The "new energy source" spreading through British gyms isn't a new stimulant. It's a familiar one, taken a different way — and the science behind it goes back more than twenty years.
Walk past a gym at six in the evening and the pre-session ritual is easy to spot. A scoop of powder, a shaker, a splash of water, and then the wait — checking your phone for twenty minutes until it kicks in. Or the version with a can: 250ml or 500ml of liquid to get down before you've even touched a weight.
A growing number of people have stopped doing any of it. No shaker. No can. No capsule to swallow. Instead, a small supplement pouch sits under the top lip for a few minutes, and they're straight into the session.
It's tempting to call it a new energy source. It isn't, really. The active ingredient in most of these pouches is caffeine — the most studied performance aid there is. What's actually new is the route: instead of being swallowed and digested, it's absorbed through the lining of the mouth.
Why the mouth changes things
That lining — the buccal mucosa — is thin and richly supplied with blood vessels. Compounds that pass through it enter the bloodstream directly, skipping the stomach and the "first-pass" processing of the gut and liver that slows everything else down.
The difference in timing is not small. Research on caffeine delivered this way — mostly through caffeinated gum and mouth sprays — shows meaningful absorption in around 5 to 10 minutes, against the 45 to 60 minutes it typically takes for a capsule or drink to work its way through digestion. A landmark study by Kamimori and colleagues first mapped this out in 2002, and reviews since have kept confirming it.
For anyone who's timed a pre-workout badly and spent the first two sets waiting to feel something, that gap is the whole point.
Why it caught on with athletes first
It's no accident this started in sport. Caffeine's effect on alertness and endurance is among the best-evidenced in nutrition, but the standard 45-to-60-minute lead time is awkward when a warm-up runs long or a match kicks off early. A faster, more predictable window is genuinely useful.
Sports scientists noticed. A 2023 meta-analysis concluded that caffeinated gum taken around 15 minutes before exercise improved performance at doses from roughly 3mg per kilogram of bodyweight, and a 2024 review of 32 studies found pre-exercise use supported endurance, repeated sprints and lower-body strength while lowering how hard the effort felt. The common thread across all of it is the delivery route, not a new molecule.
There's a practical edge too. Absorbing through the mouth means less sitting in the stomach — no half-litre of liquid to get down before you move, and nothing to mix or carry.
A format having a moment
None of this is happening in a vacuum. The functional food and drink market — products bought for what they do, not just how they taste — is valued at around $438 billion globally and forecast to nearly double by 2034. In the UK, supplements are increasingly won or lost on format: the brands growing fastest tend to be the ones making the daily habit easier, not the ones with the longest ingredient list. A pouch you can use at your desk, in the car or in the changing room fits that shift neatly — and sidesteps the sugar in a lot of energy drinks and the faff of everything else.
Who's doing it in the UK
The route has been studied in labs for two decades; the products catching up are newer. In Britain, Sync is one of the brands building around it — its Performance pouch carries 90mg of caffeine, which contributes to alertness and concentration,¹ in a mint pouch designed to be used a few minutes before you need it. The company says it's now trusted by more than 1,000 athletes across the UK.
Whether pouches replace the shaker for good or just earn a place next to it, the more interesting story is the one underneath: a twenty-year-old piece of absorption science finally arriving in a format people will actually use every day.
You can read more here: Performance Pouches
¹ Caffeine contributes to alertness and concentration. See the GB Nutrition and Health Claims Register.
Sources: Kamimori et al. (2002), Int. J. Pharm.; Barreto et al. (2023) meta-analysis on caffeinated gum and exercise; systematic review of 32 studies on caffeinated chewing gum (2024); Frontiers in Nutrition (2023, 2025) on buccal caffeine absorption; Fortune Business Insights functional F&B market valuation.