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Cold weather workouts never felt so good

By now, it’s common knowledge that taking your workout outside can be great for your mental and physical health. But this is Britain we’re talking about here, so chances are it’s going to be cold. Very cold. That’s where the best base layers come in.

These tight-fitting tops provide a lightweight layer of protection against chilly conditions. They’re handy in hotter temperatures too, working to wick sweat away from your body, keeping you comfortable whatever the weather.

So, if you’re partial to an al fresco workout, we think buying a base layer is a no-brainer. That’s why we’ve tested some of the best money can buy to bring you our top recommendations.

As we’ve already explained, the best base layers can help you stay at a comfortable temperature. They also keep sweat-spots like the lower back and armpits from getting clammy during workouts by absorbing then wicking away any moisture.

But we thought before you buy, you’d want to see their full CV.

As the name suggests, a base layer is the first thing you put on as part of your cold-weather exercise ensemble — whether you’re summiting Snowdon or undertaking a hardcore HIIT session at the park. It should act almost like a second skin, fitting tightly while still allowing you to move freely.

You want the material to be both insulating and breathable. So, if you’re boldly braving the cold to go for a winter run, it’ll help keep you warm. But, if your body temperature rises as you push for a PB, it'll wick sweat away from your skin and allow heat to escape so you don’t become uncomfortable.

More on the materials available below…

One bamboo base layer aside, every top we tested can be split into one of two camps; Merino wool or synthetic. Here’s a bit of background on each type, so you can make an informed decision on which one is right for you:

About - In this context, synthetic essentially means any material that’s man-made.

Strengths - Base layers made from these fabrics tend to be cheaper, but still have the advantages of natural materials like warming and sweat-wicking properties — albeit, not usually as effective as their natural counterparts. They usually have a lycra-esque feel, meaning they’re lightweight and flexible.

Weaknesses - They aren’t naturally antibacterial, so may hold any smells they absorb from sweat. While regular washing is an easy remedy for this, we wouldn’t recommend wearing them for two days on the run. They also aren’t as warm as Merino wool (more on that below) so are better suited to milder climates.

About - Don’t be fooled by the name, this super lightweight material bears little resemblance to a chunky knit fisherman’s jumper. The luxe fabric is grown by Merino sheep and is a favourite for its natural temperature-regulating properties.

Strengths - Not only is Merino wool brilliantly warm, it can also stop you from overheating. This might sound counterintuitive, but hear us out. When it’s cold, the fibres trap air to provide a layer of insulation. But, if you overheat, the wool will then wick sweat away from your body to cool you down — it’s a win-win. This magical fabric is also naturally antibacterial, resisting odours so you don’t have to lunge for your deodorant after a lunchtime run.

Weaknesses - As you’d expect from a natural material with this many benefits, Merino wool rarely comes cheap. Some products aren’t as comfortable as their synthetic counterparts either, so we asked testers to pay close attention to how their base layers felt.

Our testing team put 29 top base layers through their paces, wearing each one for at least three outdoor sweat sessions. We asked them to feed back on how the tops felt before, during and after exercise, noting whether they were able to keep them at a comfortable temperature, wick away sweat and move with their bodies.

They were also awarded extra points for offering a good fit, feeling comfortable and looking good, with special mentions for fancy and (more importantly) useful features like thumb holes and hidden pockets perfect for stashing your house keys. These are our 14 favourites:

Though it’s clearly made for runners (just look at the name) our panel found this flexible base layer was also great for keeping the cold at bay while out on a hike or grinding through an outdoor bootcamp class. We loved the pockets in the sleeves, and the built-in mittens can easily be rolled out to fend off the cold. It tended to fit taller testers especially well, though some of our panel found it rode up while running.

The WH Lab verdict: Warm and easy to care for, this is a great base layer for any outdoor sport. We’d suggest ordering a size up though, as some testers found it a bit constricting.

Key specifications Material: Polyamide (92%), elastance (8%) Sweat-wicking: Yes Thumb holes: Yes Pockets: Yes

If you’re after a base layer made from natural materials, consider temperature-regulating Merino wool. A far cry from the fibres that make up your nan’s fave sweater, this super lightweight top kept us toasty without causing us to overheat, and worked quickly to wick away sweat. The arms were just the right length for all testers — something that can be hard to find in a base layer — and the torso provided a looser fit that proved comfy throughout runs and (semi-enthusiastic) sets of burpees.

The WH Lab verdict: This base layer is second to none when it comes to regulating temperature. The looser torso is supremely comfortable and the arms fit like a dream— what’s not to like?

Key specifications Material: Merino wool (80%), polyester (20%) Sweat-wicking: Yes Thumb holes: No Pockets: No

Like nothing else we tried, this base layer has a cropped fit ideal for pairing with high-waisted leggings. Testers really liked this alternative style, finding it meant there was no excess material bunching up around their waist, though a few did say it left their midline exposed to the cold. Our panel also praised the patterned design, which was a nice break from the usual block colours.

The WH Lab verdict: The cropped fit divided opinion, but proved popular among those who preferred high-waisted leggings or joggers. That, twinned with its stretchy, unrestrictive material, makes this a top choice for outdoor strength workouts.

Key specifications Material: Polyester (60%), nylon (38%), elastane (2%) Sweat-wicking: Yes Thumb holes: Yes Pockets: No

This ultra-thin and stretchy base layer is great for keeping you cool throughout gruelling workouts. It provides some welcome warmth at the start of a chilly outdoor session, then the breathable fabric and ‘ventilation zones’ under the arms take over to stop you from overheating when things get sweaty. It dried brilliantly quickly and moved well with the body too, though the broad sizing system (XXS/XS, S/M, L/XL) can make finding your ideal fit a tricky task. The

WH Lab verdict: Suitable for everything from hill-walking to weight training, this is a seriously impressive bit of kit. We found the sleeves and torso were quite long, so it’s especially well-suited to taller wearers.

Key specifications Material: Polypropylene Dryarn (44%), nylon (44%), elastane (12%) Sweat-wicking: Yes Thumb holes: No Pockets: No

Relying on natural materials that (shockingly) aren’t Merino wool, this bamboo and cotton base layer looks good and feels great. Testers said they had total freedom of movement with no tightness around the shoulders or elbows, and they particularly liked the thumb holes for keeping the arms in place. They did find the fabric took longer to dry when they started sweating, leading to some discomfort, so we’d reserve this one for less strenuous activities.

The WH Lab verdict: Warm and comfortable, this would be a good fit for those looking to stay warm on a chilly hike or bike ride. The sweat-wicking left a little to be desired though, so it may not pair well with lovers of a hardcore workout.

Key specifications Material: Bamboo viscose (68%), organic cotton (28%, elastane (4%) Sweat-wicking: Yes Thumb holes: Yes Pockets: No

The fab fabric that is Merino wool strikes again, and it’s another impressive outing for the natural fibre. This dhb base layer provided plenty of heat during chilly training sessions, and there were no lingering post-workout smells (sorry, but IYKYK). Some testers said it was able to wick away sweat in record time, but others found they grew too hot in milder conditions, saying the high cut under the armpit meant the top quickly became damp when they started sweating.

The WH Lab verdict: If your sport of choice sees you constantly training in the freezing cold, look no further. This versatile top will stop spring’s chilly temperatures in their tracks.

Key specifications Material: Merino wool (100%) Sweat-wicking: Yes Thumb holes: No Pockets: No

Guess who? Yep, it’s your old pal Merino wool again. After trying this breathable Icebreaker base layer, one first-time Merino-wearer told us they were won over by its uncanny ability to keep them at a comfortable temperature, whatever the weather, while another said it looks smart enough to be worn as an everyday top. It’s light and breathable enough to wear for workouts, with most of our panel finding they had a good range of motion around their shoulders, though some said it was a little bit too tight.

The WH Lab verdict: Light and comfortable, testers said this top was super breathable and didn’t itch at all, despite its woolly composition. It would ride up occasionally, but it’s undoubtedly a quality product.

Key specifications Material: Merino wool (83%), nylon (12%), elastane (5%) Sweat-wicking: Yes Thumb holes: Yes Pockets: No

If you’re one of those perpetually cold people, this thicker base layer could be your knight in shining (and insulating) armour. Our panel found it extra warm, saying it was great for walking and cycling in seriously cold temperatures. But if you’re planning to get your heart racing with a run or workout, it might be a tad too warm.

The WH Lab verdict: This base layer is best for less intense activities, or shielding you from seriously cold conditions. The limbs are also quite long, so it’s a good fit for taller wearers.

Key specifications Material: Merino wool (57%), polypropylene (43%) Sweat-wicking: No Thumb holes: No Pockets: No

Soft, cosy and comfortable, this base layer ticks a lot of boxes — extra impressive given it retails at just £24.99. Testers said they were able to move freely and they liked the ventilation zones around hot points like the armpits, elbows and neck.

Some of our panel said the material didn’t have the premium feel of other base layers, and it wasn’t the warmest top we tried. But if you’re willing to layer up in frosty conditions, it’s still a top budget buy.

The WH Lab verdict: Best for milder conditions, this base layer is still a comfortable and effective option for a bargain price.

Key specifications Material: Polyamide (96%), elastane (4%) Sweat-wicking: No Thumb holes: No Pockets: No

It didn’t take long for our testers to fall in love with this top, which has a looser fit than your average base layer. Not only did it keep our testers at a comfortable temperature throughout chilly outdoor exercise sessions, it also has innovative features to help maximise your workout. Thumb holes stop the arms from riding up, hi-vis panels keep you safe when running at night and unique ‘windows’ in the wrist mean checking your fitness tracker is always a doddle.

The WH Lab verdict: Premium materials and exceptional performance earned this Running Crew style a place on our roundup. We’d recommend buying a size down for a snug fit, but that’s the closest our testers came to criticism.

Key specifications Material: Recycled polyester (88%), elastane (12%) Sweat-wicking: Yes Thumb holes: Yes Pockets: Yes

Norwegian sports brand Odlo has been perfecting its ergonomic seam placement for more than 70 years, and seven decades of hard work has definitely paid off! This base layer was made from comfortable fabric which stayed in place, no matter what sport or activity we were doing. Testers said it wasn’t as breathable as others they had tried, and felt the v-neck was unflattering while leaving their neck exposed to the cold. It also needed washing after every wear to stop it becoming smelly, though it did dry impressively quickly, meaning it was ready to wear again in no time.

The WH Lab verdict: This Odlo top was particularly good at keeping us shielded from the cold, though testers said the inside felt like a woolly jumper and was too warm for milder conditions.

Key specifications Material: Polyester (100%) Sweat-wicking: Yes Thumb holes: No Pockets: No

The first product Under Armour ever marketed was a stretchy, sweat-wicking top — aka, a base layer. Now, 26 years on, the brand boasts a catalogue of sports shoes, apparel and equipment, but base layers remain a key part of what they do.

This top has a looser fit than many we tried, making it much easier to put on and take off. Our panel also loved being able to roll up the sleeves if they got a bit hot. The HydraFuse was brilliant at wicking moisture away during sweaty sessions and the dropped hem proved popular with testers, who said the material felt soft against their skin. Some people found it rode up slightly during runs, but a quick readjustment soon set this right.

The WH Lab verdict: Great for keeping you at a comfortable temperature, whatever the weather or workout, this base layer will help you fend off sweaty pits and keep your cool.

Key specifications Material: Nylon (83%), elastane (17%) Sweat-wicking: Yes Thumb holes: Yes Pockets: No

Smartwool aims to combine the warmth of natural Merino wool with the fast drying times of synthetic materials in this hybrid base layer. We found the stretchy fabric fitted well and didn’t ride up while we were running. Its woolly make-up provided plenty of warmth too, despite being ultralightweight, and wicked sweat away well without becoming smelly. These impressive credentials do come at a higher price, but we think it’s a smart investment.

The WH Lab verdict: There’s no need to feel the chill with this warming top. We found it a bit too hot in milder conditions, but if you’re looking to fend off chilly weather during a run or park workout then there are few better base layers around.

Key specifications Material: Merino wool (52%), polyester (45%), elastane (2%), polyamide (1%) Sweat-wicking: Yes Thumb holes: No Pockets: No

Before we jump in, you should know that this heavy-duty base layer isn’t made for brisk walks around the park. It’s made with skiing and snowboarding in mind, and kept testers toasty warm, however low temperatures plummeted. Our panel said the material felt quite tight and restrictive, making it unsuitable for outdoor sports where you need to move your arms freely. But they loved the look, saying the design was so flattering they would wear it as a standalone top.

The WH Lab verdict: If you are hitting the slopes or have some sub-zero runs in the pipeline, it’ll help you stay comfortably warm (and look good doing it).

Key specifications Material: Polyester (63%), polypropylene (31%), polyamide (6%) Sweat-wicking: No Thumb holes: No Pockets: No