What Is a Sports Drink, Actually?
The term "sports drink" covers a wide range of products: isotonic drinks, hypotonic drinks, hypertonic drinks, electrolyte tablets, and energy drinks — all different things for different purposes and different situations.
This guide gives you a concrete decision framework: when do you need a sports drink, which type, in what amount — and when is plain water simply the better choice.
TL;DR
- Water is the best choice for most workouts under 60 minutes
- Isotonic sports drinks help in sessions over 60 minutes, especially in heat
- 6–8% carbohydrate concentration is optimal for gastric emptying and absorption
- DIY sports drink: 500 ml water + 30 g sugar + 0.5 g salt + lemon juice
- Available in Estonia: Isostar, SiS Beta Fuel, Nuun electrolyte tabs, Gatorade
Three Core Types: The Osmolality Science
Sports drink classification is based on osmolality — the concentration of dissolved solutes compared to blood plasma (~280–295 mOsm/kg).
Isotonic Drinks (270–330 mOsm/kg)
Carbohydrate concentration: 4–8% (40–80 g/L)
Isotonic drinks absorb faster than plain water because their osmolality matches blood. They provide:
- Sodium replenishment (typically 400–700 mg/L)
- Carbohydrates as exercise fuel
- Efficient fluid replacement
When to use: Prolonged exercise >60 min, training in heat, running/cycling/swimming competitions.
Examples: Gatorade Thirst Quencher, Isostar Hydrate & Perform, PowerBar Isoactive
Hypotonic Drinks (<270 mOsm/kg)
Carbohydrate concentration: <4% (<40 g/L)
Hypotonic drinks absorb fastest because fluid moves down the osmotic gradient toward blood plasma. Best for:
- High-intensity short aerobic sessions where fluid replacement is the priority
- Winter sports where carbohydrate demand is lower
- Use alongside gels or bars for separate carbohydrate delivery
Examples: Nuun electrolyte tablets, SiS Hydro tablets, diluted sports drink solutions
Hypertonic Drinks (>330 mOsm/kg)
Carbohydrate concentration: >8% (>80 g/L)
Hypertonic drinks (energy drinks, carbonated drinks, concentrated juices) absorb more slowly than blood plasma because the body must draw water into the gut to dilute the solution.
- Provide more carbohydrates but risk GI distress during exercise
- Better used for recovery (post-workout) than during exercise
- Too sugar-dense for effective hydration during intense training
Examples: Energy drinks (Red Bull, Monster), concentrated fruit juices
Electrolytes: Why Sodium Is Key
For electrolyte replacement, sodium is the most critical component — not potassium or magnesium (though both matter).
The ACSM position stand by Sawka et al. (2007, Medicine & Science in Sports & Exercise) established:
- Sweat contains 20–80 mmol/L sodium (average ~46 mmol/L)
- Sodium loss per hour is 500–1,500 mg depending on intensity and climate
- Sodium stimulates thirst and helps maintain plasma volume
- Electrolyte replacement becomes critical in sessions exceeding 2 hours
Hyponatremia risk: Shirreffs & Sawka (2011, Journal of Sports Sciences) emphasise that athletes who drink only water during long events risk exercise-associated hyponatremia (dangerous blood sodium dilution). This is particularly relevant for marathon runners and triathletes.
Sodium Content in Common Products
| Product | Sodium per 500 ml |
|---|---|
| Gatorade Thirst Quencher | ~220 mg |
| Isostar Hydrate & Perform | ~210 mg |
| Nuun Electrolyte Tablets | ~360 mg |
| DIY recipe | ~250 mg |
| Plain water | 0 mg |
Carbohydrate Concentration: What Is Optimal?
Jeukendrup (2010, Current Opinion in Clinical Nutrition and Metabolic Care) established the optimal carbohydrate concentration framework:
- <4%: Fast absorption, minimal energy
- 4–8%: Optimal balance of gastric emptying rate and energy delivery — the target for most sports drinks
- >8%: Slower absorption, GI distress more common during exercise
The type of carbohydrate also matters:
- Glucose + fructose (2:1 to 1:1 ratio) absorbs faster than glucose alone, using two different transporters (GLUT2 and SGLT1)
- This ratio allows up to 90 g carbohydrate per hour vs 60 g/hour with glucose alone (Jeukendrup & Moseley, 2010)
SiS Beta Fuel and Maurten 320 use precisely this glucose:fructose ratio.
When Is Water Enough?
This is the crucial question. Sports drink marketing targets all athletes, but the science is specific:
Water is sufficient when:
- Exercise lasts under 60 minutes
- Exercise intensity is not high (moderate weight training, yoga, walking)
- Training in cool conditions
- You consumed carbohydrates in a meal before training
A sports drink is recommended when:
- Exercise exceeds 60 minutes at high intensity
- Training in heat and/or high humidity
- You sweat heavily (white salt stains on clothing = high sodium loss)
- Performing prolonged endurance exercise (marathon, triathlon, mountain biking)
- Training twice a day
DIY Sports Drink Recipe
Commercial sports drinks are expensive. Simple homemade version:
Basic Recipe (500 ml):
- 500 ml water
- 30 g (2 tablespoons) sugar or dextrose (6% concentration)
- 0.5 g (~1/8 tsp) table salt (~200 mg Na+)
- Lemon juice or raspberry syrup for taste
For longer sessions (>90 min):
- 500 ml water
- 40 g sugar + 10 g fructose (or add orange juice)
- 0.75 g salt (~300 mg Na+)
- Lemon juice
Cost: ~€0.05–0.10 per bottle vs €1.50–2.50 for commercial products.
Sports Drinks Available in Estonia: Comparison
| Product | Type | Na+ mg/500 ml | Carbs g/500 ml | Price |
|---|---|---|---|---|
| Gatorade Thirst Quencher | Isotonic | 220 | 29 | ~€1.50 |
| Isostar Hydrate & Perform | Isotonic | 210 | 34 | ~€1.80 |
| SiS Beta Fuel Drink | Isotonic | 270 | 40 | ~€2.50 |
| Nuun Electrolyte Tabs | Hypotonic | 360 | 3 | ~€1/tab |
| Powerade ION4 | Isotonic | 165 | 32 | ~€1.20 |
| DIY homemade | Isotonic | ~200 | ~30 | ~€0.08 |
In Estonia, sports drinks are available at Selver, Rimi, Maxima, and sports shops. Sport-specific products (SiS, Maurten, GU) are available at MaxFit.ee and international sports nutrition platforms.
Common Mistakes to Avoid
Mistake 1: Using Sports Drinks During Weight Loss
Commercial sports drinks contain 120–240 kcal/L. If your goal is weight loss and your workout lasts under 60 minutes, you are adding unnecessary calories in liquid form.
Mistake 2: Mixing Energy Drinks with Sports Drinks
Energy drinks (Red Bull, Monster) are hypertonic, contain caffeine, and are designed for alertness, not hydration. Using them during training can cause dehydration and GI distress.
Mistake 3: Starting Hydration Too Late
Hydration should begin before training, not when you feel thirsty. Thirst signals that >1% body weight fluid loss has already occurred — performance is already compromised.
Mistake 4: One-Size-Fits-All Approach
Electrolyte and carbohydrate needs vary with body weight, sweat rate, climate, and exercise type. Personalisation matters for optimal performance.
Frequently Asked Questions
Are sports drinks appropriate for children?
Children need electrolyte replacement on the same principles as adults. But most commercial sports drinks are formulated for adults — sugar content may be inappropriately high for habitual use by children. Water is typically the best choice for sessions under 60 minutes for children too.
How many sports drinks can you have per day?
Sports drinks are designed for intense training, not as a daily water substitute. Their sugar content is high enough that regular non-exercise consumption can harm dental health and add unnecessary calories.
Are electrolyte tablets as good as sports drinks?
Electrolyte tablets (e.g., Nuun) provide electrolytes with minimal calories — best when you need electrolyte replacement but not added energy (e.g., long low-intensity session). For high-intensity endurance exercise requiring carbohydrate delivery, a full isotonic drink is more appropriate.
Are sports drinks safe for diabetics?
Standard sports drinks contain fast sugars and significantly raise blood glucose. Athletes with diabetes should consult their endocrinologist and may consider electrolyte-only tablets dissolved in water as a safer alternative.
What about BCAA drinks or protein sports drinks?
These serve different purposes. BCAA drinks may reduce exercise-induced muscle breakdown in trained individuals, but are not primarily hydration products. Protein added to sports drinks can slow gastric emptying and may cause GI distress during high-intensity exercise — better used post-workout.
Estonian Angle
Estonia's climate creates distinct seasonal hydration contexts. In summer (July–August, up to 30°C), fluid and electrolyte losses during outdoor training can be substantial. In winter, cold air suppresses thirst signals — but sweating still occurs during cross-country skiing, running in warm layers, or indoor training.
Estonian endurance athletes (Tallinn Marathon, SEB Tallinn Marathon in September) should plan electrolyte replacement from around 30 minutes into the race. Commercial sports drinks are widely available at race aid stations; carry electrolyte tablets as backup.
For the majority of Estonian gym-goers training for 45–60 minutes at moderate intensity: water is sufficient, and the sports drink marketing is not aimed at your actual physiological needs.
References
1. Sawka MN, Burke LM, Eichner ER, et al. (2007). American College of Sports Medicine position stand: exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390.
2. Shirreffs SM, Sawka MN. (2011). Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences, 29(S1), S39–S46.
3. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), 452–457.
4. Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. (2015). Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference. Clinical Journal of Sport Medicine, 25(4), 303–320.
5. Coombes JS, Hamilton KL. (2000). The effectiveness of commercially available sports drinks. Sports Medicine, 29(3), 181–209.
6. Jeukendrup AE, Moseley L. (2010). Multiple transportable carbohydrates enhance gastric emptying and fluid delivery. Scandinavian Journal of Medicine & Science in Sports, 20(1), 112–121.
Summary
Sports drinks are effective tools for exercise sessions exceeding 60 minutes at high intensity — especially in heat and when electrolyte losses are high. For the majority of exercisers training under 60 minutes, plain water performs equally well.
When a sports drink is warranted, choose isotonic formulas with 4–8% carbohydrate concentration and 400–700 mg/L sodium. A DIY recipe works just as well as expensive commercial products at a fraction of the cost.
See also:
