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 Mizuno Breath Thermo Review - Winter Running


Winter running is upon us...well at least up here in Wisconsin. Nightly temperatures have dipped down into the single digits at times, which means it's time to start gearing up. As a good runner friend of mine says, "There's no such thing as bad weather, just bad gear." The Mizuno Breath Thermo Collection came in for me to test a few weeks back and I've brought it out on many brisk, cool, and even windy mornings. 

The Mizuno Breath Thermo Collection operates off of their patented Body Warming Technology. The fabric operates not only on its thickness, but is designed to "activate" once it contacts sweat and uses it to warm your body. As they say, "You work for your sweat. Now let your sweat work for you." That said, each of the items I brought through the paces were most effective for heating when closer to the skin and were able to come in contact with sweat. I was sent the Base Layer Long Sleeve, FZ Vest, Fleece Gloves, Beanie, and Racer Mid Socks. Overall, this line provides effective warmth for these fall and early (and deeper) winter days, fits on the looser end of the spectrum, and is comfortable on the run. Let's dive into each.

Nathan Brown Body Type Profile: 
Height/Weight: 5'10"/155#
Chest: 38in
Arm Length: 29 in
Waist: 31in
Inseam: 32in
Thigh Diameter: 21in
Calf Diameter: 14.5in


Fit/Comfort: If I could go back, I would order a small. The top fits a bit loose throughout the chest and torso and the length went below the glutes completely (very long). Since I see this functioning as a base layer and only layering on top of the shirt (not underneath), I would want to size down to get it to be a bit more snug, particularly since there is good stretch to the material. Speaking of stretch, the feel of this shirt is overall quite comfortable. It isn't the softest shirt you will put on as you can feel the Breath Thermo stitching when putting it on, but it does not scratch or itch when running. Finally, the underarm is constructed with a softer material, which avoids irritation in more sensitive areas.

Performance: A thicker base layer like this is best (in my opinion) when it can keep the torso warm. The Mizuno Base Layer Long Sleeve does a great job at this task, and it really is because of the action of the Body Warming Technology. What this means is that until you start sweating, it'll feel like any other base layer you've used. However, the way it utilizes your sweat to warm is effective, and I found myself sweating more once things got going because I really would warm up. This leads to one piece to be aware of. Because it uses your sweat to warm you, I did find the shirt would be a bit more wet by the end of the run (and therefore my skin as well). This did not cause any problems with rubbing or irritation, but is something to know going in to using this base layer. 

Use: This base layer is likely the most versatile piece in the whole collection. It has enough breathability for the more mild winter and mid spring days to be warn alone, but is also my favorite base layer for the very cold and frigid mornings. On those colder days (in the teens or below) I've appreciated a second layer to keep my torso warm on longer runs. For me, being accustomed to the Wisconsin seasonal changes, the base layer works along for anything in the 20s.

Price/Value: The Breath Thermo Base Layer Long Sleeve checks in at $85. Thankfully, given the versatility of use and durability it has shown, investing in this shirt may give you the value you need. It has a strong construction and it has handled going through the wash without any changes. If you're looking for a durable, versatile, and effective base layer, this could be a great direction to look.


Fit/Comfort: The FZ Vest fit me very well. It is also on the slightly loose end, but this works well as it works best over a base layer underneath. The width of the shoulders will cover the entire length of the shoulder to keep things warm, and the length sits a few inches below the waist line, keeping it from letting any cold air in from below pretty well. The vest is also comfortable and flexible, with a softer material underneath and a wind resistant material that allows movement with ease.

Performance: This vest does its job overall, which is to keep the core of the body nice and warm. The wind resistant exterior and Breath Thermo internal construction provide protection from the cold and still allows the material to heat your body using your sweat. One area for improvement would be to synch up the lower part of vest or have some sort of drawstring to allow people to close up the opening under the vest depending on body type. The other thing to note is that once you layer too much underneath, you will no longer get the effects of the Breath Thermo technology, but just the effects of the thickness of the vest and wind resistant outer construction. That said, the beauty of the Breath Thermo technology is that you can get the same warmth with less combining the Breath Thermo Base Layer and this Vest was the perfect combination for me, even in the low teens (deg F). The FZ Vest also has pockets that function well for carrying gloves or a hat when things warm up throughout the run.

Use: Another very versatile option from Mizuno, but I think does shine best for mild-moderate winter temps. It gives the arms some air to keep you cool which keeping your core nice and toasty. For me living in Wisconsin, I won't be able to get through the whole winter with this, but will do well in the beginning and tail end of winter. However, for someone a bit south of me, you may get everything you need from this vest. Through this first stretch of colder weather (which has included single digits) I've really enjoyed the flexibility it has given to my arms and the natural cooling for my arms so that I don't overheat during workouts.

Price/Value: The FZ vest checks in at $120. For this price, you can find some coats with long sleeves, so if this vest is worth it will really depend on your preferences as well as climate. If you live in a more mild climate and haven't tried a vest vs. jacket, I really think this is a great vest to check out. For people who live in places like me (Stevens Point, WI), you'd likely need to get a running coat of some kind in addition to this vest to make it through the whole winter, so you'd have to weigh your value of having a vest for some more mild days and a coat for the more extreme days.


Fit/Comfort: Unlike the upper apparel discussed above, these three accessories are form fitting, and continue to sport a very comfortable overall fit. 

Let's start with the Beanie (SIZE: ONE SIZE FITS ALL). The Beanie is a very flexible and form fitting material that will stretch to any head size. I have a smaller head, and it is no way was too large for me. The hat has extension of the beanie that come over each ear that ensure full coverage. The one issue with comfort was that the tag was placed along a seam that directly covers the ear, and the tag is not easily removable. This means it was rubbing over the ear or would be sticking out of the hat. For the future, I think moving the tag is an easy adjustment for Mizuno to make.

Next up is the Fleece Gloves (SIZE: MEDIUM). My hand measures 19 inches from the base of the palm to the tip of the middle finger, and these gloves fit perfectly. I also have a slightly more slender hand (ring size 6.5/7). The gloves have a little wiggle room for me and also stretch well to accommodate if I'm wearing a ring or for those with thicker hands. The cuff of the glove moves  to accommodate my running watch as well. Comfort is fine with no irritation to the knuckles.

Finally is the Racer Mid Sock (SIZE: MEDIUM). I am a bit strange about my sock preferences. I've tried a number of different socks that have different compressive areas and typically struggle to enjoy them for various reasons. Not the case here. The compression of this sock isn't overbearing to any part of the foot and does not over-compress the toes (an issue I have with many other socks). The socks are constructed to be foot dependent (L vs R), is overall a comfortable and slightly thicker material, and the medium fits perfectly for my shoe size (9).

Performance: I've already talked about how well the Breath Thermo technology actually works above, but where it shines is with these accessories. I'm lumping the performance together because they carry several commonalities. I was very surprised at how warm the Beanie and Fleece Gloves were. It may have taken 5-10 minutes to get there, but these thin gloves and hat actually caused my hands and head to sweat in single digit weather thanks to the technology built in. Yes, for even more frigid and windier days, I would prefer a glove with wind resistance/windproof technology, but the Fleece Gloves will be my go-to for 90% of runs this winter. Same is true for the Beanie -- I may need to add a layer for the remarkably cold days, but this will carry me through most of this Wisconsin winter. Finally the socks. Thanks to the technology, the sock is able to remain relatively thin so it can fit in my shoes, but the technology allows me to get away with wearing shoes with thinner uppers without my toes falling off. My favorite winter running sock I've ever used.

Price/Value: Overall, the prices of these products line up with most competitor's prices, but these have certainly shown that their versatility, performance, and current durability make them worth the investment. 

Breath Thermo Beanie ($30): Like I said above, this hat is going to be used for pretty much every run throughout the winter and even much of the fall/spring. It is thin enough for slightly warmer temps and then the Breath Thermo technology shines for the colder temps.

Fleece Gloves ($35): These gloves are great, no doubt about that. They are thin and comfortable for performance/workout days, are lightweight, and keep the hands warm in most conditions. The question really comes down to if you want a performance glove or want to get by with layering cheaper gloves for most days and then investing in some wind proof gloves for only the extreme days.

Racer Mid Sock ($20): I think that these socks have the highest value for me. There are lots of tricks out there for keeping feet warm in the winter (like using some duct tape to block wind from getting through the upper), but these socks kept my feet toasty in any shoe that I wore without modification.


Mizuno did a great job assembling gear for the colder temperatures, and the Breath Thermo technology did very well. A direction I'd love to see Mizuno go would be to add additional visibility components, especially since days are shorter in the winter. There is some reflective components to all the gear, but expanding this would really improve the line. Also, as mentioned above, making sure tag placement doesn't interfere with the ear in the beanie would be a nice tweak. 

For those looking for high quality, durable, and affective equipment at a typical price tag, you may want to take a peek at the Breath Thermo Products. The products in this review lean towards mild winter running and transitional seasons (and as a base layer on the coldest of days), with the accessories dipping into handling the colder temperatures.  The Breath Thermo line does have product that are meant for even colder temperatures, they just were not tested in this round of product.

Thanks for reading!

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Dr. Brown is a 155 lb male with notable PRs of 18:18 5K, 39:25 10K, 1:29:01 half marathon, and 3:54 marathon. He typically runs between 20-40 miles per week at a variety of paces from 7:30-8:30 min/mile for recovery runs to 6-6:45 min/mile for tempo runs. He typically prefers shoes that provide some cushioning underfoot but still maintain a more firm and responsive feel. Current goals for 2020 are to break the 1.5 hour half marathon and 3:30 marathon. IG handle: @nate.docsofrunning

Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles area, I am currently taking clients for running evaluations.

Doctor of Physical Therapy
Board Certified Orthopedic Clinical Specialist
Fellow of the American Academy of Orthopedic Manual Physical Therapists

Nathan Brown PT DPT MS
Doctor of Physical Therapy 
Masters in Anatomy and Clinical Health Science
Movement Performance Institute Certified in Advanced Functional Biomechanics 

David Salas PT DPT CSCS
Doctor of Physical Therapy
Certified Strength and Conditioning Specialist

***Disclaimer: These apparel items were provided free of charge in exchange for a review.  We thank the  people at Mizuno USA for sending them to us..  This in no way affected the honesty of this review. We put at least 40-50 miles on clothing prior to reviewing them. Currently we have 42 miles (Nathan). Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear or apparel rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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