By Michael Ormsbee, PhD, Florida State University

Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

You may have heard that carbohydrates are a good way to fuel your workouts, but many of us are unaware of the specifics in regard to the latest nutritional science. As it turns out, there’s more to it than eating a bowl of spaghetti before a marathon. Professor Ormsbee gives the details.

Carbohydrates during Exercise

For endurance exercise that’s longer than 60–90 minutes, general recommendations for athletes are to take in between 30–60 grams (g) of carbohydrates per hour during exercise to extend performance. Along these lines, do you know what type of carbohydrates you should eat before and during exercise? The common recommendation is to eat a fast-digesting or high-glycemic index carbohydrate during activity. 

These include foods and drinks like sports beverages; pre-made gels; and whole foods like bread, jelly, and fruit. One note of caution is that high-fructose products, like some sports drinks and foods like actual fruit, can lead to an upset stomach and even diarrhea.

Most sports drinks have a combination of fructose and glucose, and you just need to experiment with them to see what works for you. Professor Ormsbee’s lab is actively researching this area, testing all types of carbohydrates and modified carbohydrates for their effectiveness.

Don’t Skimp on Protein 

Eating protein during exercise is also important. Decades of research have shown a carbohydrate and protein mix improves performance and lengthens time until exhaustion during endurance exercise, as compared to just carbohydrate alone. 

These studies have all used sports drink products that include carbohydrates and protein. Check the Nutrition Facts label to see if your favorite drink has both carbohydrates and protein. 

“One complaint that I often hear from both clients and students is that sports nutrition and exercise physiology concentrate too much on endurance sports,” Professor Ormsbee said.

When it comes to resistance training, the general recommendation is also to include both carbohydrates and protein. The media pushes protein and resistance training so much that many people think you only need protein during resistance training, but carbohydrates are important, too.

Minimizing Cortisol Production

A natural response to any stressful situation, including exercise, is to produce a hormone called cortisol, which contributes to the breakdown of your lean muscle. Cortisol has many actions in your body, and it is necessary for optimal functioning. 

However, too much cortisol—particularly, chronically elevated cortisol—can break down your lean muscle mass. Eating carbohydrates can help to minimize the production of cortisol during exercise.

One research study had participants complete 60 minutes of resistance training while consuming one of three beverages: a placebo beverage, a beverage of six-percent carbohydrates—like most sports drinks—or a combined beverage of six-percent carbohydrates plus six grams of essential amino acids. They found that serum levels of cortisol increased 105% in the placebo group, while the carbohydrate group increased only 11%, and the carbohydrate + essential amino acid group had a 7% increase in cortisol.

These results suggest that consuming carbohydrates in combination with protein will provide the most benefits during resistance exercise; in the research for endurance exercise, this has been noted, too. The benefits include optimizing muscle glycogen, gaining better performance results, and helping to repair muscles.

Although small differences exist for what to eat and how much to eat before and during endurance and resistance training, including both carbohydrates and proteins is important for optimal performance and body composition.

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.

Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his MS in Exercise Physiology from South Dakota State University and his PhD in Bioenergetics from East Carolina University.