Supplements for endurance and resistance: carbohydrates, electrolytes, gels and strategies for running and cycling

Summary: A practical and scientific guide on how to use carbohydrates, electrolytes, gels, and other nutritional strategies during running and cycling training and competitions. Includes recommendations based on duration and intensity, prevention of gastrointestinal problems, carbohydrate loading periodization, sample intake plans, and scientific references.

Introduction: Why nutrition matters in running and cycling

In endurance sports like running and cycling, the availability of energy substrates and fluid and electrolyte balance directly influence performance, the ability to maintain pace, and subsequent recovery. Glycogen stores are limited and, depending on the intensity, can be depleted in 90–120 minutes. Therefore, supplementation during races—carbohydrates, electrolytes, and convenient formats like gels or drinks—is a key tool for sustaining effort, delaying fatigue, and improving time to exhaustion.

Basic concepts: energy, glycogen, and carbohydrate oxidation

The body primarily uses carbohydrates and fats as energy sources. At moderate to high intensities, the percentage of energy derived from carbohydrates increases. Muscle and liver glycogen stores are finite (approximately 300–600 g in muscle and 80–100 g in liver, depending on body mass and diet), and their depletion is associated with a marked decrease in performance.

The rate at which we can oxidize carbohydrates per hour depends on the type of carbohydrate ingested and intestinal capacity. With a single sugar source (e.g., glucose or maltodextrin), maximum oxidation is usually around 60 g/h. Combining sugars with different intestinal transporters (e.g., glucose + fructose in a ~2:1 ratio) makes it possible to achieve ~90 g/h more in adapted athletes, while also reducing the risk of GI problems and maximizing carbohydrate delivery to the muscle ( Jeukendrup & Jentjens, 2006 ).

Types of carbohydrate supplements

• Isotonic drinks : combine carbohydrates (usually 6–8%) with electrolytes. Useful for long sessions where you simultaneously need hydration.
• Energy gels : concentrated carbohydrates (20–30 g per typical gel) and sometimes with electrolytes and caffeine. They are practical due to their format and digestibility.
• Bars and solids : more caloric and chewable; used in ultradistances or cycling, but can cause a greater GI load if used at a high pace.
• Powders and mixes : Powdered carbohydrates that can be mixed in a bottle or container. They allow for easy concentration adjustment.
• Carbohydrate blended gels : formulations that combine dextrose/maltodextrin with fructose to improve absorption.

Electrolytes: when and why

Electrolytes (sodium, potassium, magnesium, calcium) are involved in regulating plasma volume, fluid balance, muscle contraction, and nerve function. During prolonged exercise or in hot conditions, sodium loss through sweat can be significant; replenishing sodium along with water reduces the risk of hyponatremia and helps maintain performance. Replenishment should be individualized based on sweat rate and sweat composition (some people lose more sodium than others).

Studies and positionings recommend drinking to maintain performance, and sodium in the drink or in tablets helps stimulate thirst and improve fluid retention ( Sawka et al., 2007 - ACSM Position Stand ).

Strategies according to test duration

Races or training sessions < 45–60 minutes

In short, intense efforts, carbohydrate intake during activity is not mandatory if there has been adequate pre-exercise fueling and breakfast before exercise. However, small amounts of carbohydrates (e.g., a caffeinated gel) can improve performance in near-threshold tests (caffeine ergogenic stimulus).

45–75 minutes

Gels or drinks with 20–30 g of carbohydrates can help in the final stretch. When cycling, an isotonic drink in a bottle is practical.

75–150 minutes (1.5–2.5 h)

This is the range where supplementation during exercise makes a difference. General recommendation: 30–60 g of carbohydrates per hour, depending on tolerance and activity level. For sessions around 2 hours long, alternating between drinks and gels can help maintain stable blood glucose levels.

+150 minutes (ultramarathons, marathons and long-distance cyclists)

Starting at 2.5–3 hours, increase intake to 60–90 g/h by combining transportable carbohydrates (glucose + fructose). Include regular salt/electrolyte replacement to replace losses and consider introducing solids if tolerated. Plan feedings every 20–30 minutes to maintain a steady supply.

Gels: how to choose and use

Energy gels are practical due to their size, weight, and ease of consumption. When choosing:(/p>

• Look at the grams of carbohydrates per gel (20–30 g commonly).
• Check if it includes fructose in addition to glucose/maltodextrin (useful for >60 g/h).
• Look for the presence of sodium (100–200 mg per gel) if you sweat a lot.
• Consider using caffeine gels in short/decisive competitions (ergogenic 2–3 mg/kg in competition).

How to use them: Take a gel with water, not just on a dry mouth. Water helps dilute it and facilitates gastric emptying. If you take many gels in a row, alternate with an isotonic drink to replenish fluids and electrolytes.

Carbohydrate combinations: why it matters

Intestinal absorption depends on specific transporters. Glucose and its polymers use SGLT1; fructose uses GLUT5. Using multiple sources allows for greater carbohydrate entry into the bloodstream, increasing oxidation and energy delivery to the muscles. This is why many ultra-running drinks and gels recommend blends (e.g., maltodextrin + fructose) to approach absorption rates of 90 g/h.

Reference: Cermak & van Loon, 2013 ; Jeukendrup, 2010 .

Hydration: a matter of practice, not feeling

There are two main risks: dehydration and overhydration (hyponatremia). The optimal strategy is to drink according to weight loss and environmental conditions. Measuring weight loss during training (pre/post weight) allows you to calculate sweat rate and plan fluid and sodium intake.

• If the weight loss is less than 2% of body weight, performance will probably not be compromised. For larger weight losses, performance usually declines.
• Avoid excessive drinking to prevent hyponatremia; not everyone needs to drink at the rate dictated by thirst, but neither should they completely ignore it.
• It includes sodium: 300–700 mg/h in hot conditions may be appropriate for many athletes, but should be adjusted individually.

Reference: Sawka et al., 2007 (ACSM) .

Practical strategies by event type

10K and half marathon

• Prioritize carbohydrate loading at night and breakfast before the race (2–4 g/kg depending on tolerance).
• If the test is <75 min, carbohydrates during the race are not essential; a gel 15–20 min before can help.
• Light hydration: drink small sips during the journey.

Marathon (42.195 km)

• Carbohydrate loading 24–48 h before (7–12 g/kg/day in the days prior for aggressive loading or 6–10 g/kg/day for greater practicality) according to tolerance and objectives.
• During the race: 60–90 g/h is ideal if intestinal tolerance is trained (combining glucose+fructose); for practicality, 30–60 g/h is effective for most.
• Plan: gel every 20–30 min + water; alternate with isotonic drink where available.

Long-distance cycling and Gran Fondo

• In cycling it's easier to carry food: combine energy bars, gels and water bottles.
• For 3–6 hour events: 60–90 g/h with a carbohydrate mix. Use flasks with 6–8% carbohydrates and gels for energy spikes or sprints.
• Replenish sodium, especially during heat and long climbs.

Prevention and management of gastrointestinal (GI) problems

Gastrointestinal (GI) problems (nausea, abdominal cramps, diarrhea) are common in endurance efforts. Strategies to minimize them:

• Train your intake: practice with the same brands/formulations during long training sessions.
• Avoid drastic changes to food or new drinks on race day.
• Use moderate carbohydrate concentrations and drink water with the gels.
• Consider bowel training to increase tolerance to carbohydrate volumes and rates.
• Control fiber and fats in pre-competition food; reduce the risk of discomfort.

Research suggests that bowel training may increase transport and decrease GI symptoms by increasing transporter expression and neural tolerance ( Costa et al., 2017 ).

Nutritional periodization and carbohydrate loading

Classic carbohydrate loading involves increasing carbohydrate intake in the 24–72 hours prior to an event to maximize glycogen stores. Multiple protocols exist: short, high-intake loading (36–48 hours with 10–12 g/kg/day) or more moderate loading (24 hours with 6–10 g/kg). The choice depends on the athlete and their gastrointestinal tolerance.

Alternatives include the "train low, compete high" strategy, which alternates training with low carbohydrate availability to promote oxidative adaptations, while maintaining high availability on competition days. This strategy should be implemented with planning and professional supervision.

Complementary supplements: caffeine, beta-alanine, BCAAs, etc.

Some non-energy supplements offer benefits in endurance:

• Caffeine : 3–6 mg/kg ingested 30–60 minutes before or in small doses during the event can improve concentration, reduce perceived exertion, and enhance performance. It is also used in caffeinated gels for short/decisive efforts.
• Beta-alanine : helps buffer hydrogen ions during prolonged intense efforts, but its effect is more on intermittent high-intensity efforts; requires chronic supplementation (2–6 g/day, for 4 weeks).
• Nitrates (beetroot) : may improve exercise efficiency in some cases, especially in submaximal tests.
• Electrolytes and sodium : sodium tablets or sodium-containing drinks in ultradistances to maintain balance.

Avoid mixing supplements without knowing the interactions. Consult a professional before starting any combined routines.

Practical examples of intake plans

90-minute training/race (e.g., partial marathon, intense long run)

• Pre: breakfast 2–3 h before (1–2 g/kg of easily digestible carbohydrates).
• Start: 1 gel 10–15 min before with 150–200 ml of water.
• During: 30–60 g/h => 25 g gel every 25–30 min with sips of isotonic drink.
• Post: 1 g/kg carbohydrates in the first hour + 20–25 g protein for recovery.

Cycling 4–6 hours

• Pre: a high-carbohydrate meal the night before and breakfast 2–3 hours before.
• During: 60–90 g/h combining isotonic drink (6–8% carbohydrates) with gels or bars. Take sodium 300–700 mg/h depending on sweat rate.
• Drinking plan: Drink 500–750 ml/h (adjust by sweat rate), gel every 20–30 min if more carbohydrate intake is needed.

How to calculate your needs: target per hour and per intake

1. Determine the expected duration. 2. Choose a target carbohydrate intake per hour (30–60 g/h for most; 60–90 g/h if trained). 3. Divide into regular intakes: e.g., every 20–30 min. 4. Be sure to include water with each gel to aid digestion.

Example: For 75 g/h with 25 g gels => one every 20 minutes = 3 gels/h (3 x 25 = 75 g). If you use a drink with 40 g per bottle and 25 g gels, adjust to maintain the target.

Trial and error: the only sure way to know what works

Every athlete is different. Sugar tolerance, sweat rate, and digestive response vary. That's why it's essential to conduct trials during long training sessions that simulate competition conditions. Change only one variable at a time (e.g., type of gel, drink concentration) to determine what causes improvement or problems.

Quick comparison table (practical format)

Format	Carbohydrates / intake	Advantages	Disadvantages
Isotonic drink	20–60 g/h (depending on volume and %)	Hydration + electrolytes	Lower caloric density than gels
Energy gel	20–35 g per gel	Portable, fast	It can cause irritation if taken without water.
Bar	20–60 g per bar	More satiating, useful for ultra-distances	Difficult to chew at high speeds
Powder (drum)	flexible (adjustable)	Versatile, economical	Preparation required

Practical cases with examples of brands and combinations

Below are suggested intake guidelines based on event type. Adjust amounts according to your weight, tolerance, and goals.

Marathon - target 60 g/h (average runner)

• Pre: breakfast 3 hours before (white bread, banana, little fiber).
• 10–15 min before: gel with 20–25 g carbohydrates + 150 ml water.
• Every 30 minutes: 25g gel + water (every 30 minutes => 50g/h if you take 2 gels/h). To reach 60g/h, alternate with a light isotonic drink at aid stations.

Gran Fondo cycling - target 75 g/h

• Bottle: Foodelis Carbohydrate Mix (6–8%) throughout the journey.
• In addition: Foodelis Maltodextrin+Fructose gel every 20–25 min (25 g per gel).
• Dissolve Foodelis electrolyte tablets in the water bottle every 60–90 min if it is hot.

Homemade recipes and how to prepare your own drink

If you prefer homemade alternatives, you can prepare an isotonic drink with:

• 500 ml of water
• 30–40 g of maltodextrin or dextrose (6–8% solution)
• ¼ teaspoon of salt (approx. 300–400 mg of sodium)
• Optional: natural juice (without pulp) for some fructose

Mix well and adjust flavor and concentration according to tolerance. Remember that mixtures with fructose can increase tolerance and overall oxidation if used in the wrong combinations.

Legal and anti-doping aspects

Most ingredients in gels and drinks (carbohydrates, electrolytes, caffeine in common doses) are not prohibited. However, some supplements may be contaminated or contain undeclared substances. Buy from reputable, certified brands and check the ingredient list. For competitive athletes, using products with third-party certifications (e.g., Informed-Sport) reduces the risk of testing positive due to contamination.

Common myths debunked

• Myth 0: "More carbs are always better" — Proven: there is an absorption limit and excesses can cause GI discomfort. It's best to train your tolerance and adjust your target (30–90 g/h).
• Myth 0: "Drinking only water is enough" — During prolonged exertion and heavy sweating, a lack of sodium and carbohydrates impairs performance. Replenishing only water can cause hyponatremia.
• Myth 0: "Gels make you fat" — Body weight is managed by total energy balance; in competition, carbohydrates are necessary for performance, they do not "make you fat" on their own.

Selected scientific references

• Jeukendrup A, Jentjens R. Oxidation of carbohydrates during exercise: the role of multiple transportable carbohydrates. Sports Med. 2006;36(7):667-677. PubMed .
• Cermak NM, van Loon LJ. The use of carbohydrates during exercise as an ergogenic aid. Sports Med. 2013;43 Suppl 1:S1-S25. PubMed .
• Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. Exercise and Fluid Replacement. Med Sci Sports Exerc. 2007;39(2):377-390. PubMed .
• Costa RJS, Snipe RMJ, Kitic CM, Gibson PR. Systematic review: Exercise-induced gastrointestinal syndrome- implications for health and intestinal disease. Aliment Pharmacol Ther. 2017;46(3):246-265. PubMed .
• Jeukendrup AE. Carbohydrate intake during exercise and performance. Nutrition. 2004;20(7-8):669-677. PubMed .

Frequently Asked Questions (FAQ)

How much should I take if I weigh 70 kg and run for 3 hours?

If you're trained to tolerate 60–90 g/h, you can aim for 60–75 g/h as a starting point. For a 70 kg person, 60 g/h is reasonable; combine gels and isotonic drinks and train at that rate on long rides.

Can I use only gels without drinking anything?

Not recommended. Taking gels without water can increase GI discomfort and delay gastric emptying. Always accompany with sips of water or an isotonic drink.

What if I can't swallow while running (nausea)?

Stop drinking, reduce your energy intake, take small sips of water, and wait to recover. Training your intake, reducing concentrations, and avoiding fats/fibers before a race helps prevent this scenario.

Conclusion: Plan, train, and adjust

Carbohydrate and electrolyte supplementation is a core strategy in endurance sports. There's no single formula: the key is understanding your sweat rate, your gut tolerance, and training for the strategy you'll use in competition. For short events, a single gel is sufficient; for long races, it's advisable to combine drinks, gels, and electrolytes. Use products tested in training (for example, Foodelis' options such as gels, drinks, and electrolyte tablets) and adjust the amounts to your weight and environmental conditions.

Final tip: Write down and test your nutrition plan during at least 2-3 long training sessions before using it in competition. This reduces risks and gives you confidence on race day.