~ Annie Bothma, Elite Athlete, IOPN Performance Sports Nutritionist (EQF Level 7. Masters), Running & Strength Coach
It is impossible for a sick athlete to compete, let alone perform! When it comes to endurance athletes, nutrition is not only essential for powering your workouts but also for maintaining your general health, particularly your immune system. A key strategy to achieve this is by focusing on your carbohydrate consumption before and during physical activity.
In this blog post, we’ll dive into why carbohydrates are so vital, how they impact your body’s stress response, and how they can help you stay healthy while pushing your limits.
The Link Between Endurance Exercise, Stress, and the Immune System
Endurance exercise is demanding, putting your body under significant physiological stress. After a long run, bike ride, or swim, your body releases stress hormones like cortisol, epinephrine, and norepinephrine. These hormones are part of your body’s natural response to the strain of exercise, helping you to perform and endure.
However, they also have a downside: they can suppress your immune system.
When these stress hormones are elevated for too long, they can lead to a state of chronic stress, which is harmful to your immune health. For endurance athletes, who regularly push their bodies to the limit, this can mean an increased risk of illness, longer recovery times, and even overtraining syndrome.
Carbohydrates: More Than Just Fuel
Carbohydrates are often thought of as the body’s primary source of energy, but they do much more than just fuel your muscles. Research has shown that consuming carbohydrates before and during exercise can significantly influence your body’s stress response and, by extension, your immune function.
When you ingest carbohydrates during exercise, your body is less likely to rely heavily on stress hormones to maintain blood glucose levels. This reduces the activation of the hypothalamic-pituitary-adrenal (HPA) axis, which is responsible for the release of stress hormones. In simpler terms, eating carbs helps to keep stress hormone levels in check, which can protect your immune system from being compromised.
How Much Carbohydrate Do You Need?
According to the research, adjusting carbohydrate intake is recommended depending on the length of your physical activity. I suggest athletes practice their race day fueling during all of their long runs and key workouts.
For exercise lasting 1-2 hours
Aim to consume 30-60 grams of carbohydrates per hour. This amount is typically sufficient to maintain your energy levels and support your immune health.
For exercise lasting more than 2-2.5 hours
Increase your intake to 60-90 grams of carbohydrates per hour. This higher intake helps sustain energy over a longer period and further aids in managing your stress hormone levels.
This can be achieved through energy gels, sports drinks, or easily digestible snacks. The key is to ensure that you’re getting a steady supply of carbs throughout your workout.
The Risks of Glycogen-Depleted Exercise
On the flip side, exercising in a glycogen-depleted state—when your body’s carbohydrate stores are low—can actually amplify the stress response. This can lead to a more pronounced release of stress hormones, greater immune suppression, and increased risk of illness and injury. It can also hinder your training adaptations, making it harder to improve your performance over time.
Carbohydrates are your body’s preferred fuel—without them, you’re not just running on empty, you’re basically just running on fumes. So, if you want to perform at your best, ditch the depletion and fuel your body right!
Practical Tips to Optimize Your Carbohydrate Intake
Fail to Plan and Plan to Fail
Before a long training session, plan out your carbohydrate intake. Know how much you’ll need and how you’ll get it, whether through sports drinks, gels, or solid foods.
Start with a Full Tank
Avoid fasted training sessions whenever you can! Running with a full tank will help you maximize training adaptations. promote better recovery and enhance your overall enjoyment of the training session.
Below is a table featuring a selection of easily digestible carbohydrate sources that are low in fat and fiber. These options are ideal for consumption prior to your upcoming training session, with each food item providing approximately ~ 20-40 grams of carbohydrates. You can consider complementing these carbohydrates with a small amount of protein and/or fat, such as peanut butter, low-fat yogurt, or milk.
Fueling Option | Serving Size | Carbohydrate Content |
Sports Drink (6-8% carb) (Example: Energade or Powerade) | 12-16 oz (355-500 ml) | ~25-40g |
Energy Gel | 1 packet (about 1 oz or 28g) | ~25-30g |
Chews/Blocks | 3-4 pieces (varies by brand) | ~30g |
Banana | 1 medium (about 7-8 inches long) | ~27g |
White Bread | 2 slices | ~28g |
Pretzels | 1 oz (about 10 small pretzels) | ~23-25g |
Applesauce | 1 single-serving cup (4 oz or 113g) | ~22g |
Rice Cake | 4 rice cakes | ~ 28g |
Dried Fruit (e.g., raisins) | 2 tablespoons (about 1 oz or 28g) | ~30g |
Fruit Snacks (gummies) | 1 small pouch (about 0.8-1 oz or 28g) | ~22-25g |
Honey | 1 tablespoon | ~17g |
Oatmeal | 1/2 cup cooked (with water) | ~27g |
Fig Bars | 2 fig bars | ~30g |
Fuel Early and Often
Begin consuming carbohydrates about 20-30 minutes into your workout, so your body has a readily available sustained energy throughout your session. During your workout, adjust your carbohydrate intake according to the duration of your exercise:
For sessions lasting 1-2 hours, consume 30-60 grams of carbs per hour.
For longer sessions, increase this to 60-90 grams of carbs per hour.
Here is a table with a few of the top gel choices that athletes I work with rely on to power their workouts.
Brand | Product | Carbohydrates | Sodium | Calories | Gel Size |
GU Energy | GU Energy Gel | 22g | 55mg | 100 | 32g (1.1 oz) |
Maurten | Maurten Gel 100 | 25g | 34mg | 100 | 40g (1.4 oz) |
Maurten | Maurten Gel 160 | 40g | 84mg | 160 | 65g (2.3 oz) |
SIS | SIS GO Isotonic Gel | 22g | 10mg | 87 | 60ml |
SIS | SIS Beta Fuel Gel | 40g | 30mg | 150 | 60ml |
Clif | Clif Shot Energy Gel | 24g | 90mg | 100 | 34g (1.2 oz) |
Honey Stinger | Energy Gel | 24g | 50mg | 100 | 32g (1.1 oz) |
Huma | Huma Chia Energy Gel | 22g | 125mg | 100 | 43g (1.5 oz) |
PowerBar | PowerGel Original | 27g | 200mg | 110 | 41g (1.4 oz) |
Hammer | Hammer Gel | 21g | 20mg | 90 | 33g (1.2 oz) |
Torq | Torq Gel | 30g | 56mg | 120 | 45g (1.6 oz) |
High 5 | Energy Gel | 23g | 30mg | 92 | 40g (1.4 oz) |
Precision Fuel & Hydration | Precision Fuel Gel 30 | 30g | 200mg | 120 | 30g (1.06 oz) |
Adjust Based on Your Body
Since each person's body is unique, it is crucial to observe how your body reacts to consuming different carbohydrates sources. Modify your diet according to your energy levels, health status, digestive discomfort, and current volume and intensity of your training regime.
Rest Up & Recover
If you are feeling unwell, it might be beneficial to take a day off to let your body recuperate rather than pushing through. One or two rest days are better than being out for a few weeks with illness.
Conclusion: Fuel for Performance & Health
For endurance athletes, carbohydrates are more than just a source of energy—they’re a vital tool for managing your body’s stress response and protecting your immune system. By incorporating a strategic carbohydrate intake into your training and competition routine, you can not only perform better but also stay healthier in the long run.
Remember, the goal is not just to finish strong, but to stay strong throughout your entire training cycle and beyond.
If you’re looking for personalized nutrition advice tailored to your endurance training, reach out to me for nutrition guidance and coaching that fits your specific dietary and training needs.
Let’s work together to optimize your performance and keep you healthy, both on and off the course.
Contact me at anniesathletes@gmail.com for more information.
Follow @annies_athletes on Instagram for more content like this.
Resources
Christ, T., Ringleb, M., Haunhorst, S., Fennen, L., Jordan, P. M., Wagner, H., & Puta, C. (2024). The acute effects of pre- and mid-exercise carbohydrate ingestion on the immunoregulatory stress hormone release in experienced endurance athletes—a systematic review. Frontiers in Sports and Active Living, 6, 1264814. https://doi.org/10.3389/fspor.2024.1264814
Zouhal, H., Saeidi, A., Salhi, A., Li, H., Essop, M., Laher, I., Rhibi, F., & Ben Abderrahman, A. (2020). Exercise Training and Fasting: Current Insights. Open Access Journal of Sports Medicine, 11, 1-28.
Levy, E., & Chu, T. (2019). Intermittent Fasting and Its Effects on Athletic Performance: A Review. Current Sports Medicine Reports, 18(7), 233-239.
Mandal, S., Simmons, N., Awan, S. A. A., Chamari, K., & Ahmed, I. (2022). Intermittent fasting: Eating by the clock for health and exercise performance. BMJ Open Sport & Exercise Medicine, 8(1), e001170.
Kobelkova, I., Korosteleva, M., & Kobelkova, M. (2022). Impact of Fasting on the Health and Performance of the Athlete. Journal of Applied Sports Science, 4(3), 45-52.
Chérif, A., Roelands, B., Meeusen, R., & Chamari, K. (2015). Effects of Intermittent Fasting, Caloric Restriction, and Ramadan Intermittent Fasting on Cognitive Performance at Rest and During Exercise in Adults. Sports Medicine, 46, 35-47.
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