- Textiles really are in so many things that impact our daily lives.

My name is Dr.

Kendena Henriques-Thompson.

I am a textile scientist, engineer, and technologist.

My love for textiles stemmed in ag and fiber science, and then transformed and bloomed into the different layers of things I've been able to study and research on top of that.

I saw so much waste in the apparel and fashion industry, in the consumer goods industry, that I wanted to be able to speak to what I saw from a scientific standpoint.

- Dr.

Henriques-Thompson and her students conduct research at the Skin Textile Interface Lab at NC State's Wilson College of Textiles, where they test the performance of textiles like athletic apparel.

- With my background being footwear and performance apparel, I look at the impact of friction on different comfort zones, right?

So when you're looking at footwear, that's going to be your tongue, your heel counter, but specifically your insole and that sock liner textile that interacts, if you're wearing barefoot with your skin or with your socks, that interaction.

In terms of apparel, you think about high friction areas like under your arms.

For women, around the breast region.

For men, sometimes it's their shoulders.

So being able to analyze different parts, that leads to comfort, that leads to performance.

And a lot of times, wearers have issues where they get blisters or sometimes their materials or their shirts are pooling because their sweat isn't dissipating.

Just looking at those type of interactions and the biophysics of it all and how the materials impact the comfort and performance, how they perform alone as materials, but more importantly, how do they perform when they are in function with the human body?

- To look at how textiles interact with the human body during athletic activity, Dr.

Henriques-Thompson and her students conducted a study recording parameters like skin temperature, while male and female study participants perform moderate physical activity.

- This is the skin temperature probe for the wonderful Biopak machine we have here.

So we have Andreana here and she's going to put the probe on her finger.

- The probe is given time to calibrate to the person's base temperature before activity starts.

For the first phase, Andreana will lift light weights at a steady pace.

- And you can see that she started at 83 degrees and now we're about 86.

So if you want to go ahead and start doing some activity, she's doing light weight lifting, light activity, which is what we did for this study.

An activity that's pretty normal and very common for people who do weight lifting at home.

You're an average athlete.

- In addition to the temperature probe, a SEEK thermal infrared camera gives additional insight into where heat is building on participants' bodies.

- Where she is exerting energy in her arms, you see is the warmest part.

We can also see that she's warming up in her calves and lower legs and in her upper chest region, which makes sense.

When you have these thermal images, this is what helps to inform you.

Where is the wearer actually feeling the most discomfort?

- Dr.

Henriques-Thompson explained that during physical activity, including dynamic exercises like weight lifting, your feet can actually start sweating before your body feels hot because of increased metabolic demand in your extremities.

- Her toes on her right foot are actually starting to warm up and her left foot is slowly matching that, which makes sense because your feet are holding you in place.

- This highlights the importance of footwear choice when it comes to athletic apparel.

- Ideally, what you want is to have breathable socks and you want to make sure that your footwear is breathable as well.

She has on cotton socks and a knit upper.

That's breathability.

That allows some of the moisture and the sweat and the temperature to dissipate through her feet.

- As Andreana continued lifting weights, her skin temperature increased as expected.

But an unexpected outcome of the study occurred during the times when participants weren't active.

- Are we ready to go into a rest phase?

- We're going to go into a rest phase in 3, 2, and 1.

Thank you.

And so now we just see the trends of her body temperature.

And you can see it's teetering right now.

She stopped moving, but her temperature is still the same and it is still increasing slightly.

When she stopped her activity, she was about 90.2 and it went as high as 91.3.

- This increase in temperature during the rest phase was only observed in female study participants.

- The anthropometric differences between males and females, I mean, it is something that is so under-explored in so many different industries, especially when it comes to textiles.

One of the things that we saw was that males in this study generally had a higher calibration 5-minute temperature prior to the actual activity than females did.

However, in our rest time cycles, females had a higher increase in temperature during the rest after the light activity.

- The study also had participants run in place with the temperature probe held to their chest.

- We had participants do a full 45 minutes, so you can imagine at the end they were really exhausted and sweaty and tired.

- The data averaged from the running portion of the study shows the variability in female skin temperature measured by the probe during active and rest periods, while average male skin temperatures were less variable as shown by the smoother curve.

Dr.

Henriques-Thompson says this variability and the temperature increase during rest periods has implications for both apparel choice and design.

- If apparel is intended only to keep you cool and functional only during activity, then the wearer is going to experience some discomfort during rest because the heat is already still built up.

It's still pushing more heat to the surface of the skin and you're still sweating.

So it is a delayed thermal response during the rest time.

So it's important that we're not just looking at materials and how they're functioning in activity, but really how do they function post-activity for that optimal wearer comfort.

For the most part, when you think about performance apparel materials or performance footwear materials, they're kind of tested under these extreme conditions, right?

So extremely cool or extremely hot or these really peak levels, and that's not realistic.

That's not the average person going into the gym and doing a light jog on the treadmill and experiencing that their sweat is pooling and it's not spreading.

It's not dissipating and it's not being absorbed.

It's not being wicked.

This condition that we did our tests under showed that, once again, it's more about the human response than it is about the fiber.

That is really important when we're thinking about performance apparel design, that it's more about the wearer.

- And this study is just the first step.

- If you think about the results and what it means for so many stakeholders in the supply chain, it means something for science.

It means something for design.

It means something for the wearer.

It means something for athletes.

And so there's so many different angles that we can apply these data findings to.

When we think about design, designing not only for activity but also for rest.

When you see the problems of textiles, those problems influence research questions and applications that are yet to be discovered.

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