if you workout and run, would you recommend a merino wool base or mid layer for autumn/winter? or am I going to break it?

The bras & underwear from Branwyn are great. The t shirts from Unbound are also fantastic, I haven't tried their athletic stuff. Other brands I've had mixed experiences with, the socks from Smartwool I do love.

It's hot here, not cold but Merino knits are remarkably comfortable all weather items.

As the hikers say. Cotton kills...it retains water (sweat / rain / snow) and ends up being less insulating, making you susceptible to hypothermia and making the layer heavier. Typically the base layer is there to wick water away from your skin, and the mid layer is there to keep you warm. Any temp under 40f, is considered a no go, with cotton, if your hiking.

Looking at clothing recommendations, here, and here for runners, it seems if it's under 30f, they tend to stay away from cotton. Note: Obviously these people are also selling expensive clothing, whats important is the fabric type, not the brand name. Even if your not at risk of hypothermia, the cold constricts your muscles, making them tighter, which apparently is not great for running.

To answer your question, as long as it's not Kari Tra brand wools, (esp the thin ones, get holes, practically immediately, for no reason. The mid weights are better, but not by much) imo, as a hiker not a runner, i would say they should hold up for at least a season, with proper care. Especially, if your wearing something more slippery like polyester over them. Wool definitely breaks apart due to friction. Even wools Ive gotten to wear under work clothes, only last a couple years max, before they start to wear in some choice areas. If you value your wools though, I would find some polyester / synthetic base / mid layers, especially if you are running on a regular basis.

Tldr: if your running in freezing temps don't wear cotton. If you value your wools, get a polyester / synthetic base and mid layer. Also, maybe check out REI brand for some cheaper wool layers.

You can get a thin smartwool or polypro base layer from a ski shop for like $50, even cheaper on sale but it's the wrong time of year for that. That's probably all you would need unless you're planning on running in a blizzard.

When I was in the military a bazillion years ago, our winter running uniform was a beanie to add to our t-shirt and shorts. That was it. If it was SUPER cold (like, below freezing) we'd get to wear sweatpants and a sweatshirt. Then we'd go run 4 miles in the dark. If you got too cold you just had to run faster. :)

I run outdoors year-round in weather down to 20°F in a climate with high humidity. Above 40°F I wear old beat-up tshirts, a thick hoodie, and leggings-style running pants. Below 40°F I replace the T-shirt with an REI house-brand light- or mid-weight base layer, and I toss a pair of cotton exercise pants over the running pants (I bought those years ago for less than $15) and wear a cheap woven hat and my junkiest gloves. If it's raining I'll replace the heavy hoodie with a water-repellant windbreaker + light weight hoodie.

In other words my running wardrobe is comprised almost entirely of my oldest, most beat-up clothes, most of which were originally just cotton or other cheap non-technical materials purchased years ago at a fast-fashion store at the mall or used from a sporting goods store. I do invest in decent socks (I highly recommend darn tough for their durability), but unless you're braving truly cold temps, very long workouts, or cannot return indoors shortly after working out,* you really don't need anything fancy for year-round exercise. For what it's worth I'm also a woman and I get cold very easily.

*The main problem with cotton is that it will not keep you warm when wet, so if you like to take a long cool down walk or hang out on a park bench for thirty minutes post-workout you should go with wool or synthetic material so you don't freeze in your sweat-soaked clothes. But as long as you're returning to a warm indoor space before your exercise warmth dissipates, this shouldn't be an issue.

1. For people recommending brands like Smartwool, check the labels. Many of their men's products are only 20% merino.

2. Consider brands like Decathlon (like REI of Europe, but have US site) for something more affordable but 100% merino.

3. Look at backpacking cottage companies for other options

$130 is a lot for a shirt you don't want to damage. I picked up some hoodies to hike in from https://www.ridgemerino.com/ when they were cheaper and on sale and put them through their paces fine. Same with shirts from Decathlon.

What type of weather are you running in? In my area it gets just below freezing in the winter, and I run with a full length compression shirt, then a technical running tee, then a fleece jacket. Works in wind, rain and snow between around 12c and -4c. Leggings and head/face covering are also often needed.

Biggest thing for me is really socks and runners; socks are wicking insulated running socks with an ankle, shoes have GoreTex uppers to keep my feet warm and dry.

Something to also take into consideration is how hard you’re pushing/sweating.

Merino wool will definitely work as a mid layer, but you’ll likely overheat pretty quickly, and it’s hard to get the sweat out.

Wool should not be a base layer, but in the mid-layers. It can be a decent shell in lightning, and felt can hold against light rains (and will stay warm even if it does get soaked.)

Merino wool can be considerably less scratchy than lower-quality wool; alternatively wool blends will also be better (“smart wool”).

As a material, it can be quite hard wearing if it’s made sturdy. That’s less about the material and more about how it’s made.

You might want to consider a shell layer that’s wind proof, but for fall, a light sweater and a shell while active should be enough unless it’s ghastly out. (Cold and rainy. That shit seeps; and nothing wholesome ever seeps.)

Remember the critical thing is to dress in layers so you can adapt.

I don't run and would still never advise wool

As someone else mentioned I would recommend a compression type base layer. You can get slightly different thickness ones that will help in different temperatures.

I had a Nike DRI Fit one that lasted for 10 years, and would have lasted me longer if I hadn't left it on the roof of my car at one point and lost it. You can get far cheaper ones as well though, my current one cost me around £15 and has lasted me 5 years so far and hasn't stretched out of shape or have any holes in so far and I use it pretty much everyday during the winter ones.

They keep air flowing and move sweet away from your skin to keep you dry as wetness will make you colder.

In my opinion morino wool is one of the worst things I have tried. They make you sweat a lot more, dont move the wetness away from your skin exacerbating the problem and making you feel very uncomfortable and fall apart in no time when compared to compression garments.

I'd say save your expensive wool for some when else.

For other layers I tend to use a cotton t shirt over top the compression layer, maybe two t shirts if it is very cold and then add in things like gloves, something to cover your neck and face and then a wool hat of somekind.

It is always best to be able to remove these layers where possible whilst you are running. In time you'll find what works with you. I'd often start out with a few more layers for that initial start then once you get going progressively remove stuff until comfortable. I'd always rather be very slightly cold then too warm when running.

I can't speak for base/mid layers, but I wear merino wool socks at work (danish endurance, not 100% but a blend), in steel toe boots, and they last quite a while. Haven't had any holes or even wearing thin, and I'm notoriously hard on socks and footwear.

If you want a "cheaper" option to try I'd give Minus 33 a chance. If it works for you great! If not it's not as expensive as it could have been.

I do share other commenter's concerns about overheating. The line I've heard is "be bold start cold"