Safety / Injuries
Cotton vs. Synthetic: Why the natural choice may not be cotton
In the first article in this series, we introduced you to the importance of proper attire for performance. This is a topic that impacts elite athletes as much as it does weekend warriors, so we wanted to dig a little deeper…share the science with you and empower you to help your clients find the right workout gear. Let’s talk about cotton. Why is it a bad choice? What’s better? Why does it matter?
We’ve talked about dressing for fitness before (you can check out that article here for a refresher) and mentioned that 100 percent cotton isn't the best choice for workout gear.
Now, let’s go over this in a little more detail so you can help your clients understand why they should be ditching cotton for the gym and opting for synthetics instead.
Cotton, Synthetics, and Thermoregulation
While it’s true that a lot of people turn to 100 percent cotton clothing because it’s comfortable, easy to wear and wash, inexpensive, and breathable, it’s just not an ideal material for exercising.
To understand why, take a look at how our body regulates heat—called thermoregulation—and the importance of this process.
Thermoregulation is the process in which the thermoregulatory center in the hypothalamus readjusts body temperature in response to small deviations of a set point.1
In other words, when our body temperature begins to rise during a workout, the thermoregulation system gets to work bringing it back down to normal, moving heat out of the body.
For heat to be transferred out of the body and into the environment—to cool down during or after a workout, for example—it has to be able to access to the outside environment, which means not being blocked by clothing.
Heat from throughout your body is transported through the blood, then to the skin, and then to the environment. Clothing can act as a heat conductor, meaning that heat can be transferred to your clothes from your skin, kind of like when you use a heating pad.1
During exercise, the main way that the body thermoregulates itself is through evaporation. When your body gets hotter, you sweat more and this helps you to cool down.1 But, for sweat to cool your body, it has to be able to evaporate from the skin. Sweat that stays on the skin doesn’t bring your temperature down. And, the more your body is covered up by clothing, the harder it is for sweat to evaporate and for the body to cool down.
Sweating While in Cotton
Yes, cotton does absorb sweat, but then the sweat just stays there, keeping the fabric soaking wet. It doesn’t get drawn away from your skin. In other words, cotton is not moisture-wicking, which means it doesn’t pull the sweat away from the skin. It does not promote quick drying of sweat.
This is where synthetic materials come in so handy. They are moisture-wicking and help dry sweat faster by pulling the sweat away from the skin, out of the clothing, and into the environment. Rather than trapping sweat, synthetic fabric releases it, allowing for the important cooling process of evaporation.
What to Wear? Oh, What to Wear?
There are many cotton alternatives, synthetics that will help to keep you cool and dry and aid, not hinder, thermoregulation.
Some of these are blends and include some cotton to make a material feel nicer. That’s ok as long as the majority of these blends are not cotton.
Other materials you might choose from include blends with polyester, rayon, nylon, latex, bamboo, wool, and spandex. The most important factor is that a material wicks moisture. You should find that most exercise clothes on the market these days have moisture-wicking properties.
Not everything is rosy with synthetics, though. One downside to synthetic materials is that they tend to get a little stinky after multiple workouts.2 The consequences of overheating, though, are worse than the risk of offending others with your stink. Also, you can find some workout gear on the market that is made with materials embedded that kill the bacteria that cause the offending smell.
The Bottom Line: Cotton May Be an Old Favorite, But it is Not always Ideal
Some people may still choose cotton. There are still some athletes and gym goers who still stand by cotton. Some may stick to cotton shirts for weight lifting to keep the bar from slipping too much (although we couldn't find any research to support this concept), while others may use cotton sweat-shirts to sweat and “drop weight” (that’s a whole new topic in itself).
For others and in most situations, wearing synthetic clothing is a better option than cotton for working out. If you don’t believe the experts, give it a try. Wear a cotton t-shirt to hit the gym and you should find that you end up soaking wet and uncomfortably hot. Your performance may suffer too.
It’s also important to note that not using 100 percent cotton holds for everything you wear to workout, from head to toe: sports bras, socks, and even underwear need to be breathable and moisture-wicking.
As a bonus, if your skin is sensitive or sometimes gets irritated when you sweat, synthetics reduce this effect. The rubbing of soaked cotton against the skin is pretty irritating.
Researchers have shown that in longer workout sessions synthetic shirts keep body temperature lower than cotton shirts.3 You may have even personally experienced this. When you’re out and about on a hot day in your regular cotton clothes and your back starts to sweat. You notice it for the rest of the day because it just feels wet. You may also notice the cotton clothes stretch out and lose their shape (remember clothes that are closer to the body are safer to work out in than baggy ones). Just imagine if you are trying to perform, how much more you may notice this.
The next time you have a client come to the gym in that old cotton t-shirt, sit them down for a little talk. Tell them about thermoregulation, sweating, and how cotton just doesn’t cut it. For their health, comfort, and performance, share this article with your client and talk about whether swapping out that old cotton for a synthetic option is right for them.
1. Wilmore, Jack H., and David L. Costill. Physiology of sport and exercise. Champaign, IL: Human Kinetics, 2004. Print.
2. Callewaert, C., E. De Maeseneire, F.-M. Kerckhof, A. Verliefde, T. Van De Wiele, and N. Boon. "Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session." Applied and Environmental Microbiology 80.21 (2014): 6611-619. Web.
3. Sousa, Justin De, Christopher Cheatham, and Matthew Wittbrodt. "The effects of a moisture-wicking fabric shirt on the physiological and perceptual responses during acute exercise in the heat." Applied Ergonomics 45.6 (2014): 1447-453. Web.
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