Perceptual Variables Research Articles

Shorter Versus Longer Durations of Rowing-Based Interval Exercise Attenuate the Physiological and Perceptual Response

ABSTRACTPurpose: This study compared physiological and perceptual variables between short and long durations of rowing-based highintensity interval exercise (HIIE). Methods: Fourteen active adults (age = 26.4 ± 7.2 yr) performed incremental rowing exercise to fatigue to measure maximal oxygen uptake (VO2max) and peak power output (PPO). The subsequent 20 min sessions required HIIE (eight 60 s efforts at 85%PPO with 90 s of active recovery at 20%PPO or 24 20 s efforts at 85%PPO with 30 s of active recovery at 20%PPO) or moderate intensity continuous exercise (MICE) at 40%PPO. During exercise, VO2, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and affective valence were measured. Results: Data show significantly (p < 0.001) higher peak VO2 (84 ± 7 vs. 76 ± 5%VO2peak, d = 0.99), peak HR (94 ± 4%HRpeak vs. 90 ± 4%HRpeak, d = 1.12), BLa (7.0 ± 2.5 mM vs. 4.1 ± 1.0 mM, d = 1.22), end-exercise RPE (12.8 ± 2.0 vs. 11.0 ± 1.7, d = 1.29), and lower affective valence (2.1 ± 1.6 vs. 2.9 ± 1.2, d = 0.61) with long versus short HIIE. Time spent above 85%HRpeak was significantly higher (p < 0.001) in short versus long HIIE (606 ± 259 vs. 448 ± 26 s, d = 0.91). Conclusion: Longer rowing-based intervals elicit greater cardiometabolic and perceptual strain versus shorter efforts, making the latter preferable to optimize perceptual responses to HIIE.

How Gender Moderates the Mechanism across Social Experience, Self-referent Beliefs, and SE Intention

This study aims to understand how social experience influences social entrepreneurial (SE) intentions through different types of self-referent beliefs, and how gender affects this mechanism. To test our conceptual model, we conducted an online survey and recruited respondents via Amazon’s Mechanical Turk (MTurk). Our analysis is based on 743 responses. We used structural equation modeling to test the main hypotheses, conducted decomposition tests using the bootstrapping method to test mediation effects through self-referent beliefs, and executed multi-group analyses to examine gender-moderated mediation effects. The results confirm that social experience significantly influences all three types of self-referent beliefs (entrepreneurial self-efficacy, SE self-efficacy, and self-esteem). Furthermore, the mediating relationship across social experience, self-referent beliefs, and SE intentions is moderated by gender, as the relationship is stronger for women than for men. A clear gender gap exists in the relationships between the perceptual variables and attitudes towards social entrepreneurship. This study reveals gender differences in the mediating mechanism across social experience, self-referent beliefs, and SE intentions. This study also provides a practical suggestion to reduce the perceptual gender gap by showing that social experience more effectively enhances self-referent beliefs (self-efficacy and self-esteem) for women. Our findings support and extend Milliken’s (1987) framing of three distinct types of uncertainty to explain how individuals form SE intentions.

Public service media for better democracies: Testing the role of perceptual and structural variables in shaping citizens’ evaluations of public television

As PSM change and adapt –with variable outcomes– to a digital and multiplatform environment, their roles and functions are overly under severe scrutiny. The normative expectations of PSM and their performance have been extensively discussed from a theoretical and regulatory approach, but studies from an audience perspective are still rather scarce. If PSM's primary stakeholder is to be considered the citizenship it serves, it is, therefore, vital to understand what is valuable to society and how citizens assess PSM's performance. Drawing upon representative survey data from Spain (N = 1717), this study examines the role played by structural and perceptual variables in accounting for the citizen's assessment of the national public broadcaster (TVE), considering six roles: watchdog, analysis, mobilization, public forum, social empathy, and information. Findings first indicate that perceptions of independence and citizens' evaluation of TVE's journalists are positively associated with all dimensions of TVE evaluations. However, when exploring the role of political knowledge, results indicate a negative association with some of PSM's most critical functions. All in all, our research illustrates that, despite all the changes in the media landscape, when it comes to delivering the news, citizens seem to stick to values traditionally associated with PSM: independent and qualified journalism trained for and committed to the public service of delivering accurate and unbiased information.

How gender moderates the mediating mechanism across social experience, self-referent beliefs and social entrepreneurship intentions

PurposeThis study aims to understand how social experience influences social entrepreneurial (SE) intentions through different types of self-referent beliefs and how gender affects this mechanism.Design/methodology/approachTo test this study’s conceptual model, the authors conducted an online survey and recruited respondents via Amazon’s Mechanical Turk. This study’s analysis is based on 743 responses. This study used structural equation modeling to test the main hypotheses, conducted decomposition tests using the bootstrapping method to test mediation effects via self-referent beliefs and executed multi-group analyses to examine gender-moderated mediation effects.FindingsThe results confirm that social experience significantly influences all three types of self-referent beliefs (entrepreneurial self-efficacy, SE self-efficacy and self-esteem). Furthermore, the mediating relationship across social experience, self-efficacies, and SE intentions is moderated by gender, as the relationships between social experience and self-efficacies are stronger for women than for men.Originality/valueA clear gender gap exists in the way how social experience affects perceptual variables (self-referent beliefs), providing a practical suggestion to reduce the perceptual gender gap in social entrepreneurial contexts. This study also reveals the mediating mechanism across social experience, self-efficacies and SE intentions, also highlighting the importance of domain specific self-efficacies. This study’s findings support and extend Milliken’s (1987) framing of three distinct types of uncertainty to explain how individuals form SE intentions.

Effects of Bilateral Dorsolateral Prefrontal Cortex High-Definition Transcranial Direct-Current Stimulation on Physiological and Performance Responses at Severe-Intensity Exercise Domain in Elite Road Cyclists.

To investigate the effects of bilateral dorsolateral prefrontal cortex high-definition transcranial direct-current stimulation (HD-tDCS) on physiological and performance responses during exercise at the upper limit of the severe-intensity exercise domain in elite-level road cyclists. Eleven elite-level road cyclists (VO2peak: 71.8 [3.1]mL·kg-1·min-1) underwent the HD-tDCS or SHAM condition in a double-blind, counterbalanced, and randomized order. After 20minutes of receiving either HD-tDCS on dorsolateral prefrontal cortex (F3 and F4) or SHAM stimulation, participants completed a 10-minute constant-load trial (CLT1) at 90% of the first ventilatory threshold and a 2-minute CLT (CLT2) at peak power output. Thereafter, they performed a simulated 2-km time trial (TT). Maximal oxygen uptake, respiratory exchange ratio, heart rate, and rating of perceived exertion were recorded during CLT1 and CLT2, whereas performance parameters were recorded during the TT. In 6 out of 11 cyclists, the total time to complete the TT was 3.0% faster in HD-tDCS compared to SHAM. Physiological and perceptual variables measured during CLT1 and CLT2 did not change between HD-tDCS and SHAM. HD-tDCS over the dorsolateral prefrontal cortex seemed to improve cycling TT performance within the upper limit of the severe-intensity exercise domain, suggesting that an upregulation of the prefrontal cortex could be critical even in this exercise intensity domain. However, the limited dimension and the high interindividual variability require further studies to test these putative ergogenic effects.

Cortical Motion Perception Emerges from Dimensionality Reduction with Evolved Spike-Timing-Dependent Plasticity Rules.

The nervous system is under tight energy constraints and must represent information efficiently. This is particularly relevant in the dorsal part of the medial superior temporal area (MSTd) in primates where neurons encode complex motion patterns to support a variety of behaviors. A sparse decomposition model based on a dimensionality reduction principle known as non-negative matrix factorization (NMF) was previously shown to account for a wide range of monkey MSTd visual response properties. This model resulted in sparse, parts-based representations that could be regarded as basis flow fields, a linear superposition of which accurately reconstructed the input stimuli. This model provided evidence that the seemingly complex response properties of MSTd may be a by-product of MSTd neurons performing dimensionality reduction on their input. However, an open question is how a neural circuit could carry out this function. In the current study, we propose a spiking neural network (SNN) model of MSTd based on evolved spike-timing-dependent plasticity and homeostatic synaptic scaling (STDP-H) learning rules. We demonstrate that the SNN model learns compressed and efficient representations of the input patterns similar to the patterns that emerge from NMF, resulting in MSTd-like receptive fields observed in monkeys. This SNN model suggests that STDP-H observed in the nervous system may be performing a similar function as NMF with sparsity constraints, which provides a test bed for mechanistic theories of how MSTd may efficiently encode complex patterns of visual motion to support robust self-motion perception.SIGNIFICANCE STATEMENT The brain may use dimensionality reduction and sparse coding to efficiently represent stimuli under metabolic constraints. Neurons in monkey area MSTd respond to complex optic flow patterns resulting from self-motion. We developed a spiking neural network model that showed MSTd-like response properties can emerge from evolving spike-timing-dependent plasticity with STDP-H parameters of the connections between then middle temporal area and MSTd. Simulated MSTd neurons formed a sparse, reduced population code capable of encoding perceptual variables important for self-motion perception. This model demonstrates that complex neuronal responses observed in MSTd may emerge from efficient coding and suggests that neurobiological plasticity, like STDP-H, may contribute to reducing the dimensions of input stimuli and allowing spiking neurons to learn sparse representations.

Identifying key factors driving public opinion of salmon aquaculture

Salmon farming has become a controversial topic, with public opposition and conflicts challenging the sustainability of the sector. As a result, a deeper understanding of public perceptions and factors influencing opinions becomes critical for developing sustainable and socially acceptable aquaculture. Based on previous social acceptance literature, this research aimed to investigate the influence of potential motivators on opinion towards salmon aquaculture. In a case study of rural and urban Nova Scotians, 495 people provided their perceptions of salmon aquaculture. Moreover, geographical factors, socio-demographics, and contextual factors were investigated. Geographic differences in factors and attitudes across urban and rural groups suggest an important mediating influence of residence type (urban and rural) on opinion. Ordinal regression analysis found that opinion was primarily influenced by individual characteristics and perceptual variables, i.e., age, environmental value orientation, salmon consumption patterns, perception of risks, and trust in government. Of minor importance were exposure and knowledge of salmon farming. The model indicates respondents who are older, have strong relational values with the ocean, high perception of risks and are distrustful of government are more likely to express negative attitudes towards aquaculture. This study emphasizes the need to recognize that opinion is nuanced, and deeply socially situated, based not only on individual trade-offs between economic benefits and environmental risks, but also on environmental values and relationships and trust regarding how aquaculture is managed. Further, this study highlights the importance of building public trust with decision-makers, along with continued mitigation of risks, in fostering more socially acceptable salmon aquaculture.

The gradual nature of economic errors

Overwhelming evidence from the cognitive sciences shows that, in simple discrimination tasks (determining what is louder, longer, brighter, or even which number is larger) humans make more mistakes and decide more slowly when the stimuli are closer along the relevant scale. We investigate to what extent these effects are relevant for economic decisions in a setting where optimal choices are objectively known (and independent of attitudes toward risk). We find that, even for tasks with objectively-correct answers, error rates and response times increase gradually as expected values become closer. Differences in payoff-independent numerical magnitudes also play a role, which however only becomes clear when one accounts for expected values. We conclude that the gradual effects on choice found in cognitive discrimination paradigms are very much present in economic choices, and depend on economic as well as perceptual variables.

Effect of Acetaminophen on Endurance Cycling Performance in Trained Triathletes in Hot and Humid Conditions.

The effect of acetaminophen (ACT, also known as paracetamol) on endurance performance in hot and humid conditions has been shown previously in recreationally active populations. The aim of this study was to determine the effect of ACT on physiological and perceptual variables during steady-state and time-trial cycling performance of trained triathletes in hot and humid conditions. In a randomized, double-blind crossover design, 11 triathletes completed ∼60minutes steady-state cycling at 63% peak power output followed by a time trial (7kJ·kg body mass-1, ∼30min) in hot and humid conditions (∼30°C, ∼69% relative humidity) 60minutes after consuming either 20mg·kg body mass-1 ACT or a color-matched placebo. Time-trial completion time, gastrointestinal temperature, skin temperature, thermal sensation, thermal comfort, rating of perceived exertion, and fluid balance were recorded throughout each session. There was no difference in performance in the ACT trial compared with placebo (P = .086, d = 0.57), nor were there differences in gastrointestinal and skin temperature, thermal sensation and comfort, or fluid balance between trials. In conclusion, there was no effect of ACT (20mg·kg body mass-1) ingestion on physiology, perception, and performance of trained triathletes in hot and humid conditions, and existing precooling and percooling strategies appear to be more appropriate for endurance cycling performance in the heat.

Temporally Local Tactile Codes Can Be Stored in Working Memory.

Tactile exploration often involves sequential touches interspersed with stimulus-free durations (e.g., the time during which the hand moves from one textured surface to the other). Whereas it is obvious that texture-related perceptual variables, irrespective of the encoding strategy, must be stored in memory for comparison, it is rather unclear which of those variables are held in memory. There are two established variables—“intensity” and “frequency”, which are “temporally global” variables because of the long stimulus integration interval required to average the signal or derive spectral components, respectively; on the other hand, a recently established third contender is the “temporally local” variable that codes for kinematic profiles of very short, suprathreshold events in the vibrotactile signal. Here, we present the first psychophysical evidence that temporally local variables can be stored in memory. To that end, we asked participants to detect changes in pulsatile indentation stimuli at their fingertips with and without a gap of 1 s between stimulus presentations. The stimuli either contained global variables alone (change of pulse rate), or a mix of local and global variables (change of pulse shape). We found, first, that humans are much better at detecting a change in stimuli when local variables are available rather than global ones alone—as evident by the fact that 21 compared to only 6 participants out of 25 yielded a valid psychophysical curve, respectively. Second, this observation persists even when there is a gap between the stimuli, implying local variables must be stored in memory. Third, an extensive array of relevant intensity definitions failed to explain participants’ performance in any consistent manner, which implies that perceptual decisions were less likely to be driven by intensity coding. Taken together, our results suggest that humans perform pulsatile change detection utilizing local pulse shape, and to a lesser degree global pulse rate, and that both parameters can be stored in memory.

Physiological effects of exercising at different intensities wearing surgical or double-layer cotton facemasks compared to not wearing a mask

ABSTRACT Since the beginning of the SARS-CoV-2 pandemic, the community use of facemasks has been widely recommended. However, their use during exercise has raised safety concerns. Thus, we compared the physiological differences between exercising wearing a surgical (SM) or a double-layer-cotton (DLC) facemask and not wearing a mask (NM). Sixteen volunteers underwent 4 bouts of cycling-based exercise, which consisted of two different intensities: light-to-moderate and moderate-to-high. Facemasks were used as follows: bout-1 and 4: NM; bout-2: SM or DLC and bout-3: DLC or SM. Ventilatory, metabolic, pulmonary gas exchange (PGE) and perceptual variables were collected. At both exercise intensities compared to NM, both facemasks induced similar ventilatory adaptations, increasing inspiratory time and tidal volume and decreasing breathing frequency. Effect sizes (ES) were larger for DLC than for SM. At moderate-to-high, both facemasks reduced the minute ventilation, whereas at light-to-moderate, it was only seen with DLC. End tidal and mixed CO2 pressures, as well as the difference between them, increased with both facemasks. Again, ES was larger for DLC than SM. No relevant oxygen saturation drop was observed with both facemaks and exercise intensities. A small ES increament in VO2 and VCO2 were seen with both facemasks. Effort perception increased at moderate-to-high for both exercise intensities, buth larger EF were with DLC than SM . DLC increased facial temperature during both exercise intensities. In conclusion, ventilatory adjustments imposed during facemask exercise influenced PGE and metabolic and perceptual changes. Larger ES were mostly seen for DLC than SM. Abbreviations: B f : Breathing frequency.; CPET: Cardiopulmonary exercise test.; CI: Confidence interval.; DLC: Double-layer cotton.; ETCO2: End tidal CO2 pressure.; ES: Effect size.; ΔET-PECO2: Difference between ETCO2 and PECO2.; FMMT: Facemask microclimate temperature.; H R : Heart rate.; IQR: Interquartile range.; NM: No mask.; PECO2: Mixed-expired CO2 pressure.; RER: Respiratory exchange ratio.; RPE: Rate of perceived effort.; SD: Standard deviation.; SM: Surgical Mask.; SpO2: Oxygen saturation.; STP: Subjective thermal perception.; Ti/TTOT: Duty cycle.; VE: Minute ventilation.; VCO2: Carbon dioxide output.; VO2: Oxygen uptake.; V T : Tidal volume.; VT: Ventilatory threshold. Highlights Facemasks affect the breathing pattern by changing the frequency and amplitude of pulmonary ventilation. The augmented ventilatory work increases VO2, VCO2, and RPE and promotes nonconcerning drops in SpO2 and CO2 retention. Increased inspiratory and expiratory pressure can account for the reduction in pulmonary physiological dead space.

An Examination of Practice-Based Virtual Simulations and Pre-Service Mathematics Teaching Efficacy and Outcome Expectancy

Authentic practice in pedagogical approaches is essential for preparing teachers to design effective learning experiences that foster student engagement during this digital era. There is an opportunity to explore novel and effective designs of virtual experiences that may augment or better prepare preservice teachers for field placements in physical classrooms. We proffer that virtual classroom simulations can and should be further explored and leveraged, now more than ever. In this paper, we examined a model of the impact of perceptual variables on instructional effectiveness that can enhance teaching efficacy and outcome expectancy when preservice teachers engage in practice teaching experiences in a virtual classroom simulation. The relationships between perceptual variables (presence, instructional time, and engagement) and teaching efficacy and outcome expectancy, as they relate to instructional effectiveness, were analyzed using the structural equation modeling approach. The results supported all of the hypothesized relationships. For example, presence and instructional time strongly and positively influenced engagement. Engagement was strongly related to instructional effectiveness. Instructional effectiveness was strongly and positively related to teaching self-efficacy, as well as outcome expectancy. The results support that virtual world classroom simulations can be an effective space for practice teaching for prospective mathematics teachers. Furthermore, this study provides insights for teacher educators, developers, and instructional designers interested in designing and utilizing practice-based simulations.

Entrepreneurial Intention to Business Start-Up: Evidence from Asia

The purpose of the study is to explore the relationships between perceptual variables and entrepreneurial intention among 13 Asian economies, and to depict the differences in the relationships among three types of Asian economies (factor-driven, efficiency-driven, and innovation-driven). Data were drawn from the 2015 Global Entrepreneurship Monitor Adult Population Survey (GEM APS) data set. Based on the cognitive theory, relevant research questions were developed, and the data were analysed through the logistic regression model. For the case of 13 Asian countries (full sample), except social status and respect, all perceptual variables are significantly related to entrepreneurial intention, and fear of fail found a negative and significant relationship. In sub-sample analysis, we have observed that regarding risk-taking, career choice, and social status, there are some significant differences among the three types of economies. The study contributes as the first attempt on Asian samples (full) from the GEM dataset and it is also the first attempt where three types of Asian economies were analysed.

Rear-view perception in driving: Distance information is privileged in the selection of safe gaps

Selecting a safe gap before merging into the traffic is a crucial driving skill that relies on images provided by rear-view mirrors or, recently, camera-monitor systems. When using these visual aids, some drivers select dangerously small gaps to cut in front of faster vehicles. They may do so because they base their decision either on information about distance or object size, or on miscalculated information about time-to-passage (TTP). Previous experiments have been unable to compare the role of TTP, speed, and distance information for drivers’ gap selection, as they did not investigate them in the same experimental regime. The present experiments seek to determine the perceptual variables that guide drivers’ rearward gap selection. Using short videos of an approaching vehicle filmed from three different camera heights (low, conventional, high), a total of 61 subjects either made gap safety decisions (Experiment I), or estimated the TTP, speed, and distance of an approaching vehicle (Experiment II). An effect of camera height was found for gap selection, TTP, and distance estimation, but not for speed estimation. For the high camera position, smaller gaps were selected as safe, TTP estimates were longer, and the distance to the approaching vehicle was perceived as farther. An opposite pattern was found for the low camera. Regression analyses suggested that distance is an important player. The subjects strongly relied on distance information when estimating TTP, and perceived distance dominated subjects’ gap selection. Thus, drivers seem to employ distance-based strategies when selecting safe gaps in rear-view mirrors or monitors.

Homing tasks and distance matching tasks reveal different types of perceptual variables associated with perceiving self-motion during over-ground locomotion.

Self-motion perception refers to the ability to perceive how the body is moving through the environment. Perception of self-motion has been shown to depend upon the locomotor action patterns used to move the body through the environment. Two separate lines of enquiry have led to the establishment of two distinct theories regarding this effect. One theory has proposed that distances travelled during locomotion are perceived via higher order perceptual variables detected by the haptic perceptual system. This theory proposes that two higher order haptic perceptual variables exist, and that the implication of one of these variables depends upon the type of gait pattern that is used. A second theory proposes that self-motion is perceived via a higher order perceptual variable termed multimodally specified energy expenditure (MSEE). This theory proposes that the effect of locomotor actions patterns upon self-motion perception is related to changes in the metabolic cost of locomotion per unit of perceptually specified traversed distance. Here, we test the hypothesis that the development of these distinct theories is the result of different choices in methodology. The theory of gait type has been developed based largely on the results of homing tasks, whereas the effect of MSEE has been developed based on the results of distance matching tasks. Here we test the hypothesis that the seemly innocuous change in experimental design from using a homing task to using a distance matching task changes the type of perceptual variables implicated in self-motion perception. To test this hypothesis, we closely replicated a recent study of the effect of gait type in all details bar one-we investigated a distance matching task rather than a homing task. As hypothesized, this change yielded results consistent with the predictions of MSEE, and distinct from gait type. We further show that, unlike the effect of gait type, the effect of MSEE is unaffected by the availability of vision. In sum, our findings support the existence of two distinct types of higher order perceptual variables in self-motion perception. We discuss the roles of these two types of perceptual variables in supporting effective human wayfinding.

A meta-regression of task-technology fit in information systems research

Task-technology fit (TTF) is of considerable importance in information systems research. TTF predicts individuals’ perceptions, intentions, and behaviors as well as performance impacts due to technology use. While TTF is expected to have positive effects, empirical results have been mixed. This study hypothesizes that the variation in the effects of TTF may be attributed to study characteristics. Using a meta-regression of 104 findings in 100 studies, this study shows that the variation in TTF effects is explained by type of respondents, type of dependent variable, and type of TTF variable. Specifically, students reported positive effects of TTF on other variables more often than non-students, TTF had positive effects on behavioral variables less frequently than perceptual variables, and TTF had positive effects on other variables less frequently when it was computed and not measured. These imply that TTF should be directly measured, associated with perceptions rather than behaviors, and contextualized to specific types of technologies and users.

Conjoint measurement of perceived transparency and perceived contrast in variegated checkerboards.

One fundamental question in vision research is how the retinal input is segmented into perceptually relevant variables. A striking example of this segmentation process is transparency perception, in which luminance information in one location contributes to two perceptual variables: the properties of the transparent medium itself and of what is being seen in the background. Previous work by Robilotto et al. (2002, 2004) suggested that perceived transparency is closely related to perceived contrast, but how these two relate to retinal luminance has not been established. Here we studied the relationship between perceived transparency, perceived contrast, and image luminance using maximum likelihood conjoint measurement (MLCM). Stimuli were rendered images of variegated checkerboards that were composed of multiple reflectances and partially covered by a transparent overlay. We systematically varied the transmittance and reflectance of the transparent medium and measured perceptual scales of perceived transparency. We also measured scales of perceived contrast using cut-outs of the transparency stimuli that did not contain any geometrical cues to transparency. Perceptual scales for perceived transparency and contrast followed a remarkably similar pattern across observers. We tested the empirically observed scales against predictions from various contrast metrics and found that perceived transparency and perceived contrast were equally well predicted by a metric based on the logarithm of Michelson or Whittle contrast. We conclude that judgments of perceived transparency and perceived contrast are likely to be supported by a common mechanism, which can be computationally captured as a logarithmic contrast.

Behavioral illusions: The Snark is a Boojum

A behavioral illusion is a regularity of behavior that appears to reflect something about the functional characteristics of an organism when it does not. This illusion occurs when the methods appropriate to the study of an open-loop or zero feedback (Z)-system are used to study the behavior of what is, in fact, a closed-loop or negative feedback (N)-system. The situation is like the one described in Lewis Carroll’s The Hunting of the Snark, where the sought-after Snark—analogous to the actual organism function—looks just like the feared Boojum—analogous to the illusory one. This article describes examples of three different kinds of behavioral illusion and explains how researchers can avoid the mistake of taking a Boojum for a Snark by reorienting the study of behavior toward identifying the perceptual variables that organisms control and away from seeking regularities in their overt behavior.

The Impact of Grounding in Running Shoes on Indices of Performance in Elite Competitive Athletes.

The introduction of carbon fiber plate shoes has triggered a plethora of world records in running, which has encouraged shoe industries to produce novel shoe designs to enhance running performance, including shoes containing conductor elements or “grounding shoes” (GS), which could potentially reduce the energy cost of running. The aim of this study was to examine the physiological and perceptual responses of athletes subjected to grounding shoes during running. Ten elite runners were recruited. Firstly, the athletes performed an incremental running test for VO2max and anaerobic threshold (AT) determination, and were familiarized with the two shoe conditions (traditional training shoe (TTS) and GS, the latter containing a conductor element under the insole). One week apart, athletes performed running economy tests (20 min run at 80% of the AT) on a 400 m dirt track, with shoe conditions randomized. VO2, heart rate, lactate, and perceived fatigue were registered throughout the experiment. No differences in any of the physiological or perceptual variables were identified between shoe conditions, with an equal running economy in both TTS and GS (51.1 ± 4.2 vs. 50.9 ± 5.1 mL kg−1 min−1, respectively). Our results suggest that a grounding stimulus does not improve the energy cost of running, or the physiological/perceptual responses of elite athletes.

A 32-day long fieldwork in Antarctica improves heat tolerance during physical exercise.

We evaluated the influence of a 32-day camping in Antarctica on physical performance and exercise-induced thermoregulatory responses. In Brazil, before and after the Antarctic camping, the volunteers performed an incremental exercise at temperate conditions and, two days later, an exercise heat stress protocol (45-min running at 60% of maximum aerobic speed, at 31°C and 60% of relative humidity). In Antarctica, core temperature was assessed on a day of fieldwork, and average values higher than 38.5°C were reported. At pre- and post-Antarctica, physiological (whole-body and local sweat rate, number of active sweat glands, sweat gland output, core and skin temperatures) and perceptual (thermal comfort and sensation) variables were measured. The Antarctic camping improved the participants' performance and induced heat-related adaptations, as evidenced by sweat redistribution (lower in the chest but higher in grouped data from the forehead, forearm, and thigh) and reduced skin temperatures in the forehead and chest during the exercise heat stress protocol. Notwithstanding the acclimatization, the participants did not report differences of the thermal sensation and comfort. In conclusion, staying in an Antarctic camp for 32 days improved physical performance and elicited physiological adaptations to heat due to the physical exertion-induced hyperthermia in the field.