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Overreaching is often linked to a deterioration in sleep quality, yet a comprehensive review is lacking. The aim of this systemic review and meta-analysis was to synthesise the literature and quantify the effect of overreaching from endurance-based training on sleep quality. The review was conducted following the PRISMA guidelines. The final search was conducted in May 2023 using four electronic databases (Web of Science Core Collection, MEDLINE, Cochrane Central Database, SPORTDiscus). Studies were included for a qualitative review, while random-effects meta-analyses were conducted for objective and subjective sleep. The search returned 805 articles. Fourteen studies were included in the systematic review; Three and eight articles were eligible for the meta-analyses (objective and subjective, respectively). On average, the overreaching protocols were sixteen days in length (6 to 28 days) and included exercise modalities such as cycling (number of studies [k] = 5), rowing (k = 4), triathlon (k = 3), running (k = 2), and swimming (k = 1). Actigraphy was the only form of objective sleep measurement used across all studies (k = 3), while various instruments were used to capture subjective sleep quality (k = 13). When comparing objective sleep quality following the overreaching intervention to baseline (or a control), there was a significant reduction in sleep efficiency (mean difference = -2.0%; 95% CI -3.2, -0.8%; Glass' Δ = -0.83; p < 0.01). In contrast, when comparing subjective sleep quality following the overreaching intervention to baseline (or a control), there was no effect on subjective sleep quality (Glass' Δ = -0.27; 95% CI -0.79, 0.25; p = 0.08). Importantly, none of the included studies were judged to have a low risk of bias. While acknowledging the need for more high-quality studies, it appears that overreaching from endurance-based training can deteriorate objective sleep without influencing the perception of sleep quality. This protocol was registered in The International Prospective Register of Systematic Reviews (PROSPERO) on 21st November 2022, with the registration number CRD42022373204.

Numerous studies have demonstrated that executive functions benefit from high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). However, the immediate effects of HIIT and MICT on these functions in older adults have not been compared. This study aimed to examine the acute impact of HIIT and MICT on executive function components in this demographic. Twenty-five healthy community-dwelling older adults (15 females; average age 67.1 ± 4.5 years) participated. The study involved three sessions: an initial session with cognitive assessments (Stroop Task: Naming, Inhibition, and Switching) and a maximal continuous graded exercise test, followed by two sessions involving HIIT (15s at 100% peak power output, 15s rest, 2 × 20 min) or MICT (34 min at 60% peak power output) training protocols in random order. Cognitive tests were administered immediately after and 45 min post-training. The results showed a significant difference in Switching reaction times between MICT and HIIT, with HIIT showing a greater reduction in Switching times after 45 min ( p  = 0.019). In conclusion, our study indicates that HIIT’s beneficial effects on executive functions demonstrated a larger effect size than those of MICT. This suggests that brief, high-intensity exercise could be more effective in enhancing executive functions among older adults.

The aim of this study was to evaluate the effects of daily partial body cryostimulation exposures on sleep and recovery parameters in elite swimmers undergoing an intense training period. Twenty‐three elite French swimmers (7 females and 16 males) were involved in this controlled cross‐over protocol. The experiment took place during 2 weeks of intense training load. Each week (5 days and 5 nights) represented one of the two experimental conditions: partial body cryostimulation exposures (CRYO) or control sessions (CONT). Daily partial body cryostimulation exposure of 3 min at −110°C was performed (or not) during a consecutive period of 5 days, after the evening training session. Perceived wellness (anxiety, tiredness, depression and mood profile), sleep quality (via actimetry and cerebral recording) and nocturnal heart rate variability were evaluated. Collection of saliva samples permitted the measurement of C‐reactive protein and melatonin. Perceived anxiety, tiredness and depression were reduced after the CRYO week, concomitant with an improved mood profile. Recordings of cerebral activity during the night highlighted increased slow‐wave sleep duration in the first sleep cycle during the CRYO week. Other sleep parameters, including total sleep time, sleep latency, efficiency or movements during the night, remained unchanged. The concentration of C‐reactive protein in saliva was lower during the CRYO week compared with the CONT week. Moreover, sleep analysis allowed a distinction between better sleepers and poor sleepers. In the latter group, only poor sleepers among the male swimmers obtained a benefit on their sleep from cryotherapy. Repeated cryostimulation exposures during 1 week of intense training improved perceived wellness in elite swimmers, reduced inflammation, and modulated sleep architecture by increasing slow‐wave sleep duration. What is the central question of this study? We hypothesized that chronic cryostimulation sessions during intensive training would have a positive impact on sleep quality, wellness feelings, inflammation and cardiac autonomic balance. What is the main finding and its importance? Repeated cryostimulation exposures during 1 week of intense training improved perceived wellness in elite swimmers, reduced inflammation and modulated sleep architecture by increasing slow‐wave sleep duration.

There are many important sport events that are organized in environments with a very hot ambient temperature (Summer Olympics, FIFA World Cup, Tour de France, etc.) and in hot locations (e.g., Qatar). Additionally, in the context of global warming and heat wave periods, athletes are often subjected to hot ambient temperatures. It is known that exercising in the heat induces disturbances that may provoke premature fatigue and negatively affects overall performance in both endurance and high intensity exercises. Deterioration in several cognitive functions may also occur, and individuals may be at risk for heat illnesses. To train, perform, work and recover and in a safe and effective way, cooling strategies have been proposed and have been routinely applied before, during and after exercise. However, there is a limited understanding of the influences of per-cooling on performance, and it is the subject of the present review. This work examines the influences of per-cooling of different areas of the body on performance in terms of intense short-term exercises (“anaerobic” exercises), endurance exercises (“aerobic” exercises), and cognitive functioning and provides detailed strategies that can be applied when individuals train and/or perform in high ambient temperatures.

Introduction: Many studies have reported that regular physical activity is positively associated with cognitive performance and more selectively with executive functions. However, some studies reported that the association of physical activity on executive performance in younger adults was not as clearly established when compared to studies with older adults. Among the many physiological mechanisms that may influence cognitive functioning, prefrontal (PFC) oxygenation seems to play a major role. The aim of the current study was to assess whether executive function and prefrontal oxygenation are dependent on physical activity levels (active versus inactive) in healthy young males. Methods: Fifty-six healthy young males (22.1 ± 2.4 years) were classified as active (n = 26) or inactive (n = 30) according to the recommendations made by the World Health Organization (WHO) and using the Global Physical Activity Questionnaire (GPAQ). Bilateral PFC oxygenation was assessed using functional near-infrared spectroscopy (fNIRS) during a computerized Stroop task (which included naming, inhibition, and switching conditions). Accuracy (% of correct responses) and reaction times (ms) were used as behavioural indicators of cognitive performances. Changes in oxygenated (∆HbO2) and deoxygenated (∆HHb) hemoglobin were measured to capture neural changes. Several two-way repeated measures ANOVAs (Physical activity level x Stroop conditions) were performed to test the null hypothesis of an absence of interaction between physical activity level and executive performance in prefrontal oxygenation. Results: The analysis revealed an interaction between physical activity level and Stroop conditions on reaction time (p = 0.04; ES = 0.7) in which physical activity level had a moderate effect on reaction time in the switching condition (p = 0.02; ES = 0.8) but not in naming and inhibition conditions. At the neural level, a significant interaction between physical activity level and prefrontal oxygenation was found. Physical activity level had a large effect on ΔHbO2 in the switching condition in the right PFC (p = 0.04; ES = 0.8) and left PFC (p = 0.02; ES = 0.96), but not in other conditions. A large physical activity level effect was also found on ΔHHb in the inhibition condition in the right PFC (p < 0.01; ES = 0.9), but not in the left PFC or other conditions. Conclusion: The results of this cross-sectional study indicate that active young males performed better in executive tasks than their inactive counterparts and had a larger change in oxygenation in the PFC during these most complex conditions.

We assessed the effects of a 3-min partial-body cryostimulation (PBC) exposure—where the whole body is exposed to extreme cold, except the head—on cognitive inhibition performance and the possible implications of parasympathetic cardiac control and cerebral oxygenation. In a randomized controlled counterbalanced cross-over design, eighteen healthy young adults (nine males and nine females) completed a cognitive Stroop task before and after one single session of PBC (3-min exposure at − 150 °C cold air) and a control condition (3 min at room temperature, 20 °C). During the cognitive task, heart rate variability (HRV) and cerebral oxygenation of the prefrontal cortex were measured using heart rate monitoring and near-infrared spectroscopy methods. We also recorded the cerebral oxygenation during the PBC session. Stroop performance after PBC exposure was enhanced (562.0 ± 40.2 ms) compared to pre-PBC (602.0 ± 56.4 ms; P  < 0.042) in males only, accompanied by an increase ( P  < 0.05) in HRV indices of parasympathetic tone, in greater proportion in males compared to females. During PBC, cerebral oxygenation decreased in a similar proportion in males and females but the cerebral extraction (deoxyhemoglobin: ΔHHb) remained higher after exposure in males, only. These data demonstrate that a single PBC session enhances the cognitive inhibition performance on a Stroop task in males, partly mediated by a greater parasympathetic cardiac control and greater cerebral oxygenation. The effects of PBC on cognitive function seem different in females, possibly explained by a different sensitivity to cold stimulation.

The neuroimaging literature on dual-task gait clearly demonstrates increased prefrontal cortex (PFC) involvement when performing a cognitive task while walking. However, findings from direct comparisons of the cerebral oxygenation patterns of younger (YA) and older (OA) adults during dual-task walking are mixed and it is unclear how YA and OA respond to increasing cognitive load (difficulty) while walking. This functional near infra-red (fNIRS) study examined cerebral oxygenation of YA and OA during self-paced dual-task treadmill walking at two different levels of cognitive load (auditory n-back). Changes in accuracy (%) as well as oxygenated (HbO) and deoxygenated (HbR) hemoglobin were examined. For the HbO and HbR measures, eight regions of interest (ROIs) were assessed: the anterior and posterior dorsolateral and ventrolateral PFC (aDLPFC, pDLPFC, aVLPFC, pVLPFC) in each hemisphere. Nineteen YA ( = 21.83 years) and 14 OA ( = 66.85 years) walked at a self-selected pace while performing auditory 1-back and 2-back tasks. Walking alone (single motor: SM) and performing the cognitive tasks alone (single cognitive: SC) were compared to dual-task walking (DT = SM + SC). In the behavioural data, participants were more accurate in the lowest level of load (1-back) compared to the highest (2-back; < 0.001). YA were more accurate than OA overall ( = 0.009), and particularly in the 2-back task ( = 0.048). In the fNIRS data, both younger and older adults had task effects (SM < DT) in specific ROIs for ΔHbO (three YA, one OA) and ΔHbR (seven YA, eight OA). After controlling for walk speed differences, direct comparisons between YA and OA did not reveal significant age differences, but did reveal a difficulty effect in HbO in the left aDLPFC ( = 0.028) and significant task effects (SM < DT) in HbR for six of the eight ROIs. Findings suggest that YA and OA respond similarly to manipulations of cognitive load when walking on a treadmill at a self-selected pace.

Background Intermittent hypoxia (IH) has emerged as a promising strategy to enhance physical performance by eliciting adaptive responses across cardiovascular, respiratory, and muscular systems. Various IH protocols have been applied in both trained and untrained individuals to improve aerobic capacity, strength, and repeated sprint ability. However, the growing number of systematic reviews and meta-analyses (SRs/MAs) has led to heterogeneous conclusions due to variability in populations, protocols, and outcome measures. This umbrella review aimed to synthesize and critically appraise the available SRs/MAs on the effects of IH protocols on physical performance across different fitness levels. Methods A systematic search, aligned with the PRIOR (Preferred Reporting Items for Overviews of Reviews) guidelines, was conducted across seven electronic databases (PubMed/MEDLINE, Web of Science, Cochrane Database of Systematic Reviews, Scopus, Embase, PsycINFO, and SciELO) from inception to June 2025. Eligible studies included systematic reviews (SRs) with or without meta-analyses (MAs) or network meta-analyses (NMAs) evaluating the effects of intermittent hypoxia protocols on physical performance. Methodological quality was assessed using the AMSTAR-2 tool. Results A total of 22 systematic reviews (14 with meta-analyses, 3 with network meta-analyses) analyzing 487 primary studies and 5,333 participants were included. Intermittent hypoxia (IH) protocols improved both aerobic and anaerobic performance, as well as muscular strength. Live high–train low (LHTL) and live low–train high (LLTH) protocols consistently enhanced V̇O₂max, especially when combined with sea-level training. Anaerobic-focused strategies like repeated sprint training in hypoxia (RSH) and RSH induced by voluntary hypoventilation at low lung volume (RSH-VHL) led to improvements in sprint-fatigue resistance and glycolytic capacity. Intermittent hypoxic interval training (IHIT) and high-intensity interval training (HIIT) under hypoxia showed robust aerobic benefits. However, the magnitude of these effects varied depending on the type of protocol, training status, and hypoxic dose. Conclusion IH is an effective and adaptable strategy to improve aerobic and anaerobic performance, as well as to enhance muscle strength and hypertrophy. These benefits often occur without consistent hematological changes. Future studies should focus on individualized approaches, standardization of terminology, and precise quantification of both hypoxic exposure and training load to optimize outcomes and ensure reproducibility. Review registration : This overview was registered on the International Database of Systematic Review Protocols (PROSPERO ID: CRD42024465481).

Advancing age is associated with declines in cognitive function. Although physical activity is thought to protect against this decline, it is unclear how a short-term uptake in daily steps or a decline in day-to-day step variability may contribute to cognition among older adults. We tested associations between changes in step counts, day-to-day step variability and executive cognitive functions among older adults taking part in a physical activity intervention. Thirty-seven older adults (33 females; 71.4 ± 6.3 years) completed a 10-week personalized physical activity intervention. Participants wore a Fitbit to measure daily step counts throughout the study. They also completed a computerized Stroop task before and after the intervention. Average step counts and step count variability via average-real-variability (ARV) were determined. Compared to pre-intervention, step counts increased ( p  < 0.001) and step variability decreased post-intervention ( p  = 0.04). Models describing the changes in step counts and ARV over the 10-weeks were cubic (both, p  < 0.04). Reaction times during the simple ( p  = 0.002) and switching ( p  = 0.04) conditions were faster post-intervention. Change in step variability was positively associated with the change in reaction time for the switching condition (β = 0.029, p  = 0.002). On average, a reduction in day-to-day step variability was associated with improvements in cognitive flexibility.

Stroke patients often exhibit difficulties performing a cognitive task while walking, defined as a dual task (DT). Their prefrontal cortex (PFC) activity is higher in DT than in single task (ST). The effects of an increasing load on PFC activity during DT in subacute stroke patients remains unexplored. Our objective was to assess the effects of N-back tasks (low/high load) on cerebral activity, gait parameters, and cognitive performances. Eleven subacute stroke patients (days post-stroke 45.8 ± 31.6) participated in this pilot study (71.4 ± 10 years, BMI 26.7 ± 4.8 kg.m , Barthel index 81.8 ± 11.0). Patients completed a ST , and 4 conditions with 1-back (low load) and 2-back (high load): ST , ST , DT , and DT . Overground walking was performed at a comfortable pace and -N-back conditions were carried out verbally. Both gait (speed, stride variability) and cognitive (rate of correct answers) performances were recorded. Changes in PFC oxyhemoglobin (ΔO Hb) and deoxyhemoglobin (ΔHHb) were measured by functional near infrared spectroscopy (fNIRS). Results showed an increase of ΔO Hb while walking, which was not augmented by cognitive loads in DT. Walking speed was reduced by low and high cognitive loads in DT compared to ST ( < 0.05), but was not different between DT and DT . Cognitive performances were negatively impacted by both walking ( < 0.05) and cognitive load (between \"low\" and \"high,\" < 0.001). These data highlight a \"ceiling\" effect in ΔO Hb levels while walking, leaving no available resources for simultaneous cognitive tasks, during the early recovery period following stroke. In these patients, cognitive, but not motor, performances declined with a higher cognitive load.