Research regarding the study of garments and how they can affect human comfort and physiology goes back as far as 1947 when Fourt and Harrist (5) began studying the concept of “wicking,” which is the diffusion of water through textiles. The transfer of perspiration through the garment from the skin to the environment is thought to be beneficial to the athlete via 2 mechanisms. First, the comfort of the athlete would be enhanced by reducing the moisture on the skin that would otherwise be trapped until the garment is removed. Second, evaporation is the primary mechanism of heat loss during physical activity and any form of clothing provides a barrier to evaporation (10). However, if the garment has high wicking capabilities, it would be able to minimize this barrier and provide superior cooling.
These concepts were first studied by Galbraith et al. (6) in 1962, who examined the effects of varieties of C and Orlan with contrasting wicking characteristics. This study did indeed discover that garments that were unable to transfer moisture were less comfortable, although the researchers failed to observe any difference in their impact on perspiration and rectal temperature (6) in a warm environment with no physical activity. More recently, it has been suggested that although C is able to absorb water well, the water is retained in the fabric and is therefore unable to dissipate heat (3), which is lost through evaporation. Furthermore, C eventually becomes saturated and incapable of absorbing more water, therefore further preventing the loss of heat.
This observation of the drawbacks of C as a primary garment material was noticed by Kevin Plank, who went founded Under Armour and created a type of performance apparel with form fitting compression that aimed to overcome such disadvantages. For example, polyester (P) is claimed to have much greater wicking capabilities, which avoid the oversaturation of C that prevents athletes from using evaporation as a source of cooling and also causes discomfort. Where the early studies in garment materials made comparisons among natural fabrics, more recent research has compared the modern synthetic materials with traditional C garments and their effects on physiology and comfort.
For example, Brazaitis et al. (2) revealed greater sweat rates and a superior reduction in skin temperature when subjects wore a P garment during a light running treadmill task (8 km·h−1), although surprisingly the subjects did not report subjective differences in dampness or temperature. In contrast, Kaplan and Okur (9) failed to find differences in physiological parameters, such as skin temperature and heart rate, but did report differences in the subjects' sensations of wetness, coolness, and ultimately comfort in a walking and light running treadmill protocol (6–9 km·h−1). Because of the light nature of these exercise protocols, these studies may have failed to fully demonstrate the differences in the performances of these 2 fabrics by being unable to produce enough perspiration that the benefits of the moisture wicking technology can be fully elucidated. In fact, it has been noted that there is a need for studies in this area to provide protocols which more closely represent sporting activities (4).
Although there has been a trend toward greater use of synthetic apparel in sports and exercise as a whole, the superiority of such garments has not been demonstrated fully in an athletic context. Therefore, the purpose of this study is to assess whether comfort, thermal physiological parameters, and physical performance can be affected by the choice of a traditional C or a modern synthetic garment in an athletic testing protocol.
Experimental Approach to the Problem
To study the performance of traditional and modern garments in the context of greater relevance to sporting activities, a test for speed and agility and a maximal aerobic test were used. An agility test was chosen to test the performance of the garment under conditions with rapid changes in direction, where movement of the garment could cause irritation and discomfort, particularly when wet. To further enhance the relevance of the results to the sporting world, the agility test was also performed while wearing protective padding that is used in American Football to observe if the measures remain consistent in a condition that further compromises comfort. A maximal aerobic test was also used to test the longer term effects of the garments, particularly under conditions of heavy sweating to assess the impact of the contrasting wicking characteristics.
A within-group crossover counterbalanced design was used. The study consisted of 3 visits separated by a minimum of 48 hours. The first visit included height and weight measurements followed by a familiarization of the testing protocol, which also included familiarization with the questionnaires that would be used during data collection. Visits 2 and 3 were experimental visits where each subject was randomly assigned to perform an athletic testing protocol while wearing 1 of 2 garments: a traditional C garment or a P garment (described below).
Ten men (age: 27.5 ± 4.4 years; height: 169.29 ± 14.24 cm; weight: 80.05 ± 10.87 kg) and 10 women (age: 26.8 ± 3.7 years; height: 166.6 ± 4.46 cm; weight: 64.63 ± 4.49 kg) who were all recreationally active volunteered to participate in the study. All the risks and benefits were explained to the subjects before the investigation. Each subject then signed an informed consent document that was approved by the University's institutional review board for use of human subjects in research.
Upon arrival to the laboratory, subjects were provided either a traditional C or a synthetic P garment to wear while performing the protocol for that visit. To assess the effects of the garment under conditions of high perspiration, the garments were first submersed in room temperature water. The garments were also weighed before and after submersion to quantify water retention. Once the subjects were wearing the garment, a body mass measurement was taken. The exercise portion of the protocol was conducted in a climate-controlled environment, and subjects were instructed not to consume water during the protocol so that body mass changes could be attributed exclusively to sweat loss. A standardized warm-up was performed, which included 5 minutes of light jogging followed by a series of dynamic stretches including bodyweight squats, forward and lateral lunges, quad pulls, knee hugs, and straight leg kicks. The first test performed was the Illinois Agility Run (IAR) (described below), which was timed by the use of a stopwatch. Women performed the test once each visit, but men performed the test twice: once while wearing just the garment for that visit and another time wearing American Football protective padding. The protective padding used was that which is worn at the wide receiver position, and either medium or large size was used depending on the best fit for each subject. The pads were buckled down and held firmly in place. The order in which the men performed the test with and without protective padding was randomized. After the IAR, the Multistage Fitness Test (MSFT) was performed (described below). At the conclusion of MSFT, a posttesting body mass measurement was taken to assess how much water was lost through evaporation during the visit. Subjects were instructed to duplicate footwear and all clothing (other than the experimental garments) for each visit. Subjects were also instructed not to exercise in the 48 hours before data collection.
Illinois Agility Run
The IAR is a speed and agility test that involves completing a short course (Figure 1A) as quickly as possible.
Multistage Fitness Test
The MSFT is an aerobic endurance test that is performed to volitional failure (Figure 1B). Two lines, created with the use of cones, are placed 20 m apart. An audio recording is played at sufficient volume that the subjects can hear it at all parts of the course. A series of beeps are omitted, and the subjects are required to reach the line before the sound of the beep. If a subject is unable to get to the line on 2 consecutive beeps, the test is terminated.
Subjects were asked for their typical garment size, which was used as a starting point during sizing. The garments were designed to be loose fitting but not oversized, and this was checked before a garment was issued to each subject. Therefore, each subject was given an off the hanger size, but the fit was monitored by research personnel to ensure that the sizing was appropriate for each individual. The sizes for the 2 garments were duplicated for every subject.
The Gildan G200 model (Gildan, Montreal, Canada) was used, consisting of 90% C and 10% P (Figure 2A).
The Under Armour HeatGear ArmourVent Training tee-shirt (Under Armour, Baltimore, MD, USA), style number: 1242802, was used. The garment was 100% P, with a mesh design across the shoulders, back, and on the sides of the garment from the armpit to the base (Figure 2B).
Two separate short questionnaires were given after each test, similar to questionnaires used in previous research regarding comfort during physical activity (9). After the IAR, subjects were instructed to rate the amount of abrasion and movement they felt from the garment on a 5-point scale, with zero meaning no abrasion/movement and 5 meaning maximal abrasion/movement. They were also given a visual analog scale 10 cm in length, which referred to overall comfort. The subjects were instructed to draw a line that intersected the 10-cm line. The exact point that the 2 lines intersected was then measured and recorded. After the MSFT, subjects were again instructed to answer questions on a 5-point scale, this time referring to coolness, dampness, and weight. Furthermore, another 10-cm analog scale was used to determine overall comfort during the test.
Pairwise comparisons were performed on all dependent variables for men and women separately. Outliers were defined as data points that were greater than 1.5 SD from the mean and were removed and replaced with the mean. For men, pairwise comparisons were also made between tests performed with and without protective equipment. Significance was set at p ≤0.05.
For data including multiple time points (bodyweight before and bodyweight after; garment weight before and garment weight after), separate repeated measures analysis of variances were used for men and women, with garment set as the within-subject factor. Significance was set at p ≤0.05.
Illinois Agility Run
Psychological scales and physical performance results for men wearing C and P garments are displayed in Table 1. While not wearing protective equipment, the P garment provided significantly (p ≤ 0.05) less movement and greater (p ≤ 0.05) comfort. While wearing protective equipment, the P garment again demonstrated significantly (p ≤ 0.05) greater comfort, although the comfort was significantly (p ≤ 0.05) lower than when not wearing protective equipment.
Psychological scales and physical performance results for women wearing C and P garments are presented in Table 2. Abrasion and movement were significantly (p ≤ 0.05) lower in the P garment group. Time to completion was also significantly (p ≤ 0.05) lower in the P group (Figure 3). Also, comfort was significantly (p ≤ 0.05) higher for the P garment.
Multistage Fitness Test
Psychological scales and physical performance results for men and women are shown in Table 3. In both men and women, dampness and weight were significantly (p ≤ 0.05) lower for the P garment and comfort was significantly (p ≤ 0.05) higher.
No significant time × garment interaction was noted in men. However, both groups demonstrated significant body mass reduction after the protocol (p ≤ 0.05) (Figure 4A).
A significant time × garment interaction (p ≤ 0.05) was identified for the pre- and post-body mass measurements for women. Both groups demonstrated significant body mass reduction after the protocol (p ≤ 0.05). Post hoc analyses including pairwise comparisons of the change scores for the respective garment in men and women revealed a significantly greater body mass reduction (p ≤ 0.05) (Figure 4B) for the P garment in women.
A significant time × garment interaction (p ≤ 0.05) and a significant main effect for time (p ≤ 0.05) for both men and women were identified. Post hoc analyses revealed a significantly (p ≤ 0.05) greater increase in weight for the C garment in both men and women when performing pairwise comparisons on the respective change scores (Table 4).
This experiment demonstrated substantial benefits of modern synthetic garments over traditional C garments in aspects including overall comfort, thermal physiological parameters, and physical performance differences while performing athletic tasks.
Where many of the previous studies in this area have observed the performance of garments under light aerobic exercise conditions (2,9), this study was the first to observe differences in an anaerobic task and to assess garment comfort while wearing protective equipment. As the results demonstrate in Table 1, men reported that P garments are more comfortable while performing a speed and agility task, and this is partly because of the significantly lower movement of the garment. When the stressor of wearing protective equipment is added, the higher comfort ratings are maintained for the P garment in comparison with the C garment. This difference is likely maintained because of the substantial increase in the perception of abrasion when wearing the C garment. However, although it has been previously reported that comfort can ultimately affect physical performance (1), this does not seem to be the case with men in a speed and agility task.
In much the same manner as the men, women also reported much higher ratings of comfort when wearing the P garment and also lower ratings for movement and abrasion (Table 2). Unlike men, however, the P garment actually leads to a significantly better performance of the IAR (Figure 3B). The reason for such a difference in women that was not seen in men could be explained through changes in relative mass of the garment compared with body mass. That is, although there is no difference in the weights of the garments between men and women (Table 4), the weight of the garment in women was greater relative to body mass, which may have had a positive effect on power output and ultimately enhanced IAR time.
After the MSFT, the synthetic garment led to more favorable ratings of dampness, weight, and comfort in both men and women (Table 3). Previous studies that had compared C and P garments have not asked for the participants' perception of comfort as a whole but have reported subjective data on other sensations, such as temperature and dampness. In terms of dampness, the only study that made statistical comparisons of garment dampness between P and C failed to find significant differences (2), but this may have been because of light intensity of the activity (60 minutes of treadmill walking at 8 km·h−1) that failed to stimulate enough perspiration to accurately make such a comparison. In this study, the changes in dampness of the garment were clearly a greater determinant of changes in comfort when compared with temperature sensation, as differences were not seen in this variable.
Failure to find changes in temperature sensation have also been reported previously (2,7), including in studies which also found a difference in sweat evaporation (2), much like this study that demonstrated no change in temperature sensation despite a greater sweat loss in women (Figure 4B). Although core temperature was not measured, the change in body mass certainly suggests that the thermoregulatory mechanisms, such as evaporation, were more active. Although this may seem contradictory, these findings highlight the limitations of perceptual scales and speak to the inability of individuals to sense their overall temperature. Clearly, there are benefits of wearing synthetic garments during exhaustive exercise, even factors that individuals may not be able to consciously sense, which could be a significant advantage for athletes as the loss of heat through evaporation of perspiration is the primary means of thermoregulation during physical activity.
Although there were body mass changes in women, body mass changes were not found in men (Figure 4A), despite men losing greater amounts of sweat overall. This is a novel finding as the majority of research in this area has been performed on men. In fact, to the author's knowledge, only one study has been published in this area using women participants and used only 5 subjects (8). This greater sensitivity of changes in women could be because of lower overall volumes of sweat in these subjects. It is possible that the larger volumes of sweat overwhelm the wicking capabilities of synthetic garments and that this perspiration is still able to escape the garment because of their loose fitting nature. With the lower volumes of sweat in women, the wicking capabilities were not overwhelmed, and the superior transfer of water through the garment was demonstrated by greater body mass loss.
One might expect, particularly in the women, that the greater contribution to the thermoregulatory response of the synthetic garment would have led to enhanced performance in the maximal aerobic task, i.e., the MSFT. However, despite the effort to recruit recreationally active subjects, as can be seen in Table 3, the variance in the women subjects in particular was very high and may have prevented a difference in the 2 groups from being revealed, thus leading to a type 2 error.
Overall, this study has demonstrated novel findings by quantifying dramatic increases in overall comfort of P garments, including the use of protective equipment, portraying the influence of P garments on anaerobic tasks, and revealing dramatic sex differences, where women seem to be much more sensitive to the benefits of P garments in terms of improved thermoregulatory responses and athletic performance.
Strength and conditioning coaches should be aware of the dramatic impact of garment choice, particularly in women. Coaches should encourage the use of modern synthetic garments during sporting activities and during activities that require protective padding, either by providing the athletes with garments or, if this is not possible, by encouraging the athletes themselves to invest in the technology. Garment choice is not merely a luxury, but it actually enhances human performance, and strength coaches may use this information to justify these products to either the athletes themselves or the people who provide the garments. Such a choice can have an impact on a wide range of factors, from improvements in comfort, thermoregulatory response, and even athletic performance. These differences can also be seen in anaerobic and aerobic tasks and also with protective padding.
The authors would like to thank a dedicated group of subjects and research assistants who made this study possible. This study was supported in part by a grant from Under Armour, Baltimore, MD. The results of the present study do not constitute endorsement of the product by the authors or the National Strength and Conditioning Association.
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