Read Those Labels


Nutritionists often talk about reading labels, encouraging you to look for healthy ingredients and recognizable foods that are close to their original source, such as whole wheat instead of white flour. But what happens when you pick up a packet of gel, a sports bar or a canister of powdered fuel? The ingredients read more like a chemistry class than something recognizable. When we switch over from healthy eating for life to fueling our endurance running, the way our body preferentially uses food for energy changes, and the type of carbohydrate and protein (and eventually fat) sources that best fit each activity also changes. Reading product labels will help you make the right choice when using sports nutrition products.

An understanding of the human energy systems, and the type of training or sports each one supports is helpful. When we start running, or doing any exercise for that matter, we use (in order) the ATP that we have in our muscles first, then the Phosphate-creatine system, the Lactate system and finally, the Oxygen system. ATP provides only a few calories of energy before it runs out and must be replenished by the next system, the Phosphate-creatine system. This system only lasts about one – ten seconds (think 100-yard sprint) before it runs out and the Lactate system kicks in (now think 200—800-meter races). Although lactic acid will build up quickly at this speed, some lactate will be recycled for energy. Still, some will cause an acid situation in the muscles, releasing hydrogen ions and causing fatigue…which causes us to slow down or stop. This system lasts about 30 – 120 seconds. After that, the Oxygen system takes over and produces lots of ATP for energy, but at a much slower rate than the previous systems. The advantage of the Oxygen system is that it can use many types of food as fuel including carbohydrates (which work the fastest), fats, and even proteins through gluconeogenesis, as we run out of other fuels or late in the race. In a 24-hour or longer race, an athlete works their way through all these systems, but obviously the oxygen system dominates since the other sources of energy are much shorter term.

First, let’s look at the type of carbohydrates and proteins available and then see what role the different ingredients listed on the labels actually play. Most products do not include fat since we have plenty of stored fat in our bodies for endurance events; we just need to keep ingesting a steady stream of carbs in order to utilize that fat for energy. Fat does help with satiety however, and is included in sports recovery products for that purpose.


Carbohydrates vary a lot in their structure—from one or two molecules (“simple” carbohydrates or sugars) to long chains of molecules (“complex” carbohydrates or starch). The sweetness depends on the length, as does the carbohydrates’ insulinspiking ability. There is a general misunderstanding regarding “good” carbs versus “bad” carbs amongst the athletic community. When you are not exercising, you don’t want to consume foods that will increase the secretion of insulin with the resultant drop in blood sugar. But when you are exercising, the insulin release response is blunted and it becomes important to maintain blood sugar levels. An endurance runner will want to emphasize carbohydrate sources from whole grains, fruits, vegetables and low-fat dairy products in their daily diet, but their exercise carbohydrate calories will need to be quickly absorbable, easily digestible and readily available to the blood and exercising muscles for fuel. Carbohydrates are the most efficient fuel when exercising since they require less oxygen to burn than is required for burning protein or fat, therefore using fewer calories to process. See the following definitions for clarification.

Simple Carbohydrates

Monosaccharides – one molecule long. Includes glucose (the body’s number one energy source and what most carbohydrates are eventually converted to, fructose (found in fruit, honey and the sweetest natural sugar) and galactose.
Disaccharides – – two molecules long. Includes sucrose or table sugar (glucose + fructose), lactose, the “milk” sugar (glucose + galactose) and maltose (glucose + glucose), which muscles love.

Complex Carbohydrates

Oligosaccharides – three to ten molecules long. Includes maltodextrins (at least five glucose units) found in sports products and corn syrup found in processed foods.
Polysaccharides – composed of over ten molecules, and possibly hundreds. Includes most carbohydrates found in the plant world and some glucose polymers (commercially made starches found in sports products).

Another way of looking at complex carbohydrates is to classify them by type.

Starch – a “digestible” complex carbohydrate; it is the storage form of carbohydrates in plants
Fiber – a non-digestible complex carbohydrate found in plants; it includes both soluble and insoluble carbohydrates
Glucose Polymers – starch made up solely of glucose (at least two molecules)
Maltodextrin – starch made up solely of glucose (at least five molecules)

Soy Protein – purely vegan source of protein. This type of protein is easily digestible and has a substantial proportion of branched chain amino acids. It does not readily produce ammonia when metabolized and has some antioxidant properties.
Whey Protein – this is the most bioavailable form of all proteins and therefore helps speed the recovery process after long bouts of exercise. It has the highest percentage of essential amino acids and helps with muscle repair and rebuilding.

SPORTS NUTRITION LABELS – Roles of the various ingredients

Maltodextrin – A type of glucose polymer chain manufactured from complex carbohydrates. It provides lots of very usable glucose for energy in a rather tasteless medium. It has minimal sweetness and can provide more calories in the same amount of liquid as compared to a glucose-alone solution.
Brown Rice Syrup – Made from sprouted brown rice, this is a complex carbohydrate that can take two to three hours to be absorbed. Low GI (Glycemic Index).
Glucose Polymers – A large category including maltodextrins and brown rice syrup. These are entirely made up of glucose molecules and are considered a complex carb. They leave your stomach quickly and are easily absorbed in your small intestine. Think of them as “time release” energy.
Glucose (also known as Dextrose ) – A simple sugar, it is the primary energy source used by the central nervous system and can be immediately used by working muscles for fuel and energy.
Fructose – Fruit sugar, a simple sugar that can cause gastric upset in athletes if used alone, but if used in conjunction with other sugars can actually aid absorption. Known as “Dumping Syndrome”, a high concentration of fructose exerts a reverse osmotic effect in the intestines causing weakness, sweating and diarrhea.
Sucrose (or “table sugar”) – A simple sugar made up of one molecule each of glucose and fructose. Because of the combination, there is less chance of stomach upset and it is quickly absorbed.
Soy Protein – best used before and during exercise because it produces less ammonia when metabolized. Ammonia causes muscle fatigue. Soy protein also acts as a buffering agent and an antioxidant. The additional phenylalanine in soy may help in maintaining alertness in endurance events.
Whey Protein – the most rapidly absorbed protein and the most bioavailable. This is important for muscle repair post-workout. The amino acid profile with the high content of branched chain amino acids helps in reducing muscle soreness following exercise.


Sodium Citrate, Citric Acid, Potassium Citrate – act as neutralizing and buffering agents, maintain pH.
Calcium Carbonate, Calcium – act as anti-acids, also help prevent muscle cramps and weakness if the athlete is hydrated.
Magnesium – aids in releasing energy from muscle storage and helps regulate body temperature.
Vitamins – mostly a marketing scheme when used in products made for consumption during exercise. May help in recovery.
Sodium, Chloride, Sodium Chloride – (salt or table salt) necessary for maintaining body fluid levels and body temperature regulation. Sodium helps absorption of carbohydrates across the wall of the small intestine. Too much can be as problematic as too little.
Manganese – trace amounts are needed for enzyme reactions in muscle cells. Helps convert protein and fatty acids into energy, therefore not necessary in 100-percent carbohydrate products.

When checking sports nutrition labels, choose products and amounts that will give you about 60 grams of carbohydrate per hour, or four calories of carbohydrates per minute. A trained athlete can absorb up to 100 grams per hour if the exercise is not too high an intensity. These should be easily digestible and agreeable in taste and texture. Studies show that athletes drink (and eat) according to taste, saltiness, sweetness and digestibility, so be sure you like what you are consuming, as well as taking it for performance. Combining different sugars will have a synergistic effect on exercise performance. You can maximize the amount of absorbed fuel because each sugar has a different rate of absorption; this allows you to take in more calories without gastric upset. Maltodextrin, glucose and fructose seem to give the most benefit. Be more careful of brown rice syrup since it is a complex type of carbohydrate that takes longer to be broken down and is therefore slower to be absorbed. This can be an advantage if you are sugar-sensitive, as long as you start early enough with consumption. Keep in mind that electrolytes balance sports products by making them more palatable.

When you are using sports nutrition products start reading those labels and use what you need for your energy system. Ultrarunning is hard enough—make your nutrition count.


About Author

Sunny Blende, M.S. is a Sports Nutritionist who writes and counsels individuals and teams on fueling for enhanced performance and making healthy food choices. Currently she writes the nutrition column for UltraRunning magazine and runs ultras herself. She has presented at the National RRCA Convention, the National Rowing Convention, Nike San Francisco Marathon Expo, and the Runners World San Francisco Marathon and worked as an assistant with the Los Angeles Marathon Association. An avid master competitor herself, she trains and competes in the San Francisco Bay Area and beyond. Sunny received her Bachelor of Science degree from University of Southern California and her Masters in Human Nutrition degree from University of New Haven. (Photo at left, by Luis Escobar).

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