Race Day Boost: Pre-Race Phosphate Loading
When the race matters, prepare before the start line. Race Day Boost is not a stimulant-driven pre-workout. It is a four-day sodium phosphate loading protocol for runners, cyclists and triathletes preparing for an A-race, time trial, long climb or personal-best attempt.
Protocol
- Start: four days before race day.
- Take: 4 capsules, 4 times daily, with food and water.
- Provides: 8 g sodium phosphate per day from 16 capsules.
- Complete plan: one 64-capsule bottle supplies the full four-day load.
Why it works
Phosphate loading increases red-blood-cell 2,3-DPG. This helps haemoglobin release oxygen to working muscle — exactly the demand when you must hold a hard pace for a long time, stay committed on a climb, or defend your speed late in a race.
Research
- Trained cyclists: a phosphate-loading study recorded 9.8% higher mean power and a 3.0% faster 16.1 km laboratory time trial.
- Trained runners: phosphate loading increased VO₂max and reduced post-exercise blood lactate.
Read the cycling study · Read the runner study
Best for
- A marathon, ultra, long-course triathlon or gran fondo.
- A time trial, hilly race or sustained-effort event where pace must be held.
- A specific race rehearsal or personal-best attempt — not an everyday supplement.
Race plan
Race Day Boost prepares the four days before the event. On race day, run your practised energy and hydration plan, use the electrolyte strategy that matches your conditions, and recover with post-exercise nutrition.
Preparing for a key race? Race Day Boost is also part of the Race PB Kit.
Supplement facts
Serving size: 1 capsule | Servings per container: 64
Per capsule: Sodium phosphate 500 mg
Other ingredients: vegetable capsule, malic acid
Dietary suitability: gluten-free, vegan-friendly
Learn more
Race Day Boost: four days away from a personal best
Video
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Hammer Nutrition Perpetuem was a key part of my fuelling strategy for the Leeds Ironman last weekend.
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No heavy feeling, I was able to keep fuelling consistently right throughout my cycling. A great product for long-distance — so glad this was recommended to me during my early training in preparation.
Extremely useful to use whilst cycling, removes the faff of opening gels whilst cycling and the solid bottle makes it easy to get in / out of jersey pockets.
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I’ve used Hammer products for around 6 years now & my favourite by a mile is the hammer Perpetuem, it’s fueled my last 100 mile ultra marathon not to mention multiple long distance triathlon's . It has 180calories per serving and it’s 34g of carbs & 5g of protein seems to work well . I’d strongly recommend for anyone who wants to take on ultra races as this fuel will support you when you need it most .
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Frequently Asked Questions
How long will my delivery take and how much does it cost?
Orders placed before 2:00 PM (UK time) are dispatched the same working day. Standard delivery to mainland Great Britain takes 2–5 days at a flat rate of £3.50, or free on orders over £20.
Large tubs are automatically upgraded to DPD next-day delivery. Shipping to Northern Ireland, the Channel Islands, and the Scottish Highlands costs £4.50, or free on orders over £80.
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To cancel an order, you must contact us on the same calendar day it was placed. If dispatch has already occurred, you can return the unused items within 14 days at your own shipping expense.
What is your returns policy if I change my mind?
You have 14 days from the day after delivery to cancel your order. Items must be unused, in their original packaging, and in resaleable condition. Important Step:
You must email us via the bottom of our Home Page first to obtain a Returns Authorisation Number and a free Royal Mail returns sticker; unauthorised returns cannot be processed.
Note that opened, sealed supplements cannot be returned for hygiene reasons.
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Please include your order number, a description of the issue, and photos of the damaged items and packaging. We will provide a free replacement or full refund.
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Once your return is received, inspected, and approved, we process refunds back to your original payment method (card, PayPal, or bank transfer).
This typically takes place within 7 working days, and always within a maximum window of 30 days.
Are Hammer Nutrition products safe for drug-tested athletes?
Yes. Key products within our range—including Endurolytes (4ct/120ct), Endurolytes Extreme (3ct/120ct), Endurolytes Extreme Powder, and Endurolytes Fizz - are officially Informed Sport certified.
Additionally, our products are manufactured in strict ISO, GMP-compliant, and SQF Level 3 Certified facilities to ensure the highest standards of food safety and purity.
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We use only premium ingredients with zero artificial flavours, artificial sweeteners, or chemical colorants.
Our natural flavours are extracted from real food sources (such as fruits, essential oils, and botanicals) in full compliance with FDA regulations.
They are entirely derived from non-allergenic materials and are formulated for a clean, subtle, non-sweet taste.
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Are your supplements suitable for specific dietary restrictions?
Our clean sports nutrition range is formulated to support optimal body function and is completely free from gluten, artificial preservatives, and artificial colorants.
If you have specific medical conditions or severe allergen concerns, we recommend checking the explicit ingredient panels or consulting a healthcare professional prior to consumption.