Simultaneous assessment of motor and cognitive tasks reveals reductions in working memory performance following exercise in the heat

ABSTRACT

This study tested the hypothesis that, following exercise in the heat, motor task performance will be impaired when assessed simultaneously with a cognitive task. In a randomized, crossover and counterbalanced design, twelve healthy adults (23 ± 2 years, 5 women) completed four 10-minute exercise circuits involving upper and lower body exercise in a moderate (18.1 ± 1.7°C, 38 ± 10% relative humidity) and a hot (40.3 ± 1.1°C, 26 ± 5% relative humidity) environment. Experimental testing was completed in a temperate thermal environment before exercise (~25°C) and in either the moderate or hot environment following exercise. The 3 Back test (a test of working memory) was used as the cognitive task and postural sway was used as the motor task. Cognitive and motor task performance assessments were conducted both individually (solo) and simultaneously (dual). At the end of exercise, core temperature (by 0.4 ± 0.3°C, P < 0.001), heart rate (by 12 ± 18 bpm, P = 0.025), and mean skin temperature (by 7.6 ± 0.8°C, P < 0.001) were higher in the Hot trial compared to Moderate. During solo testing, postural sway increased from pre- to post-exercise in the Hot (P ≤ 0.028), but not the Moderate (P ≥ 0.261) trial. During dual testing, postural sway did not differ between trials (P ≥ 0.065) or over time (P ≥ 0.094). During solo testing, 3 Back performance did not differ between trials (P = 0.810) or over time (P = 0.707), but during dual testing 3 Back performance following exercise was reduced in the Hot compared to the Moderate trial (P = 0.028). Simultaneous assessment of motor and cognitive tasks reveals that motor performance is reduced following exercise in the heat. 

KEYWORDS:

• Cognitive function
• postural sway
• heat stress
• exercise
• hyperthermia

Introduction

The risk of accidents [1–3] and injuries [4–6] in physically demanding occupations increases as a function of elevations at ambient temperature. This is supported by the observations that the incidence of errors [2,7] and behaviors deemed unsafe at the worksite [8] is higher in hot conditions compared to cooler conditions. The elevated risk of occupational accidents and injuries in hot conditions is often attributed, in part, to changes in mental functioning. For instance, a rise in core body temperature (i.e., hyperthermia) is often associated with alterations in neural processing [9,10] and impairments in cognitive functioning, particularly those involving sustained attention, memory, and executive function [11–18]. However, hyperthermia-induced alterations in cognitive function are not a universal finding [19–23]. To our knowledge, the reasons underlying this discrepancy in the scientific literature are not fully understood.

Current evidence supports that the reason some studies demonstrate impairments in cognitive function with hyperthermia [11–18] and others do not [19–23] may be a function of methodology [24]. For instance, it may be that the employed tests used to examine many aspects of cognition during hyperthermia are not consistently appropriate for identifying subtle, acute changes in cognitive function. Along these same lines, it is possible that the cognitive demands required of the employed tests do not sufficiently challenge the available neuronal resources, which could mask any effects of hyperthermia on cognitive performance [24]. One potential way to overcome both limitations is to examine motor and cognitive functioning simultaneously [25]. In this way, subtle changes in performance on one or both examined parameters may be exposed when examined simultaneously, independent of whether motor or cognitive functions were altered when examined in isolation (i.e., when neuronal demand is comparatively lower). Indeed, by employing a dual task approach, Piil et al. [26] recently identified that fine motor task performance when assessed at the same time as a cognitive task was degraded by hyperthermia provoked by ~60 minutes of cycling exercise in the heat, but that there was minimal effect of hyperthermia on cognitive function, as assessed via a math-related task. Building on these findings, the purpose of the current study was to examine solo and dual task performance as assessed via postural sway (a motor task involving large muscle groups) and working memory performance (a cognitive task) following the completion of occupationally relevant exercise conducted in moderate and hot thermal conditions. Based on the findings of Piil et al. [26], we tested the hypothesis that, following exercise in the heat, postural sway will be greater when assessed simultaneous with a test of working memory.

Methods

Ethical approval

The study and informed consent were approved by the Institutional Review Board at the University of Buffalo. The study conformed to the standards set by the Declaration of Helsinki, except for registration in a database. Before completing any study-related activities, each subject was fully informed of the experimental procedures and possible risks before giving informed, written consent.

Subjects

Twelve healthy adults (five women) participated in this study. The subject characteristics are presented in Table 1. All subjects self-reported to be healthy, were nonsmokers, not taking medications known to influence responses to exercise or thermoregulation, and reported to be free from any cardiovascular, neurological, psychological, or gastrointestinal disease (necessary for ingesting the telemetry pill, see below). Subjects were not heat acclimated, self-reported to regularly engage in physical activity, and were in the normal range for cognitive ability, as assessed via the Montreal Cognitive Assessment [27]. Women were not pregnant, which was confirmed via a urine pregnancy test, and completed their trials during the first ten days following self-identified menstruation. Experimental testing in women was completed during this time because estrogen and progesterone are relatively low during this time period [28].

Table 1. Subject characteristics.

Number of subjects (Men/Women)	12 (7/5)
Age (years)	23 ± 2
Self-reported Race (Caucasian/Asian/More than one)	7/4/1
Height (cm)	166 ± 10
Weight (kg)	67 ± 12
Body mass index (kg/m^2)	24 ± 3
Montreal Cognitive Assessment score ^a	29 ± 1

Data are mean ± SD.

^aAll subjects scored within the normal range for their age group (≥25) [50].

Instrumentation and measurements

Height and weight were measured with a stadiometer and scale (Satorius Corp., Bohemia, NY, USA). Urine-specific gravity was measured using a handheld refractometer (Atago, Bellevue, WA). Nude body weight was measured pre- and post-exercise after towel drying. Heart rate was measured using a standard heart rate monitor (Polar Electro, Bethpage, NY, USA). Approximately 90 minutes prior to experimental testing, each subject swallowed a telemetry pill (HQ Inc., Palmetto, FL, USA) for the measurement of core temperature. This approach provides a valid measure of core temperature, particularly when drinking is prohibited [29]. Mean skin temperature was measured as the weighted average of four thermochron iButtons (Maxim Integrated, San Jose, CA, USA) using the following equation: 0.3 · (chest + triceps) + 0.2 · (quadriceps + calf) [30].

The nBack test, which is a test of working memory [31], was used as a standardized test to assess cognitive performance, as we have used previously [22]. The test was administered as a part of the Inquisit Web psychological testing platform (Millisecond Software, LLC, Seattle, WA). We employed the “3 Back” version of the nBack test given that this test is more difficult than other nBack versions in the psychological testing platform (e.g., “1 Back” or “2 Back”) [31]. During the 3 Back test the subject monitored a series of letters and was instructed to press a button on the handheld clicker that was held in their dominant hand whenever a letter was presented that matched the one presented 3 trials previously. The test was 60 seconds in duration and completed in the standing position on the dense foam pad. The tablet utilized for 3 Back was placed at eye level and one meter away. The 3 Back dependent variables were the percentage of correct responses and response latency. During the screening and familiarization visit, subjects were familiarized with the 3 Back test by completing it three times [22] and subjects were not re-familiarized on the experimental visits. Throughout all testing, subjects not informed of their performance on the 3 Back test.

Postural sway was measured by having subjects stand as still as possible on a force platform (Advanced Mechanical Technology, Inc. (AMTI), Watertown, MA, USA) that captured ground reaction forces and moments at 100 Hz, which were then transformed to center of pressure location profiles. During each stand test, subjects stood on a dense foam pad to create a compliant surface that challenges postural control [32] and held the same clicker used for the 3 Back test in their dominant hand. At each measurement interval subjects completed one 60-second stand test while looking at a target on a tablet placed at eye level one meter away. The postural sway-dependent variables are the center of pressure distance traveled (sway length) and ellipse area (sway area), both of which are reliable measures of postural sway both within- and between-days [33]. These measures were calculated for the middle 45 seconds of the 60-second trial. During the screening and familiarization visit, subjects were familiarized with the postural sway test by completing it three times, and subjects were not re-familiarized on the experimental visits.

For the dual-task assessment, participants completed the 3 Back test, while simultaneously engaging in the postural sway procedures. For this assessment, participants were instructed to stand as still as possible and to do the best they could perform on the 3 Back test. To ensure the dual-task assessment was novel, subjects were informed they would be completing the stand and 3 Back tests simultaneously during the experimental visits, but they did not practice the test.

Experimental protocol

Subjects visited the laboratory on three occasions separated by at least 72 hours. Visit one was the screening and familiarization visit, while visits two and three were the experimental trials that differed only by the environmental conditions. In one experimental trial subjects underwent 40 minutes of exercise in a moderate thermal environment (mean ± SD during exercise: 18.1 ± 1.7°C, 38 ± 10% relative humidity), while in the other, subjects undertook the same exercise in a hot environment (mean ± SD during exercise: 40.3 ± 1.1°C, 26 ± 5% relative humidity). These trials were completed in a randomized, counterbalanced manner and subjects completed both trials (i.e., fully crossover design). Subjects could not be blinded to the experimental conditions, but they were unaware of the research hypotheses. All experimental testing was completed throughout the calendar year in Buffalo, NY, USA, a climate that has been shown to induce minimal heat acclimatization [34].

Subjects avoided exercise, alcohol, and caffeine for at least 12 hours prior to arrival at the laboratory, and all subjects ate a light meal approximately 2 hours prior to arrival. Upon arrival, subjects voided their bladder and provided a urine sample, and a nude body weight was obtained. Euhydration, defined as a urine specific gravity ≤1.020 [35], was confirmed using this urine sample. The actual measured urine specific gravity values upon arrival at the laboratory were – Moderate: 1.007 ± 0.008 and Hot: 1.009 ± 0.008, and there were no differences between trials (paired t-test: P = 0.181). Throughout all experimental testing, subjects wore a cotton t-shirt, long work pants, and athletic shoes. Following instrumentation, subjects then completed a stand test, 3 Back test, and a dual task test in a moderate thermal environment (Moderate: 25.0 ± 0.8°C, 37 ± 15% relative humidity; Hot: 25.7 ± 1.3°C, 34 ± 16% relative humidity, paired t-tests: P ≥ 0.201). These tests were administered in a randomized order and there were 60 seconds of seated rest between each test. Heart rate, core temperature, and mean skin temperature data were recorded before completion of each test. Immediately following the completion of these tests, the subjects entered the environmental chamber. Upon entry into the chamber, baseline heart rate, core temperature and mean skin temperature data were obtained in the standing position. Following this, the subjects completed four exercise circuits that mimicked many occupational demands by involving upper and lower body exercise, and dynamic and isometric contractions, like that we have employed previously [36]. The exercise circuit involved five tasks. The first task involved walking on a treadmill at 5.6 kph at 0% grade carrying a 15.2 m length of bundled 4.4 cm fire hose over one shoulder for 3 minutes. The second task was a lifting task that was performed by moving one of five objects (three weighing 4.1 kg, 5.4 kg, and 6.8 kg and two weighing 21.1 kg) from a 73 cm platform to the floor and returning them to the platform every 12 seconds for 2 minutes. The third exercise in the circuit required subjects to use a 4.1 kg dead blow to strike the end of a 72 kg I-beam along a track. Subjects hit the beam every 10 seconds for 2 minutes. The final exercise required subjects to pull a 4.4 cm wide hose looped around a pivot point while in a kneeling position. The hose was pulled continuously for two 45 second intervals separated by 15 seconds of rest. Heart rate, core temperature, and mean skin temperature were recorded during the rest period. The final task involved a 60 second standing rest, which took place immediately before the start of the next circuit. Subjects repeated the circuit four times for a total of 40 min of exertion. Immediately following the completion of the fourth exercise circuit, the subjects completed a stand test, 3 Back test, and a dual task test. This testing was completed in the same environment in which the exercise was completed, such that both ambient temperature (paired t-test: P < 0.001) and relative humidity (paired t-test: P = 0.008) differed between trials during post-exercise testing (Moderate: 17.9 ± 1.0°C, 33 ± 6% relative humidity; Hot: 40.5 ± 1.3°C, 43 ± 8% relative humidity). Like pre-exercise, these tests were administered in a randomized order, there were 60 seconds of seated rest between each test, and heart rate, core temperature and mean skin temperature were recorded before completion of each test. Immediately following the completion of post-exercise testing, the subjects exited the environmental chamber, were de-instrumented and, after a nude body weight was obtained, were free to leave the laboratory.

Data and statistical analyses

During the completion of the pre-exercise stand test, 3 Back test and dual-task test, core temperature, and heart rate were only collected in seven participants. Thus, these data were analyzed and are presented as n = 7. Due to an error that was not identified until after data collection, postural sway data were not available for one subject. Thus, these data were analyzed and are presented as n = 11. All other data were analyzed and are presented as n = 12.

Percentage changes in body weight loss between the Moderate and Hot trials were analyzed using a paired t-test. Heart rate, core temperature, and mean skin temperature data obtained prior to completion of the stand test, 3 Back test, and dual-task tests at pre- and post-exercise were analyzed using linear mixed models with two within-subject factors of trial (two levels: Moderate, Hot) and test (three levels: Sway, 3 Back, Dual). These same data obtained during exercise were also analyzed using linear mixed models but with the two within-subject factors of trial (two levels: Moderate, Hot) and time (five levels: Baseline, Circuit 1, Circuit 2, Circuit 3, Circuit 4). Finally, postural sway and 3 Back data collected as both solo and dual assessments were analyzed using linear mixed models with two within-subject factors of trial (two levels: Moderate, Hot) and time (two levels: Pre-Exercise, Post-Exercise). In all instances, when the linear mixed models revealed a significant main effect or interaction [37], post hoc Sidak’s adjusted pairwise comparisons were made. At the time of study design, there were no direct data to inform sample size estimates. Thus, secondary purpose of this study was also to identify effect size for the solo and dual-task assessments, so that the design of future studies can be improved. Therefore, where the pairwise comparisons have been reported for the solo and dual-task data, effect size (Cohen’s d_z) has been reported. All data were analyzed using Prism software (Version 9.0.0, GraphPad Software Inc. La Jolla, CA, USA). A priori statistical significance was set at P ≤ 0.05 and actual p-values are reported where possible. Data are reported as mean ± SD or as mean with individual values where possible.

Results

Thermal responses

During pre-exercise testing, core temperature (Figure 1a), heart rate (Figure 1c), and mean skin temperature (Figure 1e) did not differ between trials (main effects: P ≥ 0.326) or tests (main effects: P ≥ 0.182). At the end of exercise, core temperature (by 0.4 ± 0.3°C, P < 0.001, Figure 2a), heart rate (by 12 ± 18 bpm, P = 0.025, Figure 2b), and mean skin temperature (by 7.6 ± 0.8°C, P < 0.001, Figure 2c) were higher in the Hot trial compared to Moderate. During post-exercise testing, core temperature (Figure 1b), heart rate (Figure 1d), and mean skin temperature (figure 1f) were higher in the Hot trial (main effects: P < 0.001) but did not differ between tests (main effects: P ≥ 0.258). Body weight loss due to sweating was greater in the Hot trial (1.2 ± 0.1%) compared to the Moderate trial (0.5 ± 0.2%, P < 0.001).

Figure 1. Core temperature (A & B), heart rate (C & D), and mean skin temperature (E & F) measured immediately before completing the postural sway, 3 Back, and dual task tests before (on left) and after (on right) exercise that was completed in a moderate and hot thermal environment. Data are presented as mean with individual values. Data were analyzed using linear mixed models and P-values for the linear mixed model are presented.

Figure 2. Core temperature (a), heart rate (b), and mean skin temperature (c) measured immediately before (Baseline) and at the end of each exercise circuit completed during exposure to a moderate and hot thermal environment. Data are presented as mean ± SD. Data were analyzed using linear mixed models and P-values for the linear mixed model are presented. If a significant main effect or interaction was identified, Sidak’s multiple comparisons test was utilized. * Indicates different from Moderate trial at same timepoint (P ≤ 0.025).

Postural sway

During solo testing, postural sway area (Figure 3a) and length (Figure 3c) increased from pre- to post-exercise in the Hot trial (pairwise comparisons: P ≤ 0.028, Cohen’s d_z ≥0.867) but not the Moderate trial (pairwise comparisons: P ≥ 0.261, Cohen’s d_z ≤0.456) and did not differ between trials (pairwise comparisons: P ≥ 0.188, Cohen’s d_z ≤0.520). During dual testing, postural sway area (Figure 3b) did not differ between trials (main effect: P = 0.204) or over time (main effect: P = 0.173). While postural sway length during dual testing (Figure 3d) demonstrated a significant main effect of time (P = 0.014), pairwise comparisons did not reveal differences from pre- to post-exercise (pairwise comparisons: P ≥ 0.094, Cohen’s d_z ≤0.747) or between trials (pairwise comparisons: P ≥ 0.065, Cohen’s d_z ≤0.484).

Figure 3. Solo (on left) and dual (on right) task measures of postural sway area (A & B) and length (C & D) measured immediately before (Pre-Exercise) and after (Post-Exercise) exercise that was competed in a moderate and hot thermal environment. Data are presented as mean with individual values. Data were analyzed using linear mixed models and P-values for the linear mixed model are presented. If a significant main effect or interaction was identified, Sidak’s multiple comparisons test was utilized, with P-values for the pairwise comparisons between Pre-Exercise and Post-Exercise and associated effect sizes (Cohen’s d_z) presented.

Back

During solo testing, 3 Back performance (Figure 4a) did not differ between trials (main effect: P = 0.810) or over time (main effect: P = 0.707). While 3 Back response latency during solo testing (Figure 4c) demonstrated a significant main effect of time (P = 0.024), pairwise comparisons did not reveal differences from pre- to post-exercise (pairwise comparisons: P ≥ 0.137, Cohen’s d_z ≥0.681) or between trials (pairwise comparisons: P ≥ 0.916, Cohen’s d_z ≥0.110). During dual testing, 3 Back performance (Figure 4b) did not change from pre- to post-exercise in either trial (pairwise comparisons: P ≥ 0.267, Cohen’s d_z ≥0.454), but at post-exercise, 3 Back performance was reduced in the Hot trial compared to the Moderate trial (P = 0.028, Cohen’s d_z = 0.843). 3 Back response latency during dual testing (Figure 4d) did not differ between trials (main effect: P = 0.648) or over time (main effect: P = 0.800).

Figure 4. Solo (on left) and dual (on right) task measures of 3 Back performance (percent correct answers, A & B) and response latency (C & D) measured immediately before (Pre-Exercise) and after (Post-Exercise) exercise that was competed in a moderate and hot thermal environment. Data are presented as mean with individual values. Data were analyzed using linear mixed models and P-values for the linear mixed model are presented. If a significant main effect or interaction was identified, Sidak’s multiple comparisons test was utilized, with P-values for the pairwise comparisons between Pre-Exercise and Post-Exercise and associated effect sizes (Cohen’s d_z) presented. * Indicates different from Moderate trial at same Post-Exercise timepoint (P = 0.028, d_z = 0.844).

Discussion

This study examined solo and dual motor (postural sway) and cognitive (3 Back) performance before and after the completion of 40 minutes of exercise that involved upper and lower body work conducted in moderate and hot thermal conditions. In contrast to our hypothesis, we found that, when assessed alone, postural sway increased following exercise in the Hot trial only, but when examined during the dual task assessment, postural sway did not differ from pre- to post-exercise in either the Moderate or Hot trials (Figure 3). Interestingly, however, while 3 Back performance was not modified from pre- to post-exercise or between trials when assessed alone, during the dual task assessment 3 Back performance was lower following exercise in the Hot trial compared to following exercise in the Moderate trial (Figure 4). Importantly, the observed differences between the solo and dual assessments cannot be explained by differences in core temperature, heart rate, or mean skin temperature (Figure 1). Collectively, therefore, these findings support previous work [26] and indicate that simultaneous assessment of motor and cognitive tasks reveals impairments in one or more aspects of functioning. Moreover, this study supports a growing body of evidence indicating that hyperthermia reduces cognitive function in a manner consistent with the complexity of the combined cognitive and motor demands [24,38,39].

Our laboratory has identified that postural sway is increased following a similar exercise regimen conducted in the heat [40]. The findings of the present study further this observation by demonstrating that the increase in postural sway following intense exercise involving both upper and lower body work is unique to when conducted in hot conditions, as a greater sway area and sway length were observed only following the Hot trial during the solo assessment of postural sway (Figure 3). The mechanisms underlying this observation are not clear from the present study. However, it may be that the increase in postural sway following exercise in the Hot trial is related to alterations in the neuromuscular circuit, including central neural drive, sensory feedback, and/or responsiveness of muscle, neurophysiological changes that are all affected by prior intense exercise completed in the heat [41]. That said, the increase in postural sway following exercise in the Hot trial was abolished when the sway assessment was completed at the same time as the 3 Back test. Although the mechanism underlying this interesting observation cannot be identified from this study, this observation does suggest that the increased postural sway following exercise in the Hot trial was not necessarily due to neurophysiological impairments. We speculate, therefore, that the increased postural sway following exercise in the Hot trial contributed to blood pressure regulation. We do not have measures of blood pressure during the stand test. However, it is well established that hyperthermia compromises blood pressure regulation during orthostasis, which ultimately promotes cerebral hypoperfusion [42]. Moreover, previous work has identified that postural sway is higher in people with low orthostatic tolerance when measured in the laboratory but have never experienced syncope in free living conditions [43,44]. These data were subsequently interpreted to indicate that involuntary postural sway may contribute to blood pressure regulation and ultimately the maintenance of cerebral perfusion during orthostasis by augmenting venous return due to activation of the muscle pump [43,44]. We speculate that the same phenomenon occurred in the present study, and that when the stand test was completed at the same time as the 3 Back test, the subsequent elevations in blood pressure and cerebral perfusion likely caused by cognitive activation [22] prevented the need for an increased postural sway following exercise in the Hot trial. Clearly, further research is needed to better understand the mechanisms of postural control during and following exercise in the heat.

Hyperthermia has frequently been shown to reduce working memory performance [12,15–18]. Our assessment of solo 3 Back performance does not support this contention, such that following exercise in the Hot trial 3 Back performance did not differ from pre- to post-exercise nor between trials (Figure 4). These findings support previous work showing that 3 Back performance specifically is not impacted by hyperthermia [22]. Thus, we speculate that the combination of the 3 Back test and magnitude of hyperthermia following exercise in the Hot trial did not require a sufficient neuronal demand required to compromise performance [45]. Importantly, however, when the 3 Back test was completed simultaneously with the postural sway assessment, 3 Back performance was impaired post-exercise in the Hot trial. These findings support a growing body of research indicating that simple or even more complex cognitive tasks involving executive functioning are not consistently affected by hyperthermia [19–23], but when cognitive tasks are combined with motor tasks, decrements in motor [26] or cognitive (Figure 4) performance can be observed. Further work is needed to understand how to mitigate the impact of hyperthermia on dual-task performance, with a recent study demonstrating that heat acclimation is not an effective countermeasure [46]. This is important because such knowledge is necessary to offset the increased incidence of errors [2,7] and unsafe behaviors [8] often observed at the worksite in hot conditions.

Experimental considerations

A few experimental considerations warrant mentioning. This study involved only 40 minutes of physical work, which is shorter than the periods of continuous work that may be experienced in the workplace in the Moderate trial. For work performed in the heat, however, current CDC/NIOSH recommendations suggest workers perform no more than 30 minutes of sustained medium intensity work per hour at similar temperatures as the conditions tested in the current study [47]. Thus, the exercise duration utilized herein likely exceeds current recommendations. Future studies should incorporate conditions that are more likely to be experienced by workers who undertake manual labor in hot conditions. To this latter point, it would also be important for future studies to incorporate more occupationally relevant cognitive and motor tasks. It is also worth noting that it is possible that some of the comparisons in our study may be underpowered. This was an acceptable limitation given that a secondary purpose of this study was to identify effect sizes for the solo and dual task assessments that can be used to improve the design of future studies. Therefore, we have reported effect size for all reported pairwise comparisons for the solo and dual task data to aid in the interpretation of the data presented herein. Finally, our study included both men and women, and the women were tested during the first 10 days following menstruation. Moreover, this study was not designed to make comparisons between men and women. There are likely subtle differences in thermoregulation between men and women, and across the menstrual cycle [28,48,49]. To our knowledge, the effect of hyperthermia on aspects of cognitive function across the menstrual cycle or between men and women remains unknown. Therefore, further work in this field is warranted.

Conclusions

When assessed alone, postural sway increased following exercise in the heat. However, when examined during dual assessment involving both postural sway and working memory tests, postural sway did not differ from pre- to post-exercise. Interestingly, however, while working memory performance was not modified from pre- to post-exercise or between hot or moderate thermal conditions when assessed alone, during the dual-task assessment working memory performance was lower following exercise in the heat trial compared to following exercise in a moderately thermal environment. These apparent differences between the solo and dual assessments cannot likely be explained by differences in core temperature, heart rate, or mean skin temperature. Collectively, these findings support that simultaneous assessment of motor and cognitive tasks reveals impairments in one or more aspects of functioning following exercise in the heat.

Acknowledgments

We thank the individuals who participated in this study and Eric Paccione who wrote the code for the postural sway analyses.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by the Buffalo Blue Sky Initiative from the Office of the Vice President for Research and Economic Development at the University at Buffalo;Office of the Vice President for Research and Economic Development, University at Buffalo.