Endurance supplements: carbohydrates, electrolytes, and iron
Endurance sports require specific nutritional preparation where an endurance supplement plays a decisive role. Whether you're preparing for a marathon, half-marathon, triathlon, or any other endurance sport, improving your nutrition with the right supplements can transform your performance and recovery.
Why use an endurance supplement?
Endurance sports intensely tax the body's energy reserves and physiological systems. A well-chosen endurance supplement allows you to:
- Maintain a stable energy level over time
- Delay the onset of muscle fatigue
- Improve hydration and electrolyte balance
- Accelerate recovery between sessions
- Preserve muscle mass during high-volume training
Unlike strength sports, where the focus is on explosive power, endurance requires a specialized nutritional approach centered on continuous energy supply and prolonged effort management.
Carbohydrates: the primary fuel for endurance supplements
For long outings, the choice of carbohydrate matters as much as the quantity: we detail the case of branched cyclodextrin in our article on Cluster Dextrin during exercise, and more classic alternatives in our maltodextrin section.
In our store
A 25g serving provides 24g of Cluster Dextrin, a highly branched dextrin, with no added sugar.
Endurance energy drinks
Energy drinks are the most commonly used endurance supplement during exercise. They combine carbohydrates with varied glycemic indexes, electrolytes, and sometimes caffeine to maintain performance.
Correct composition of an endurance drink:
- 30-60g of carbohydrates per hour depending on intensity
- Maltodextrin/fructose ratio 2:1 to improve absorption
- Sodium 300-700mg/L to compensate for sweat losses
- Potassium and magnesium for electrolyte balance
This nutritional strategy is particularly crucial for marathon nutrition where liver and muscle glycogen reserves are depleted after 90-120 minutes of effort.
Energy gels and endurance bars
Energy gels represent a practical and rapidly assimilated endurance supplement. Their liquid texture facilitates swallowing even during intense efforts, while their carbohydrate concentration (20-30g per gel) allows for precise dosing.
Correct usage protocol:
- First gel after 45-60 minutes of effort
- Then one gel every 30-45 minutes
- Always accompany with water to facilitate absorption
- Test during training before any competition
OLIMP
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Electrolytes: the vital balance of endurance supplements
The question of the drink itself deserves its own development: see the role of electrolytes in athletes to know what to replace, in what quantity, and when.
In our store
A 5.5g serving provides 300mg of sodium, 460mg of chloride, 99mg of potassium, 60mg of magnesium, and 50mg of calcium.
Sodium and hydration maintenance
Sodium is the most critical electrolyte in an endurance supplement. Sodium losses through sweating can reach 1-3g per hour depending on climatic conditions and individual perspiration.
Sodium deficiency causes:
- Muscle cramps
- Hyponatremia (in extreme cases)
- Decreased fluid retention
- Reduced cognitive performance
Electrolyte supplements in effervescent tablets or powder provide a targeted intake, particularly useful for half-marathon nutrition and long events.
Magnesium and muscle function
Magnesium is involved in more than 300 enzymatic reactions, especially those related to ATP production. Magnesium contributes to normal muscle function and normal energy metabolism: these are the only two authorized formulations in Europe, and they are enough to explain why it appears in almost all endurance routines.
Recommended dosage: 200-400mg per day, preferably in the evening to promote nocturnal recovery.
Endurance supplements for cellular energy
Creatine for endurance
Although traditionally associated with strength sports, creatine offers benefits for endurance. This endurance supplement improves ATP resynthesis during acceleration phases and supports recovery between training intervals.
Regarding the timing of intake, rest days, and the famous loading phase, everything is covered in our guide on creatine intake timing.
Endurance-specific protocol:
- 3-5g per day in a single post-workout dose
- No loading phase necessary
- Possible combination with carbohydrates to improve absorption
Coenzyme Q10: the energetic antioxidant
CoQ10 plays a central role in the mitochondrial respiratory chain. It's important to be clear about its status: no health claims have been authorized in Europe for coenzyme Q10, and available studies in athletes show mixed results depending on the protocols and duration of supplementation. What is established is its role in the functioning of the mitochondrial respiratory chain. The rest is hypothetical, and we will not present it otherwise.
L-carnitine and fat metabolism
L-carnitine facilitates the transport of fatty acids to the mitochondria for oxidation. This is a documented metabolic role, but it does not lead to an authorized claim: EFSA rejected applications for L-carnitine, and supplementation only slightly increases muscle concentrations in a person whose diet is already correct. Consider it a complementary supplement, not a performance lever.
Commonly used dosages: 2 to 3g before training, preferably with carbohydrates, which facilitate entry into the muscle.
Adaptation and recovery: advanced endurance supplements
Branched-chain amino acids (BCAAs)
BCAAs are a particularly useful endurance supplement during long sessions. They can serve as an auxiliary energy substrate when glycogen levels drop. Note, however: if your intake of complete proteins is sufficient throughout the day, their specific interest becomes very debatable.
Correct ratio: 2:1:1 (leucine:isoleucine:valine) Timing: During effort for sessions exceeding 2 hours
Glutamine: what do we really know?
Glutamine is the most abundant amino acid in muscle, and it's also one of the best-selling. However, it has no authorized claims in Europe: neither on immunity, nor on recovery, nor on the intestine. The studies that best document it focus on hospitalized patients, not runners.
We list it because it's requested, and because it's safe at usual doses. But if your budget is limited, it's not where we would advise you to start.
Beta-alanine for lactic power
Beta-alanine increases muscle carnosine concentrations, a natural buffer against acidosis. This endurance supplement improves performance in intense efforts lasting one to four minutes, and in repeated sprints.
Beta-alanine is not taken as a one-off pre-workout: it requires a course of supplementation. We explain the daily dose, duration, and tingling in our article dedicated to beta-alanine.
Loading protocol: 3-5g per day for 4-6 weeks, divided into 800mg doses to avoid paresthesia.
Trained by JP
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Should you take antioxidants?
Vitamins C and E: the nuance that matters
Endurance exercise does indeed generate oxidative stress. The authorized claims are precise: vitamin C and vitamin E contribute to protecting cells from oxidative stress, and vitamin C contributes to the normal function of the immune system.
But there's a downside: several studies suggest that high-dose antioxidant supplementation, taken continuously, can blunt training adaptations — it's precisely oxidative stress that triggers some of these adaptations. Therefore, stick to reference intakes rather than megadoses, and never exceed the maximum doses indicated on the label.
Polyphenols
Quercetin, resveratrol, curcumin: these molecules are extensively studied and widely marketed, but none have obtained claims in Europe. Therefore, we will not attribute any anti-inflammatory action or effect on recovery to them.
Nutritional strategies by type of endurance
Marathon nutrition: specific protocol
Marathon nutrition requires a carbohydrate loading strategy (carb loading) in the days leading up to the race, followed by a regular intake during the event.
Pre-marathon protocol:
- D-7 to D-4: Degenerative training with normal diet
- D-3 to D-1: Rest with carbohydrate loading (8-10g/kg body weight)
- Race Day: Breakfast 3-4 hours before, rich in carbohydrates
During the marathon:
- 30-60g of carbohydrates per hour after the first hour
- Alternating gels/energy drinks depending on tolerance
- Maintaining hydration without over-hydrating
Half-marathon nutrition: the intermediate distance
Half-marathon nutrition allows for more flexibility than a full marathon. The duration of effort (1h15 to 2h30 depending on skill level) places this event at the limit of natural carbohydrate reserves.
Half-marathon nutritional strategy:
- No carbohydrate loading necessary
- Usual breakfast 2-3 hours before the start
- One energy gel at the 10th km for slower runners
- Hydration primarily with water and electrolytes
Cyclic sports: cycling, swimming, triathlon
These disciplines require endurance supplements adapted to specific constraints:
Cycling: Ease of fueling allows for the use of energy bars and concentrated drinks.
Swimming: Limited to pre- and post-exercise intake, importance of BCAAs to limit catabolism.
Triathlon: Complex nutritional management across three disciplines, primarily requiring liquid supplements.
Timing and periodization of endurance supplements
Base training phase
During this period of aerobic development, the focus is on:
- Multivitamins to cover increased needs
- Omega-3: EPA and DHA contribute to normal heart function from 250 mg per day
- Iron if necessary (especially in women)
- Probiotics to maintain gut health
Pre-competition tapering phase
The last few weeks before the goal require:
- Improvement of glycogen stores
- Antioxidant reinforcement
- Testing of race endurance supplements
- Immune system support
Recovery period
After intense effort, the priority is:
- Rapid replenishment of reserves (carbohydrates + proteins)
- Rehydration with electrolytes
- Support for restorative sleep
NOW FOODS
Now Foods Iron 18 mg - Ferrochel™ Chelated Ferrous Bisglycinate
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Precautions and interactions
Safety of endurance supplements
The use of endurance supplements must respect certain precautions:
Anti-doping controls: Check product certification for licensed athletes.
Drug Interactions: Consult a healthcare professional if taking other medications concurrently.
Individual Tolerances: Always test during training before using in competition.
Warning Signs
Innovation and Future Prospects
Emerging Endurance Supplements
Research continues to develop new endurance supplements:
Exogenous Ketones: An alternative energy source to carbohydrates for some athletes.
Nitrates: Improve energy efficiency by enhancing nitric oxide metabolism.
Specific Probiotics: Bacterial strains selected for their benefits on endurance.
Genetic Personalization
The future of endurance supplements is moving towards personalization based on:
- Genetic polymorphisms affecting metabolism
- Individual gut microbiome
- Personalized metabolic profiles
Key Takeaways on Endurance Supplements
Endurance supplements are a valuable tool for any endurance athlete looking to improve their performance. However, their effectiveness depends on a methodical, individualized, and progressive approach.
Marathon nutrition and half-marathon nutrition clearly illustrate the importance of adapting the nutritional strategy to the specific demands of the event. Whether you're aiming for a specific time goal or simply the pleasure of finishing your race, the right endurance supplements can make the difference between succeeding and excelling.
Always remember that these supplements are complementary to a balanced diet and appropriate training. Consult a sports nutritionist to develop a personalized and safe strategy, especially if you are preparing for your first endurance event.
Endurance is built day by day, and your nutrition must support this progression with the same rigor as your training. Investing in the right endurance supplements is investing in your potential for athletic achievement.
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