How Energy Drinks Impact Your Workout

Woman getting ready to play tennis

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Whether you workout first thing in the morning or prefer to fit it in at the end of the day, you'll need energy to fuel your steps, spins, or strokes. While food is fuel for the body, there are also ingredients found in energy drinks, such as caffeine, that promise to give you an edge. But the real question is, is it helpful to consume energy drinks before a workout? Or is this method of pre-workout fuel just hype?

Energy Drinks vs. Coffee

An energy drink is a beverage that is specifically blended with caffeine and other energy boosters to add some pep into your day and help you get the most out of your workout. Drinks like Monster, Rockstar, Red Bull, and 5-Hour Energy fall into this category.

Most energy drinks contain water, sugar (or an artificial sweetener), and caffeine, and may also include additional ingredients such as B-vitamins, amino acids like taurine, and plant extracts such as ginseng or guarana. But caffeine is the common ingredient that provides energy. How do energy drinks compare to coffee in terms of caffeine content?

Coffee drinks:

  • Starbucks Dark Roast Coffee - tall: 196 mg caffeine
  • Starbucks Dark Roast Coffee - grande: 260 mg caffeine
  • Dunkin' Donuts Coffee - medium: 210 mg caffeine
  • Espresso - one shot: 150 mg caffeine
  • Latte or cappuccino - medium: 155 mg caffeine
  • Starbucks Coffee Frappuccino - grande : 95 mg caffeine
  • Instant coffee - 2 tsp: 62 mg caffeine

To compare, most energy drinks come in 8.4 oz. (250 ml) cans, and have roughly 75-90 mg caffeine per can. There are also energy drink "shots" available, where a 2 oz. serving has 100-230 mg caffeine.

It's important to read labels to see how much caffeine there is per serving in an energy drink, as the amount is not standardized across brands. If you are drinking coffee before a workout, you likely do not need an energy drink as well.

If you are watching your sugar or carbohydrate intake, there's a huge range between drinks. The amount of sugar in both coffee drinks and energy drinks can range from zero for black coffee or artificially sweetened energy drinks, to 26 g (about 6 teaspoons) of sugar in energy drinks like Red Bull, and upwards of 48 g (12 teaspoons) of sugar in blended coffee drinks, such as a Starbucks Frappuccino. Read labels or check online menus to know for sure what you're putting into your body.

Energy Drinks vs. Pre-Workout Supplements 

To enhance workouts, some people rely on supplements such as protein powder, beta-alanine, nitrate powder or creatine to help with muscle gain, endurance or to reduce fatigue. These can come in the form of drinks, food, powders and supplements, and each have their own blend of performance-enhancing ingredients.

Caffeine is another popular pre-workout supplement, and is often ingested as a beverage.

These is ongoing interest in studying the effects of different pre-workout supplements and energy drinks, both individually and in combination, to look at safety and efficacy. It's important to work with a registered dietitian or certified personal trainer to figure out which supplements work best to meet your personal needs.

What Is a Safe Amount of Caffeine? 

Caffeine is a natural stimulant, added to energy drinks to enhance exercise endurance and performance. Scientists at the FDA say that caffeine is safe for adults, within reason. Caffeine intake up to 400 milligrams a day does not seem to have negative side effects, but once you get above that level, you run the risk of developing side effects including:

  • Insomnia
  • Anxiety
  • Rapid heart rate
  • Upset stomach or nausea
  • Headache

More serious side effects, such as seizures, can happen when people consume around 1,200 milligrams of caffeine in a day. Speak to a medical professional if you have any questions or concerns about caffeine intake. 

When related specifically to sport, International Society of Sports Nutrition (ISSN) says that caffeine improves exercise performance when consumed in doses of 3-6 mg/kg body mass, but high doses of caffeine (e.g. 9 mg/kg) are associated with negative, unhelpful side effects.

When considering your caffeine intake, it's important to count the caffeine content in coffee, tea, soda, chocolate and energy drinks. It's easy to overdo it by drinking a large coffee in the morning and a few energy drinks during the day. Use caution and stay in the range of no more than 400 mg caffeine per day.

Energy Drinks and Athletic Performance 

The ISSN recently released a position paper regarding caffeine intake and exercise, which included information about energy drinks. They found that energy drinks containing caffeine enhance both anaerobic and aerobic performance, and caffeine is commonly ingested about 60 minutes prior to activity.

The ISSN cited studies to show that benefits from caffeine include muscular endurance; muscular strength; improved sprinting, jumping, and throwing performance; and aerobic endurance in a wide variety of physical activities, from soccer to volleyball to cross-country skiing. Caffeine has also been found to be helpful for cognitive function, including attention and vigilance in sports.

Side Effects of Energy Drinks 

Of course, not everyone reacts the same way to caffeine in energy drinks, so it’s not always helpful for all athletes. Some people are more sensitive to the side effects of caffeine, such as a rapid heart beat or headache, which can negatively affect athletic performance.

Ultimately, our genetics will determine the way we absorb, metabolize, and utilize caffeine. Studies show an individual variability in how well caffeine can affect exercise performance. In fact, one study on the effect of caffeine in cycling showed that 50 percent of athletes improved due to caffeine, while the other half had a worse performance. It really is a user-dependent substance.

If you find that caffeine makes you jittery or has a negative impact on your athletic performance, cut back or eliminate energy drinks from your routine. While temporarily helpful, longer-term use of energy drinks may also increase blood pressure and lead to hypertension, rapid heart beat, and nervousness, which are linked to cardiovascular disorders.

Some energy drinks also contain ginseng, an herb native to China, which is known to promote well-being. Short-term use of ginseng (up to 6 months) appears to be safe for most people, but it has not been well-studied in children or people who are pregnant or breastfeeding. There are also some concerns that ginseng can interact with certain medications, so check with a pharmacist before using energy drinks containing ginseng.

A Word from Verywell

Energy drinks may provide an additional edge for your athletic endeavors, as long as you tolerate caffeine well. Avoid pushing the limit on caffeine consumption—stay under 400 mg day of caffeine from all sources, including coffee. Signs that your energy drink is doing more harm than good include sleeplessness, jitters, rapid heart beat and high blood pressure. If these symptoms arise, cut back on your caffeine intake and talk to a health care provider.

Frequently Asked Questions

  • Is caffeine good before a workout?

    Ingesting caffeine about 60 minutes before a workout can help with muscular endurance, muscular strength, improved sprinting, jumping, and throwing performance, cognitive function, and aerobic endurance.

  • How much caffeine is too much?

    The FDA recommends no more than 400 mg caffeine per day. A cup of instant coffee has about 60 mg, brewed coffee has 100-200 mg, and an energy drink has about 80-200 mg of caffeine.

  • How can I boost my energy without caffeine?

    Food is fuel. Enjoy a meal or snack about an hour before your workout, with a good combination of protein and carbs. Getting enough sleep can help keep your workouts energized as well.

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Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cara Rosenbloom, RD
 Cara Rosenbloom RD is a dietitian, journalist, book author, and the founder of Words to Eat By, a nutrition communications company in Toronto, ON.