Fuel for Thought: Gels, Bloks and Beans

Endurance athletes often need an energy boost during an event. STACK Expert Heather Mangieri breaks down the ingredients in the most popular energy products.

GU Energy Gel

Halfway through a full marathon or as you embark on the biking segment of a triathlon, your energy level dips. This is when an energy supplement can come into play. So you grab a gel, blok or bean and continue pounding away. (Read Training Like a Pro on an Amateur Budget: Advice From an Ironman Age Grouper.)

What is it about these products that makes you run longer or faster, and which ones do you really need? Just because a product contains certain ingredients doesn't necessarily mean it confers a performance benefit. Each ingredient in each product should be evaluated individually for safety and efficacy. Here is what you need to know.

The Basics

The main purpose of any endurance supplement is to supply ample energy to ensure optimum performance. This energy comes mostly from simple sugars, ranging from glucose, fructose, maltodextrin, fruit extracts and syrups, to juice and honey. Simple sugars are important for quick delivery of energy to fatigued muscles.

Endurance supplements also contain electrolytes, especially sodium and potassium. Electrolytes play an important role in fluid balance and muscle contraction. Check out the ingredient list. Salt, sodium citrate, sodium lactate, potassium chloride and potassium citrate are the most common ones you will find.

Other Common Ingredients

Caffeine: Green Tea Extract

Green tea contains caffeine, which if taken correctly may enhance performance. Caffeine has been shown to reduce an athlete's perception of how hard his or her body is working. (Fifty mg of caffeine equals about 1/2 cup of coffee.)

A variety of products contain caffeine:

  • PowerBar Energy Gels: 50 mg, 25 mg, or caffeine-free
  • Clif Shot Turbo Energy Gel: 100 mg
  • Clif Shot Bloks: 50 mg, 25 mg, or caffeine-free
  • GU Chomps: 20 mg

Antioxidant blend: Vitamins C & E

Antioxidants work to protect cells during exercise. As the body becomes more stressed, muscle tissues are more likely to break down. Antioxidants help combat this.

Examples of supplements with a mix of antioxidants:

  • GU Chomps & Energy Gels
  • Jelly Belly Sport Beans (only vitamin C).

Amino Acid Blend: Leucine, Valine, Histidine and Isoleucine

Leucine, valine, and isoleucine are amino acids that are branched in structure. In theory, they work to lessen fatigue by decreasing the brain's production of serotonin. Serotonin increases mental (and maybe even physical) fatigue. This theory is known as the "central fatigue theory." Histidine, on the other hand, acts as a buffer against lactic acid buildup, fighting fatigue.


  • GU Chomps
  • GU Energy Gels
  • Hammer Gels

B-Vitamin Blend: Thiamin, Riboflavin, Niacin, Vitamin B6, Vitamin B12 and Antothenic acid

B vitamins play a role in energy metabolism, converting carbohydrates and sugar into usable energy. Different products contain different combinations of B vitamins.


  • Jelly Belly Sport Beans (only thiamin, riboflavin, niacin)
  • Honey Stinger Energy Gels
  • Gatorade Prime 01

Herbal Blend: Chamomile & Ginger

Chamomile is touted as an anti-inflammatory, and ginger works to soothe the stomach.

Try: GU Energy Gels, including chamomile and ginger.

Your Main Goal

Your main goal should be to find the brand and flavor that work best for you, a product that does not cause stomach distress and that provides the right boost. Try several different kinds during your training so you know what will work on race day. (See also 5 Foods to Avoid Before a Race.)

Photo: coachlevi.com

Photo Credit: Getty Images // Thinkstock