Effects of functional shirts with different fiber compositions on thermoregulation in well-trained runners

Abstract

This study aimed to investigate the effects of two functional sport shirts with different fiber compositions (polyester: 100% polyester vs polyester–lyocell combination: 67%–33%) on thermoregulation and wearing comfort during treadmill walking at an average intensity under moderate environmental conditions. It was hypothesized that the hydrophilic lyocell fibers would benefit sweat evaporation and, thus, provide a superior cooling effect. Using a repeated-measures study design, core, surface and between skin-and-shirt temperatures were measured in 11 men while wearing either the polyester or polyester–lyocell shirt. Additionally, sweat loss, heart rate and subjective perception of comfort were determined. In spite of significantly greater sweat production, relative humidity was lower with the polyester–lyocell shirt. In the later phases of the walking intervention, the temperatures were consistently higher with polyester–lyocell, although between-shirt differences failed to reach significance. These results suggest that greater water retention limits the thermoregulatory efficiency of cellulosic fibers when excessive sweat production occurs.