Endurance Sports Nutrition Timeline: From Pre-Race Loading to Post-Workout Recovery
This article is for you if you're preparing for a marathon, long-distance cycling, triathlon, or trail running event. If you experience slowing down in the latter stages of long training sessions, gastrointestinal discomfort, or are unsure what to eat, this article is for you.
01Why Endurance Sports Nutrition Needs a Timeline Approach
The primary fuel for prolonged exercise is carbohydrates, stored as glycogen in muscles and the liver. When glycogen levels drop to a certain point, the body is forced to switch to slower fat oxidation, and pace decreases, commonly known as "hitting the wall."
Research indicates that for high-intensity endurance events lasting over 90 minutes, glycogen depletion significantly impacts performance if no external carbohydrates are supplemented. The good news about glycogen is: it can be pre-loaded and supplemented during exercise, which is the core of the timeline strategy.
| Energy Source | Energy Contribution (Median) |
|---|---|
| Glycogen | Approx. 82% |
| Fat | Approx. 18% |
- Jeukendrup, Sports Med 2014
- Bangsbo et al., Scand J Med Sci Sports 2025
021–2 Days Before the Race: Fill up your glycogen stores
The goal of carbohydrate loading is to maximize muscle and liver glycogen reserves before the race. The modern approach involves increasing carbohydrate intake to 8–12 g/kg body weight/day for 1–2 days before the race, combined with tapering training to allow the body to store glycogen.
In practice, choosing low-fat, low-fiber refined carbohydrates makes it easier to achieve this goal. White rice, pasta, bananas, and bagels are good choices. For example, a 70 kg athlete needs to consume approximately 560–840 g of carbohydrates daily for two days before the race (equivalent to the total carbohydrates in 12–18 bowls of white rice). This is difficult to achieve with meals alone, so Energy Oat Bars (40 g carbohydrates per 70 g serving) can be used as a supplement.
- Bangsbo et al., Scand J Med Sci Sports 2025
- SiS official product information
03The Last Pre-Race Meal: Stabilize Blood Sugar and Minimize Gastric Burden
The last meal before the race aims to stabilize blood sugar and ensure high liver glycogen levels at the start. It is generally recommended to supplement 30–60 minutes before the start:
| Training Duration | Carbohydrate Target | Example for a 60 kg athlete |
|---|---|---|
| < 60 minutes | 0.5 g/kg | 1 large banana (approx. 30 g carbs) |
| > 90 minutes | 1 g/kg | 2 muffins + jam (approx. 60 g carbs) |
Choose low-fiber, low-fat, familiar foods to avoid pre-race stomach discomfort. If only 30 minutes remain before the start, you can switch to GO Isotonic Energy Gels (22 g carbohydrates per 60 ml, isotonic formula requires no water), to reduce gastric burden.
- Thomas et al., J Acad Nutr Diet 2016
- Kerksick et al., J Int Soc Sports Nutr 2017
- SiS official product information
04In-Race Carbohydrate Intake Rate: From 30 g/h to 120 g/h
Supplementing carbohydrates during exercise can delay glycogen depletion, especially for events lasting over 90 minutes. Requirements vary depending on intensity and individual tolerance, generally ranging from 30–120 g/hour. The longer the race and the faster glycogen reserves are depleted, the higher the hourly intake target.
| Race Duration | Carbohydrate Intake Target |
|---|---|
| Less than 60 minutes | No external supplementation needed (pre-race loading is sufficient) |
| 60–90 minutes | Approx. 30 g/hour |
| 90 minutes–3 hours | Approx. 60 g/hour |
| More than 3 hours | Approx. 90 g/hour |
| Dual-source carbohydrates + gut training | Approx. 120 g/hour (upper limit for amateur runners) |
When intake exceeds 60 g/hour, the single glucose channel (SGLT1) hits a ceiling. This requires dual-source carbohydrates: maltodextrin + fructose. The former uses SGLT1, and the latter uses GLUT5 (imagine a single lane road widened to two lanes), which can increase the absorption limit from 60 g/h to 90 g/h or even 120 g/h, while reducing gastrointestinal discomfort. BETA FUEL Dual Energy Gels (40 g dual-source carbohydrates per 60 ml) are formulated according to this ratio.
- Jeukendrup, Sports Med 2014
- Currell & Jeukendrup, Med Sci Sports Exerc 2008
- SiS official website product information
05Gut Training: The Key to Maximizing Absorption
Setting a target intake of 90 g/h doesn't mean you can reach it immediately – your gut's tolerance for carbohydrates needs to be trained. Studies show that supplementing carbohydrates during long training sessions at race pace for 2 consecutive weeks can reduce gastrointestinal discomfort by about 47% and increase carbohydrate absorption by 45–54%.
The practical approach is to practice with the products you intend to use on race day during your regular long training sessions. For 1-2 long sessions per week (e.g., 60-90 minutes or more on weekends), consume carbohydrates at race intake levels to train your gut. By race day, your stomach will be accustomed to this rate of sugar intake. Common quantifiable progress includes a 47% reduction in gastrointestinal discomfort and a 45–54% increase in carbohydrate absorption after 2 weeks of training.
- Cox et al., J Appl Physiol 2010
- SiS official website product information
06Hydration and Electrolytes: Weight Management and Sodium Intake
During prolonged exercise, fluid loss can affect thermoregulation and cardiovascular function. When body weight decreases by more than 2% due to dehydration, aerobic endurance and perceived exertion significantly worsen. Measuring your individual sweat rate is the first step in creating a hydration plan: weigh yourself before and after exercise, add the amount of fluid consumed during exercise, and divide by the exercise duration to get your hourly fluid loss. Most athletes' sweat rate is 1.0–1.5 L/hour, but actual fluid intake is often lower than this.
Among electrolytes, sodium is the most crucial – it maintains plasma volume, drives water absorption in the intestines, and prevents hyponatremia. The sodium concentration in typical sports drinks, around 500–700 mg/L, is sufficient for most people. If you are a "salty sweater," your race duration exceeds 3 hours, or you are exercising in a hot and humid environment, you will need a higher sodium intake.
| Scenario | Hydration Focus | SiS Product Example |
|---|---|---|
| Daily training < 90 minutes | Guided by thirst | HYDRO Tablets (345 mg sodium per tablet) |
| Hot weather / Long duration race | Planned hydration + sodium intake | GO Electrolyte Powder (237 mg sodium per serving) |
| Rapid post-race rehydration | Replenish 1.25–1.5 times fluid loss | REGO Rapid Recovery Protein Powder (483 mg sodium per serving) |
- Barley et al., Front Physiol 2018
- Veniamakis et al., Int J Environ Res Public Health 2022
- SiS official website product information
07Caffeine: Dosage and Timing
Caffeine is one of the few performance-enhancing aids with "strong evidence of support" according to the International Olympic Committee consensus. It reduces fatigue perception and enhances alertness by blocking adenosine receptors, and it can also promote carbohydrate absorption in the intestines.
| Dosage Level | mg/kg body weight | Target for 70 kg athlete | Risk |
|---|---|---|---|
| Low Dose | 1.5–3 mg/kg | 105–210 mg | Standard starting point |
| Medium Dose | 3–6 mg/kg | 210–420 mg | Upper limit for most people |
| High Dose | 4–6 mg/kg | 280–420 mg | High risk of side effects |
The generally recommended dose is 1.5–3 mg/kg, taken 45–60 minutes before the race. For a 70 kg athlete, 3 mg/kg is approximately 210 mg, which is equivalent to two GO ENERGY Caffeine Energy Gels in Citrus/Cola/Berry flavors (75 mg per gel) plus a small amount of coffee, or one Double Espresso flavor (150 mg per gel) plus one espresso shot.
- Maughan et al., Br J Sports Med 2018
- Glaister et al., Int J Sports Physiol Perform 2018
- Carvalho et al., Sports Med 2022
- SiS official website product information
084 Hours Post-Training: Glycogen Resynthesis and Protein Intake
After training, muscle sensitivity to carbohydrates and protein significantly increases, making this window the most efficient time for glycogen resynthesis. Studies recommend consuming approximately 1.2 g of carbohydrates/kg of body weight per hour within 4 hours post-training, and at least 20 g of high-quality protein with the first meal to aid in glycogen resynthesis and muscle recovery.
For a 60 kg athlete, the carbohydrate target for 4 hours post-training is approximately 288 g, which can be broken down as follows:
| Time | Food Combination | Approximate Carbohydrate Content |
|---|---|---|
| Immediately Post-Workout | Banana + REGO Rapid Recovery Protein Powder (50g per serving) | Approx. 60g |
| 1 Hour Post-Workout | Oats + Skim milk + Fruit + Nuts | Approx. 70g |
| 3 Hours Post-Workout | Whole wheat sandwich + Chicken + Avocado + Salad | Approx. 70g |
If there is only a 4–6 hour gap between two training sessions, it is even more crucial to seize this window for rapid carbohydrate replenishment. BETA Recovery Powder (100g per serving contains 58g carbohydrates, 30g protein) is a convenient post-workout option, but a balanced meal should still be the primary focus in the long run.
- Kerksick et al., J Int Soc Sports Nutr 2017
- Thomas et al., J Acad Nutr Diet 2016
- SiS Official Website Product Information
09FREQUENTLY ASKED QUESTIONS
Q: Is 90 g/h really safe? What if I experience gastrointestinal discomfort?
A: 90 g/h is the achievable upper limit for most amateur runners after at least 2 weeks of gut training, provided they practice long runs at race pace 2–3 times a week. Without training, it's recommended to stabilize at 60 g/h first, using an "isotonic + dual-source" combination to reduce stress on a single pathway. If significant gastrointestinal discomfort occurs, reduce to 30–45 g/h for a week before gradually increasing again.
Q: How many carbohydrates should I eat the night before a race?
A: 1–2 days before the race, consume 8–12 g/kg body weight/day (e.g., 560–840g/day for a 70kg individual), along with reduced training volume. On race morning, replenish with an additional 1–2 g/kg body weight of carbohydrates (approximately 60–120g for a typical athlete), choosing familiar low-fiber foods and avoiding high-fat or spicy options.
Q: How do carbohydrate requirements differ for half-marathons, marathons, and ultramarathons?
A: For events under 90 minutes (e.g., 10k, half marathon), pre-race carbohydrate loading may suffice, with no need for exogenous carbohydrates during the race. For events between 90 minutes and 3 hours (early to mid-marathon), 30–60 g/h is recommended. For events over 3 hours (late-marathon, trail running, ultramarathon), 60–90 g/h is needed, using dual-source carbohydrates. Altitude, temperature, and intensity of the race will further increase requirements.
Q: When is the best time to consume caffeine? Who should avoid it?
A: Consume 1.5–3 mg/kg (e.g., 105–210mg for a 70kg individual) 45–60 minutes before the race. Individuals with slow CYP1A2 metabolism, arrhythmias, pregnant women, and those with insomnia should avoid high doses. First-time users should try it during training, not on race day, and avoid consumption after 3 PM to prevent sleep disturbances.
Q: Do I have to eat immediately after a workout?
A: The 4-hour window is a sensitive period for glycogen repletion. Consume 1.2 g/kg carbohydrates per hour (e.g., approximately 72 g/h for a 60kg individual) and at least 20g of protein with the first meal. If there's a short interval between two training sessions (4–6 hours), the quicker you replenish, the better your performance in the next session. If the interval is long (24 hours or more), the window still exists but is relatively more flexible.
10CONCLUSION
The essence of endurance sports nutrition is to strategically distribute carbohydrates, water, electrolytes, and caffeine over time: fully load glycogen 1–2 days before the race, stabilize blood sugar on race morning, replenish carbohydrates and electrolytes at a steady pace during the race, and refuel within 4 hours post-race – then adjust hydration and sodium intake based on environmental conditions and individual sweat rate.
In practice, we recommend starting with your next long run:
- First, measure your sweat rate: weigh yourself before and after exercise to calculate hourly fluid loss and establish your personal hydration plan.
- Train your gut before the race: use the energy gels and sports drinks you plan to use on race day for simulated training.
- Stabilize at 60 g/h first: aim for 60 g of carbohydrates per hour during the race, then gradually increase as tolerated.
By making nutrition a part of your training, you naturally eliminate one variable on race day.
- Bangsbo J, et al. Consensus statements—Optimising performance of the elite athlete. Scand J Med Sci Sports 2025;e70112. PMID:40781883. DOI:10.1111/sms.70112. https://pubmed.ncbi.nlm.nih.gov/40781883/
- Barley OR, et al. Acute Dehydration Impairs Endurance Without Modulating Neuromuscular Function. Front Physiol 2018;9:1562. PMID:30450056. DOI:10.3389/fphys.2018.01562. https://pubmed.ncbi.nlm.nih.gov/30450056/
- Carvalho A, et al. Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine. Sports Med 2022;52(9):2209–2220. PMID:35536449. DOI:10.1007/s40279-022-01685-0. https://pubmed.ncbi.nlm.nih.gov/35536449/
- Cox GR, et al. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. J Appl Physiol (1985) 2010;109(1):126–134. PMID:20466803. DOI:10.1152/japplphysiol.00950.2009. https://pubmed.ncbi.nlm.nih.gov/20466803/
- Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc 2008;40(2):275–281. PMID:18202568. DOI:10.1249/mss.0b013e31815adf19. https://pubmed.ncbi.nlm.nih.gov/18202568/
- Glaister M, et al. Caffeine and Physiological Responses to Submaximal Exercise: A Meta-Analysis. Int J Sports Physiol Perform 2018;13(4):402–411. PMID:28872376. DOI:10.1123/ijspp.2017-0312. https://pubmed.ncbi.nlm.nih.gov/28872376/
- Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med 2014;44 Suppl 1:S25–S33. PMID:24791914. DOI:10.1007/s40279-014-0148-z. https://pubmed.ncbi.nlm.nih.gov/24791914/
- Kerksick CM, et al. International society of sports nutrition position stand: nutrient timing. J Int Soc Sports Nutr 2017;14:33. PMID:28919842. DOI:10.1186/s12970-017-0189-4. https://pubmed.ncbi.nlm.nih.gov/28919842/
- Maughan RJ, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med 2018;52(7):439–455. PMID:29540367. DOI:10.1136/bjsports-2018-099027. https://pubmed.ncbi.nlm.nih.gov/29540367/
- Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet 2016;116(3):501–528. PMID:26920240. DOI:10.1016/j.jand.2015.12.006. https://pubmed.ncbi.nlm.nih.gov/26920240/
- Veniamakis E, et al. Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports. Int J Environ Res Public Health 2022;19(6):3651. PMID:35329337. DOI:10.3390/ijerph19063651. https://pubmed.ncbi.nlm.nih.gov/35329337/
- SiS Official Website Product Information: https://scienceinsport.com.hk/collections/all-products
