Search Results (186)

Background/Objectives: Regular physical exercise conditioning attenuates nociceptive responses. However, it remains unclear whether physical exercise performed before local inflammation exerts prolonged preventive effects. This study determined whether treadmill run (TR) preconditioning produces sustained preventive effects on craniofacial nociception and associated brain responses following persistent craniofacial inflammation. Methods: Male C57BL/6J mice were assigned to sedentary or TR groups. Daily TR conditioning was performed for 10 days before masseter muscle injection of complete Freund’s adjuvant (CFA) on Day 0. Craniofacial-pain- and related anxiety-like behaviors were determined by the orofacial formalin, elevated plus maze, and open-field tests before and 3 (CFA3) or 7 (CFA7) days after CFA injection. Brain responses in the amygdala, insular cortex, hippocampal CA1, and primary motor cortex were assessed using multiple epigenetic- and neural-activity-related markers. Results: Under sedentary conditions, both CFA3 and CFA7 groups showed increased pain- and anxiety-like behaviors and elevated expression of epigenetic- and neural-activity-related markers in most brain regions. TR preconditioning attenuated these behavioral responses even three and seven days after TR cessation and altered the expression of epigenetic markers in several brain regions, although the direction of change varied by region and time point. TR preconditioning consistently reduced the expression of neural activity markers in most brain areas in both the CFA3 and CFA7 groups, with a few exceptions. Conclusions: TR preconditioning exerted prolonged preventive effects on craniofacial-pain-like behaviors and associated brain responses following craniofacial inflammation. Full article

Running is a widely practiced exercise modality in which central and peripheral fatigue can influence performance and pacing strategy. This study investigated the influence of cognitive–emotional factors, based on the psychobiological model of fatigue, on 5 km time trial performance using a randomized crossover design. Twenty-two recreational male runners (23.0 ± 3.05 years) completed four laboratory visits. During the first visit, participants underwent body composition assessment and an incremental test to determine maximal oxygen uptake (VO₂max) and the velocity associated with VO₂max. In the subsequent three visits, participants performed a 5 km treadmill time trial as fast as possible under three conditions: no feedback (5k-NF), distance-only feedback (5k-Dist), and full feedback (5k-FF). No significant differences in performance were observed between conditions (5k-FF: 24.3 ± 1.8 min; 5k-NF: 24.8 ± 2.1 min; 5k-Dist: 24.7 ± 2.7 min). Regardless of the condition, ratings of perceived exertion and heart rate increased progressively throughout the trials. Other physiological variables showed similar responses across conditions. These findings indicate that manipulating feedback availability during a 5 km time trial did not significantly alter performance or physiological responses under the specific laboratory conditions examined, despite that the true absolute absence of effect should be interpreted with appropriate caution. Full article

Background: The use of wearable sensors to measure and monitor heart rate has exponentially grown in recent years, representing an inexpensive, time-efficient, and non-invasive method to assess the status of cardiovascular fitness and the autonomic nervous system. Validating new devices against a criterion standard, such as electrocardiography (ECG), is essential to ensure their accuracy and reliability. This study examined the accuracy and validity of the Prevayl heart rate monitor against 3-lead ECG. Methods: Twenty-six healthy adults (15 female, mean age 32.0 ± 10.4 years) completed a 16-min, incremental running test on a treadmill. Heart rate data were recorded simultaneously throughout the test via ECG and the Prevayl wearable and compared retrospectively. Beat count error (%), mean heart rate absolute error (beats per minute (bpm)), and percentage error (bpm) were calculated. In addition, a Bland–Altman analysis and Pearson’s correlation coefficient were conducted to assess agreement and correlation, respectively. Results: The Prevayl device demonstrated a median beat count agreement of 100.5% with ECG (range: 98.6–104.4%; N_part = 26). Strong correlations were observed between ECG and Prevayl for both raw beat count (r = 0.94, p < 0.01) and heart rate (beats per minute (bpm)) from ECG and the Prevayl algorithm (r = 0.96, p < 0.01). Across running speeds (0–12 kph), a strong correlation was found between raw beat count from ECG and Prevayl (r = 0.82–0.89, p < 0.01) and between bpm from ECG and Prevayl (r = 0.86–0.93, p < 0.01). Bland–Altman plots demonstrated negligible systematic bias. Conclusions: The Prevayl system provides valid measurements when compared to ECG during incremental running. This is demonstrated through strong correlations to ECG heart rate data at different speeds and with different analysis methods, supporting its use for monitoring cardiovascular responses during exercise. Full article

Background: The Global Positioning System (GPS) and wearable monitoring technologies are increasingly applied in sport science to quantify training load; however, data from female cross-country skiers in nations with emerging competitive programs remain scarce. This case series covering the complete national team roster analyzed the complete annual training cycle of the Korean women’s national cross-country skiing team (KCF) using GPS and heart rate-based wearable sensors. Methods: All three national team members were monitored throughout the 2022–2023 season (52 weeks), structured into General Preparation Period 1 (April–July), General Preparation Period 2 (August–November), and Competition Period (December–March). Individualized five-zone intensity thresholds were established through graded exercise testing on a roller ski treadmill with ventilatory threshold and blood lactate determination, independently assessed by two exercise physiologists (PhD level). Results: The total annual training volume was 667.72 h, comprising roller/on-snow skiing (54.0%), running (23.3%), and strength training (22.7%). The endurance-only intensity distribution demonstrated a polarized pattern (Zones 1–2: 91.5%). The total annual training distance reached 4673.30 km. The mean FIS points were 108.46 ± 38.60, and the mean VO₂max was 60.17 ± 6.11 mL·kg⁻¹·min⁻¹. Conclusions: When benchmarked against world-class female (WCF) standards (800–950 h annually), the overall training volume was approximately 18–30% lower. The relative strength training allocation (22.7%) exceeded typical WCF values (10–15%). These observations should be interpreted cautiously given the small sample size and cross-study comparison design, using published literature-based benchmarks. Full article

This study aimed to identify distinct lactate kinetic phenotypes in professional soccer players using unsupervised machine learning and determine their relationship with maximal running velocity (V_max) through explainable artificial intelligence methods. A total of 361 professional male soccer players from the First Division participated in the study. Incremental treadmill tests measured lactate concentrations at five standardized velocities, alongside VO_2max, V_max, lactate threshold (LT), and anaerobic threshold (AT) parameters. Three distinct lactate kinetic phenotypes emerged: Economical Aerobic (n = 216), Balanced Metabolic (n = 19), and High Producer (n = 126). The Economical Aerobic phenotype demonstrated superior performance metrics compared to High Producer (V_max: 15.85 ± 0.85 km/h; VO_2max: 56.20 ± 4.26 mL/kg/min; p < 0.001). Initial multicollinearity assessment revealed notable collinearity among all 10 candidate predictors (VIF > 10; maximum VIF = 10.75 for V_AT), necessitating rigorous feature selection. Ridge regression with 4 selected features (V_AT, VO_2max, 9.5 km/h lactate, 14 km/h lactate) achieved moderate but statistically significant predictive performance: 10-fold cross-validation R²= 0.392 ± 0.147 (permutation test p = 0.001). Standardized coefficients identified V_AT (β = 0.399) as the dominant predictor, followed by VO_2max (β = 0.253), 9.5 km/h lactate (β = 0.107), and 14 km/h lactate (β = −0.066). Lactate kinetic phenotyping reveals position-independent metabolic profiles with potentially meaningful performance associations in professional soccer. The Economical Aerobic phenotype demonstrates performance advantages associated with superior anaerobic threshold capacity. These exploratory findings suggest that individualized training strategies based on metabolic phenotype rather than playing position alone warrant further investigation, with potential applications for talent identification, training periodization, and return-to-play protocols pending prospective validation. Full article

Chronic neuroinflammation is a prominent feature of several central nervous system disorders and contributes significantly to cognitive impairment. The present study aimed to investigate the effects of pretreatment with L-theanine (LT), aerobic exercise (ex), and their combination on cognitive deficits induced by subchronic lipopolysaccharide (LPS) administration in rats. Male Wistar rats were assigned to the following groups: control; veh-sed-LPS, sedentary (sed) rats treated with vehicle (veh) and LPS; LT-sed-LPS; veh-ex-LPS; and LT-ex-LPS. L-theanine treatment and/or treadmill running were administered for 5 weeks. Following these interventions, neuroinflammation was induced by LPS injections for 7 days, while the control group received veh treatment. Cognitive function was assessed using Y-maze, object recognition, and object location tests. Hippocampal cAMP response element-binding protein (CREB) phosphorylation status, β-amyloid (Aβ_1–42) accumulation, and pro-inflammatory cytokines (TNF-α, IL-1β) were measured by ELISA. Pretreatment with LT, ex, or their combination improved Y-maze performance and recognition memory, partly restoring the LPS-induced reduction in the pCREB/CREB ratio. Exercise, but not LT, reduced Aβ_1–42 levels and neuroinflammatory cytokine expression. Combined treatment produced additive benefits for some cognitive measures but not for spatial memory. These findings suggest that the prophylactic combination of LT and ex can partially attenuate cognitive impairments associated with subchronic neuroinflammation in this model. Full article

Background: Research on vibrations induced by running has gained significant attention due to its implications for athletes’ performance, injury prevention, and overall well-being. Distance running exposes the body to repetitive impulsive forces, causing significant vibrations to travel through physiological systems and biomechanical structures. These vibrations increase fatigue and the risk of injury. Although it has gained importance, research on induced vibration during running and wearable equipment for monitoring is scarce. This study aims to evaluate the performance of a measurement system for monitoring the acceleration levels of induced vibrations during long-distance running, exploring the capability of non-invasive wearable devices to characterise vibration transmissibility and exposure. Moreover, a preliminary quantitative assessment of induced vibration levels for an indoor testing scenario is given. Methods: Metrological characterisation of Xsens Motion Trackers Awinda (MTw), off-the-shelf inertial magnetic motion trackers, was performed by measuring the sensors’ frequency bandwidth in a controlled environment, providing logarithmic sweep sine excitations at different levels (2 g, 5 g, 7 g, where g is meant to be the gravitational acceleration). A testing protocol for indoor testing was derived from the literature, allowing characterisation of the sensors’ behaviour in terms of vibration transmissibility and exposure detection in the intended application. Time domain and frequency domain analyses were conducted by following the ISO 2631 standard guideline for vibration exposure assessment, and measurement uncertainty was defined, either for the dynamic correction of the sensors’ frequency behaviour or for the computed time and frequency domain metrics. In this framework, a treadmill-based test was conducted. The aim was to evaluate the Xsens sensors’ performance in measuring vibration dose exposure and transmissibility. Three MTws were placed on the subject’s right tibia, back, and forehead using elastic bands. A 25-year-old female amateur runner completed a series of tests consisting of walking for 1 min at 3.5 km/h (instrumentation setup), followed by running at two speeds (8 km/h and 11 km/h) for 2–4 min per trial, with 5 min rest periods between tests. Conclusions: The tested measurement system showed promising results due to its capability to assess vibration exposure during sports activities, but dynamic correction was found to be mandatory for accurate vibration level assessment. The main outcome of this study is a method for characterising the accelerometers embedded in the proposed devices, along with an analysis strategy for future testing campaigns. Thanks to the portability of IMUs (inertial measurement units), this approach enables the evaluation of induced vibrations during in-field running measurements. Full article

Background/Objectives: Spinal excitability may undergo adaptive modulation in response to training load, sport-specific demands, and fatigue. While high-impact sports are known to influence reflex responsiveness, the extent to which these changes differ from athletes in lower-impact disciplines remains unclear. This study aimed to investigate post-exercise changes in Hmax/Mmax ratio among trained runners with varied sport backgrounds, and to identify emergent physiological profiles that may reflect differential spinal adaptation to fatigue. Methods: Twenty-two trained athletes underwent unilateral H-reflex testing before and after treadmill running performed to voluntary exhaustion. Amplitudes of the H-reflex and M-wave were recorded, and Hmax/Mmax ratios were analyzed. Based on a physiologically relevant threshold commonly used to distinguish normal from suppressed reflex amplitudes, participants were post hoc classified into three groups: Group A (pre- and post-test ratios above threshold), Group B (pre above, post below), and Group C (both below). A two-way repeated-measures ANOVA was used to assess between-group effects. Results: Significant differences were found across groups and conditions (p < 0.001). Group A maintained reflex ratios above the threshold, indicating stable excitability. Group B showed the greatest suppression (approximately 66%), transitioning from normal to subthreshold values. Group C remained consistently below-threshold. A significant interaction (p < 0.0001) confirmed that reflex modulation varied by physiological profile. A small but statistically significant reduction in H-reflex latency was also observed; however, this change remained within normal physiological variability. Conclusions: Postexercise H-reflex modulation revealed heterogeneous neuromuscular responses among athletes. These findings may contribute to understanding how sport-specific demands and fatigue shape spinal excitability and may help identify individuals with adaptive or potentially pathological profiles relevant to sports diagnostics. Full article

Running shoe midsoles are designed to attenuate impact forces while maintaining or improving performance. However, the literature is equivocal, likely due to measurement systems, whereas in vitro testing is conclusively favourable. This study investigated three densities of ATPU foam, comparing in vitro mechanical properties with in vivo plantar force spectral characteristics derived from individualised pressure distributions during treadmill running at varied speeds. In vitro results of slab foam and shoes showed strong positive relationships between impact variables normalised to total impact energy and foam density (r² > 0.90), and strong negative relationships for time-domain variables normalised to deformation (mm) as density increased (r² > 0.89). During running, lower midsole density increased ground contact time across speeds (p = 0.041), while spatially resolved high-frequency PSD and peak impact force both decreased (p = 0.043; p = 0.030). However, there were no differences between total vertical force and midsole density (p = 0.232). Relationships between in vitro Peak G and high-frequency PSD were strong across all speeds (r² = 0.63–0.91). Conversely, reducing midsole density increased active peak force across speeds (p = 0.003), which was strongly related to in vitro energy return (r² > 0.89). Therefore, plantar force spectra and spatially resolved analyses demonstrate how foam density properties translate from in vitro to in vivo treadmill running, with lower-density foam improving impact attenuation but elevating propulsive forces. Future work needs to verify this in an outdoor setting. Full article

Background/Objectives: Running is associated with increased Achilles Tendon (AT) loading and cross-sectional area (CSA). Achilles tendinopathy is a common unilateral injury. Differences in AT loading variables between dominant and non-dominant lower extremities while running have not been characterized. This study examined the AT loading variables between dominant and non-dominant lower extremities in healthy recreational runners. Methods: Twenty-four females ran at 3.3 m/s (11.88 km/hr) on an instrumented treadmill. Achilles Tendon CSA (AT-CSA) was measured from ultrasound images. Kinematic and kinetic data were used as input into a musculoskeletal model. Paired t-tests examined inter-limb differences in peak vertical ground reaction force, Achilles Tendon-related loading variables (AT force, AT-CSA, AT stress), total gastrocnemius force, soleus force, foot strike angle, and stance time. Results: No differences were shown between dominant and non-dominant lower extremities in stance time, vertical ground reaction force, gastrocnemius and soleus force, AT force, AT-CSA, or AT stress. Foot strike angle was different between limbs (p = 0.015); however, the absolute difference was about 2°. Conclusions: These data indicated that AT loading was similar between dominant and non-dominant lower extremities in healthy female recreational runners. While some asymmetry can be expected during a bilateral task such as running, runners displayed differences in AT force and stress less than 18%. These data may assist clinicians in the assessment and management of runners recovering from AT tendinopathy. Full article

Background: This study aimed to provide reference values for estimating training intensities in long-distance runners based on progressive incremental tests, considering differences related to sex and performance level. Methods: A total of 1411 endurance-trained runners (819 men and 592 women) completed a standardized treadmill protocol with gas exchange analysis to determine ventilatory thresholds and peak oxygen consumption (VO_2peak). Heart rate (HR) and running speed at each threshold were expressed relative to their peak values. Results: HR at second ventilatory threshold (VT2) occurred at 93.5 ± 2.5% of HR peak, and HR at first ventilatory threshold at 85.1 ± 4.6%. The relative running speeds at VT2 and VT1 corresponded to 87.6 ± 3.9% and 73.9 ± 5.5% of the speed at VO_2peak, respectively. In men, beginners exhibited higher relative HR and VO₂ values at the ventilatory thresholds than elite runners. In contrast, women displayed higher and more stable relative values across performance levels. Conclusions: These findings establish precise, evidence-based reference ranges derived from a large cohort of runners and highlight the need to consider sex and performance level when estimating exercise intensities. Individualized physiological assessment remains essential for accurate training prescription and performance optimization. Full article

Aging contributes to neurodegeneration, predominantly characterized by increased oxidative stress, which leads to neurodegenerative changes and cognitive decline. This cognitive impairment is often associated with neuroinflammation, oxidative stress, and neuronal damage. Exercise is widely recognized for its capacity to elevate levels of irisin, a hormone derived from the cleavage of fibronectin type III domain-containing protein 5 (FNDC5). FNDC5/irisin acts as a myokine that mediates numerous beneficial effects of physical activity on metabolic health. It has also been recognized for its neuroprotective roles, suggesting its potential to mitigate neurodegenerative processes by promoting neuronal survival, reducing oxidative stress, and enhancing synaptic plasticity. However, the specific impact of exercise on the FNDC5/irisin pathway and antioxidant mechanisms in the aged brain remains insufficiently explored. In this study, we aimed to validate the neuroprotective role of exercise-induced FNDC5/irisin against aging-related oxidative stress, glial activation, neuronal damage, and cognitive impairment in 20-month-old mice. The exercise group underwent treadmill running for 60 min daily over an 8-week period. Our findings indicated that aging mice exhibited cognitive impairment, as evidenced by the Y-maze test; however, treadmill exercise effectively alleviated this impairment. Aged mice showed the activation of microglia and astrocytes in the hippocampus, which was notably reduced by exercise. Moreover, exercise improved the levels of calbindin and irisin, which were diminished due to aging. Our study demonstrated that aging led to a decrease in the antioxidant response element system and FNDC5/irisin pathway. However, exercise effectively activated Nrf2 and FNDC5/irisin expression, subsequently enhancing levels of SOD1, GSTO1/2, Sirt1, PGC-1α, BDNF, IGF-1, and IGF-2 in the hippocampus. The exercise-induced activation of Nrf2 signaling and FNDC5/irisin has emerged as a potent mechanism for alleviating oxidative stress and neuroinflammation associated with aging. In conclusion, our findings suggest that regular exercise has the potential to alleviate cognitive impairment through the activation of PGC-1α-FNDC5/irisin signaling, the Nrf2 ARE system, and neurotrophic factors in aged mice. Full article

This study tested whether classic and specific bioelectrical impedance vector analysis (BIVA) parameters could explain metabolic and mechanical performance in endurance-trained trail runners. Fifteen males ($\dot{\mathrm{V}}$O₂max 61.04 ± 6.91 mL·kg⁻¹·min⁻¹) completed a 60-min treadmill protocol at 70% $\dot{\mathrm{V}}$O₂max across randomized slopes (−7% to +7%), with continuous gas-exchange, heart-rate, and running-power recording; whole-body BIVA was obtained immediately pre- and post-exercise. Post-test, impedance and resistance increased (+2.73%, +2.84%), while reactance (Xc) and phase angle decreased (−2.36%, −4.91%); all were significant and mirrored by both classic and specific indices, consistent with acute fluid loss and altered cellular status. After Benjamini–Hochberg adjustment, baseline Xc/height correlated inversely with $\dot{\mathrm{V}}$CO₂peak and $\dot{\mathrm{V}}$CO₂mean, whereas exercise-induced changes in ΔXc/height and ΔXcspecific correlated positively with both metabolic variables and mean power. Stepwise regression retained ΔXc/h or ΔXcspecific as the only BIVA predictors for $\dot{\mathrm{V}}$CO₂peak, $\dot{\mathrm{V}}$CO₂mean, and mean power output, explaining ~31–36% and ~22–23% of the variance, respectively; classic and specific approaches performed similarly. No bioelectrical variable predicted $\dot{\mathrm{V}}$O₂max. These preliminary findings suggest that acute reactance shifts may provide a modest yet sensitive, non-invasive index of exercise-induced physiological responses, warranting confirmation in larger and more diverse cohorts. Full article

5-aminolevulinic acid (5-ALA) is a heme precursor involved in mitochondrial activation. A clinical study suggested that 5-ALA supplementation alleviates fatigue in healthy individuals who experience chronic physical tiredness. However, the detailed mechanisms are unknown. Therefore, we investigated the mechanism underlying the antifatigue effect of 5-ALA using fatigue mouse models. C57BL/6N mice were orally administered 5-ALA hydrochloride or distilled water for 8 weeks. Fatigue mouse models were developed by housing the mice in a cage filled with water for 4 days. Fatigue was evaluated through running distance via a treadmill test. The decrease in the running distance in female mice significantly recovered after 5-ALA administration. 5-ALA administration ameliorated the decreased blood glucose levels in fatigue mouse models. These results suggest that 5-ALA improves fatigue-induced hypoglycemia by promoting the use of fatty acids. PpIX’s concentration in the FCX of the fatigue mouse models significantly increased after 5-ALA treatment. Decreased levels of 3-methoxy-4-hydroxyphenylglycol and noradrenaline (NA) turnover ratio in the FCX recovered to non-fatigue levels after 5-ALA treatment. Therefore, the antifatigue effect of 5-ALA in mice could be related to the activation of the NA neuronal systems in the FCX and the increase in energy production via glycogenesis activation from peripheral adipose tissue. Full article

Curved non-motorized treadmills (cNMTs) have been demonstrated to reduce impact accelerations in comparison with motorized treadmills (MTs). Most studies have analyzed impacts in the time domain, but analysis in the frequency domain can provide useful information associated with the increase in the running risk of injury. The purpose of this study was to analyze the frequency components (low- and high-frequency bands) of impact accelerations, countermovement jump (CMJ) height, and perceived comfort during a prolonged run on different surfaces: MT, cNMT, and overground (OVG). Twenty-one recreational runners completed three randomized prolonged running tests on cNMT, MT, and OVG for 30 min (80% of the individual maximal aerobic speed). Impact accelerations were registered at minutes 5 and 30 of the test, the countermovement jump test (CMJ) was performed before (PreTest) and after (PostTest) the test, and perceived comfort was determined at the end of each test. A two-way repeated-measures analysis of variance (significance at p < 0.05) showed a reduction on cNMT in both low- and high-frequency bands of impact accelerations, such as head power (p < 0.001, ESd = 3.0) on the cNMT vs. the MT and tibia peak power (p = 0.001, ESd = 2.2) on the cNMT vs. OVG. However, cNMT was perceived as the least comfortable surface by runners. The prolonged running effect decreased impact accelerations during the treadmill running test (MT and cNMT) in the low-frequency band, while CMJ height decreased (p = 0.024, ESd = 1.4) during the PostTest vs. PreTest with the cNMT. Using a cNMT could be an interesting strategy for load reduction in long-distance runners or in return-to-play rehabilitation protocols. Full article