April 2017 Issue

Fueling for Fitness: Ingredients That Boost Performance
By Jenna A. Bell, PhD, RD
Today's Dietitian
Vol. 19, No. 4, P. 12

Given the demands of vigorous exercise and the impact a few improvements in speed or strength can have on athletic performance, individuals who are physically fit pay close attention to the ingredients in sports nutrition products. Whether it's the RD/mom next door deadlifting 155 lbs in a CrossFit class or a 25-year-old triathlete pushing to shave five minutes off his Ironman time, a variety of nutrients in snack bars, beverages, powders, and pills can help them get the most out of their workout. That said, there are some pre-, mid-, and postworkout sports nutrition products that contain various ingredients with empty promises. However, some do offer real value—especially reputable brands from companies that have studied the ingredients that can improve performance before their products hit the shelves.

In this article, Today's Dietitian reviews the common goals of avid exercisers and athletes and the evidence-based ingredients that could boost performance.

Goal: Maximize Muscle Protein Synthesis

Muscle protein synthesis is necessary for the ongoing growth, repair, and maintenance of its skeletal muscle groups. Thus, it's the main goal for any athlete who wants to maintain or build lean body mass and optimize performance. According to the Nutrition and Athletic Performance Joint Position Statement of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine, protein needs are no longer separate for strength or endurance athletes—guidelines are created in accordance with the type of training and competition, athletic goals, nutrient needs, energy requirements, and food choices.1

For muscle protein synthesis, protein timing is key. The Nutrition and Athletic Performance joint position statement recommends maximizing recovery by consuming roughly 10 g essential amino acids (equal to 15 to 25 g protein) up to two hours after exercise, then follow up with 0.14 g/lb of body weight every three to five hours over multiple meals.1

Whey Protein
Whey protein is a soluble protein, permitting faster digestion. An example of its beneficial effects was seen in a comparison study between whey and casein following exercise. Researchers observed that whey protein provided a more significant initial surge of amino acids, which triggered muscle protein synthesis in the early postexercise period (ie, first three hours).2 Similarly, during a nine-month resistance training trial, untrained subjects who consumed 1 to 1.2 g whey protein per kilogram of body weight per day saw higher gains in lean body mass than soy protein or carbohydrate supplementation.3

Clients can find 100% whey protein in powder form to make shakes, beverages, and sports bars. In addition, clients can consume whey in lesser amounts than most supplements in dairy foods such as cottage cheese and yogurt.

Branched Chain Amino Acids: Leucine, Isoleucine, and Valine
Branched chain amino acid (BCAA) oxidation increases during exercise so there's a reduction in plasma and intracellular leucine concentrations. Dietary protein-containing BCAAs therefore are helpful after exercise to preserve and support gains in lean body mass. BCAA ingestion can increase leucine in the tissues and stimulate the mTOR pathway in muscles to stimulate protein synthesis.4

Clients can find BCAAs in chicken, fish, and eggs, as well as in beans, lentils, nuts, and soy. In sports supplements, BCAAs often are found in powders to make shakes, beverages, and sports bars; they're also found in capsule form.

L-glutamine is a conditionally essential amino acid that's necessary for synthesizing protein, including muscle protein synthesis. In general, normal resting, fasting plasma L-glutamine concentration is 500 to 700 μmol/L. Concentrations tend to be higher in athletes, particularly during muscle contractions. They can reach 20 mmol, 60% of the intramuscular pool, but can be reduced significantly with prolonged, exhaustive exercise.5 Therefore, L-glutamine replenishment may help support muscle protein synthesis for athletes.

Foods that contain the most L-glutamine are beef, chicken, fish, dairy, and eggs. Clients can find nonanimal sources of L-glutamine in beans, beets, cabbage, vegetable juices, and fermented foods such as miso and wheat. L-glutamine may be added to sports supplements such as powders, bars, and capsules.

Goal: Increase Muscle Mass

Beta-Hydroxy Beta-Methylbutyrate
The amino acid metabolite beta-hydroxy beta-methylbutyrate (HMB) helps protect against excessive muscle protein breakdown and increase muscle mass with exercise. HMB investigations and the position statement from the International Society of Sports Nutrition state that HMB reduces muscle protein breakdown in humans and increases muscle mass when subjects are appropriately resistance trained.6-8

It's pretty tough for clients to eat enough HMB from food. It's found in small quantities in grapefruit, alfalfa, and catfish. Sports supplements add HMB to powders, bars, and capsules.

Goal: Increase Power and Strength

Creatine Monohydrate
Creatine isn't new, and most RDs and athletes are familiar with its use. That's because creatine has become one of the most extensively studied and scientifically validated nutritional ergogenic aids for athletes. The rationale for taking creatine is to boost the quality and volume of work performed during exercise. By energizing high-intensity, short-duration exercise, power output can be enhanced. This, theoretically, can further strength gains.9

Athletic clients can find creatine in animal products, but for performance doses closer to 20 to 30 g, they can find it in powder form for beverages and shakes.

Goal: Increase Stamina

The objective of consuming beta-alanine (BA) is to increase the synthesis and storage of carnosine in the muscle. Carnosine is a dipeptide of BA and histidine and has been shown to have significant buffering capacity. Its ability to buffer muscle pH is thought to thwart fatigue that occurs when acidosis develops.10 Without the fatigue, there's a greater capacity for individuals to do more exercise or physical work.

Clients can find BA in beef, pork, poultry, chicken broth, and fish. It's added to sports supplement powders and found in capsules.

Goal: Increase Blood Flow

Beetroot Extract: Nitric Oxide
Because of the role nitric oxide (NO) plays in delivering blood, oxygen, and nutrients to exercising muscles, researchers have shown great interest for many years in developing sports nutrition strategies that could help increase NO production and blood flow. Several studies have discovered that beetroot extract (highly concentrated beetroot juice) is a rich source of nitrates that are converted to NO in the body. While more studies are warranted, emerging evidence suggests that beetroot juice supplementation (containing 300 to 500 mg nitrates) may improve exercise performance for athletes.11-13

Clients can find beetroot extract in capsules, powders, dissolvable tablets, and beverages.

Guiding Athletes Through the Supplement Aisle
Despite the many sports nutrition supplements that can help boost athletic performance, many dietitians still take a food-first approach. However, knowing there are supplements that can help manage the demands of exercise and optimize performance can help guide counseling sessions and clients through the aisles of product options.

Suggestions on how to counsel athletes about supplements include the following:

• When choosing a supplement, make sure the label states that it has been tested for quality and safety by outside organizations such as NSF International and/or bears the Informed-Choice logo.

• If your client is working with a trainer, coach, or sports physician, recommend they inform everyone about all the supplements they're taking.

• Make sure supplement choices are acceptable to all governing bodies for their sport, whether at the collegiate, professional, or Olympic level.

• Be realistic with recommendations. Consider convenience, portability, and preferences when giving any advice.

• Remind clients that they can't out-train or out-supplement a deficient eating pattern. Dietary supplements should complement a well-balanced training diet, not take precedence over it.

— Jenna A. Bell, PhD, RD, is the senior vice president, director of Food & Wellness at Pollock Communications. She has worked with several of the top sports nutrition companies and is a physically fit RD and mom with a PhD in exercise physiology who tries to practice what she writes, presents, and counsels.

1. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and athletic performance., Academy of Nutrition and Dietetics, and Dietitians of Canada. Med Sci Sports Exerc. 2016;48(3):543-568.

2. Reitelseder S, Agergaard J, Doessing S, et al. Whey and casein labeled with L-[1-13-C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion. Am J Physiol Endocrinol Metab. 2011;300(1):E231-E242.

3. Volek JS, Volk BM, Gómez AL, et al. Whey protein supplementation during resistance training augments lean body mass. J Am Coll Nutr. 2013;32(2):122-135.

4. Norton LE, Layman DK. Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise. J Nutr. 2006;136(2):533S-537S.

5. Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol Occup Physiol. 1996;73(5):488-490.

6. Gallagher PM, Carrithers JA, Godard MP, Schulze KE, Trappe SW. Beta-hydroxy-beta-methylbutyrate ingestion, part I: effects on strength and fat free mass. Med Sci Sports Exerc. 2000;32(12):2109-2115.

7. Wilson JM, Lowery RP, Joy JM, et al. The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study. Eur J Appl Physiol. 2014;114(6):1217-1227.

8. Wilson JM, Fitschen PJ, Campbell B, et al. International Society of Sports Nutrition position stand: beta-hydroxy-beta-methylbutyrate (HMB). J Int Soc Sports Nutr. 2013;10(1):6.

9. Bufort TW, Kreider RB, Stout JR, et al. International Society of Sports Nutrition position stand: creatine supplementation and exercise. J Int Soc Sports Nutr. 2007;4:6.

10. Begum G, Cunliffe A, Leveritt M. Physiological role of carnosine in contracting muscle. Int J Sport Nutr Exerc Metab. 2005;15(5):493-514.

11. Cermak NM, Gibala MJ, van Loon LJ. Nitrate supplementation's improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab. 2012;22(1):64-71.

12. Lansley KE, Winyard PG, Bailey SJ, et al. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011;43(6):1125-1131.

13. Wylie LJ, Kelly J, Bailey SJ, et al. Beetroot juice and exercise: pharmacodynamic and dose-response relationships. J Appl Physiol (1985). 2013;115(3):325-336.