Handbook of Eating and Drinking by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030145040
Publisher: Springer International Publishing

Are There Optimal Diets for Performance?

A number of different diets have been put forward as means to improve athletic performance. Given the diversity of athletic events, it is clear there can be no “one-size-fits-all” approach. Furthermore, given that an athlete’s preparation can include several phases, such as preparation, pre-competition, and competition, the nutritional demands imposed by such activities are considerably different. In order for the body to ambulate or perform PA through muscular contraction, adenosine triphosphate (ATP) is needed. ATP is supplied from an interrelated series of metabolic pathways and energy stores including non-oxidative (oxygen-independent, including phosphagen and glycolytic) and oxidative (oxygen-dependent, fat, and carbohydrate oxidation) pathways (Brooks et al. 2005). The phosphagen system provides for rapidly available energy for muscular contraction, but its stores are limited to ~10 s. The anaerobic glycolytic pathway provides rapid catabolism of glucose and muscle glycogen and primarily supports short duration (10–180 s), high-intensity exercise. In activities lasting longer than ~2 min, oxidative metabolism is the predominant energy pathway. Substrates for oxidative metabolism are mainly muscle and liver glycogen and intramuscular and adipose tissue triglycerides, with amino acids playing a smaller role. It is important that the reader understands that no one system is ever the sole source of energy and that the contribution of energy pathways and the crossover between pathways are influenced by a number of factors, including but not limited to intensity, frequency, duration, and type of training; sex; individual training/fitness level; environmental conditions; and prior nutrient intake and availability of substrates (Brooks et al. 2005).

Instead of a specific dietary plan, current sports nutrition guidelines instead focus on ensuring that athletes exceed minimum energy requirements by achieving sufficient energy availability. Energy availability is dietary intake minus the energy expenditure of exercise, adjusted for fat-free mass (FFM) (Thomas et al. 2016). Initial data were collected in females and suggested an optimal level of energy intake that is equivalent to 45 kcal per kilogram of fat-free mass per day and that levels below 30 lead to a number of adverse consequences to health and performance (Loucks et al. 1998). When individuals fail to meet nutritional requirements to maintain optimal bodily function, this has been termed relative energy deficiency in sport (RED-S), which is described in detail elsewhere (Mountjoy et al. 2014).

Past nutritional guidelines for athletes and active individuals were necessarily broad. Currently, guidelines are becoming more individualized and also account for the different types of training. For example, the recent ACSM-ADA position stand published specific guidance for CHO intake in individuals undergoing light-, moderate-, and high-volume/intensity training programs (Thomas et al. 2016). A recent review paper also explored the topic of dietary manipulation for endurance sport athletes, an area of recent interest (Burke et al. 2018). Protein intake is also essential for supporting optimal health in athletes and active people, and their suggested intakes are considerably higher than the current US recommended daily allowance (RDA) of 0.8 grams per kilogram of body mass. Protein supports muscle growth and repair and therefore is important during the postexercise recovery period (Thomas et al.

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