We stock two ProSupps lines, and they sit at opposite ends of the same category: Mr Hyde (£58) is the stimulant pre-workout, Dr Jekyll (£43) is the low-stimulant one. The naming is not decoration — it tells you which one to take at 6am and which not to take at 7pm.
Stimulant versus non-stimulant
A pre-workout does two separable jobs: it makes you feel alert, and it changes what happens in the muscle. Those come from different ingredient classes, and most products blend both.
- Stimulants — caffeine and relatives. These produce the noticeable effect: alertness, perceived energy, higher training drive. They do very little directly to muscle performance beyond letting you push harder.
- Performance ingredients — beta-alanine, citrulline, betaine. These work on buffering and blood flow. They are unglamorous, they build up over weeks rather than acting acutely, and they are the part with the better evidence base.
Mr Hyde leans stimulant. Dr Jekyll is formulated for people who want the second group without the first — training late, stimulant sensitivity, or simply not wanting a racing heart rate.
The tolerance problem
Caffeine tolerance develops quickly — within one to two weeks of daily use, the subjective hit is substantially reduced. The usual response is to increase the dose, which raises the side-effect burden without restoring the original effect.
A more sensible pattern is to keep the stimulant product for sessions that genuinely need it and use a non-stimulant option otherwise. That is what having both in a range is for.
Watch the total daily caffeine load too. A pre-workout scoop can carry 200–350mg — comparable to two or three coffees — and it stacks on top of everything else you drink.
If you are drug tested
Pre-workouts are one of the higher-risk supplement categories for inadvertent anti-doping violations. The reason is structural: they are stimulant products, stimulants are heavily represented on prohibited lists, and the category has a documented history of ingredients being reformulated or renamed.
Under strict liability the positive test is yours regardless of intent. If you compete:
- Use only products with batch-level third-party certification, and check the batch number rather than trusting the brand name
- Re-check the label on every purchase — formulations change without the product name changing
- Keep the tub and a sample
We do not hold certification data for these two lines. If certification matters to you, treat that absence as your answer.
Where this sits in the catalogue
ProSupps is a mainstream sports-nutrition brand, not a pharmaceutical or underground one. It is legal to buy and hold, and it is not assessed for content or efficacy before sale. The rest of that category is in sports supplements, alongside creatine and protein — both of which have considerably more evidence behind them than any pre-workout blend.
If you are choosing where to spend, creatine is the better-supported purchase. See what creatine actually does.
Frequently asked questions
What is the difference between Mr Hyde and Dr Jekyll?
Stimulant load. Mr Hyde is the high-stimulant option; Dr Jekyll is built for training without one. Same category, opposite purposes.
Can I take a pre-workout every session?
You can, but caffeine tolerance will blunt the effect within a couple of weeks. Cycling the stimulant product and using a non-stimulant option otherwise keeps it working.
Are ProSupps products safe for tested athletes?
Not automatically. Without batch-level certification there is no basis for assuming a pre-workout is clean, and this category carries more risk than most.