Among the different types of athletes is a vast difference in nutritional needs for each type of athlete to perform at it’s absolute best. According to American College of Sports Medicine, an athlete’s energy requirements depend on the competition and training cycle. This will vary from each day and throughout the annual training plan according to the intensity and volume of training. Factors that will raise the need of energy include fear, high altitude exposure, specific drugs or medications, exposure to heat or cold environments, stress, some physical injuries, and the luteal phase of the menstrual cycle (A., D., & A,, 2015). Energy requirements are decreased by age, reduction in training, and fat free mass, and the follicular phase of the menstrual cycle.
Timing and the amount of intake of macronutrients in the athlete’s diet should be reinforced by an ultimate understanding of how training-nutrient relations affect energy systems, substrate availability, and training adaptations. Fuels for exercise include a unified series of energy systems of non-oxidative (glycolytic and phosphagen), and aerobic (carbohydrate oxidation and fat) pathways, using substrates that are both endogenous and exogenous in origin. The phosphagen system provides a quickly available energy source for muscular contraction enough for strength/ power athletes, but not at enough levels to provide a continues supply of energy for ultra-endurance/ endurance athletes and intermittent athletes. The anaerobic glycolytic pathway rapidly metabolizes glucose and muscle glycogen through the glycolytic cascade and is the primary pathway supporting high-intensity exercise enough for strength/ power athletes.
Since neither the glycolytic or phosphagen pathway can serve the energy demands to allow muscles to contract at a very high rate for longer lasting events, oxidative pathways provide the primary fuels for events that would include ultra-endurance/ endurance athletes and intermittent athletes (A., D., & A,, 2015). Major substrates include liver and muscle glycogen, adipose tissue triglycerides, amino acids from muscle, blood, the gut, and liver, and intramuscular lipid. When oxygen is more available to the working muscle, the body will use more of the aerobic (oxidative) energy pathways. Some muscle substrates are present in relatively large quantities, others may need to be used according to exact needs.
Due to its number of special features of its role in the performance and adaption to training, carbohydrate has received a great deal of consideration. Carbohydrates are manipulated day-to-day by dietary intake or by a single sitting of exercise, all depending on the body’s storage. Carbohydrates offer fuel for the brain and central nervous system where it can sustenance exercise over a large range of intensity. Due to its use by both the anaerobic, and aerobic energy pathways. Since it provides more adenosine triphosphate per volume of oxygen that can be delivered to the mitochondria, carbohydrate offers more compensations than fat. Prolonged continuous, or intermittent high-intensity exercise is boosted by strategies that preserve high carbohydrate availability. Depletion of the bodies storage of carbohydrate marks in impaired skill and attentiveness, and reduced work rates. Recommendations on a daily intake of carbohydrate should be made in reflection of the athlete’s training/competition program and the relative importance of undertaking it with high or low carbohydrate according to the urgency of endorsing the performance of high-quality exercise versus enhancing training.
Protein interacts with exercise, providing both a substrate and a trigger for the synthesis of contractile and metabolic proteins. It also improves the structure of non-muscle tissues like tendons and bones. Studies show that the response to resistance training show upregulation of muscle protein synthesis for at least twenty-four hours in response to a single session of exercise (A., D., & A,, 2015). It also displayed an amplified sensitivity to the dietary intake of protein over that time. Parallel responses were shown succeeding aerobic exercise and other exercise types like intermittent activities. Recently, recommendations have prevailed the importance of a well-timed intake of protein for all types of athletes even if muscle hypertrophy is not the main goal. Future research will further improve the recommendations for total daily amounts, quality of protein intake, timing tactics, and provide new recommendations for protein supplements resulting from various sources.
Currently it is suggested that the dietary protein intake that is essential to support repair, remodeling, and metabolic adaptation for protein ranges from 1.2 to 2.0 g/kg/day (A., D., & A,, 2015). A higher intake may be necessary for a short period during times of intensified training or reducing energy intake. Rather than general daily ranges being provided for individuals exclusively categorized as strength or endurance athletes, guidelines should be founded around ideal adaptation to exact sessions of training/competition within a periodized program. All of which can alter based off nutrient needs, athletic goals, food choices, and energy considerations. The protein requirements can also vary based on the status of the athlete, whether they are experienced athletes which would entail less or training athletes that involve high frequencies and intensities. In the case of an energy restriction or inactivity due to an injury, raised protein intakes as high as 2.0 g/kg/day or higher, when spread over the day has its advantages in preventing fat free mass loss (A., D., & A,, 2015).
Believe it or not fat is also an essential component to a healthy diet. Fat provides essential elements of cell membranes, energy, and the facilitation of the absorption of fat-soluble vitamins. Athletes fat consumption should be according to public health guidelines and individualized based on the body composition goals and training level. Some specific cases may occur where high-fat diets offer some advantage or at least the absence of disadvantages for performance, in general it seems to reduce rather than improve metabolic flexibility by reducing carbohydrate availability and capacity to use it effectively as an exercise substrate. Athletes can decide to limit their fat intake extremely in efforts to improve body composition or lose body weight but should be guided against continuing application of a fat intake below twenty percent of energy intake since it is likely to decrease the intake of a variety of nutrients.
When determining pre-, during and post-event eating several factors related to nutrition must be addressed. Nutritional factors that can cause deterioration and fatigue in the outputs of performance, throughout or toward the end of the event. A few examples of these factors include, dehydration, hypoglycemia, electrolyte imbalances, and glycogen depletion (Science of Sports Nutrition). Any fluids or supplements consumed before, during or after events can reduce or postpone the onset of said nutritional factors. In some scenarios, pre-event nutrition may need to recompence the effects of other activities commenced by the athlete such as dehydration or restrictive eating associated with weigh restricted sports. Something always in mind that an athlete wants to achieve is gut comfort throughout the event. Avoid the feeling of uneasiness, hunger, and gastrointestinal upsets may reduce the pleasure and the performance of exercise and inhibit with ongoing nutritional support. Lastly, athletes want to provide nutritional support for health, and adaptation to exercise, especially in the case of competitive events that last days and sometimes weeks at a time.
Hydration underwrites to optimal health and exercise performance. In addition to daily water loss from respiration, renal, and sweat sources, athletes need to replenish sweat loss. To reserve optimal body function, performance, and perception of well-being, athletes should try to take on approaches of fluid management before, during and after exercise that will uphold euhydration. All depending on the athlete, kind of exercise and environments. In response to dehydration, fluid deficits of two percent or greater body weight can compromise cognitive function and aerobic exercise performance, particularly in hot weather.
Some athletes choose a vegetarian diet for several reasons. Whether it be from philosophical beliefs, to health, food aversions, financial constraints, or to disguise disordered eating. As with any other self-induced dietary restriction, it would be wise to explore whether the vegetarian athlete also presents with disordered eating. A vegetarian diet can be satisfactory containing high intakes of fruit, whole grains, soy products, vegetables, nuts, phytochemicals, fiber and antioxidants. Research is presently lacking regarding the impact a long-term vegetarian diet has on athletic performance among athletic populations. Athletes who choose to eat a vegetarian diet may have a bigger risk of low bone mineral density and stress fractures.
According to the International Society of Sports Nutrition, there are many guidelines for pre-, during, and post-event dietary intakes. According to The International Society of Sports Nutrition the different macronutrient pre-, during, and post-even dietary guidelines will go as follows. Considerations prior to exercise have traditionally consisted of maximization of carbohydrate during endurance exercise to sustain serum glucose levels. More recently though, studies have shown that ingestion of carbohydrate, amino acids, and proteins prior to resistance training are effective modalities for enhancing exercise training adaptations and decreasing exercise associated muscle damage. The body storage of glycogen is restricted and will only last a few hours at best throughout moderate to high intensity levels. As the body’s glycogen levels decrease, exercise intensity, and work output decrease as well as muscle tissue breakdown.
The concept of carb loading is likely to be the oldest form of all nutrient timing practices (Kerksick, et al., 2008). It is suggested to have a daily intake of high carbohydrate meals to maintain muscle glycogen.
A study examining the relationship of ingesting protein alone or in a mixture with carbohydrate compared the ingestion of said relationship both immediately before, or immediately after a single session of resistance exercise at eighty percent one-repetition maximum. The study determined that the protein status was greater when ingested immediately before the exercise rather than immediately after. Pre-exercise ingestion of protein alone increases muscle protein synthesis. Additionally, the ingestion of both protein and carbohydrate pre-exercise shows to yield a substantial high level of muscle protein synthesis.
Carbohydrate availability through exercise and muscle glycogen levels are key factors of endurance performance according to ISSN. When muscle glycogen levels are low at the beginning of exercise, carbohydrate administration becomes even more important. As an exercise period exceeds sixty minutes, exogenous sources of carbohydrate become required to keep blood glucose and muscle glycogen stores. Ingesting carbohydrate alone or along protein during resistance exercise increase muscle glycogen stores, counterbalance muscle damage and facilitates greater training adaptations after acute and prolonged periods of resistance training.
Post-exercise ingestion of amino acids has been shown to stimulate healthy growths in muscle protein synthesis. The addition of carbohydrate may increase protein synthesis even more, while pre-exercise consumption may result in the best response of the two. During prolonged resistance training, post-exercise consumption of both carbohydrate and protein in varying amounts have been shown to stimulate improvements in strength and body composition when compared. The addition of creatine to a carbohydrate and protein supplements may also facilitate an even greater adaptation to resistance training (Kerksick, et al., 2008).
In accordance to the National Athletic Trainers Association, a healthy diet/ meal plan should contain adequate calories to achieve body weight goals, supply essential nutrients and sustain hydration. To guarantee effective performance, energy intake must come from a suitable balance of the three-essential energy-producing nutrients, which are protein, fats, and carbohydrates (GATORADE). Carbohydrates should provide anywhere from fifty-five to seventy percent of the total caloric intake need of athletes and active individuals and may be as high as twelve grams or more per kilogram of body weight (Turocy, et al., 2011). Blood glucose and muscle glycogen, both derived from carbohydrates are the principal energy substrates for working muscle. The more aerobic activity the larger need of carbohydrates.
In order to regulate the recommended protein intake, one must first identify the type of exercise and the intensity of that exercise. Protein supports with many functions of the body, but most athletes are concerned in the building of muscle and connective tissue. Protein provides eight to ten percent of the body’s total energy needs (Turocy, et al., 2011). Especially in events exceeding sixty to seventy minutes, amino acid oxidation rises, thereby increasing the use of protein to back the greater energy demands. For the strength athletes who are searching to build fat free mass they need the most protein in the diet. More modest amounts of protein are wanted for those who are not interested in developing as much fat free mass but are looking to meet the desires for aerobic activity. Excessive protein of the body’s physical requirements increases the needs of hydration and overloads the kidneys and liver.
Lastly, dietary fats are an essential factor to a healthy diet because they provide energy, help transport and use fat soluble vitamins, and protect cells. For low to moderate intensity exercise fat metabolism provides a percentage of energy needed. The typical intake of fat in athletes is roughly thirty percent of total caloric intake. Commonly held consensus states that twenty to twenty-five percent of total caloric intake should truly come from fats.
