Chapter 12 - Periodization and Nutrient Timing Flashcards
nutrient periodization
the planned process of altering energy and macronutrient intake to meet the training, performance, and body composition goals of the individual athlete.
nutrient timing
based on
1. how various macronutrients are absorbed and metabolized
2. the enhanced sensitivity to these macronutrients surrounding exercise
3. how the availability of these macronutrients can completely alter the molecular signals that determine how the body adapts to exercise
In other words, simply altering the meal timing can impact an athlete’s ability to perform optimally, recover quickly, and adapt to a training stimulus
myofibrillar proteins
Proteins that make up skeletal muscle tissue
3 Rs of Recovery
Repair: Repair damaged muscle fibers.
Restore: Restore depleted carbohydrate stores.
Rehydrate: Rehydrate from fluids lost during exercise.
The fundamental goals during recovery from exercise are to repair damaged muscle fibers, restore depleted glycogen stores within both the muscle and liver, and replace bodily fluids and electrolytes lost through sweat.
restoring muscle glycogen
Because muscle glycogen provides the most important fuel source for the exercising muscle, the primary goal for the athlete should be to restore depleted carbohydrate stores within the post-exercise recovery period
carbohydrate feeding at hourly intervals
immediate intake of carbohydrate equivalent to 1.2 g/kg body mass for maximizing the restoration of glycogen (this would equate to 84 g carbohydrate within the first hour after exercise)
highly important during short recovery periods, because delaying carbohydrate intake by just two hours following exercise has been demonstrated to reduce the rate at which carbohydrate can be restored by up to 50%
Following this immediate intake, carbohydrate should then be provided at regular hourly intervals at an amount equivalent to 1.2 g/kg body mass for 3–6 hours, depending on the interval between exercise sessions
how long is protein synthesis elevated after exercise?
3–4 hours following protein intake
In reality, protein synthesis is elevated for up to 24–48 hours after exercise, and thus provides an opportunity to take advantage of a much larger anabolic window that can enhance the effectiveness of each meal consumed during this period
protein
muscle repair and reconditioning
The immediate post-workout period is often referred to as the “anabolic window of opportunity” due to the muscles’ increased sensitivity to amino acids. For instance, because protein synthesis has been shown to be elevated for 3–4 hours following protein intake immediate protein ingestion may be less important for those who consume protein in close proximity to training, such as in a pre-training meal 60–90 minutes prior, or those who consume amino acids during the session itself, because protein synthesis is already likely to be elevated. For example, consuming 20 g of whey protein just prior to exercise increases the availability of amino acids for the muscle for up to three hours after exercise.
protein pacing
the regular consumption of 20 g of protein every three hours is more effective at maintaining protein synthesis than consuming 40 g protein every six hours
Research has shown that adopting a protein pacing approach where 30 g protein is consumed at breakfast, lunch, and dinner allows protein synthesis to be maintained to a greater extent when compared with the typical skewed intake pattern (10 g at breakfast, 15 g at lunch, and 65 g at dinner) that people regularly adopt
Strategies to Promote Training Adaptations
Endurance Training Adaptations
3 total
The primary goal of the endurance athlete is to become more efficient in how they produce energy.
This requirement relies on specific adaptations, such as
1. increased number of capillaries to deliver oxygen to the exercising muscle
2. increase in enzymes that allow for the metabolism of fat and carbohydrate
3. increased number of mitochondria to support the production of ATP
low carbohydrate training (“train-low”)
simply modifying the timing of nutrient intake can completely alter the signaling process that underpins how the muscle adapts to training
intentionally restricting the intake of carbohydrate before, during, or after exercise places an additional stimulus on the muscle and can amplify the desired signals that support the adaptation process
While there are different train-low strategies that can be used, the most common approaches are fasted and low glycogen training.
Strategies to Promote Training Adaptations
Fasted Exercise for Endurance Adaptations
Fasted exercise represents the simplest of train-low models, whereby exercise is performed prior to breakfast. Although the glycogen storage pool within the muscle is unaltered with this method, the storage pool within the liver is approximately 50% depleted as a result of the overnight fasting period
Refraining from breakfast also increases the availability of fatty acids, subsequently increasing the reliance on fat as a fuel source
Some athletes will consume protein prior to fasted sessions to reduce any catabolic effects on muscle. Although this does not represent a true fasted state, research shows that such practices do not negatively affect the use of fat or the required signaling processes to promote endurance-related adaptations
It should be noted that research on the increased use of fats as fuel following a period of fasting remains inconclusive.
Strategies to Promote Training Adaptations
Low Glycogen Exercise
approach is typically designed for athletes who train multiple times per day, where carbohydrate intake is purposefully restricted in the period between the first and second session of the day so that the second exercise session is completed with low muscle glycogen stores
Alternatively, for those who do not regularly perform multiple sessions per day, low glycogen training can be achieved by performing the first exercise session later in the evening,** restricting carbohydrate intake throughout the night,** and performing the second session in a fasted state the following morning
train-low effects on performance (3 total)
train-low strategies have been reported to result in
1. enhanced ability to use fat as a fuel
2. increased number of capillaries to deliver oxygen to the exercising muscle
3. increased efficiency in generating ATP for energy production
all of which have the potential to improve performance
Strategies to Promote Training Adaptations
Resistance Training Adaptations
While carbohydrate-restricted training does not support these requirements, the protein pacing strategies discussed earlier to support recovery are able to support long-term changes in muscle mass and strength.
This is based on the fact that regular protein intake allows protein synthesis to remain elevated throughout the day, promoting a state of anabolism. Over time, these changes at the cellular level will support muscle hypertrophy and increases in strength
protein pacing
protein pacing strategies help
* to increase total daily protein intake that may have otherwise been insufficient
* should still provide an important consideration for maximizing resistance training specific adaptations
Fasted Exercise for Body Composition Changes
Fasted exercise represents a commonly used nutrient timing strategy, where exercise is performed in a fasted state to accelerate the loss of body fat.
even a small amount of carbohydrate (equivalent to 0.8 g/kg body weight)
The practice of fasted exercise is based on the premise that **low levels of the hormone insulin allow the body to break down fatty acids from lipids stored within the adipose tissue **
Fat Utilization
In this study, subjects performed 60 min of low-intensity running exercise either before breakfast, after lunch, or after dinner with energy intake across the course of 24 hours matched between all three conditions. Only when exercise was performed before breakfast was 24-hour fat use increase.
This equated to approximately 250 kcal of fat, resulting in an approximate use of 25 g worth of additional fat
When considered collectively, these studies demonstrate that fasted exercise provides a useful nutrient timing tool to enhance daily fat oxidation. Over time, these daily increases should manifest into reductions in overall body fat, although long-term training studies have yet to demonstrate this
pros and cons of fasted training
Pros
Increased fat use across 24 hours
Improved metabolic flexibility through the support of adaptations that facilitate greater reliance on fat as a fuel source
Reduction of the risk of gastrointestinal distress
Convenient strategy for athletes performing early morning training
Cons
Potential for increased protein breakdown if protein is not consumed
Potential risk of athlete having low blood glucose
Potential for training intensity to be compromised due to a lack of energy availability
meal frequency and body composition
the practice of eating smaller meals more frequently (as opposed to 1–2 larger meals) has been adopted on the basis that a more frequent eating pattern provides better appetite control while also increasing the thermic effect of food
This would ultimately result in a reduction in overall energy intake, due to reduced hunger and a simultaneous increase in energy expenditure from the energy required to absorb and digest meals
recommendations on meal frequency
consuming three daily meals (breakfast, lunch, and dinner) reduced feelings of hunger between meals and increased daily fat use when compared with two meals (breakfast and dinner) despite no changes in total daily energy expenditure.
Furthermore, a recent analysis of all available studies to date suggested that consuming 3–5 meals per day appears to be superior for fat loss when compared with 1–2 meals per day
meal frequency and athletic performance
Despite the potential for meal frequency to impact the athlete’s body composition, there is currently a lack of scientific evidence to support a specific meal frequency strategy to improve athletic performance. Nonetheless, given the high energy requirements of many athletes, multiple meals are likely to be required to ensure that the athlete is consuming adequate daily energy
body composition alterations
popular intermitent fasting methods
alternate day fasting or two fasting days per week have proven most popular
Alternate day fasting typically consists of alternating between fasting days and feeding days. During fasting days, energy intake is reduced to 25% of requirements, and feeding days, energy intake is either increased to over 100% of requirements or is unlimited
two fasting days per week typically involves either complete fasting or severe energy restriction for two days, and increased energy intake on the other five days of the week
body composition alterations
intermitent fasting
Intermittent fasting is typically used as an umbrella term to define specific patterns of eating where individuals typically go 16–48 hours without eating or eating very little
