An athlete’s body weight has very little to do with carbohydrate requirements.
Jeukendrup explains that the amount of carbohydrates needed during exercise depends on the intensity, type and duration of activity.
Carbohydrate sources can be divided into two categories. Some carbohydrates, like glucose and sucrose, are used rapidly, while others, like fructose, are used more slowly.
van Loon explains that rapidly digested and absorbed protein sources rich in the amino acid leucine, such as whey protein, are most anabolic following exercise.
van Loon explains the amount of carbohydrate needed after a workout and what sources athletes should look to consume.
Sleep-deprived people may consume more food.
Approximately 30-50% of athletes experience GI problems during exercise.
Experts recommend avoiding NSAID use before a marathon due to increased risk of GI problems.
Keys to avoiding GI distress include hydration and avoiding fiber, protein, fat and lactose rich foods.
Foods rich in fiber, protein, fat and lactose slow gastric emptying and should be avoided before and during exericse.
Movement of organs and decreased blood flow may contribute to GI issues during exercise.
Factors that may increase an athlete's chance of experiencing GI distress.
During exercise of less than one hour, GI distress may be prevented by gargling rather than consuming carbohydrate.
Heat cramps are a result of excessive sweat lost and a consequent sodium deficit.
Prior to exercise in the heat, athletes may gain a thermoregulatory and performance advantage by 'pre-cooling' their bodies rather than using a traditional 'warm-up.'
Athletes can acclimatize to a hot, humid environment. However, at high intensities the athlete will still have a difficult time evaporating sweat and will feel the effect of the environment.
Sweat tests can help identify individual fluid and electrolyte needs and improve hydration strategies.
To maximize performance, athletes should to acclimatize to the heat, practice proper hydration, and cool the body during breaks.
Heat stress is the effect of the environment on the athlete, whereas heat strain describes how the athlete's body responds to the environmental stress.
Primary causes of fatigue during exercise in the heat include cardiovascular strain and high rates of glycogen utilization.
Both skin and core temperature are related to fatigue in the heat; skin temperature is close to environmental temperature and is related to the perception of heat felt by the athlete.
A lack of water in the body inhibits sweating which causes body temperature to rise, ultimately reducing the athlete's ability to continue exercising.
Fluid intake before and during exercise can help the body maintain an appropriate body temperature.
Genetics explain about 50 percent of performance outcomes, nutrition and other aspects of gene regulation also play important roles.
Predicting an individual's response to nutrition is challenging, since scientists need to account for both the genetic variation of the athlete and the gut biome.
Exercise in the heat results in greater sweat losses as compared to a thermoneutral environment, resulting in a greater need to replace both fluid and electrolytes.
Two warning signs of over-hydration during exercise are 1) drinking large volumes of water without producing urine and 2) gaining weight over the course of a training session or competition.
If a critical core temperature does contribute to fatigue, it is likely related to the environment.
Studies have shown that moderate intake of caffeine will not impair fluid balance or thermoregulation.
The dietary nitrates in beet root juice alter running economy and cycling efficiency to help improve performance.
Jones has found that beet root juice is effective for increasing older individuals’ exercise tolerance and lowering blood pressure.
Jones explains why nitric oxide is important to various physiological processes, including the delivery of oxygen to muscles and the production of oxidative energy.
Jones explains that beet root juice contains an abundance of inorganic nitrate, which converts to nitric oxide in the body. Nitric oxide helps deliver blood and oxygen to muscle tissue.
Jones explains how he discovered beet root juice as a nitrate source.
Jeukendrup explains that mouth rinsing can help improve performance. Sensors in the mouth signal the brain which sends a message to the muscles.
While the form of carbohydrate delivery doesn’t impact performance, it is important that carbohydrate supplements are low in fat, protein and fiber.
The thought that the body switches from carbohydrates to fat for energy is a myth. While the levels do change, athletes burn both at the same time.
Experts have determined that extreme carbohydrate loading is unneccessary. Athletes can gradually increase their carbohydrate intake while reducing training load leading up to the race.
Stachenfeld explains the circumstances when over-hydration may become an issue.
Hyponatremia is not very common. Stachenfeld discusses strategies for susceptible athletes to prevent hyponatremia.
Hyponatremia is a fall in blood sodium below a level that can be tolerated by an individual.
A normal, healthy diet requires about 10-15% of the total energy requirement come from protein.
van Loon discusses why branched chain amino acids (BCAA’s) are not a good source of energy for athletes.
Ingesting about 20-25 grams of protein is sufficient to allow a maximal post-exercise muscle response.
Larger athletes may need to eat more protein after exercise because they require larger doses of protein to stimulate new protein synthesis.
Phillips recommends 20-25 grams of protein to stimulate the rate of new muscle synthesis; however, the specific amount of protein within this range depends on the size of the athlete.
Phillips explains why there is not a significant difference between protein isolates, concentrates and hydrosylates with respect to post-exercise recovery.
Phillips explains the types of protein athletes should choose post-workout.
Halson explains why sleep is important for sports performance.
Reasons some athletes suffer from poor sleep.
Two key components to improving sleep are routine and environment.
Researchers believe athletes should get at least eight hours of sleep per night.
Halson explains how too little sleep and sleep extensions affect performance.
An athlete has greater recovery needs since they usually expend more energy than the average population.
Fatty acids found in fish oil and antioxidants found in red fruit and berries are important for brain development.
Athletes can train their intestines to absorb carbohydrates during exercise, resulting in decreased GI problems and improved performance.
The sodium levels in pickle juice are very high, but it doesn't contain the right amount of fluid to rehydrate athletes.
The best way for athletes to prevent heat cramps is to match sweat losses with fluid and sodium intake.
Examining the color of urine is an easy way for athletes to assess their hydration status.
Genetics attempts to link DNA variations to performance. Transcriptomics takes into account DNA and environmental factors, making it easier to detect differences in performance.
In the future, genomics may be able to help athletes personalize their training approach and predict injury-related responses.
The most common nutrition mistake made by marathon runners is not practicing their race day nutrition plan during training.
If their goal is to increase muscle mass, athletes may want to train later in the day. This timing may associate their training with their largest intake of amino acids. Relaxing at night will also help to decrease metabolic stress, which impairs adaptations to training.
The night before a marathon is the last chance to fill muscle glycogen stores, so runners should choose foods high in carbohydrate. Good options are rice, potatoes or pasta.
The choice of what to eat for breakfast before a marathon is highly individual. The most important consideration is to get enough carbohydrate, at least 100 g, to have enough fuel for the race.
Endurance training will increase aerobic capacity, while strength training will increase muscle mass and alter the functionality of connective tissue.
Athletes looking to lose weight should balance energy intake and output, and eating before sleep is a personal preference. However, there could be an advantage to eating protein before sleep to promote protein synthesis.
The biggest misconception about protein consumption is the notion that "more is better." The right timing helps the body use more of the ingested protein for muscle adaptations.
Advice on the use of antioxidants depends on the type of training. Athletes should consume antioxidants during resistance training, but not endurance training.
Individuals should consume fat in their diet since this nutrient is an important fuel source, aids vitamin absorption, acts as shock absorber for organs and is a component of membranes.
During exercise fat stored in the muscle and adipose tissue supplies energy, so the type of dietary fat doesn't matter for performance. However, good health saturated fats should be limited and omega-3 fatty acids encouraged.
Carbohydrates are the main fuel source for an athlete during training, so this macronutrient should not be avoided when trying to lose weight.
Sugar and salt, along with water and flavor, are the key components of a sports drink. Carbohydrates, including sugars, provide fuel and salt helps replace sweat losses.
The game of football involves repeated, short, high-intensity bursts of muscle contraction. The preferred energy source for burst or sprint activities is carbohydrate.
Stop-and-go sports involve frequent transitions from one intensity to another. Therefore, the muscle relies heavily on carbohydrate as the main fuel source.
Fluid needs during a race are highly individual and athletes should determine and practice their hydration strategy during training.
The type of beverage to consume during a race is a personal decision. However, for races of longer durations, athletes should include electrolytes. Athletes should also plan ahead and train with the beverages availabe on the course.
To gain muscle mass, athletes should eat ~30% of their total calories from protein. It is also important the athlete is in positive energy balance and consumes additional calories from fat and carbohydrate.
Endurance-trained athletes, similar to resistance-trained athletes, should eat ~20-25 g high quality protein for recovery.
Due to the type of training stress and high energy expenditure, endurance athletes do not need to reduce protein intake to avoid gains in muscle mass. Dietary protein may help promote adaptations to endurance training.
Powerlifters are stronger than bodybuilders due to their type of training program.
The biological mechanism for muscle gain is exactly the same for powerlifters and bodybuilders.