Class Review: Pump Chasers (Upper)

28th February

Arms. They’re something every gym-goer secretly obsesses over. But let’s face it, getting that Popeye effect on point ain’t easy. That’s why we thought we’d help you cheat a bit. (Don’t get used to it.) Pump Chasers is the Gymbox upper body workout with a twist – as resident blogger Louise Smith discovered when she put her guns through their paces earlier this week.


I didn’t expect I’d ever say this, but readers: I am swole.

I’ve just been to a Pump Chasers (Upper) class, and I have muscles where I’ve never seen muscles before. I can actually feel a bicep. Arnold Schwarzenegger said “the greatest feeling you can get in a gym, or the most satisfying feeling you can get in the gym is... The Pump” – and Pump Chasers is all about getting you there.

The Pump is that tight feeling you get when you’ve really worked your muscles hard, when your muscles look and feel noticeably “fuller”. Pump Chasers uses a technique known as blood flow restriction (BFR) training to maximise that feeling while building muscle and strength quickly.

BFR has been around for decades but has only recently started breaking through to the mainstream. It works by wrapping something tightly around the top of a limb to restrict blood flow out of the muscle. Importantly, it doesn’t stop the blood flowing in, which would be entirely counter productive and also pretty unpleasant. This has three key effects – swelling the muscle encourages muscle growth, while the build up of metabolites due to restricted blood flow does the same. Your muscles also get tired more quickly– that forces the use of fast-twitch muscle fibres, which have the greatest capacity to grow.

I’ve recently started climbing, so am really keen to try out anything that might bring my upper body strength up to scratch more quickly. I join Dino Portelli’s class at Stratford on a Friday evening, where I join my fellow pump chasers in fastening special BFR bands around the tops of my arms. We’re told to aim for 6-7 on a scale where zero is no bands and 10 is cutting off all feeling in your arms. I spend ages tightening and loosening the straps before deciding to just get on with it – you quickly work out if you’ve gone too far either way!


We work our way through two minute rounds followed by thirty seconds rest, using dumbbells, barbells, bands and bodyweight to get to every single muscle in the upper body. Each round includes a series of exercises, from hammer curls and overhead tricep extensions to bent over rows and push ups. The variety means that the class flies by.

We also shift between counting reps at a normal tempo, and slowing down the eccentric (lowering) phase of each rep. You quickly feel the burn at either speed and the rounds are carefully structured to push you hard. With everyone working with their own set of weights, no-one gets away lightly regardless of their starting strength – and as you get stronger, increasing your weights means you’ll always find the challenge you need.

The class would be an impressive upper body workout with or without the bands. However, the difference they make is obvious. My muscles tire even quicker than normal, and I have to drop down a weight from what I’d normally use within minutes. By the end of the class, my triceps aren’t even pretending to attempt movement anymore.

And on top of that, The Pump is very real! Working through some bicep curls, I suddenly realise I can actually feel my bicep at the top of each rep – it’s not a feeling I’m used to, and I spend the entire set staring at my new muscle, baffled and kind of impressed.


Dino spends the class walking through the group, checking people’s bands are tight enough and that the form for every movement is right to get the absolute most out of the session. He also keeps the energy up the whole time, teasing out that last few reps from each of us even as everyone’s arms start to give out towards the end of each round.

Having read the research and experienced the class for myself, I’m totally sold. Upper body strength (or lack thereof) is a real weakness of mine, but I tend not to work that much on it because I prefer doing what I’m good at. This class is exactly what I need to actually enjoy building it up, and to see great results quickly to keep the motivation going. I can see myself being a regular at this one!

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