The aim of this study was to verify the hypothesis that hyperthermia represents a cognitive load limiting available resources for executing concurrent cognitive tasks. Electroencephalographic activity (EEG: alpha and theta power) was obtained in 10 hyperthermic participants in HOT (50°C, 50% RH) conditions and in a normothermic state in CON (25°C, 50% RH) conditions in counterbalanced order. In each trial, EEG was measured over the frontal lobe prior to task engagement (PRE) in each condition and during simple (One Touch Stockings of Cambridge, OTS-4) and complex (OTS-6) cognitive tasks. Core (39.5 ± 0.5 vs. 36.9 ± 0.2°C) and mean skin (39.06 ± 0.3 vs. 31.6 ± 0.6°C) temperatures were significantly higher in HOT than CON (p < 0.005). Theta power significantly increased with task demand (p = 0.017, η² = 0.36) and was significantly higher in HOT than CON (p = 0.041, η² = 0.39). The difference between HOT and CON was large (η² = 0.40) and significant (p = 0.036) PRE, large (η² = 0.20) but not significant (p = 0.17) during OTS-4, and disappeared during OTS-6 (p = 0.87, η² = 0.00). Those changes in theta power suggest that hyperthermia may act as an additional cognitive load. However, this load disappeared during OTS-6 together with an impaired performance, suggesting a potential saturation of the available resources.

Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioural coping strategies. In this (mini) review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5oC in Norway to 30oC in Spain for example. Despite these conditions, the referee’s responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees’ decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies.

We compared the effects of short-term, perceptually regulated training using interval-walking in hypoxia vs. normoxia on health outcomes in overweight-to-obese individuals. Sixteen adults (body mass index = 33 ± 3 kg·m-2) completed eight interval-walk training sessions (15 × 2 min walking at a rating of perceived exertion of 14 on the 6-20 Borg scale; rest = 2 min) either in hypoxia (FiO2 = 13.0%) or normoxia during two weeks. Treadmill velocity did not differ between conditions or over time (p > 0.05). Heart rate was higher in hypoxia (+10 ± 3%; p = 0.04) during the first session and this was consistent within condition across the training sessions (p > 0.05). Similarly, arterial oxygen saturation was lower in hypoxia than normoxia (83 ± 1% vs. 96 ± 1%, p < 0.05), and did not vary over time (p > 0.05). After training, perceived mood state (+11.8 ± 2.7%, p = 0.06) and exercise self-efficacy (+10.6 ± 4.1%, p = 0.03) improved in both groups. Body mass (p = 0.55), systolic and diastolic blood pressure (p = 0.19 and 0.07, respectively) and distance covered during a 6-min walk test (p = 0.11) did not change from pre- to post-tests. Short term (2-week) perceptually regulated interval-walk training sessions with or without hypoxia had no effect on exercise-related sensations, health markers and functional performance. This mode and duration of hypoxic conditioning does not appear to modify the measured cardiometabolic risk factors or improve exercise tolerance in overweight-to-obese individuals.

Fermented foods are increasingly recognized for their potential to support gut and brain health via microbiome modulation. However, most research focuses on isolated probiotics or lab-prepared products, leaving limited evidence for real-world fermented foods with live bacteria. This study evaluated the effects of three commercially available fermented foods—dairy kefir, coconut kefir, and fermented red cabbage and beetroot—on gastrointestinal, cognitive, and emotional outcomes in healthy adults. Over a 4-week randomized controlled intervention, cognitive function was assessed using the CANTAB, emotional health via validated self-report measures, and stool samples analysed using the Genova Diagnostics GI Effects test. Dairy kefir improved decision-making, sustained attention, working memory, reduced depression, anxiety and stress. The coconut kefir reduced waiting impulsivity, enhanced short-term memory, improved total mood, and increased butyrate-associated commensals, Faecalibacterium prausnitzii, Bifidobacterium spp., Lactobacillus spp., and Anaerotruncus colihominis, alongside elevated butyrate levels. The fermented red cabbage and beetroot improved sustained attention, working memory, reduced stress, improved total mood, and increased both butyrate and propionate. In contrast, the control group showed a rise in Fusobacterium spp. These findings support fermented foods as functional dietary interventions for gut–brain health.