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.

The Role of Sports Clothing in Thermoregulation, Comfort, and Performance During Exercise in the Heat: A Narrative Review

“…A similar interaction was observed by Herten et al [51] with results that approached statistical significance (p > 0.06). Herten et al [51] noted lower microclimate humidity (10%) following 15 min of walking during a 60-min trial when a shirt with higher air permeability was worn compared to a shirt with lower air permeability. Taken together, these results suggest that greater air permeability may decrease the insulative effect of clothing, thereby reducing the barrier to evaporative heat loss in hot environments.…”

“…Thermal comfort ratings were poorer (p < 0.05) when the t-shirt with the lowest air permeability was used compared to all other t-shirts [21]. A similar interaction was observed by Herten et al [51] with results that approached statistical significance (p > 0.06). Herten et al [51] noted lower microclimate humidity (10%) following 15 min of walking during a 60-min trial when a shirt with higher air permeability was worn compared to a shirt with lower air permeability.…”

“…Moreover, this may suggest that sports clothing may only provide thermal, perceptual, and performance benefits during long duration and high intensity exercise bouts, though further research incorporating such protocols is warranted to confirm this. Recent studies have also prescribed moderate and vigorous intensities during 60-min exercise bouts [46,51]. MacRae et al [46] prescribed a 60 min protocol at 65% VO 2 peak followed by a 6 km time trial but observed no significant differences in thermoregulatory, physiology, comfort, or performance-based measures when comparing correctly fitted (11-15 mmHg) and oversized (8-13 mmHg) compression garments.…”

“…MacRae et al [46] prescribed a 60 min protocol at 65% VO 2 peak followed by a 6 km time trial but observed no significant differences in thermoregulatory, physiology, comfort, or performance-based measures when comparing correctly fitted (11-15 mmHg) and oversized (8-13 mmHg) compression garments. Herten et al [51] compared a blended synthetic t-shirt to a purely synthetic t-shirt (100% polyester) using two consecutive 30-min trials performed at 50% and 60% VO 2 peak but only observed significant differences in absolute and relative sweat loss and not in core temperature, heart rate, or thermal comfort. Though these results may indicate the need for exercise protocols to exceed 60 min to sufficiently examine the capacity of clothing to aid thermoregulation, comfort, and performance, the environmental conditions were mild in both studies (24-25 °C, 50-60% RH) [46,51].…”

“…Herten et al [51] compared a blended synthetic t-shirt to a purely synthetic t-shirt (100% polyester) using two consecutive 30-min trials performed at 50% and 60% VO 2 peak but only observed significant differences in absolute and relative sweat loss and not in core temperature, heart rate, or thermal comfort. Though these results may indicate the need for exercise protocols to exceed 60 min to sufficiently examine the capacity of clothing to aid thermoregulation, comfort, and performance, the environmental conditions were mild in both studies (24-25 °C, 50-60% RH) [46,51]. Clearly, the feasibility, ethical, and logistical challenges of designing appropriate exercise protocols for the assessment of sports clothing during exercise in the heat should be considered.…”