Rugby Union Pre-Season Nutrition (Part 3): Muscle Gain
In the first part of this series we outlined achievable rates of muscle gain from which individuals can base goals for the pre-season. If you have not read this the I recommend you go back and check this out prior to reading the below. The purpose of this article is to build upon those initial principles and to outline key components of dietary setup for muscle gain. Following this article you should be able to appreciate how daily energy and macronutrient intakes are estimated. Particular focus within this article shall be given to energy intake and protein intake.
Let’s get started …
Setting daily calorie intake is the foundation from which your dietary setup is based. Once this is determined assignment of amounts of individual macronutrients (protein, carbohydrate and fat) can be made. As our goal is to enhance muscle/body mass a calorie surplus is required, which requires energy intake to be greater than energy expenditure. Building muscle is an energy costly process. By creating a positive energy balance, in combination with strength training, you are implementing the most effective strategy to optimise the anabolic stimulus to enhance muscle mass. However, this is not a free pass to raid the buffet every night! I would also like to re-iterate that muscle can be acquired when within calorie deficit. You may remember though from part one there are certain instances where this may indeed occur, and this shall be further expanded upon in part four of this nutrition series.
Research from rugby league has shown the distinctive large energy expenditures of professional academy players during pre-season, highlighting the requirement for equally large energy intake via the diet to aid targeted body composition and physical development. Furthermore, when contact training is integrated within a training programme energy expenditure is elevated due to the collision induced muscle damage. Although from rugby league, such findings can help inform rugby union players due to the collision-based activity within rugby union. It is therefore important that rugby players during pre-season account within their dietary intake for not only the energy expenditure of the work required (e.g. movement demands), but also the muscle damage from contact activity.
Daily Energy Intake Calculation
We can estimate calorie intake based upon the utilisation of prediction equations. However, it is important to stress the word ‘PREDICTION’. These equations provide an estimate of energy expended at rest – Basal Metabolic Rate (BMR) or Resting Metabolic Rate (RMR). This is then multiplied by an estimated physical activity level (PAL), incorporating work and physical activity. These estimates are not perfect and have their limitations. However, having said that they can provide an initial ball park figure for calorie intake, from which you can then re-evaluate progress using the tracking methods outlined in the previous article and making energy intake adjustments accordingly.
Three of the most popular popular equations for estimating BMR/RMR include:
(1) Harris and Benedict – incorporates height (cm), weight (kg) and age (years)
(2) Cunningham – incorporates fat-free mass (kg)
(3) Schoefield – incorporates weight (kg) and age (years)
The purpose of such equations has been to predict energy expenditures within the general population and have also been used with active and athletic individuals. However, it is important to acknowledge that these equations were not based upon individuals who have large amounts of muscle mass, such as rugby players. Research amongst senior professional rugby league players found that measured RMR was 16.5% (approximately 310kcal) lower than that predicted via the Cunningham equation. Furthermore, Cunningham, Harris-Benedict and Schoefield equations typically underestimated total energy expenditure (TEE) for u16 to u24 rugby league and union players, although an over prediction was seen in some instances, highlighting the great individual variability in predictions.
It is therefore important to remember the limitations of energy expenditure prediction equations, particularly within athletes. Their use however may give an approximate initial starting point from which this can then be adapted to the individual and re-evaluated based upon progress. As mentioned above to calculate estimated total energy energy expenditure you must first utilise a prediction equation to estimate the energy you expend at rest. This is then multiplied by PAL value that corresponds to your self-estimated activity demands. Below is a table outlining the range of PAL values from which to base your estimation.
Although useful, the above can be confusing for individuals when trying to estimate both their expenditure during the day (e.g. job) and training. We are not all professional rugby players and therefore have to consider expenditure at work/school etc. The below table outlines the estimated PAL for differing levels of activity.
A PAL of 1.6 represents the average activity level of a normally active individual, but sedentary for periods. 2.0-2.5 is considered the PAL for athletes engaging in normal training, whereas a PAL of 2.5-4.0 for athletes engaged in rigorous training/competition. In reference to the above PAL guide, a 2.0 PAL was utilised for professional Australian rugby union players during the pre-season, based upon 1.6-1.7 PAL (seated work with discretion to move around) and addition of 0.3 (significant amounts of sport and strenuous activity). For further context, an average PAL for rugby union players (U16-U24) who were training/competing in-season was 2.0±0.4.
I have created a spreadsheet where you can predict energy intake based upon the three prediction equations above (click here to download).
Okay, so now we have predicted how many kcal are required to maintain current body mass. However, as you are reading this article, I assume you are interesting in increasing your muscle mass. Below are the suggesting rates of gain based upon the guidelines put forward by Alan Aragon previously outlined in part one. There will be inter-individual difference with regards to rate of of muscle gain (especially in those new to resistance training). Those who may wish to gain at a quicker rate than suggested may find that this comes with a greater accumulation of fat mass, which may be of relevance to certain position groups.
A typical strategy to increase body mass is to utilise a weekly 3500kcal surplus to add 0.5kg (1lb) of muscle/mass per week. Technically muscle is not the same as fat, as there is only 800kcal in 1lb (0.5kg) of muscle. However it is an energy costly process to build muscle, so an additional kcal buffer from 3500 kcal can assist this muscle building process. However, caution must also be used with the utilisation of a higher than required surplus, as there is a risk that such an increase could result in excessive additional fat accumulation. Interestingly, it has been suggested that a 200-300kcal day surplus is more appropriate than 500kcal per day for individuals who have been resistance training for some years, as their rate of muscle gain will be much slower, and the smaller surplus will minimise fat mass gain. Based upon Alan Aragon’s suggested rates of muscle gain outlined in the table above, I would encourage you to individualise your nutritional strategy.
It is important that once you have implemented your nutrition strategy you then regularly track your progress – methods of tracking progress were previously covered in article two. The data derived from tracking body mass and body composition can highlight whether kcal intake needs to be increased, decreased or kept the same according to how you have progressed thus far. I would encourage all players to track both gym and conditioning progress, whilst additionally some individuals may also wish to track daily wellness data to provide further insight. As stated in part two I have created a spreadsheet where you can log daily body mass progress (click here to download).
It is important to appreciate the inter-individual variation in response to dietary strategies, which can influence the rate of progression. For example, when non-obese adults were overfed by 1000kcal above maintenance for 8 weeks, on average only 4.6kg body was was gained, with weight gained ranging 1.4-7.2kg. You would roughly expect to gain around 1kg of body mass when overfeeding 1000kcal, which would equate to an estimated 8kg gain over 8 weeks. Why wasn’t this so? The energy expended from Non-Exercise Activity Thermogenesis, otherwise known as NEAT (energy expended through fidgeting, maintaining posture and spontaneous/non-planned activity) varied from -98 to +692kcal. This therefore unknowingly reduced the size of the imposed surplus, which would explain why less weight was gained than expected. A further consideration with regards to maintaining your target calorie surplus must be given if contact sessions are increasingly implemented over the pre-season period, as collision based training increases energy expenditure.
Structure of Daily/Weekly Energy Intake
It is important to re-iterate that consistency is needed when implementing such a nutritional strategy for the achievement of daily targets, and ultimately your weekly targets. It is is easy to sell yourself short by not being consistent with energy intake and therefore not progressing at the expected rate. It is therefore important to opt for a dietary setup that you will be able to adhere to, whilst suiting your individual training schedule. I shall now highlight two example dietary intake structure options:
This would be considered a linear approach, as kcal intake is the same each day of the week. For example, if your maintenance kcal intake is 3000kcal and you are looking to gain 0.5kg per week then you would need to increase weekly intake by an additional 3500kcal. This on average over the week would require an additional 500kcal per day on top of maintenance kcal (3000kcal), which would bring your average daily intake to 3500kcal.
This would be considered a non-linear or undulating approach, as kcal intake varies across the days of the week. For example, if your maintenance kcal intake is 3000kcal and you are looking to gain 0.5kg per week then you would need to increase weekly intake by an additional 3500kcal. As above, this on average over the week would require an additional 500kcal per day on top of maintenance kcal (3000kcal), which would bring your average daily intake to 3500kcal. However, the intensity/volume of your training sessions (e.g. weights, conditioning) or rest day would require varying amounts of daily energy expenditure. Therefore, you could vary your energy intake over different days to accommodate this and fuel training. When averaged out over the week you would still be a 3500kcal surplus.
When muscle gain and nutrition are discussed initial thoughts typically turn towards protein. As you shall read during this section, protein intake is indeed important. However, first a little theory to set the scene with the goal to help you understand how muscle is built over time.
If you just want to know how much to eat? Scroll to the next sub-section – ‘Daily Protein Intake’.
I want to first introduce you to two key processes:
Muscle protein synthesis (MPS)
Muscle protein breakdown (MPB)
A common analogy utilised to explain their role is that of a wall. How does this apply? Well, think of your muscle as a wall. The bricks that comprise this wall can be compared to proteins. MPS is the process of building the wall by adding bricks (protein), whereas MPB is the removal of bricks (protein). When at rest, and in a fasted state, the rate of MPB is greater than MPS, which results in a negative net protein balance. However, when protein is consumed there is a transient increase in MPS above rates of MPB, resulting in a positive net protein balance. Following resistance exercise MPS rates are primed for an increased sensitivity to protein feeding. Following resistance training the elevated rates of MPS remain above resting levels for 48hrs within non-resistance trained individuals, whilst persisting for up to 24hrs in resistance trained individuals. It is the repeated accumulation of resistance training, protein feeding and periods of positive protein balance over time that leads to muscle hypertrophy (increase in muscle size).
Daily Protein Intake
During pre-season professional rugby union players been reported to consume on average daily protein intakes of around 2.5g per kg of body mass. Individual intake ranged from 1.6 – 4.0g per kg of body mass in European rugby union players and 1.5 – 2.9g per kg of body mass in Australian rugby players. Note: Caution should be utilised when interpreting the protein intakes of the above European and Australian rugby players as we do not know their individual goals.
To give some context to the above numbers, 0.8g per kg of body mass is the recommended daily intake to cover the needs of 97.5% of the population. However, this is the intake to avoid protein insufficiency and therefore cannot be considered applicable to athletes seeking adaptation to training. For individuals engaged in resistance training when eating at maintenance or in a calorie surplus a protein intake of 1.6 – 2.2g per kg of body mass is recommended. Daily protein requirements are suggested to be higher than this when in a calorie deficit and this shall be expanded upon in part four in this nutrition series. It is important to ensure that protein intake is not set unnecessarily high, as this could impact upon the total consumption of other macronutrients (carbohydrate and fat). For example, the underconsumption of carbohydrate could impair high-intensity performance.
DAILY PROTEIN INTAKE = (BODY MASS in kilograms) x 1.6 to 2.2
Individual Protein Dose
So, how much protein is required in a single meal or snack to optimise the MPS response? Is this a saturable process? Initial research suggested that the consumption of 20g of protein (around 0.25g per kg of body mass) was found to maximally stimulate MPS, with no statistically significant benefit by ingesting a larger 40g protein dose amongst healthy individuals with a range of training experience and trained individuals. With MPS found to be optimised at 20g, protein intakes higher than this were oxidised at a higher rate or utilised for other processes within the body. However around a 10% mean increase in MPS was seen when consuming 40g as opposed to 20g, which suggests there may be some additional benefit for those looking to leave nothing on the table with regards to their gains. Interestingly, recent research has suggested that a 40g protein dose is superior to 20g in optimising MPS post whole body resistance training, with the 40g dose displaying a 20% greater response. It is important to highlight that the greater amount of muscle mass recruited in this study (whole body resistance training) compared to the previous (lower body training only) may have therefore required a greater demand for protein to optimise MPS.
Although initial suggestions stated that a protein dose of 0.25g per kg of body ass would optimise MPS, this has since been increased to 0.4g per kg of body mass to account for inter-individual variation.
Protein content of common foods:
Protein content of common vegetarian protein sources:
Protein is comprised of building blocks, otherwise knowns as amino acids. There are 20 amino acids, with 11 considered non-essential (synthesised within the body) and 9 essential (required via dietary intake). Proteins can be ranked according to their quality based upon 2 important criteria:
(1) Essential Amino Acid (EAA) Composition
EAA play an important role in the stimulation of MPS, with around 10g of EAA (equating to 20g protein) found to optimally stimulate MPS. The EAA composition of a protein source is therefore predictive of its ability to stimulate MPS, with particular focus upon the indispensable amino acids content. However, “the leucine content of a protein is the strongest determinant of the capacity of a protein to affect MPS and likely hypertrophy”.Why is this so? Well, the EAA leucine is often refereed to as the metabolic trigger that bring about a rise in MPS. Therefore, it is important that if looking to optimise MPS you consume foods rich in all EAA, with leucine being of particular importance.
(2) Digestion/Absorption Properties
Quite simply, this refers to how quickly a protein source can be broken down, enter the blood and be utilised by muscle for MPS. The benefit of rapid digestion would enable a quick increase in amino acid concentration, and in particular leucine to trigger MPS. One of the faster digesting protein sources is whey protein, with casein protein considered a slower digesting protein source. Both are considered high quality protein sources due to their EAA content with leucine making up 12.5% of total protein within whey and 8.5% of total protein within casein. However, it is important to consider that the majority of daily protein intake will be via meal consumption, not supplemental protein, which therefore will result in the co-ingestion of other macronutrients, which can influence the meal digestion rate.
Table data as reported by Van Vliet et al., (2015)
When compared to animal-based protein, plant-based sources are typically of a lower EAA content – see the table above. Additionally, plant-based protein have a lower digestibility than animal protein sources. Therefore, via the previously discussed criteria of assessing protein quality, plant-based protein sources can be considered of lower quality. However, this is not to say they cannot be of use – they certainly can and they can make up some quite tasty meals! However, you have to be a bit more mindful of putting your meal together, as a common solution is to combine sources to build a complete EAA profile.
If incorporating plant-based protein sources within your dietary intake, it is important to mindful that you will require a greater overall protein serving to match the EAA content of that seen in animal protein sources. Note that the the lower content of protein/EAA seen within the majority of plant-based protein sources typically also comes with a higher kcal content, typically via increased carbohydrate.
A common misconception when it comes to protein intake is the belief that more is better. You may have seen at some point the individual with the Tupperware cramming in some protein on the hour. Such people are of the belief that continually consuming protein via high meal frequencies will continually stimulate MPS and lead to continued muscle mass gains – if only!!
The ‘muscle full effect’ suggests that in the face of continued protein feeding the muscle will eventually become refractory once maximally stimulated, with excess protein either oxidised for energy or utilised for other roles within the body. Following the consumption of a saturable dose of protein, a 30 minute lag follows before a large increase in MPS, which peaks around 90 minutes before returning to baseline at roughly by 120mins, highlighting the transient nature of MPS . This is where the basis for protein feeding every 3-4 hours has been suggested to maximally stimulate rates of MPS.
As analogy let’s take a light bulb …
Interestingly, recent research within Australian rugby players found that “there was no clear effect of increasing protein distribution from approximately 4 to 6 eating occasions on changes in lean mass during a rugby preseason”. However, an individual looking to leave no stone unturned in their pursuit of optimising their muscle gains may opt for distributing protein consumption every 3-5 hours over 4 protein containing meals/snacks throughout the day and then an additional pre-sleep casein feeding of a higher dose.
‘The anabolic window’ is a time period of great notoriety, particularly amongst resistance training individuals, where the timing of protein pre and post-training is considered immediately necessary for super-compensated muscular repair and remodelling.The increased sensitivity of MPS to protein feeding following resistance training highlights that protein consumption following resistance training is of importance for those individuals with goals regarding increased muscle mass. However, such a short window of anabolic opportunity is not as narrow as the often mentioned 30-60 minute window.
Based upon the research it has been put forward that the timing and contents of the pre-workout meal dictate the timing needs of the next protein feeding due to the time course of digestion and absorption. The closer the meal is consumed to the training bout, the longer the time needed for post-training protein consumption due to the sustained delivery of amino acids. Based upon previous findings of muscle protein stimulation every 3-4 hours, and the typical resistance training bout of most individuals lasting 60 minutes, individuals wishing to optimise their muscle gain efforts may look to consume protein 90mins pre-training and ensure protein within 90 minutes following training. This can be adjusted based upon personal preference with regards to how close or far away you wish to consume a protein dose pre-training. Individuals opting for a large mixed meal (containing both protein and carbohydrate) should be aware that this may be digested and absorbed over a longer period of time (roughly up to around 5-6 hours). This may further decrease the necessity for immediate post-training protein consumption if consuming a meal a couple of hours pre-training. For example, again based upon a 60 minute training session, if consuming a decent sized mixed meal 2 hours pre-training, one would look to consume protein within the 2-3 hours following training. In the scenario that an individual opts to train fasted first thing in the morning prior to work, there should be an increased emphasis upon the timing of protein soon after the completion of training, likewise those individuals who have not consumed a large mixed meal within the previous 5-6 hours.
It is important to remember …
“the individual is free to choose, based on individual factors (i.e. based upon preference, tolerance, convenience and availability), whether to consume protein immediately pre or post exercise.”
The consumption of protein prior to sleep is a strategy of great interest amongst the strength training population. This strategy was put forward based upon the principle that the overnight period presents an extended fasting period where an individual would be expected to be in a negative protein balance (MPB greater than MPS). Therefore, to promote a positive protein balance whilst sleeping it has been suggested to ingest a casein based protein feeding (slow release protein) at a higher dose (around 30-40g) than that recommended for a daytime dose, which equates to roughly 0.5-0.6g per kg body mass. A popular approach is to integrate dairy based foods (e.g. greek yogurt) into this feeding opportunity (food-first approach where possible), or for those that wish not to opt for food a casein based protein supplement could be utilised.
When setting up a diet for body composition once protein intake has been set, I then like to calculate fat intake and then fill the remaining kcal intake with carbohydrate. Why is fat intake important? Fats are an energy source for low intensity activity, an important part of cell membranes, aid the absorption of fat soluble vitamins and aid immune function. It is important that essential fats, omega-3 and omega-6, are included within the diet. The American College of Sports Medicine in their recent position stand recommend that fat intake should be between 20-35% of total energy intake. From experience working with a variety of athletes I would typically see fat intake at around 0.9 – 1.4g/kg/body mass depending upon the individuals preference and training schedule/demands.
As mentioned above, during pre-season I set both protein and fat intakes first, and then fill the remaining kcal intake with carbohydrate. However, during the season I typically set carbohydrate second following protein to ensure that sufficient fuelling for training/competition/recovery is met (occasionally I may do this for pre-season depending upon the individual/goal).
Carbohydrate intake is an important fuel for high intensity activity. With both field and gym sessions being of decent intensity and volume it is important to ensure you are fuelling appropriately. Chronically under-fuelling during pre-season may not only decrease training performance/progression, but may also suppress immune function, impair adaptation and increase susceptibility to injuries. The American College of Sports Medicine in their recent position stand suggest the following carbohydrate intakes, although these guidelines were not specifically based from the rugby athlete:
With regards to the calorie surplus, individuals often ask should this be via additional carbohydrate or fat? With the popularity of high fat and lower carbohydrate intakes for weight management, individuals have become increasingly conscious of carbohydrate intake making them increase fat mass. However, carbohydrate consumption causing fat gain is common myth, as increases in body mass are due to the over-consumption of energy intake (kcal), and not necessarily a single macronutrient group. The majority of the time diet setup comes down to personal preference – what can you adhere to? However, it is important to remember that rugby players are engaging in high intensity pre-season training and should therefore consider utilising the majority of the surplus as carbohydrate to fuel training performance.
I didn’t want to end this article without a mention of the importance of micronutrients, which is often overlooked. To support not only your training, but also your health, it is important to include a variety of nutrients within your dietary intake.
There you have it. An overview of how to construct dietary intake for muscle gain with reference to energy intake and macronutrient consumption. The next part in this nutrition series shall look at another common goal for rugby union players during pre-season, fat loss.