Evidence-Based Guides

Losing just 2% of your body weight in fluids — roughly 1.4kg for a 70kg person — drops physical performance by up to 20%. Cognitive performance degrades even faster. This isn't theory; it's been demonstrated in controlled studies across endurance, strength, and team sports.

The Research

A 2007 meta-analysis by Armstrong et al. reviewed 28 studies and found that dehydration beyond 2% consistently impaired endurance capacity, thermoregulation, and motivation. At 3–4%, the effects become severe: reduced blood volume, increased heart rate, and impaired heat dissipation.

What's less known: cognitive performance drops at just 1% dehydration. A 2012 study in the Journal of Nutrition found that young women experiencing 1.36% fluid loss had degraded mood, increased perception of task difficulty, and headache symptoms — without any physical exertion.

Why Water Alone Isn't Enough

The performance drop from dehydration isn't just about "less water in the tank." It's about electrolyte concentration. When you sweat, you lose sodium and potassium at ratios that pure water doesn't replace. Drink only water, and you dilute blood sodium further — potentially worsening symptoms.

This is why sports drinks were developed. The problem: most commercial options contain 20–40g of sugar per serving, flavourings that cause GI distress in some users, and electrolyte doses too low to meaningfully replace losses.

The Rival Approach

We designed Rival RAW around the actual science of sweat loss:

• Pre-hydration: 500ml with one scoop 2 hours before activity
• During activity: 150–250ml every 15–20 minutes for sessions >60 min
• Post-activity: 1.5x fluid lost, with electrolytes, within 2 hours

At Rival, we make two things: Rival RAW (unflavoured, zero sweeteners) and Rival Flavoured (with flavours and Sucralose). Both have their place. This guide explains why we believe unflavoured is the smarter daily choice for most people — and why we built our entire brand around it.

The Problem with Sugar

Sugar is added to sports drinks for palatability and rapid energy. The second point is legitimate for endurance athletes burning 60–90g of carbohydrate per hour. The first is a problem for everyone else.

A standard 500ml sports drink contains 30–40g of sugar — nearly the NHS daily recommendation in a single bottle. For non-endurance use (daily hydration, office work, gym sessions under 90 minutes), this sugar serves no functional purpose. It spikes insulin, promotes energy crashes, and contributes to the very fatigue users are trying to solve.

This is why neither Rival RAW nor Rival Flavoured contains sugar. Full stop.

Sweeteners: A Nuanced Conversation

Rival Flavoured uses Sucralose to make the product palatable for people who simply won't drink unflavoured liquids. That's a valid preference, and we respect it. But Sucralose isn't without trade-offs.

A 2023 WHO review found that non-sugar sweeteners don't confer long-term weight loss benefits and may increase risk of type 2 diabetes and cardiovascular disease in some populations. Sucralose specifically has been shown to alter gut microbiome composition in certain individuals. It is better tolerated than some alternatives but can still trigger digestive sensitivity in a minority of users.

Flavour Fatigue: The Hidden Killer of Consistency

Even the best flavours cause flavour fatigue — after 2–3 weeks of daily use, the same taste becomes progressively less palatable. Users skip doses, abandon the product, or switch brands chasing novelty. We've seen it across every flavoured product we've sold since 2010.

Unflavoured products bypass this entirely. Rival RAW mixes into anything — coffee, smoothies, pre-workout, plain water — without clashing or overwhelming. After 10 months of daily use, it still works the same way. No fatigue. No abandonment.

Stackability: The Unflavoured Advantage

This is where unflavoured wins decisively. Modern nutrition is stacked — protein, creatine, pre-workout, coffee, greens powders. Adding a flavoured electrolyte to this stack creates flavour chaos: lemon electrolyte + chocolate protein + berry pre-workout = chemical fruit salad.

Rival RAW disappears into whatever you're already drinking. No flavour profile to clash. No sweetness to compete. Just the electrolytes you need, where you need them.

Which Should You Choose?

Choose Rival RAW if: You drink coffee, take protein or pre-workout, want zero flavour fatigue, have sweetener sensitivity, or simply prefer clean, invisible nutrition.

Choose Rival Flavoured if: You genuinely won't drink unflavoured liquids, want variety, or need a gateway product to build the hydration habit.

Both are third-party tested, UK manufactured, and sugar-free. The difference is philosophy: RAW is designed to be forgotten — so you never forget to hydrate.

Rival RAW is deliberately simple — one scoop, any liquid, any time. But "simple" doesn't mean "without strategy." Here's how to get the most from your 312 servings based on activity level, climate, and personal goals.

The Baseline: Daily Maintenance

For sedentary to lightly active individuals, one scoop (800mg powder, providing 852mg sodium, 511mg potassium, 79mg magnesium citrate) in 500ml of water each morning covers baseline electrolyte needs. This is particularly important if you:

• Drink 2+ litres of plain water daily (dilutes electrolytes)
• Consume caffeine regularly (diuretic effect)
• Follow low-carb or ketogenic diets (increased sodium excretion)
• Work in air-conditioned or heated environments (insensible water loss)

Pre-Workout: 60–90 Minutes Before

Take one scoop in 500ml water. This pre-loads sodium and fluid, expanding plasma volume and improving thermoregulation. Studies show pre-exercise sodium loading can reduce cardiovascular strain and improve endurance capacity by 5–10% in hot conditions.

During Exercise: The 60-Minute Rule

For sessions under 60 minutes in moderate temperatures, water plus your morning Rival RAW is sufficient. Beyond 60 minutes, or in heat/humidity, add a second scoop to your bottle:

Post-Workout: The Replacement Window

You have a 2-hour window post-exercise where electrolyte replacement is most effective. Weigh yourself before and after; drink 1.5x the fluid weight lost. Include 1–2 scoops of Rival RAW depending on session intensity.

Stacking: The Unflavoured Advantage

Because Rival RAW has zero taste, it stacks seamlessly:

Muscle cramps are the most common complaint we hear from athletes — and the most misunderstood. They're not caused by magnesium deficiency alone, or by "tight muscles," or by insufficient stretching. In most cases, they're a neuromuscular response to electrolyte imbalance, specifically the sodium-potassium gradient that controls muscle contraction and relaxation.

The Cramp Mechanism

Muscles contract when nerves signal them to. That signal depends on sodium rushing into muscle cells and potassium rushing out. When either mineral is depleted, the signal misfires — the muscle contracts but doesn't receive the "relax" command. Result: a cramp.

This is why stretching helps temporarily (mechanical override) but doesn't prevent recurrence. Only restoring electrolyte balance does.

Dehydration vs. Electrolyte Depletion

These are related but distinct. You can be:

• Dehydrated but electrolyte-balanced (rare — usually medical condition)
• Electrolyte-depleted but well-hydrated (common — drinking lots of plain water)
• Both dehydrated and electrolyte-depleted (most common — heavy sweating without replacement)

The third state is what most athletes experience. The solution isn't just "drink more" or "take salt" — it's both, in the right ratio.

Recovery Protocol

Post-exercise recovery isn't passive. It's an active process of restoring what was lost:

Sleep & Recovery

Magnesium's role in sleep is well-established — it regulates GABA, the neurotransmitter that calms nervous system activity. We use magnesium citrate in Rival RAW, the form most studied for sleep support and muscle relaxation. Athletes with high magnesium turnover (heavy sweaters, high-stress training) often report improved sleep quality within 7–10 days of consistent electrolyte replacement.

We've been in the electrolyte market since 2010. In that time, we've watched the industry fragment into two camps: sugar-laden sports drinks masquerading as health products, and premium "clean" electrolytes priced at £1–£2 per serving. Neither serves the everyday athlete or health-conscious consumer well.

The Sugar Camp

Lucozade Sport, Gatorade, Powerade. The original sports drinks, developed for elite endurance athletes burning 1,000+ calories per hour. For a 45-minute gym session or office hydration, they're wildly inappropriate — 30g+ sugar, artificial colours, and electrolyte doses too low to matter.

The Premium Camp

Newer entrants (LMNT, Element, etc.) got the formula right — no sugar, clinical doses, clean ingredients. But they price at £1.20–£1.80 per serving in UK markets, making daily use prohibitively expensive. A month's supply costs more than a gym membership.

Head-to-Head Comparison

*High5 uses artificial sweeteners (sucralose) and flavourings.

The Rival Difference

We're not trying to be the most expensive or the most marketed. We're trying to be the most useful — the product you actually take every day because it works, it fits your routine, and it doesn't drain your wallet.

• 312 servings — 10+ months of daily use, not 2 weeks
• Unflavoured — stacks with anything, no flavour fatigue
• Clinical doses — based on sweat loss research, not marketing claims
• Magnesium citrate — superior absorption vs. oxide, well-studied for muscle and sleep
• UK manufactured — shorter supply chain, fresher product, lower carbon
• Third-party tested — every batch, no exceptions