Don’t pet the sweaty stuff

Tech shirts. All of the major companies make them now. Mostly polyester, they were designed originally to increase evaporation to provide a “cool” feeling and decrease the amount of sweat present in the clothing after a workout. They were popular with military in the Middle East until they were banned due to the injuries they cause when burned. Living in south Texas, I’m infinitely familiar with clothing soaked with sweat.

This article took 3 different kinds of synthetic shirts and 1 ordinary cotton shirt (Fruit of the Loom!) and compared them. The methods section makes me never want to be friends with these guys, as they made them start at 7 kph, going up 1kph per minute up to 14 kph. Then inclination was increased by 1 degree per minute until exhaustion. This was to determine peak oxygen uptake. Then for each individual fabric test they made them perform at 70% of that maximum uptake for 30 minutes, then increased the inclination to exhaustion again. At least there was a fan blowing on them from the front. Temperature was controlled at 31.7C and relative humidity was kept at 42%.

During testing, they measured

  • Temperatures (ambient, skin, body, and core)
  • Relative humidity (ambient, chest, and back)
  • Blood lactate (from the ear)
  • Ratings of
    • perceived exertion on a 6-20 scale
    • thermal sensation on a 1-9 scale
    • wettedness sensation on a 1-4 scale
    • shivering and sweating sensation on a 1-7 scale
  • Heart rate
  • Respiratory exchange ratio
  • Ventilation
  • Oxygen uptake

They found that 2 of the 3 synthetic shirts did lower body temperatures, decreased relative humidity, and made the runners “feel cooler” during exercise. They did not demonstrate any increase in performance ability. Thus, it is likely that this kind of shirt may make you feel less wet, but is unlikely to make you an Olympic athlete right out of the box. Certainly they aren’t worth a huge premium over regular shirts.

Sperlich B, Born DP, Lefter MD, Holmberg HC. Exercising in a Hot Environment: Which T-shirt to Wear? Wilderness Environ Med. 2013 Sep;24(3):211-20 [PMID 23870763]

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EBM Gone Wild

Wilderness Medicine

Emergency physician with interests in wilderness and prehospital medicine. Medical Director of the Texas State Aquarium, Padre Island National Seashore, Robstown EMS, and Code 3 ER | EBM gone Wild | @EBMGoneWild |

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