PT on the Net Research

Nutrition for Sport Performance: Part 1

The widespread use of performance enhancing drugs (PEDs) has tarnished the careers of successful athletes in almost every major sport. There is no question the temptation to administer exogenous hormones such as growth hormone (GH), testosterone (Te), insulin-like growth factor-I (IGF-I), anabolic-androgenic steroids (AAS), and insulin is quite strong as they can dramatically improve muscle mass, strength, recovery, healing, and body composition, among other benefits. There are, however, serious health risks and side effects if these drugs are abused, plus the risk of getting caught by a governing sport agency, which could suspend or potentially impose a ban on further participation.

The purpose of this article is to analyze current literature to determine the best-proven, nutritional strategies that can effectively increase the body’s natural production of these hormones, or that can at least facilitate similar changes in body composition. If athletes can learn safe, legal, and effective ways to improve their performance, it might reduce the temptation to use PED’s and avoid potential damage to their health and careers. 

Part 1 of this article series will focus on how to optimize the hormonal response to a training program for athletes. This article will analyze current literature to determine the best nutritional strategies that can effectively, safely, and legally increase the body’s natural production of anabolic hormones, and discuss the importance of nutritional timing for athletes in regard to enhancing body composition for improved sport performance. Nutrition for Sport Performance: Part 2 will discuss specific foods and supplementation that have shown beneficial to optimally enhance body composition.

Learning Objectives:

  1. Determine the hormones responsible for maximizing training results.
  2. Discuss dietary strategies for timing and proper consumption of carbohydrate ingestion.
  3. Discuss nutrient timing strategies for pre-workout and during recovery that can directly or indirectly increase protein synthesis, decrease fat mass, or influence the mechanisms of both.

Optimizing the Hormonal Response to Training

Exercise is any athlete's greatest weapon to trigger the endocrine system to respond and release anabolic hormones responsible for improving performance. The next important weapon is an athlete’s nutritional strategy to take full advantage of these increased anabolic conditions. Anabolic hormones such as testosterone (Te), growth hormone (GH), insulin-like growth factor-I (IGF-I), and insulin are all secreted throughout the day in different amounts and significantly increase during and after exercise. The timing of nutrient consumption is just as important as what those nutrients consist of in terms of improving recovery and hypertrophy. Depending on what is consumed and when, there can be dramatic differences in the catabolic environment post-exercise and when the shift to anabolism begins; as well as how long the anabolic environment lasts.  Many individuals are tempted to use exogenous hormones to further enhance muscle growth, recovery, healing, and fat oxidation. The following sections seek to describe safe, nutritional strategies to gain the most out of the body’s natural hormonal release and safely enhance muscle mass, recovery, healing, and fat oxidation without the potential health risks of abusing drugs. 

Dietary Strategies

When it comes to building muscle and maintaining an optimal body composition, dietary carbohydrates must be used intelligently. Insulin is one of the most anabolic hormones in the body. Te and GH trigger muscle growth indirectly through target cell receptors, whereas insulin directly causes growth because it is a storage hormone; it likes to put things (glucose & amino acids) into storage units (muscle, liver, & fat cells). High blood sugar is a toxic environment, therefore when blood glucose levels rise, insulin gets released from the pancreas causing a hypoglycemic action by which the first option is to increase muscle glycogen synthesis, next followed by liver glycogen synthesis, and finally the last option is storing excess glucose in fat cells in the form of triglycerides.

Consequently, insulin can potentially be a beneficial hormone for improving body composition if used correctly because when released post-exercise (due to a rise in blood sugar from ingesting carbohydrates), the response would be to send nutrients to the muscle cells. However, insulin is the main hormone responsible for growing fat cells too, so throughout the rest of the day (when muscle glycogen synthesis is not a main concern), insulin levels must be managed for optimal body composition, and the way to manage insulin levels is to limit simple-carbohydrate intake and increase protein and fat intake - as they do not cause the same spike in blood sugar, while creating more of an anabolic response.

One study comparing high protein supplementation with a calorically-equivalent carbohydrate supplement during a strength and conditioning program for six months found the protein group noticed a greater increase in serum IGF-I concentrations along with greater increases in markers for bone turnover; potentially helping to increase bone density (Ballard, Clapper, Specker, Binkley, & Vukovich, 2005). Moreover, reducing carbohydrate intake improves weight loss by increasing the body’s efficiency in burning fatty acids for energy, and also reduces serum triglycerides; hence less fat storage will occur (Parks, 2001) along with improving countless risk factors for cardiovascular disease (Westman, Feinman, Mavropoulos, Vernon, Volek, Wortman, & Phinney, 2007).

Nutrient timing


In order to grow muscle, the body needs plenty of available amino acids to build with. For example, ingesting a pre-workout drink that contains amino acids, creatine, and caffeine effectively improves the quality of high-intensity workouts by increasing work output, time to exhaustion, and subsequently body composition (Smith, Fukuda, Kendall, & Stout, 2010). Consuming amino acids in a rested state has been shown to effectively increase protein synthesis, but when consumed prior to exercise, it can help to prevent the typical catabolic effects of exercise by increasing muscle anabolism.

When comparing the difference in timing with a 6g-amino acid/35g-carbohydrate supplement on the effectiveness of protein synthesis, it was determined that pre-workout supplementation actually increased protein synthesis (during and after the workout) better than post-workout supplementation (Tipton, Rasmussen, Miller, Wolf, Owens-Stovall, Petrini, & Wolfe, 2001). The researchers believed consuming the pre-workout supplement increased the availability of amino acids, therefore when blood flow was increased during the workout, overall delivery of amino acids into the muscle cells improved, offering the maximal stimulation of muscle protein synthesis. 


After intense exercise, the rates of both protein synthesis and protein breakdown are simultaneously increased. The ingestion of amino acids greatly increases amino acid transport into the muscles, likely due to increased blood circulation. This maximally enhances muscle anabolism by increasing protein synthesis and decreasing protein breakdown (Biolo, Tipton, Klein, & Wolfe, 1997). If nothing is consumed post-exercise, net protein balance will decrease due to the inhibition of protein synthesis because nothing is available to rebuild with, as the first 48 hours post-exercise is critical for building muscle (Fielding & Parkington, 2002). Ingestion of essential amino acids (EAA) immediately after exercise can increase the rate of protein synthesis by three-fold compared to at-rest, whereas ingestion six hours post-exercise actually results in a net protein loss (Børsheim, Tipton, Wolf, & Wolfe, 2002; Fielding & Parkington, 2002).  Immediate ingestion also stimulates an inhibitory effect on protein breakdown that results in a net gain in protein balance (Fielding & Parkington, 2002).  Intakes of a small amount (6g EAA) resulted in a transient increase in protein synthesis, with a dose response in which more EAA ingestion will result in increased synthesis up to a maximum effective dose of ~21g EAA. It does not appear necessary to include non-essential amino acids (NEAA) in a post exercise recovery meal because the inclusion of additional NEAA did not increase protein synthesis any greater than the EAA alone (Børsheim, Tipton, Wolf, & Wolfe, 2002; Tipton, Ferrando, Phillips, Doyle, & Wolfe, 1999). 

The post-exercise period is one of the best opportunities to take advantage of the anabolic effects of insulin on muscle. Børsheim, Tipton, Wolf, & Wolfe, (2002) found the inclusion of 35g of carbohydrates with EAA post-exercise significantly reduced protein breakdown, while also working to increase muscle glycogen synthesis, with available EAA as a necessary component to stimulate those effects (Biolo, Williams, Fleming, & Wolfe, 1999; Fielding & Parkington, 2002). Using a combination of EAA and carbohydrates during recovery has also been shown to elevate growth hormone concentrations up to six hours post-exercise, which is significantly longer than protein ingestion alone (Chandler, Byrne, Patterson, & Ivy, 1994). 

Therefore, to achieve optimal increases in muscle growth, it is recommended that EAA must be consumed before, during, or immediately after exercise to maximally stimulate protein synthesis and inhibit protein breakdown, along with ample carbohydrate ingestion post-workout to create an insulin response that also helps blunt protein breakdown, while replenishing necessary muscle glycogen and stimulating growth hormone elevations hours after exercise.

Nocturnal Feedings

For optimal growth of muscle tissue, it is important to consistently keep amino acids available to the muscles. Depending on the training goal, nocturnal feedings might be necessary to optimize a period typically neglected when it comes to building or replenishing muscle. In a study which looked at protein synthesis after different lengths of fasting in rats (12 hours vs. 36 hours), protein synthesis was reduced in the 12 hour fasted state when compared to a fed state, and was significantly more reduced in all muscles after the 36 hour fasted state (Baillie & Garlick, 1991). It is important to note, however, that insulin sensitivity increases with the length of the fast, so if weight management is a concern, fasting overnight is beneficial; but not if muscle growth is the main objective. The longer an athlete fasts, the less muscle building will occur. Every athlete wishes to prevent protein degradation, but depending on the type of exercise performed, endurance athletes have a tougher battle against muscle catabolism than typical strength or sprint athletes. 

When looking at the hormonal release patterns during sleep of two different endurance cycling groups after performing 40 km or 120 km, the longer and more intense endurance exercise resulted in considerably less Te levels throughout the night. During normal sleep patterns, GH is typically higher and cortisol is typically lower in the first half of sleep, and vice versa during the second half of sleep. This study found the longer, more intense exercise group experienced a reverse pattern of the GH and cortisol concentrations (Kern, Perras, Wodick, Fehm, & Born, 1995). Since it is known that Te and GH play a synergistic role in building muscle (Sattler, Castaneda-Sceppa, Binder, Schroeder, Wang,  Bhasin, & Azen, 2009), the opportunity to grow muscle is shunted in endurance athletes during the first half of sleep. If these endurance athletes are attempting to perform on consecutive days, the hormonal sleep patterns can certainly throw a wrench in protein metabolism. In trained weight lifters, for example, the nocturnal GH and cortisol levels were not affected by an intense bout of resistance exercise, whereas Te steadily increased above control levels throughout the subsequent night’s sleep (McMurray, Eubank, & Hackney, 1995). This may partly explain why it is easier for strength athletes to maintain and grow muscle mass while endurance athletes constantly struggle to maintain muscle mass.  Therefore, nutritional strategies which include protein or EAA prior to bedtime and mid-sleep might be necessary to continue the promotion of protein synthesis for those athletes who compete at high intensities on consecutive days or who are attempting to optimally grow muscle mass. 


The endocrine system controls the physiological functions in the body through the interdependent actions of different hormones and enzymes. Many individuals are tempted to administer exogenous hormones in attempt to grow muscle, improve body composition, and help post-exercise recovery. This article used current literature to determine proven, nutritional strategies that effectively increase the body’s natural production of the hormones responsible for building muscle and decreasing fat, as well as improving exercise recovery.

When it comes to improving body composition for athletes and subsequently exercise performance, the main take-away points are as follows: (1) Timing of food consumptions is just as important as what is consumed, (2) Ingesting amino acids and carbohydrates before, during and after workouts helps to minimize protein breakdown, while maximizing protein synthesis rates. 

Part 2 of this article series will discuss specific foods that should regularly be consumed to optimize the body’s anabolic hormones; including the addition of supplementation with omega-3’s, vitamin D, and zinc/magnesium to help promote muscle building, fat burning, and improve insulin sensitivity - which all safely improve exercise performance.


Baillie, A. G., & Garlick, P. J., (1991). Responses of protein synthesis in different skeletal muscles to fasting and insulin in rats. American Journal of Physiology, Endocrinology, and Metabolism, 260(6 Pt 1):E891-6.

Ballard, T., Clapper, J., Specker, B., Binkley, T., & Vukovich, M. (2005). Effect of protein supplementation during a 6-mo strength and conditioning program on insulin-like growth factor I and markers of bone turnover in young adults. American Journal Of Clinical Nutrition, 81(6), 1442-1448.

Biolo, G., Tipton, K., Klein, S., & Wolfe, R. (1997). An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein. The American Journal Of Physiology, 273(1 Pt 1), E122-E129.

Biolo, G., Williams, B., Fleming, R., & Wolfe, R. (1999). Insulin action on muscle protein kinetics and amino acid transport during recovery after resistance exercise. Diabetes, 48(5), 949-957.

Børsheim, E., Tipton, K., Wolf, S., & Wolfe, R. (2002). Essential amino acids and muscle protein recovery from resistance exercise. American Journal Of Physiology. Endocrinology And Metabolism, 283(4), E648-E657.

Chandler, R. M., Byrne, H. K., Patterson, J. G., & Ivy, J. L. (1994). Dietary supplements affect the anabolic hormones after weight-training exercise.  Journal of Applied Physiology, 76(2), 839-845.

Fielding, R. A., & Parkington, J. (2002). What Are the Dietary Protein Requirements of Physically Active Individuals? New Evidence on the Effects of Exercise on Protein Utilization During Post-Exercise Recovery. Nutrition In Clinical Care, 5(4), 191-196.

Kern, W., Perras, B., Wodick, R., Fehm, H., & Born, J. (1995). Hormonal secretion during nighttime sleep indicating stress of daytime exercise. Journal Of Applied Physiology, 79(5), 1461-1468.

McMurray, R. G., Eubank, T. K., & Hackney, A. C. (1995). Nocturnal hormonal responses to resistance exercise. European Journal Of Applied Physiology & Occupational Physiology, 72(1/2), 121-126.

Parks, E. J. (2001). Effect of dietary carbohydrate on triglyceride metabolism in humans. Journal Of Nutrition, 131(10), 2772s-2774s.

Sattler, F., Castaneda-Sceppa, C., Binder, E., Schroeder, E., Wang, Y., Bhasin, S., & Azen, S. (2009). Testosterone and growth hormone improve body composition and muscle performance in older men. The Journal Of Clinical Endocrinology And Metabolism, 94(6), 1991-2001.

Smith, A. E., Fukuda, D. H., Kendall, K. L., & Stout, J. R. (2010). The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance. Journal Of The International Society Of Sports Nutrition, 710-20.

Tipton, K., Ferrando, A., Phillips, S., Doyle, D., & Wolfe, R. (1999). Postexercise net protein synthesis in human muscle from orally administered amino acids. The American Journal Of Physiology, 276(4 Pt 1), E628-E634.

Tipton, K., Rasmussen, B., Miller, S., Wolf, S., Owens-Stovall, S., Petrini, B., & Wolfe, R. (2001). Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. American Journal Of Physiology. Endocrinology And Metabolism, 281(2), E197-E206.

Westman, E., Feinman, R., Mavropoulos, J., Vernon, M., Volek, J., Wortman, J., & Phinney, S. (2007). Low-carbohydrate nutrition and metabolism. The American Journal Of Clinical Nutrition, 86(2), 276-284.