Training Ground

Why Athletes Need Carbohydrates

Why Athletes Need Carbohydrates

If you’re an athlete considering a low-carb diet, you’ll need to ensure you are getting enough carbohydrates to fuel your training routine. Whether your focus is strength, cardiovascular endurance, or a combination of both as a CrossFit athlete, carbs are essential for fueling your muscles, as well as maintaining optimal hormone health.

The standard diet protocol includes a variety of refined carbohydrates, with added sugar found in nearly every product on the shelves of your grocery store. While we may want to reduce these parts of the diet for lowering inflammation and disease, many athletes are looking towards low-carb diets for health purposes in addition to lowering body fat levels. This approach is dangerous for a variety of hormonal reasons, in addition to being problematic for optimal athletic performance.

Here are some of the top reasons carbs should be a staple in your diet as an athlete:

Why Athletes Need Carbohydrates For Performance

Performance Relies on Muscle Glycogen

Glucose, the simple sugar and energy source, is stored in the form of glycogen in the body and is stored in both the liver and skeletal muscles throughout the body. The main source of energy during exercise is the muscle glycogen stores, and the capacity to exercise at higher intensities is directly related to pre-exercise levels of muscle glycogen. Our bodies are capable of storying around 2,000 calories of muscle glycogen, and pull from these energy sources as needed during longer duration exercise to directly fuel the muscles.

In fitness, we all tend to be familiar with the sensation of “hitting the wall,” where we run out of energy, our muscles reach fatigue and we struggle to continue using them in the same capacity. For some muscle groups, this may look like the muscles reaching full fatigue and no longer being able to function, especially when it comes to strength capacities.

Decreased Thyroid Output

Hormone T3 is the most active thyroid hormone and is responsible for managing blood glucose levels and metabolic function. We also have rT3 (reverse T3) which inhibits the production of T3. When we don't have enough carbs, not only does our T3 production slow down, but rT3 increases and blocks the capacity of the T3. The result is that metabolism slows with the decrease of T3 production, making carbohydrates an important factor for the production of the peripheral metabolism of thyroid hormones.

Thyroid function is not only important for weight loss, but also for overall health and energy levels. Without adequate carb intake, energy levels will plummet and your training will suffer.

Why Athletes Need Carbohydrates For CrossFit

Increased Cortisol Output

Cortisol is our stress response hormone released by the adrenal glands, which sit directly on top of the kidneys. As an important system for our “fight or flight” mode, cortisol is vital for keeping us out of harm's way, as well as playing an important role in blood sugar regulation. As athletes, we put ourselves into a “stressed” state through exercise, which is healthy in certain doses. However, when combined with a low-carb diet, cortisol output increases, leading to HPA-axis dysfunction, commonly referred to as adrenal fatigue. In women, this can lead to hypothalamic amenorrhea.

Decreased Testosterone

In conjunction with increased cortisol output, low carbohydrate intake can lead to decreased testosterone levels. Glucose is a precursor for gonadotropin-releasing hormone (GnRH), responsible for triggering the release of testosterone. It’s also important to remember that testosterone is important for everyone regardless of gender, as testosterone gives us the ability to grow our muscles and function actively, as well as promote bone strength. The combination of these two hormones being out of sync leads to negative effects in performance and the ability to recover since carb intake prevents a drop in testosterone levels post-exercise. 


Why Athletes Need Carbohydrates Muscle Catabolism

Muscle Catabolism

When you're exercising, the goal is to typically break down muscle and then rebuild it to build new muscle fibers and strength. When you aren't eating enough carbs, however, your muscles breakdown and are unable to rebuild themselves. As we mentioned earlier, carbs are required to create glycogen stores in muscles, but in order to build muscle, insulin must be released into the bloodstream to shuttle glucose to cells to replenish those glycogen stores. When your muscles deplete glycogen stores with being replenished, your body is also unable to repair muscle fibers and develop new muscle fibers. The result is a consistent process of breaking down muscles through exercise, without allowing them to rebuild and repair.

How to Utilize Carbs as an Athlete

As an athlete, you need to fuel yourself properly with the intent of training as needed. This means you not only need to consider getting adequate carbs throughout the day, but timing those carbs around your training sessions to increase your muscle glycogen levels and provide readily available fuel sources for your body, but also focus on recovery by consuming carbohydrates post-workout to replenish depleted glycogen stores in muscles and prevent testosterone drops.

First, you’ll want to ensure you have adequate amounts of both slow digesting carbohydrates for sustained, long-term energy, as well as quick digesting carbohydrates for quick, short-term energy to fuel your workout. Aim to get between 25-50 grams of carbohydrates prior to beginning exercise. Our Glyco-Muscle Fueler is best taken 30 minutes prior to beginning exercise to provide both slow- and fast-digesting carbs to fuel your training session.

The scientific evidence shows the need for protein intake post-workout, but also carbohydrate intake for full recovery of muscles. This helps us recover by both allowing damaged muscle fibers to be repaired, generate new muscle fibers, and replenish energy stores to set us up for success. Adequate protein and carbs post-workout may lead to less muscle soreness post-workout, as well as improved recovery for your next workout. After your training sessions wraps up, consume another 25-50 grams of carbohydrates to encourage glycogen store replenishment.

As athletes, we are focused on our athletic performance in the gym, on the track, and in our sport. Fueling ourselves is vital to promoting productive training sessions and recovering properly, in addition to supporting healthy hormone levels in a variety of capacities. Low-carb intake will inhibit the body’s natural athletic ability as it relies on carb intake for fuel and as a precursor to many of the hormones necessary to perform athletically.

Carbohydrate Supplement Powder

Deidre Bloomquist
Deidre Bloomquist - Author

Deidre Bloomquist is the nutritionist and owner of Always Growing Nutrition based in Denver, CO. She is a Precision Nutrition L1, Institute of Integrative Nutrition Health Coach, studying Nutritional Therapy Practitioner, NASM CPT, and Certified CrossFit Trainer (L3), as well a freelance health writer. Deidre studied journalism at the University of Denver.


Also in Training Ground