Harvey requires enough energy to perform. Consequently, he must consume enough calories to meet all his energy needs. The actual requirement for calorie intake depends on one’s level of fitness and bodyweight. In addition, the intensity, frequency, and duration of physical activity also greatly influence one’s actual energy requirement.
Carbohydrates
Given that Harvey’s daily workouts involve high-intensity activities, his calorie intake should comprise of between55 to 70 percent carbohydrates. In this case, 3 grams per pound of body weight would be appropriate. Based on this recommendation, Harvey should consume approximately 480 grams of carbohydrates per day in order to meet all his daily energy needs inclusive of energy expenditure during workouts and the expenditure involved in other normal physical activities, as well as basal metabolic expenditure.
Consumption of carbohydrates during workouts is not much significant for Harvey since all his workouts last for less than one hour. Therefore, glycogen and other stored carbohydrates can supply adequate energy to sustain the activities for the short periods within which they occur. However, carbohydrate intake in the forms and amounts that can be tolerated by Harvey during performance or workouts is not discouraged.
The body draws its energy from different fuels depending on one’s duration of physical activity, intensity of physical activity, and state of oxygen supply. At the onset of an activity, the muscle derives its energy from the stored ATP. In addition, a high-energy compound known as creatine phosphate, supplied by muscle cells also supplements the energy used at this stage. When ATP and creatine phosphate supplies get depleted, the muscles resort to glycogen stores within the muscle cells for energy replenishment. By this time, the muscle cells are still obtaining their energy through anaerobic means since enough oxygen has not been supplied to them. As the exercise continues, the muscle stores of glycogen get depleted. Consequently, the liver releases breaks down its glycogen into glucose and release the glucose into the blood stream. Muscle cells pick the glucose and use them to generate more energy. After sometimes, enough oxygen supply is availed to the muscle cells. Consequently, energy metabolism shifts from anaerobic to aerobic means. As the exercise continues, the energy metabolism alternates from aerobic to anaerobic means.
Carbohydrate is the only fuel metabolized to generate energy under anaerobic conditions. Therefore, it is the only source of muscle fuel at the onset of an exercise or workout. Carbohydrates are predominantly used for supplying energy during physical activities that take short duration and of high-intensity. For instance, high intensity physical activities such as sprinting require mainly carbohydrates for energy supply. However, carbohydrate metabolism for energy supply decreases as the duration of exercise increases. The process through which carbohydrate is used to generate energy under anaerobic conditions is referred to as anaerobic glycolysis. The first step of glycolysis involves in the muscle involves the breakdown of glycogen stored in the muscle cells to produce glucose. The glucose then undergoes phosphorylation under the influence of hexokinase. This reaction is non-reversible. In this case, fructose-1, 6-bisphosphate is produced. It is then split into two 3-carbon molecules. ND+ is then reduced to NADH followed by the re-phosphorylation of two ADP to ATP. Eventually pyruvate is produced. The pyruvate then forms lactate which accumulates in the muscle cells as exercise continues under anaerobic conditions.
Proteins
Amino acids supply up to approximately 10 percent of the total energy required to support a sustained exercise. They are used to supply the muscle with energy in order to supplement other energy sources. The body relies on various fuel sources for energy during exercise. Some amino acids are used directly to supply oxidizable fuel during exercise. One of such amino acids is the essential amino acid leucine (Brooks, 1987). During protein energy metabolism, the carbon skeleton is separated from the amino group. The amino group is then transported to the liver where it is used in the synthesis of non-essential amino acid or excreted as urea. Transamination takes place leading to the ultimate formation of pyruvate. Pyruvate then continues through the energy metabolism pathway to produce energy.
Protein needs of an athlete are determined by two main factors: the athlete’s training regime and the athlete’s habitual nutrient intake (Tipton and Wolfe, 2004).). In terms of the training regimes, protein needs vary depending on whether the athlete’s training regime involves endurance exercise or resistance exercise. Most of the workouts that Harvey undertakes are resistance exercises rather than endurance exercises. Therefore, protein intake would be beneficial to him. Several studies that support the need for intake of proteins in levels higher than the recommended levels for normal and healthy people with normal body weight have been conducted. Studies by Fern and colleagues and Meredith and colleagues indicate that protein intake ranging from 1.7 to 1.8 grams of protein per kilogram of body weight (Caffery, 2010) enhance muscle development especially when combined with weight training.
While these studies indicate the need to increase dietary intake of protein among athletes especially those whose training regimes involve weight lifting exercises, the dietary reference intake states that dietary protein intake of 0.8 grams protein per kilogram body weight daily is adequate for individuals aged nineteen years and older (Phillips, 2006). These conflicting recommendations indicate the controversy surrounding protein intake recommendations. However, the fact that several scientific studies have resulted into the finding that intake of higher levels of protein among strength and endurance athletes than the level recommended for the general population is beneficial justifies the need to modify Harvey’s dietary protein intake. To this end, protein intake of 1.7 grams per kilograms of bodyweight per day would be appropriate for Harvey. This recommendation would help build Harvey’s muscles and increase his strength, as well as his agility.
Fats
Fats are important fuels for exercise. They supplement carbohydrates as sources of fuel for exercise. The amount required of fat intake among athletes depends on the athletes’ exercise regime, the duration of their physical activities, and the intensity of the activities. At the beginning of an exercise, the muscle cells do not have adequate supply of oxygen. Fats cannot be metabolized to provide energy under anaerobic conditions. Consequently, they cater for a smaller proportion of energy expended at the onset of an exercise. However, as the exercise proceeds, oxygen supply to the muscle cells increase due to the increase in the rate of breathing by the performer. This increase leads to the increase in the proportion of fats metabolized to produce energy. Eventually, fats supply more energy for the exercise than carbohydrates. Fat metabolism for energy increases with an increase in the duration of exercise. In addition, it increases with a decrease in the intensity of exercise.
Based on the changes in fat metabolism during exercise, the recommendations for fat intake also vary during an exercise. However, a general intake of fat ranging from 20 to 35 percent of the total calories is recommended. On this basis, Harvey’s fat intake should be 20 to 30 percent of calories.
Fat metabolism during an exercise depends on the duration of the exercise and the intensity of the exercise. Fat metabolism is higher under aerobic conditions and low intensity physical activities. The metabolism involves the breakdown of triglyceride molecule into a glycerol or monoglyceride and fatty acid molecules. The fatty acid molecules undergo a process called beta oxidation to eventually produce energy. The glycerol molecules also continue through a different path to eventually produce energy. In general, fats are very essential for energy production among athletes during exercise. However, fats should not be consumed in the process of an exercise. The main reason for the need to avoid consumption of fats during an exercise is the feeling of nausea associated with fats. Most people do not tolerate fats while doing an exercise. Apart from carbohydrates, fats, and proteins, athletes should also observe their water intake during exercise to prevent the effects of dehydration.
References
Brooks, G. A. (1987). Amino acid and protein metabolism during exercise and recovery. Medicine and Science in sports and Exercise, 19(5 Suppl), S150-6.
Caffery, L. K. (2010). How Much Protein Do Athletes Need?. Vanderbilt University. Retrieved April, 25.
Phillips, S. M. (2006). Dietary protein for athletes: from requirements to metabolic advantage. Applied Physiology, Nutrition, and Metabolism, 31(6), 647-654.
Tipton, K. D., & Wolfe, R. R. (2004). Protein and amino acids for athletes. Journal of Sports Sciences, 22(1), 65-79.
