Timing of Eating and Exercise (Technical)

The role of nutrition in regard to physical activity and athletic performance is of high importance for all athletes. There are many aspects to consider in the realm of sports nutrition, and an important area is the timing of food and fluid consumption around exercise. The research in this area points to several specific guidelines to assist athletes in optimizing their performance by not only consuming the proper nutrients, but also consuming them in the appropriate time frame around exercise.

In general, nutrition guidelines for athletes for each of the macronutrients are as follows: 6-10 grams carbohydrate per kilogram body weight per day, 1.2- 1.7 grams protein per kilogram body weight per day, and 20% to 30% of total daily energy from fat (Rodriguez et al. 2009). For maximum benefit, spacing the consumption of each of these nutrients appropriately is essential. Each of these nutrients plays a specific role in regard to physical activity.

Carbohydrates are the body’s preferred source of energy, and consumption of carbohydrates is beneficial in supporting activity. Ingesting carbohydrates assists with the maintenance of blood glucose levels during exercise, and also replenishes muscle glycogen (the storage form of carbohydrates in the body; Dunford and Doyle 2012). The specific recommendations for total daily carbohydrate intake based on training load and type of exercise are shown in Table 1 (Nutrition Booklet 2010).

Table 1.

Training Load Type of Exercise Carbohydrate Intake Targets (g/kg body mass)
Light Low intensity or skill-based activities 3-5 g/kg/d
Moderate Moderate exercise program (i.e. ~1 hour per day) 5-7 g/kg/d
High Endurance program (e.g. 1-3 hours per day of mod-high-intensity exercise) 6-10 g/kg/d
Very High Extreme commitment (i.e., at least 4-5 hours per day of mod-high intensity exercise) 8-12 g/kg/d

Protein has many unique functions in the body, however protein can only be used for these important roles when there is sufficient caloric intake from carbohydrates and fat (Dunford and Doyle 2012). Though the body can use protein for energy, consuming sufficient carbohydrates will provide a protein-sparing effect. This means that protein will not be converted to energy, and can instead be used to carry out its other important functions in the body, such as tissue maintenance and repair, nutrient transport, muscle protein synthesis, and so forth (Gropper et al. 2008).

Fat is a necessary nutrient for athletes, and together with carbohydrate acts as an important energy source for moderate-intensity exercise. Fat provides essential fatty acids, and allows absorption of fat soluble vitamins (Mahan and Escott-Stump 2008). Careful consideration is required to allow sufficient but not excessive fat intake. Of particular concern is that fat slows gastric emptying and takes longer to digest than either carbohydrates or protein, so the timing of fat intake around exercise is a key factor to consider in meal planning (Dunford and Doyle 2012).

As has been demonstrated, each macronutrient plays a key role in exercise performance, and the timing of intake for each of these nutrients is an important consideration. The specific recommendations for food and fluid intake within each time frame surrounding exercise are detailed below.

Before Exercise

In sports nutrition, the recommendations for nutrition prior to exercise generally refers to the time frame approximately four hours before exercise begins (Dunford and Doyle 2012). Though overall nutrition status plays a role in athletic performance, this time frame has the most immediate impact on the upcoming bout of exercise. Fueling before exercise is important as improvement in exercise performance has been shown when food is ingested prior to exercise, as compared to exercising in a fasted state (Maffucci and McMurray 2000, Jentjens et al. 2003, Mosely et al. 2003).

There are several purposes to fueling the body appropriately before exercise. Though maximizing performance is the key benefit, avoiding gastrointestinal distress during exercise, maintaining blood glucose levels, and avoiding excessive or inadequate hydration are other purposes for fueling properly prior to exercise. Though fatigue during exercise cannot be prevented, the onset of fatigue can be delayed with proper fueling before exercise (Dunford and Doyle 2012). In order to accomplish these purposes, it is recommended that the pre-exercise meal or snack should be of a particular composition. In regard to macronutrients, it should be high in carbohydrates, low in fat, and moderate in protein. Other important considerations include low fiber options and adequate fluid consumption (Rodriguez et al. 2009).

The total amount of food consumed before exercise will be determined by the time between eating and the onset of exercise. The general guide is that larger meals can be consumed when there is a greater time gap between eating and exercise, whereas smaller amounts of food should be consumed if eating and exercise are in close proximity. In terms of carbohydrate, it is often recommended that 1-4 grams carbohydrate per kilogram body weight be consumed 1-4 hours prior to exercise (1 gram per kilogram if 1 hour prior, 2 grams per kilogram if 2 hours prior, etc.; Dunford and Doyle 2012). The key to pre-exercise feedings is that the athlete should start the exercise bout without feeling hungry, but also without food in the stomach that is undigested. As each athlete will tolerate various foods differently, the most important consideration with pre-exercise meals is that they should be familiar to the athlete, and new foods should be tried during training sessions before being used in competition settings (Rodriguez et al. 2009).

Considerations in regard to fluid intake include achieving sufficient hydration, while allowing sufficient time for fluid voiding prior to exercise. At least four hours prior to exercise it is recommended that water or a sports drink be consumed in the amount of approximately 5 to 7 milliliters per kilogram body weight (Rodriguez et al. 2009).

4673-clocks-81During Exercise

The ingestion of nutrients during exercise becomes of greatest importance during prolonged exercise. The purposes of fueling during exercise include maximizing performance, delaying fatigue, managing fluid and electrolyte balance, and avoiding gastrointestinal distress (Dunford and Doyle 2012). The composition and timing of the pre-exercise meal contributes to the determination of proper fueling during exercise. Of the body of research available, the two aspects of most importance for consumption during exercise include fluid and carbohydrate replacement.  For exercise bouts lasting less than 45-60 minutes, water is generally sufficient. However, endurance performance has been shown to be benefited with sports beverages that contain 6-8 percent carbohydrate, and this composition is appropriate for ingestion during exercise (Nicholas et al. 1995, Jeunjendrup et al. 1997, Sugiura and Kobayashi 1998). For events lasting longer than one hour it is recommended that carbohydrate intake be in the range of 30-60 grams carbohydrate per hour, or 0.7 grams carbohydrate per kilogram body weight per hour (Coggan and Coyle 1991, Currell and Jeukendrup 2008).

Though total carbohydrate ingestion is important, the type of carbohydrate consumed is another relevant consideration. Evidence suggests that fructose alone may not be tolerated or used as effectively as other forms of carbohydrate, such as mixtures of glucose and fructose, other simple sugars, and maltodextrins (Coggan and Coyle 1991). Carbohydrates may be obtained from food, gels, or sports beverages, the latter option also providing needed fluid. If carbohydrates are consumed from food or gels, water should also be consumed to maintain hydration status during exercise.

It is beneficial to begin carbohydrate ingestion shortly after beginning exercise, rather than waiting until later in the exercise bout. Additionally, the timing of carbohydrate consumption during exercise has been shown to be more effective when ingested every 15 to 20 minutes throughout activity rather than as a single bolus (McConell et al. 1996, Rodriguez et al. 2009).

In regard to fluid intake during exercise, the goal is to prevent dehydration, particularly fluid losses in excess of two percent of body weight. The regimen for fluid replacement should be determined based on individual sweat rate, environmental conditions, opportunities to drink, and the duration and intensity of exercise (Sawka et al. 2007). The American College of Sports Medicine has not established specific general recommendations for fluid replacement during exercise, as these general guides would likely be inappropriate for many situations and could lead to significant under- or over-consumption of fluid, which could have detrimental effects (Sawka et al. 2007).

After Exercise

The significance of the post-exercise meal is determined largely by the length of time until the next exercise bout, as well as the duration and intensity of activity. The purpose of the meal after exercise is to replenish glycogen stores, repair muscle protein, replace fluid and electrolyte losses, and aid in overall recovery (Dunford and Doyle 2012).

The timing of the post-exercise meal in regard to replenishing glycogen stores is of most importance if the next exercise bout will occur in twelve hours or less, however the period immediately following exercise is a time frame when the body is best positioned to restore glycogen stores at the highest rate (Dunford and Doyle 2012). Delaying carbohydrate intake can significantly reduce glycogen synthesis (Ivy 1998). In light of this, it is generally recommended that carbohydrates be consumed within 30 minutes after exercise and that 1.5 grams carbohydrate per kilogram be consumed in the first hour following exercise (Ivy et al. 1998, Dunford and Doyle 2012). In regard to the type of carbohydrate, fructose alone is less effective than either glucose or sucrose (Blom et al. 1987).

Other macronutrient considerations do not necessarily impact the rate of glycogen synthesis, however they may have other benefits. Adding protein as part of a meal after exercise may be beneficial in regard to muscle protein repair (Rodriguez et al. 2007). In order to increase the rate of muscle protein synthesis after exercise, it is requisite to consume protein in the period following exercise (van Loon et al. 2013). In regard to specific amounts of protein and a specific time frame for protein ingestion surrounding exercise, additional research is required in this area (van Loon et al. 2013).

In regard to fluid needs post-exercise, recovery time is once again the key. If recovery time is not limited normal meals, snacks, and water intake should be sufficient to replenish fluid that has been lost. In situations where recovery time is limited, or there is excess dehydration, 1.5 liters of fluid for each kilogram of body weight lost should be consumed (Sawka et al. 2007). Body weight lost can be determined using pre- and post-exercise weighing. It is preferable to drink the recommended amount over time rather than as a larger bolus to assist in rehydration(Wong et al. 1998, Kovacs et al. 2002).

Though post-exercise nutrition recommendations may be difficult to implement due to other demands and factors (sleep due to fatigue, returning to school or work after training, decreased appetite, etc.), this is a critical time to replenish nutrient stores and set up properly for the next bout of exercise (Dunford and Doyle 2012).

Conclusion

In sum, when attempting to meet nutrition needs the timing of eating surrounding exercise is an important consideration. Appropriate meal timing and composition before, during, and after exercise can assist in improving athletic performance. 

By: Jamie Saunders, University of Utah
Jamie Saunders has always been interested in the area of nutrition and wellness. Saunders graduated from Southern Utah University with a Bachelor’s degree in Human Nutrition, and from the University of Utah’s Coordinated Master’s Program in Dietetics, with an emphasis in Sports Dietetics. She is a Registered Dietitian and currently works as the Outpatient Dietitian for the University Health Care’s South Jordan Health Center.

Literature Cited

Blom, P. C., A. T. Hostmark, O. Vaage, K. R. Kardel, and S. Maehlum. 1987. Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis. Med Sci Sports Exerc 19:491-496.

Coggan, A. R., and E. F. Coyle. 1991. Carbohydrate ingestion during prolonged exercise: Effects on metabolism and performance. Exerc Sport Sci Rev 19:1-40.

Currell, K.,  and A. E. Jeukendrup. 2008. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sport Exerc 40:275-281.

Dunford, M., and J. A. Doyle. 2012. Nutrition for sport and exercise 2nd edition. Wadsworth, Belmont, California, USA.

Gropper, S. S., J. L. Smith, and J. L. Grogg. 2008. Advanced Nutrition and Human Metabolism, 5th Edition. Thompson Wadsworth, Belmont, California, USA.

Ivy, J. L. 1998. Glycogen resynthesis after exercise: Effect of carbohydrate intake. International Journal of Sports Medicine 19(Suppl.2),S142-S145.

Ivy, J. L., A. L. Katz, C. L. Cutler, W. M. Sherman, and E. F. Coyle. 1988. Muscle glycogen synthesis after exercise: Effect of time of carbohydrate ingestion. J Appl Physiol 64:1480-1485.

Jentjens R. L., C. Cale, C. Gutch, and A. E. Jeukendrup. 2003. Effects of pre-exercise ingestion of differing amounts of carbohydrate on subsequent metabolism and cycling performance. European Journal of Applied Physiology. 88:444-452.

Jeukendrup, A., F. Grouns, A. J. Wagenmakers, and W. H. Saris. 1997. Carbohydrate-electrolyte feedings improve1 h time trial cycling performance. Int J Sports Med 18:125-129.

Kovacs, E. M., R. M. Schmahl, J. M. Senden, and F. Brouns. 2002. Effect of high and low rates of fluid intake on post-exercise rehydration. Int J Sport Nutr Exerc Metab 12:14-23.

Maffucci, D. M., and R. G. McMurray. 2000. Towards optimizing the timing of the pre-exercise meal. International Journal of Sport Nutrition and Exercise Metabolism 10(2):103-113.

Mahan, L. K., and S. Escott-Stump. 2008. Krause’s food and nutrition therapy 12th edition. Saunders Elsevier, St. Louis, Missouri, USA.

McConell, G., K. Kloot, and M. Hargreaves. 1996. Effect of timing of carbohydrate ingestion on endurance exercise performance. Med Sci Sports Exerc 28:1300-1304.

Moseley L., G. I. Lancaster, and A. E. Jeukendrup. 2003. Effects of timing of pre-exercise ingestion of carbohydrate on subsequent metabolism and cycling performance. European Journal of Applied Physiology. 88:453-458.

Nicholas, C. W., C. Williams, H. K. Lakomy, G. Phillips, and A. Nowitz. 1995. Influence of ingesting a carbohydrate-electrolyte solution on endurance capacity during intermittent, high-intensity shuttle running. J Sports Sci 13:283-290.

Nutrition Booklet: Nutrition for Athletes- A practical guide to eating for health and performance. International Olympic Committee Documents. 2009. 2:36. Based on: Maughan RG, Shirreffs SM. IOC Consensus Conference on Nutrition in Sport, 25–27 October 2010, International Olympic Committee, Lausanne, Switzerland. Journal of Sports Sciences. 2011;29:sup1.

Rodriguez, N. R., L. M. Vislocky, and P. C. Gaine. 2007. Dietary protein, endurance, exercise, and human skeletal-muscle protein turnover. Curr Opin Clin Nutr Metab Care 10:40-45.

Rodriquez, N. R., N. M. DiMarco, L. Langley, American Dietetic Association, Dietitians of Canada, & the American College of Sports Medicine. 2009. Nutrition and athletic performance. Journal of the American Dietetic Association. 109(3): 509-527.

Sawka, M. N., L. M. Burke, E. R. Eichner, R. J. Maughan, S. J. Montain, and N. S. Stachenfeld. 2007. American college of sports medicine position stand: Exercise and fluid replacement. Medicine and Science in Sports and Exercise 39:377-390.

Sugiura K., and K. Kobayashi. 1998. Effect of carbohydrate ingestion on sprint performance following continuous and intermittent exercise. Med Sci Sports Exerc 30:1624-1630.

van Loon, L. J. C., T. D. Tipton KD, and L. J. C. van Loon (eds). 2013. Role of dietary protein in post-exercise muscle reconditioning. Nutritional Coaching Strategy to Modulate Training Efficiency. Nestlé Nutr Inst Workshop Ser. Nestec Ltd. Vevey/S. Karger AG Basel 75:73-83.

Wong, S. H., C. Williams, M. Simpson, and T. Ogaki. 1998. Influence of fluid intake pattern on short-term recovery from prolonged, submaximal running and subsequent exercise capacity. J. Sports Sci 16:143-152.

 

Putting Protein in Its Place

newfoodpyramid_largeProtein powders, bars, and drinks are often touted as the key to enhancing muscle growth, increasing energy, and losing excess body fat. Nutrition science indicates that excess protein intake can cause a decrease in the intake of other essential macronutrients. It can also saturate the body’s protein supply and result in depleted calcium stores, adversely affected kidney function, and damage to other critical systems of the body, including the cardiovascular system. Scientists recommend meeting the majority of nutritional needs from a nutrient-rich diet that balances the intake of carbohydrates, fats, and protein.

Learn the basics of how protein affects your performance or read the more technical explanation.

Articles by Jamie Saunders

How Much Do Genes Affect Your Athletic Potential? (Basic)

DNA-databaseGenes are heritable units, made of a sequence of deoxyribonucleic acid (DNA) contained in every cell of your body. They act as codes to produce proteins, and they play a major role in determining an individual’s predisposition toward athleticism. We all have two copies of each gene, one inherited from our dad and the other from our mom. Research has found that an athlete’s genes may determine 20-80% of his/her performance.

In 2003, a group of scientists from Australia demonstrated that ATCN-3 gene is closely related to athletic performance. ATCN-3 gene produces the protein α-actinin-3 expressed in fast-twitch muscle fibers and is responsible for generating force for high-velocity movement. Two alleles (or variants) of ACTN-3 have been found – the R allele and the X allele. Scientists have found that power athletes tend to have the R allele, while endurance athletes tend to have the X allele.

Another potential ‘sports’ gene with distinct allelic drifts between power and endurance athletes is the ACE gene. ACE activates a hormone angiotensin that regulates constriction of blood vessels, which in turn, controls the rate of blood flow through the circulatory system of your body.  Thus, ACE activity regulates blood pressure and has an effect on cardiac health. ACE also helps retain salt-water in your body that allows cells to stay healthy and metabolize better to produce lots of energy.

Although training and exercise contribute to athletic excellence, genetic predisposition also steers one’s chance towards being the star athlete. Some national team coaches even think it is beneficial to have genetic testing done on the candidates during selection of team members. It may also be beneficial for athletes to have a basic knowledge of their genes, so that they know how to customize their diet or training to promote better health or performance.

Despite advances in the field of genetics, it is not wise to consider one’s athletic abilities to be dependent on only the variations of a single or a couple of genes. The way our physiology is maintained in response to a network of genes and genetic pathways is far more complex than we can imagine. Gene expression is an entire field of study that investigates all those factors that help the expression of a gene to produce the functional protein. There are instances where you have the correct gene variant on your DNA strand, but it does not get expressed. Studies of the ATCN3 gene in a famous Olympic long jumper show that he has no copies of the R variant, but still he is the star. There are lots of environmental factors like nutrition, coaching, careful planning and a disciplined lifestyle that play a major role in athletic ability.

By: Riddhita Chakraborty, University of Utah 

Learn the technical details of how genetics affect athletic potential.

Putting Protein in its Place (Basic)

newfoodpyramid_largeThe three macronutrients- carbohydrate, protein, and fat- tend to rotate through periods of time in the sports nutrition spotlight. Each of these nutrients performs numerous important functions in the body, and all are required in the diet of athletes. Of these nutrients, protein is often promoted as the most important in relation to athletes’ requirements. In fact, the Greek word proteos, from which the term protein is derived, translates to mean “primary” or “taking first place”.  In order to put protein in its proper place in sports nutrition, a look at the current research and recommendations is needed.

Protein has several important functions in the body, such as transporting nutrients and oxygen in the blood. Protein also plays a role in tissue growth and repair, the immune system, fluid balance, wound healing, and many chemical reactions in the body. These functions are unique to protein. Protein can also provide energy for the body; however the body prefers to use carbohydrates and fat for energy.

Athletes need to consume enough protein to meet their needs. It is recommended that protein provide 10% to 35% of an individual’s total calories. Another form of protein recommendations is based on an individual’s body weight. These recommendations are shown in Table 1, and are usually given in ranges. With each of these ranges, athletes exercising longer and harder should aim for the upper end of the range, while athletes exercising shorter and at lower intensities should aim for the lower end of the range. Table 2 shows appropriate protein requirements per day according to body weight and various protein recommendation levels.

Although many athletes believe they need protein supplements to meet their protein needs, most athletes can get enough protein simply by eating a healthy diet. Foods rich in protein include meat, poultry, fish, dairy products, eggs, beans, nuts, and some grains. Because protein is readily available in many foods, protein powders are generally unnecessary for athletes. Protein bars and protein drinks may be a convenient alternative in certain situations, however obtaining protein from food sources is always the recommended approach.

Many athletes believe they need excess amounts of protein to help them build muscle. In fact, no benefit has been demonstrated for protein intakes above 2.0 grams per kilogram, and there are several possible negative effects to bone, kidney, and cardiovascular health with excess protein intake. Eating extra protein also likely means that the athlete is not getting enough carbohydrates and fat. All three of these nutrients are important for athletes, and all are needed for athletes to perform at their best. If any of the three represent a disproportionately high amount in the body, the athlete may not be getting enough of the other two. Thus, it is in the appropriate balance of the three macronutrients that athletes can maximize their performance.

Table 1. Daily protein recommendations in grams per kilogram body weight by population type.

Population

Protein Recommendations

General Population

0.8 grams per kilogram body weight

Recreational Athlete

0.8-1.0 grams per kilogram body weight

Endurance Athletes

1.2-1.4 grams per kilogram body weight

Ultra-Endurance Athletes

1.2-2.0 grams per kilogram body weight

Strength Athletes

1.2-1.7 grams per kilogram body weight

 

Table 2.  Daily protein recommendations in grams according to body weight and varying protein recommendation levels.

0.8 g/kg

1.0 g/kg

1.2 g/kg

1.4 g/kg

1.6 g/kg

2.0 g/kg

125 lbs.

45 g pro

57 g pro

68 g pro

80 g pro

91 g pro

114 g pro

150 lbs.

55 g pro

68 g pro

82 g pro

96 g pro

109 g pro

136 g pro

175 lbs.

64 g pro

80 g pro

95 g pro

111 g pro

127 g pro

159 g pro

200 lbs.

73 g pro

91 g pro

109 g pro

127 g pro

145 g pro

182 g pro

225 lbs.

82 g pro

102 g pro

123 g pro

143 g pro

164 g pro

205 g pro

Learn more technical details about protein.

By: Jamie Saunders, University of Utah
Jamie Saunders has always been interested in the area of nutrition and wellness. Saunders graduated from Southern Utah University with a Bachelor’s degree in Human Nutrition, and from the University of Utah’s Coordinated Master’s Program in Dietetics, with an emphasis in Sports Dietetics. She is a Registered Dietitian and currently works as the Outpatient Dietitian for the University Health Care’s South Jordan Health Center. 

 

Putting Protein in Its Place (Technical)

The three macronutrients- carbohydrate, protein, and fat- tend to rotate through periods of time in the sports nutrition spotlight. Each of these nutrients performs numerous important functions in the body, and all are required in the diet of athletes. Of these nutrients, protein is often touted as the most important in relation to athletes’ requirements. In fact, the Greek word proteos, from which the term protein is derived, translates to mean “primary” or “taking first place” (Gropper et al. 2008).  In order to put protein in its proper place in sports nutrition, an examination of the current research literature and recommendations is warranted.

The basic units of proteins are amino acids. There are twenty different amino acids, which connect by peptide bonds in varying combinations and lengths, to form polypeptides (Albert et al. 2002). Proteins are organized into primary, secondary, tertiary, and quaternary levels of structure, with each subsequent level becoming more complex in nature. The structure of protein is important because the functional role of protein is determined by its organization and structure (Gropper et al. 2008).

Proteins in the body function as catalysts, enzymes, hormone messengers, and transporters of nutrients and oxygen in the blood (Gropper et al. 2008).Protein is involved in the synthesis, maintenance, growth, and repair of tissue (Zieve et al. 2011). Protein also plays a role in the immune system as it is involved in the formation of enzymes, hormones, and antibodies. Protein can act as a buffer in the body, and it assists in the maintenance of fluid, electrolyte, and acid-base balance. Another function of protein is the role it plays in blood clotting, and therefore wound healing. Lastly, protein plays a role in the provision of energy. More precisely, one gram of protein provides four calories of energy (Gropper et al. 2008).

A review of the listed functions of protein reveals the importance of this macronutrient in the realm of athletics. Another important note is that aside from the function of providing energy, all of the functions discussed are unique to protein, meaning carbohydrates and fat cannot carry out these functions (Gropper et al. 2008). Thus, the necessity of protein is certain; however, it is essential to determine how much of this nutrient is required in order to assure the proper functioning of these roles in the body.

newfoodpyramid_largeThe Recommended Dietary Allowance (RDA) for protein is 0.8 grams of protein per kilogram of body weight, and this recommendation is defined as the average daily amount of protein sufficient to meet the nutrient needs of approximately 97% to 98% of healthy individuals. The Acceptable Macronutrient Distribution Range demonstrates that protein should provide 10% to 35% of total energy (Otten et al. 2006). Both of these recommendations are geared toward the general healthy population, and a topic of popular debate is to what extent athletes require greater than this general recommendation for protein (Fuhrman and Ferrerl 2010).

According to a Joint Position Stand of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine, athletes have varying levels of protein needs depending on the type, duration, and intensity of exercise (Rodriguez et al. 2009). For recreational athletes, protein needs range from 0.8 to 1.0 grams per kilogram body weight per day. For endurance athletes, the recommendation is 1.2 to 1.4 grams per kilogram of body weight, with the needs of ultra endurance athletes ranging from 1.2 to 2.0 grams per kilogram of body weight. Strength athletes require approximately 1.2 to 1.7 grams of protein per kilogram of body weight (Rodriguez et al. 2009). With each of these ranges, athletes participating at higher intensities or longer durations within the particular sport type will have requirements toward the upper end of the range, while athletes performing at lower intensities or shorter durations should meet their protein needs if they follow the recommendations given for the lower end of the range (Dunford and Doyle 2012). Table 1 shows appropriate protein requirements per day according to body weight and various protein recommendation levels.

Table 1. Daily protein recommendations in grams according to body weight and varying protein recommendation levels.

0.8 g/kg

1.0 g/kg

1.2 g/kg

1.4 g/kg

1.6 g/kg

2.0 g/kg

125 lbs.

45 g pro

57 g pro

68 g pro

80 g pro

91 g pro

114 g pro

150 lbs.

55 g pro

68 g pro

82 g pro

96 g pro

109 g pro

136 g pro

175 lbs.

64 g pro

80 g pro

95 g pro

111 g pro

127 g pro

159 g pro

200 lbs.

73 g pro

91 g pro

109 g pro

127 g pro

145 g pro

182 g pro

225 lbs.

82 g pro

102 g pro

123 g pro

143 g pro

164 g pro

205 g pro

 

Numerous research endeavors were examined to determine the protein recommendation ranges for athletes, and these levels of protein intake are thought to allow sufficient protein amounts for the body to perform its essential roles (Otten et al. 2006). The  numerical recommendations must be translated into actual food intake. Protein is found in a wide variety of foods, including both animal and plant sources. Animal sources include meat, poultry, fish, dairy products (milk, yogurt, cheese, etc.), and eggs. Plant sources of protein include beans, lentils, legumes, nuts, nut butters, seeds, some grains, and certain vegetables (Zieve et al. 2011).

Competitive athletes involved in heavy training commonly believe they cannot meet their protein requirements through food sources alone. Such athletes frequently turn to protein supplements, which come in the form of protein powders, protein bars, and protein drink or shake options. Popular protein bars range from approximately 8 to 20 grams of protein per bar, and protein drink or shake products (premixed or powder) range from about 4 to 50 grams of protein per serving (High protein drinks 2009, Protein bars 2009). Such protein levels can easily be met by consuming regular foods, such as meat. One three-ounce serving of beef provides 30 grams of protein, a similar serving of chicken or turkey provides 26 grams of protein, and three ounces of fish provides 20 grams of protein (Dunford and Doyle 2012). In reality, most individuals consume larger portions of meat, poultry, and fish than three ounces, and therefore may easily get double or more the amount of protein listed. Other protein sources such as dairy products and beans typically provide about 8 grams of protein per serving.  Nuts, such as almonds or peanuts, provide 32 to 40 grams of protein per cup (Dunford and Doyle 2012). As is demonstrated by these examples, athletes should generally not have a difficulty meeting their protein needs through food sources alone.

A few exceptions should be noted, such as in the case of athletes who are not consuming sufficient overall calories, and therefore likely have inadequate protein intakes. In certain cases, consuming adequate protein may be a concern for vegetarian or vegan athletes (Association, Dietitians of Canada 2003). However, it is possible to obtain sufficient protein from a plant-based diet. Thus, protein powders are generally unnecessary for athletes (Mahan and Escott-Stump 2008). Protein bars and protein drinks may be a convenient alternative in certain cases of sport nutrition; however, obtaining needed protein from food sources is always the recommended approach.

Most athletes are able to meet their protein requirements quite easily if they are eating sufficient calories. A common notion is the idea that excess amounts of protein must be consumed in order to assist in muscle gains (Maughan and Shirreffs 2012). In fact, no benefit has been demonstrated for protein intakes above 2.0 grams per kilogram body weight, and there are several possible negative effects with excess protein intake. These include a potentially negative effect on calcium stores, bone health, kidney function in individuals with impaired renal function, and cardiovascular health (Frank et al. 2009).

When considering issues related to excess protein, it is illuminating to examine the processes involved in hypertrophy and net protein balance. The process of hypertrophy, or muscle growth, requires a positive net protein balance (NPB). NPB is comprised of muscle protein synthesis and muscle protein breakdown. If the rate of synthesis exceeds that of breakdown, positive NPB will result, thereby leading to hypertrophy (Phillips and van Loon 2011). As protein intake plays a key role in promoting muscle protein synthesis, many athletes erroneously believe that as their protein intake increases, their muscle protein synthesis increases linearly, indefinitely.  This, however, is not the case. Excess protein will not continue to promote protein synthesis, but rather will be used as a substrate for the process of oxidative metabolism (Frank et al. 2009). As was discussed earlier, protein has numerous unique roles. Thus it is advantageous for protein to be used for executing these roles, rather than acting as an energy substrate- a role filled far better by carbohydrates and fat. Along these lines, if protein is in excess, it follows that fat, carbohydrate, or both are consequently lessened in the diet (Gibala 2007). This displacement of other macronutrients by protein points to another concern with excess protein consumption, as fat and carbohydrates fulfill numerous important functions in the body.

Carbohydrates are the preferred energy source for the body, and they are a required energy source for certain tissues such as the brain, white blood cells, and red blood cells (Dunford and Doyle 2012). Carbohydrates also provide numerous essential vitamins and minerals. If sufficient carbohydrates are consumed, they also provide a protein-sparing effect, in that carbohydrates will be used for energy production rather than protein being used for energy through the process of gluconeogenesis (Gropper et al. 2008). The current recommendations for daily carbohydrate intake are 3 to 5 grams of carbohydrate per kilogram body weight for low intensity, skill-based sports and 5 to 7 grams of carbohydrate per kilogram body weight for moderate intensity exercise less than one hour in duration. For moderate to high intensity endurance or stop and go sports lasting one to three hours in duration, 6 to 10 grams per kilogram body weight is recommended. For high intensity endurance events lasting greater than four hours, the recommendation is 8 to 12 grams carbohydrate per kilogram body weight (Rodriguez et al. 2009). Carbohydrates are found in numerous foods, including grains, cereal, pasta, rice, milk, yogurt, fruit, and starchy vegetables (Dunford and Doyle 2012).

Fats, or lipids, are also an important source of energy for the body (Gibala 2007). Fat also provides essential fatty acids, which are omega-three and omega-six fatty acids. These fatty acids are not made by the body and therefore must be obtained through the diet (American Dietetic Association, Dietitians of Canada 2007). Fat is also a source of fat soluble vitamins (vitamins A, D, E, and K), and fat is required for the absorption of these vitamins (Mahan and Escott-Stump 2008). A few other key roles include insulation, protection of vital organs, and shock absorption. There is not a recommendation in grams per kilogram of body weight for fat, as there is for protein and carbohydrate. However, the Acceptable Macronutrient Distribution Range for fat is 20 to 35% of total energy, with suggested recommendation of 10 to 25% for endurance athletes and 15 to 20% for strength athletes (Phillips and van Loon 2011). Although many athletes believe fat should be minimized in the diet, it is not recommended that athletes ever go below 10% of total energy from fat (Rodriguez et al. 2009).

The three macronutrients- protein, fat, and carbohydrate- all play key roles in the body, and all are necessary for promoting optimal athletic performance. Consuming any of these nutrients in excess above the recommended amounts frequently leads to displacement of one or both of the other macronutrients. Though protein does perform numerous essential functions required for physical activity processes, carbohydrates and fat are similarly important for the athlete. Thus, it is in the appropriate balance of the three macronutrients, rather than the disproportionate ranking of one above the others, that athletes can maximize their performance.

By: Jamie Saunders, University of Utah
Jamie Saunders has always been interested in the area of nutrition and wellness. Saunders graduated from Southern Utah University with a Bachelor’s degree in Human Nutrition, and from the University of Utah’s Coordinated Master’s Program in Dietetics, with an emphasis in Sports Dietetics. She is a Registered Dietitian and currently works as the Outpatient Dietitian for the University Health Care’s South Jordan Health Center.

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