Fuel. Pep. Stim. Boost. Jump. Jolt. Perk. All names for energy and the ingredients that promote energy production (or delayed fatigue).  Energy needs are addressed in various stages of workout, but the bottom line is consumers want to feel more energized to meet exercise goals and to be ready for the next workout. Several natural ingredients can help, but each has a specific role or method of either promoting energy production/restoration or delaying fatigue.

In scientific terms, energy is the capacity to do work. Just as there are many types of energy in physical science (potential, kinetic, chemical, etc.), there are many ways the human body makes energy and controls fatigue.

Biochemical Energy

Some dietary ingredients are involved in biochemical energy production.

Inside body cells, energy is stored in the bonds of the molecule adenosine triphosphate (ATP). When ATP is broken down into adenosine diphosphate (ADP) and inorganic phosphate, energy is released.

In the center of the ATP molecule is ribose, a five-carbon carbohydrate either made in the body from glucose or ingested via the diet. Because these internal and external sources of ribose are limited and due to ribose’s structural role in this energy molecule, athletes and other active consumers turn to ribose supplementation for increased energy production.

Specifically, Bioenergy Ribose®, from Bioenergy, helps active adults reproduce ATP more quickly than either sucrose (table sugar) or maltodextrin (sports nutrition industry staple) alone.1 For bodybuilders, Bioenergy Ribose’s energy benefits can contribute to increased bench press strength and total repetitions before muscle failure, compared to dextrose.2

The body uses carbs immediately to make ATP or stores them as glycogen in the muscles and elsewhere. Dextrose is a simple carbohydrate (monosccharide), as are glucose and fructose, and can be used to replenish certain glycogen stores, but complex carbs such as maltodextrin (polysaccharide) are better at restoring muscle glycogen. However, dextrins and glucose are low molecular weight and, when used in an energy beverage, can increase the osmotic pressure. This can cause gastric emptying time to increase, potentially causing nausea and other digestive distresses.

Highly branched cyclic dextrin (HBCD), a type of maltodextrin, has a higher molecular weight and does not increase osmotic pressure or gastric emptying time—other nutrients (e.g., vitamins, minerals and organic acids) can be added to such an HBCD beverage without increasing gastric emptying time. Male swimmers who took HBCD (as Cluster Dextrin®, from Glico Nutrition) performed at optimal output for 70 percent longer than those taking water or glucose, and they had higher plasma glucose levels before swimming intervals, suggesting more sustained energizing glucose than did carbs.3

During bursts of exercise, the body can make ATP quickly from creatine phosphate stored in the muscles—a phosphate is donated to ADP to make ATP.  Known as the phosphagen system, this method of energy production can drive the initial 10 to 12 seconds of intense exercise.

Creatine supplementation has become a popular way for athletes to increase muscle stores of creatine phosphate to provide longer bursts of energy and improve intense exercise performance. In elite athletes, creatine monohydrate, the most popular form, may help preserve muscle power during exercise, while dextrose has a negative effect on power.4

Several other forms of creatine have emerged to address absorption and stability issues. Buffered creatine (Kre-Alkalyn®, from All American Pharmaceutical) was developed as a safer, more stable form. Kre-Alkalyn limits the breakdown of creatine to creatinine before it enters the muscle, according to Jeff Golini, the company’s CEO and executive scientist.

Creatine is also offered chelated with magnesium—this mineral is important for muscle, nerve and bone health. Two weeks of supplementation with CreatineMagnaPower®, from Albion, may increase torque and peak power.5

Yet another form offers the synergistic benefits of energy production of creatine and the improved blood flow associated with nitrates. Patented by Thermolife International, creatine nitrate promises improved absorption and lower dosing, and research has found strength increases and body composition improvements in active males taking creatine nitrate supplied by Nutrabolt Corp.6

Nitrates are popular in sports nutrition for their conversion to nitric oxide (NO), a vasodilator (opens blood vessels) that promotes improved blood flow and better nutrient delivery to the muscles. The conditionally essential amino acid L-Arginine is a precursor to NO and can be found as an ingredient in sports supplement formulas. Supplementation with a newer form of arginine, bonded to silicon (as Nitrosigine®, from Nutrition 21), increases blood arginine and NO levels, resulting in better blood flow to the muscles and brain, and improved muscle and cognitive function.7,8,9

The non-essential amino acid L-citrulline also plays a role in NO and blood flow benefits to athletes and active consumers. In one study, adult males experienced reduced fatigue—both oxidative ATP production and phosphocreatine restoration increased—after taking citrulline combine with malate (ester of malic acid), a component of the citric acid or krebs cycle of ATP production.10 Combined with the potent antioxidant glutathione, citrulline (as Setria®, from Kyowa Hakko) also increases nitrate and NO levels.11

Several other ingredients increase NO. Beetroot may be the most well-known natural source of nitrates in sports nutrition, but amaranth (red spinach) and a combination of grape and apple polyphenols are newer entrants to the botanical NO booster category.

Other dietary ingredients for biochemical energy boosting are tied to advanced processes of making ATP. After the phosphagen system is depleted during the initial bursts of exercise, the body uses glycolysis to turn blood glucose or muscle glycogen into ATP. Initially, glycolysis takes place in an anaerobic environment until the increased oxygen intake reaches the muscles. This “fast" glycolysis produces ATP via enzymatic reactions that also produce pyruvate and hydrogen ions. This only nets a small number of ATPs, but it is a fast way to make energy until the oxygen hits the muscle cells.

Without oxygen, hydrogen ions and lactate can flood the muscles, changing the pH to a state of acidosis, leading to fatigue. Carnosine, a dipeptide made from the amino acids beta alanine and histidine, can buffer these hydrogen ions, removing them from the muscles and staving off fatigue. Studies have demonstrated beta-alanine (as Carnosyn®, from Natural Alternatives International) can increase muscle carnosine levels, inhibit fatigue and increase power and work output in athletes.12,13,14

Delayed fatigue is also a benefit associated with a combination of L-alanine and L-glutamine (as Sustamine®, from Kyowa Hakko).15 Glutamine, a conditionally essential amino acid, helps remove ammonia created in the muscles from amino acid metabolism, and it plays a role in the tricarboxylic acid (TCA) cycle, commonly known as the Krebs cycle.

When oxygen is present, pyruvate leftover from glycolysis is oxidized into coenzyme A (CoA) inside the cell’s inner area, the mitochondria. CoA combines with oxaloacetate to form citric acid, which feeds a series of reduction and oxidation reactions within the TCA or Krebs cycle, producing ATP molecules. At the end of the cycle, oxaloacetate is formed, ready to again combine with CoA from pyruvate/glycolysis to keep the cycle going. Glutamine can be enzymatically converted into α-ketoglutarate, which feeds the TCA or Krebs cycle at a different position than does CoA.

In addition to glucose via glycolysis, dietary fats can be converted into CoA via lipolysis. Fats stored as triglycerides are broken down into glycerol and free fatty acids, which can be oxidized into hydrogen and CoA. To facilitate this process, the fatty acids must be shuttled into the mitochondria, a job performed by carnitine. The skeletal muscles store most of the body’s carnitine (about 95 percent), which can be made in the liver and kidneys or ingested from the diet (e.g., red meat and dairy).

As a sports supplement, carnitine is taken to improve muscle bioenergetics. Healthy males taking a combination of carnitine tartrate (as Carnipure®, from Lonza) and carbohydrates had 11 percent higher work output during exercise than those who took only carbs.16 Long-term supplementation can raise muscle carnitine levels and spare muscle glycogen stores during exercise.

The vitamin-like choline also factors in the use of fats for energy. Present in the body primarily as phospholipids, namely phosphatidylcholine, choline helps transport lipids from the liver, preventing fatty liver and making it available for energy production. Choline is a precursor to acetylcholine, a neurotransmitter that signals muscles to contract.

The TCA or Krebs cycle produces several molecules of NADH and FADH2, which essentially carry electrons from the cycle to the next step in the ATP production process, oxidative phosphorylation. As part of this process, electrons carried by NADH and FADH2—from both the Krebs cycle and glycolysis—go through a chain of redox reactions inside the mitochondria’s inner membrane, producing ATP. Coenzyme Q10 (CoQ10) helps move electrons through the electron transport chain to create ATP.

Acute and chronic CoQ10 supplementation by both athletes and non-athletes can increase muscle and plasma CoQ10 levels, increasing energy production and staving off fatigue during exercise.17

Enzymes employed throughout the processes of making ATP require minerals such as iron, copper and manganese. These processes can generate reactive oxygen species (ROS) that can be harmful to the mitochondria if not scavenged. A combination of minerals from ancient peat and antioxidant polyphenols from apple extract (as elevATP™, from Futureceuticals) addresses these issues. Supplementation with elevATP can increase ATP levels in the blood and muscles, but not plasma, resulting in improved exercise performance, including strength and peak power.18

Limiting Fatigue

Stimulating energy production is an obvious way for athletes to avoid being tired too soon. However, other biochemical approaches delay fatigue.

Cleaning up free radicals resulting from exercise and energy production appears to provide anti-fatigue benefits. Antioxidants in numerous botanical ingredients can help athletes and active consumers preserve energy.

Astaxanthin protects mitochondria from oxidative stress during intense exercise and can reduce muscle fatigue and lactic acid build-up.19,20 The flavonoid quercetin (from apples, onions, grapes, tea, etc.) can increase muscle mitochondria count, improve endurance and delay fatigue.21,22 Compounds from grapes can provide not only antioxidant benefits, but also increase time to exhaustion in recreational athletes.23,24

A new antioxidant ingredient on the market comes from French oak wood (Quercus robur) and can have a positive effect on energy state, according to research on chronic fatigue subjects.25 The extract (as Robuvit®, from Horphag Research) contains antioxidant ellagitannin, including tannins called roburins, that appear to improve symptoms of fatigue as well as exercise performance and recovery—higher levels of oxidative stress lead to slower recovery.26

Tea is also a treasure trove of antioxidants and other compounds that address oxidative stress and support energy production, including fatty acid oxidation.27

Tea is also a well-known source of caffeine, which acts central nervous system (CNS) to limit fatigue. Adenosine accumulates after ATP synthesis and can occupy receptors in the brain and signal fatigue. Caffeine competes with adenosine for these neural receptors and staves off fatigue signaling. However, this can stimulate the body’s fight-or-flight response, which can be harmful if chronically activated. Further, chronic caffeine overstimulation can lead to production of more adenosine receptors in the brain and caffeine tolerance.

Caffeine is popular in sports formulas because it works quickly and provides a noticeable stimulant effect. Low and moderate doses of caffeine ingested during exercise can improve performance and race time in cyclists.28

Theacrine from tea is a purine alkaloid like caffeine, but without the negative side effects.  Research has shown theacrine supplementation (as TeaCrine®, from Compound Solutions) in healthy adults is safe for the cardiovascular system and is not habit-forming.29 Increased energy, focus and concentration are some of the performance benefits of theacrine supplementation.30

Energy will always be primary target for sports nutrition. As more ingredients are researched for specific mechanism and benefits to biochemical energy production and delayed fatigue, energy formulas will better cover all the angles of providing fuel to drive better workouts and performance.

For a list of references, email [email protected].

Looking to understand how to do the right things in product development, formulation and marketing in the sports nutrition space, and the potential consequences of doing it wrong? Join us for Exploring the Opportunities, Challenges in the Sports Nutrition Space workshop on Tuesday, Sept. 26, at SupplySide West 2017. The Workshop is underwritten by Arranti, Cluster Dextrin, PharmaGaba, Nutrition21, Nitrosigine, Velositil, Shanghai Freeman and XSTO Solutions.