How do you ensure that your trail running backpack doesn’t rub when you run, and fits perfectly? That’s easy, you ditch the idea of a backpack altogether, and instead wear a vest with large, backpack-sized pockets - one that’s sized and fitted like an item of clothing rather than a bag.

Vests like this one have become increasingly popular amongst trail runners in recent years, but Inov-8 have taken it one stage further with this latest one, an update on their Race Ultra 5 and 10 models. This is effectively two backpacks in one, with a stripped down vest designed for race days that can be augmented with an additional 15-litre pocket that can be strapped on for longer training runs.

The vest at the core is available in three different sizes, S/M, M/L and L/XL, each of which is fully adjustable with two front straps and two straps on each side meaning you can tailor it to fit any body shape. The additional pocket is fixed on with six compression straps to minimise bounce when you’re running, and it really works - our testers were impressed at the amount of weight you could pack into the extra pocket without really feeling the difference in terms of movement.

“The stripped down version of the vest weighs just 187g, roughly the same as a can of tuna."

It helps that the weight of water is distributed away from the backpack - the primary hydration system on the Inov-8 All-Terrain Pro Vest are the two 500ml soft flasks which fit into pockets on the shoulder straps. There is room for an extra water bladder in the bag itself should you want it, but Inov-8 don’t supply one as standard.

Compartments and pockets on the straps themselves hold things that you might need on the fly, while the main pack itself is super easy to access once you take it off. Of course, this being a piece of trail-running kit, the overall weight is of paramount importance and this is where the two in one design really comes into its own. If you take the water flasks out, the stripped down version of the vest weighs just 187g, roughly the same as a can of tuna.

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Even with the add-on pocket, the whole thing weighs just 320g, thanks to its lightweight nylon, spandex and polyester construction, and if you’re travelling to get to your trail running destination, the whole thing folds nicely flat so it’ll fit in a duffel or a suitcase easily. Basically if you’re a serious trail runner looking for a serious backpack, you’ll be hard pushed to beat the Inov-8 All-Terrain Pro Vest.

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