptations (microcycles 4–6). A limitation is of the ‘Periodised Nutrition System’ is that it hasn’t been utilised in a hypertrophy or team sport scenario. Therefore, whether the nutrition periodisation system would be appropriate for a Rugby Union player aiming to increase lean mass as an example remains to be seen.

An understanding of behaviour change science is becoming recognised as an important consideration for performance nutritionists [58]. Anecdotally, the swimmer referenced a greater adherence to nutritional strategies as the periodisation was bespoke to their training periodisation and their performance goal(s). They felt more motivated to include monitoring tools such as food diaries and complete them more accurately as they valued the data so that they could make appropriate adjustments if required. The performance nutritionist also experienced an increase in communication with the athlete, most likely due to embedding the ‘Periodised Nutrition System’ and following an athlete centred approach, empowering them to drive the process, increasing the athlete’s motivation. Consequently, future research should aim to capture any behaviour changes which occur when utilising the ‘Periodised Nutrition System’.

The purpose of this current opinion was to (1) propose a ‘Periodised Nutrition System’ which can be utilised by nutritionists when working with athletes; (2) discuss how this can be administered in practice, collaborating with the coach, multidisciplinary team and athlete; (3) present a case study of the proposed ‘nutrition periodisation system’ and its utilisation with a world class swimmer in the build-up to the 2024 Paris Olympic Games. Previous research has highlighted that there is little planning and organisation from performance nutritionists when delivering nutrition support. To this extent, the ‘Periodised Nutrition System’ enables the practitioner to develop structure to their support aligning nutritional strategies with the training periodisation of the athlete, allowing for an individual approach, specific to the athlete’s performance goal(s) and the desired adaptation of a training session. Future research should determine the ‘nutrition periodisation systems’ validity in a variety of other athletes and sports as well as capturing any behaviour change tools utilised to optimise nutrition support provided to athletes.

Institutional Review Board Statement

The swimmer and coach were informed about the purpose of the support provision, and the first author answered any questions had. Written informed consent which adopted the ethical principles described by Sheffield Hallam University Ethics Committee was provided by the athlete and coach, and consequently both provided consent for the publication of this case study.

Informed Consent Statement

The swimmer and coach were informed about the purpose of the support provision, and the first author answered any questions had. Written informed consent which adopted the ethical principles described by Sheffield Hallam University Ethics Committee was provided by the athlete and coach, and consequently both provided consent for the publication of this case study.

Availability of Data and Materials

All data which supports the conclusions made within the manuscript are provided in the main text. Supplementary materials such as the ‘Periodised Nutrition System’ infographics and ‘periodised nutrition plans’ which were presented to the swimmer have also provided been provided as supplementary materials.

Competing Interests

The authors declare that they have no competing interests.

Funding

No funding was required for this study

Author Contributions

O Turner, N Mitchell, and R Chessor developed the ‘Periodised Nutrition System’. O Turner provided nutrition support to the world class swimmer. O Turner drafted the manuscript and oversaw manuscript preparation. N Mitchell and R Chessor assisted with revising the manuscript. All authors read and approved the final manuscript.

Acknowledgements

The authors would like to thank David Hemmings (Loughborough Performance Centre Aquatics GB coach) for his role in the development of the ‘Periodised Nutrition System’. His challenge to practitioners to deliver world class sports science support alongside his pursuit to provide world class coaching to his swimmers has enabled O Turner to reflect and critique his way of working and develop a system which may achieve better performance outcomes. The authors also appreciate the level of detail and planning in the athlete’s periodisation plans from David as well as numerous meetings which has enabled this system to be developed. The authors would also like to thank: Dr Kate Jordan (Chief Medical Officer, Aquatics GB) for supporting the Aquatics GB screening process; Michael Pugh (Strength and Conditioning Coach, UKSI) for providing periodised conditioning plans, as well as feeding back force jump data; Dr Ben Scott (Physiologist, Aquatics GB) for collecting blood lactate data and feeding this back; Scott Goadby (Loughborough Performance Centre Support Coach, Aquatics GB) and Joe Tomley (Loughborough Performance Centre Coach Support, Aquatics GB) for collecting monitoring data.

Authors Information

Ollie Turner is a Performance Nutritionist at the UK Sports Institute working with Aquatics GB providing nutrition support to Olympic and Paralympic swimmers. He is also a PhD student at Sheffield Hallam University.

Nigel Mitchell is a Technical Lead Performance Nutritionist at the UK Sports Institute. He is also the Lead Performance Nutrition consultant for British Athletics and a Senior Lecturer at Leeds Beckett University.

Richard Chessor is the Head of Physical Performance at Aquatics GB.

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No competing interests reported.

Fuelling Gold Medals: Developing a Periodised Nutrition System for Elite Athletes and Applying it in Practice

Status:

Version 1

Abstract

Figures

1.0 Introduction

2.0 ‘Periodised Nutrition System’

3.0 From Theory to Practice: ‘’Periodised Nutrition System’ Case Study with a World Class Level Swimmer