Running base layers are essential for the colder months of the year. This additional tight-fitting layer gives you more warmth without inhibiting breathability too much. Pair them with an appropriate running jacket and you've got a great cold weather running combo.
In this guide you'll find our best tested base layers for running. The term 'base layer' is a bit of an umbrella term these days. So if you're really after running tops, you can find the best of those in our roundup of the best running t-shirts.
What to look for in a running base layer
Comfort: Crew neck, zip, short sleeve - go for what you like best. It's a totally personal preference. But everyone should look for base layers with a seamless design to avoid chafing. Stretch is important too because it allows freedom of movement.
Breathability: Technical polyester such as Coolmax is great for breathability. Lightweight merino is too, and an excellent thermoregulator, meaning it helps keep you at a comfortable temperature irrespective of the ambient temperature. Mesh panels in base layers are always a big help to breathability. You can even find these on merino base layers now.
Material: Running base layers have diversified to be made of all sorts of materials, from polyester to merino to plant based Tencel. All focus on breathability and warmth but the balance of each varies between base layers.
Odour control: Merino is naturally antibacterial and therefore does a stellar job of battling odour. Synthetic fabrics need anti-odour treatments.
Sustainability: With running base layers made from synthetic material, the use of recycled material is always best. For merino look for mulesing-free or certification such as the Responsible Wool Standard.
When wet: Cotton is a no-no. It drains body heat when wet and gets super heavy since it's so absorbent. Polyester and nylon do a much better job of remaining effective when wet. Merino wool is the best.
Thumb loops: These are a non-essential feature that simply come down to whether you like them or not. If you tend to get cold hands when running but don't want to slip on a pair of running gloves, thumb loops could be a good compromise to kepeing you warm.
The best running base layers
Best in Test
www.ellis-brigham.com
This is a remarkable merino base layer. For those after a dependable companion for winter runs, go for this. It’s unquestionably pricey but seriously impressive all the same.
The Goldhill 125 Zoned Crew is lightweight 125gsm Nuyarn merino. The Nuyarn bit is important because it refers to the way the merino is spun. In short, Nuyarn makes the base layer better in every way: faster drying, more breathable, lighter with more loft, more durable – it's an all-round win.
There are very subtle thumb loops that you can ignore if you hate them and mesh-type panels on the back and arms further aid breathability. The upfront cost might raise your eyebrows, but it’s the most versatile base layer we've come across. Whether for running, hiking, snowboarding, or cycling, it’s the only option you need.
Pros
- Versatile
- Like merino on steroids
- Sustainable
Cons
- Expensive
Best Value
www.freewheel.co.uk
Those after a low-cost base layer will find it hard to go past this. This skin-tight mesh base layer is great for milder weather.
The Isoler’s breathability is impressive, thanks to the mesh design. But it does mean a biting wind easily penetrates it. The Isoler Mesh can therefore be quite a good option to pair with a windproof jacket or waterproof jacket.
In terms of sizing, the ‘Race Fit’ speaks for itself, but because there are only three sizes on offer, it’s best to round up. For example, if you’re normally L, you’d be better off going for the XL/XXL size option than the M/L.
Pros
- Very affordable
- Very breathable
- Short sleeve available
Cons
- Only 3 size options
- No mention of sustainable materials
Best base layer for high intensity runs
www.sportsshoes.com
If you’re a fast, hard, gritted-teeth kind of trail runner, Craft’s Active Extreme X is for you. No doubt you’ll already be swooned by the collection of adjectives in the name. But you’ll be pleased to know they aren’t empty words.
Craft’s Active Extreme X is a blend of polyesters: Coolmax, and recycled Seaqual. Coolmax is great for breathability, and so too is Seaqual, which is made from plastic hauled out of the ocean.
The breathability and comfort of this base layer makes it superb for long runs, intense runs, and races when the temperature is low. The Craft Active Extreme X came very close to being our overall winner.
Pros
- Great for intense winter runs
- Contains recycled material
Cons
- Tad pricey (but worth it)
Best running base layer for winter
golfsupport.com
The first thing you notice about the Zerofit Heatrub Move, is that it’s thicker than most base layers. This is because it’s got two layers. The inside layer is polypropylene, the outer is polyester.
This immediately raised suspicion about whether it would be way too warm for running. We used it in the low negatives and were seriously impressed. Normally when running, you start a bit cold and warm up after a few minutes. With the Zerofit, I was warm immediately and remained comfortably so, without overheating on leisurely winter runs.
On the downside, it's a disappointment not to see any recycled or sustainable material used here. The Zerofit Heatrub Move is a unisex fit.
Pros
- Very warm
- Very breathable
- Big size range
Cons
- No recycled material used
Best short sleeve base layer
www.icebreaker.com
Long gone are the days of wool being itchy and unsuitable for sport. The outdoor industry like to use the word ‘technical’ to describe a lot of its gear. Well, if you want to apply that word to wool, now is the time do so.
Icebreaker’s 125 ZoneKnit is great for almost year-round use. Key to its success is that it’s mostly (60%) Tencel. Tencel is that fibre made from wood pulp, very adept at moving moisture. Teamed up with merino (remaining 40%), this is a warm yet very breathable base layer.
And of course, like the Artilect base layer, if this gets wet it will still keep you warm. Bring on the rain.
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Take a look at the women's version here**
Pros
- Highly breathable
- Naturally anti-odour
- Sustainable
Cons
- Expensive
Recommended
www.inov-8.com
Inov-8's long sleeve base layer is a versatile option that will appeal to many. It is suitable for use all year, except perhaps in high summer. It’s not skin-tight either, which means it can be boosted with a layer underneath if it’s too cold to be worn on its own.
In terms of box-ticking this does very well. It’s made from recycled material, has an anti-odour treatment, is very light and breathable, and made to a very high standard for longevity.
Those ticked boxes have a noticeable effect in the real world. Indeed, this is simply a great base layer to run in for most of the year.
Pros
- Made from recycled material
- Versatile
- Short sleeve available
Cons
- You’ll want another option for summer
Best running mid layer
www.salomon.com
The Essential Lightwarm Half Zip is ideal for trail running in the cold or for warming up. Many mid layers are too thick to be any good, but the Essential Lightwarm is very lean with a half zip. This helps it remain highly breathable while the lightly ribbed fleece fabric aids warmth.
It's a seamless design and slim but not tight-fitting for excellent comfort. We also like how it's made of recycled, blue-sign-approved polyester. In addition to running, this is a great mid-layer for other high-octane outdoor pursuits such as skiing.
Pros
- Lightweight
- Highly breathable
- Warm
- Versatile
Cons
- No anti-odour treatment