Hydration as a pillar of performance

Hydration is not just a matter of comfort during exercise; It is a physiological determinant of performance and health. During exercise, especially in endurance sports, a progressive loss of water and electrolytes occurs through sweat. This loss impacts:

• The plasma volume
• The thermoregulatory capacity
• cardiac output
• The perception of effort
• neuromuscular function

Dehydration equivalent to 2% of body weight can already compromise aerobic performance. In hot contexts or prolonged sessions, the impact may be greater.

However, not all hydration strategies are created equal. The composition of the drink—especially its concentration of solutes—determines its physiological effect.

Types of drinks according to their osmolarity: what is each one for?

The classification into hypotonic, isotonic and hypertonic drinks is based on their osmolarity with respect to plasma (~275–295 mOsm/kg).

a) Hypotonic drinks

They contain a lower concentration of solutes than plasma.

What are they for?

• Rapid rehydration
• Short duration or low intensity sports
• Situations where the priority is to absorb water quickly

By having a low concentration of solutes, they promote rapid gastric emptying and efficient intestinal absorption of water.

b) Isotonic drinks

They have a concentration similar to that of plasma.

What are they for?

• Moderate-high intensity endurance sports
• Simultaneous replacement of water and electrolytes
• Competition in hot conditions

They balance water replacement and energy intake (carbohydrates), being the classic option in events >60 minutes.

c) Hypertonic drinks

They have a higher concentration of solutes than plasma.

What are they for?

• Mineral replacement in situations of high sweating
• Post-exercise phase for electrolyte recovery
• Specific strategies in ultra-endurance sports

They are not designed for immediate rehydration during intense exercise, as they may slow gastric emptying if consumed in large volumes without dilution.

This is where the filtered seawater is located.

Sea water as a hypertonic drink

The HYDRAZERO SEA WATER product from 226ERS is a drink composed of 100% filtered seawater, presented in 20 mL sticks.

Each stick provides approximately:

• 220 mg sodium
• 26 mg magnesium
• 360 mg chloride
• More than 80 trace elements

Its concentration (2.75 g of salt per 100 mL) gives it a hypertonic character.

What does scientific evidence say about seawater in sports?

Rigorous scientific studies on the ingestion of seawater in endurance athletes indicate:

• Possible improvement in recovery of electrolyte balance.
• Potential reduction of muscle damage markers in some protocols.
• No consistent evidence of direct acute performance improvement.

In practical terms, seawater cannot be said to improve performance per se, but it could play a role in mineral replenishment.

Sodium: risk-benefit

Sodium is the main extracellular cation, responsible for hydration and fluid retention, in addition to fulfilling essential functions:

• Maintains plasma volume
• Participates in nerve transmission
• Regulates muscle contraction
• Facilitates intestinal glucose transport (sodium-glucose cotransport)

during exercise

In endurance sports, sodium losses can range between 300 and 1500 mg per hour, depending on the individual and the environment.

Proper replenishment can:

• Reduce the risk of dilutional hyponatremia
• Maintain blood pressure during prolonged efforts
• Optimize intestinal absorption of fluids

Is there risk?

Given that sodium is highly present in seawater, studies indicate that chronic consumption of highly saline water (>200 mg/L sodium) is associated with a higher risk of hypertension in general populations.

However, it is key to distinguish:

• Chronic daily consumption
• Occasional use in a sports context with high sweating

In athletes with high sodium losses, the risk-benefit balance can lean towards benefit, provided that:

• There is no diagnosed hypertension
• No kidney disease
• It is used strategically and not as indiscriminate daily consumption

Potential benefits of hypertonic seawater in sports

1. Concentrated sodium replacement without the need for large volumes.
2. Contribution of magnesium, relevant in muscle contraction and reduction of fatigue.
3. Complete mineral profile from natural source.
4. Useful in athletes with high sweating rates or sodium losses.

Risks and limitations of the use of seawater

• It is not a primary hydration drink during intense exercise.
• It may cause gastrointestinal discomfort if ingested undiluted in large quantities.
• It is not a substitute for a complete hydration strategy.
• Scientific evidence still limited in sample size.

Practical recommendations for athletes and coaches

Before exercise

It can be used as a mineral supplement before long sessions in heat.

during exercise

Best diluted in water.

Useful in long-term tests (>2–3 h) with high sweating, although isotonic or hypotonic drinks may be more recommended.

After exercise

Interesting for recovering sodium and magnesium after prolonged efforts.

Always individualize

Evaluate:

• Sweat rate
• Sodium concentration in sweat
• Duration of effort
• Environmental conditions

It is not a universal substitute for isotonic drinks.

Final synthesis

Filtered seawater, such as that proposed by 226ERS, is a hypertonic drink rich in sodium and minerals that can play a strategic role in electrolyte replacement in endurance sports.

Current scientific evidence suggests:

• Potential benefit in mineral recovery
• Lack of strong evidence of direct performance improvement
• Need to contextualize its use

Sodium is essential for endurance performance, but its consumption must be strategic and adapted to the real physiological demands of the athlete.

Conclusion

Hydration in sports is not just a matter of water, but of electrolyte balance.

• Hypotonic drinks hydrate quickly.
• Isotonic balance energy and fluids.
• Hypertonic ones, such as sea water, provide concentrated minerals.

Seawater can be a useful tool in specific contexts of high physiological demand, always within an individualized and evidence-based strategy.

As in any nutritional intervention in sports: context is everything.