Different levels of arterial occlusion pressure (AOP) can influence microcirculatory responses and autonomic nervous system activity, potentially affecting individuals undergoing training methods that incorporate AOP, such as blood flow restriction (BFR) training. Therefore, this study aimed to compare the effects of four distinct AOP levels on microcirculatory responses and autonomic nervous system activity—specifically investigating the relationship between post-occlusive reactive hyperemia (PORH), hemodynamic parameters, and heart rate variability (HRV) metrics. This prospective experimental study involved 30 healthy adults who underwent standardized assessments of heart rate variability (HRV) and post-occlusive reactive hyperemia (PORH) across four arterial occlusion pressure (AOP) levels (40, 80, 100, 130%). Measurements were conducted under controlled environmental conditions and consistent body positioning, enabling an analysis of microcirculatory and autonomic responses under progressive vascular occlusion. The results showed no significant changes in resting flow across AOP levels (p = 0.847), while all other parameters—biological zero, peak hyperemia, time to peak, average NN interval, standard deviation of NN intervals, and heart rate—exhibited significant differences between AOP conditions (all p < 0.001, except low frequency to high frequency ratio p < 0.05). However, for most variables, no significant differences were observed between 100 and 130% AOP (p > 0.999), indicating a possible stabilization of physiological responses at higher occlusion pressures. This study concludes that while increasing arterial occlusion pressure significantly affects multiple physiological parameters, responses tend to stabilize between 100 and 130% AOP, suggesting a threshold beyond which further increases yield minimal additional physiological impact. Trial registration trial number ISRCTN15418049.
The study aimed to determine the influence of functional asymmetry on the kinematic parameters of the 50 m run and its significance in shaping maximum speed in sprinters at various sports levels. The analysis included 18 Polish sprinters (elite: ≤ 10.40 s, sub-elite: ≤ 11.10 s per 100 m) who performed four 50 m runs with 5-minute breaks. Kinematic parameters were recorded using the OptoJumpNEXT system and WittyGate photocells. The fastest and slowest run of each athlete was selected for analysis. The results showed that kinematic asymmetry has a significant impact on sprint performance. Elite sprinters had less asymmetry in stride length, frequency, and ground contact time, which correlated with better results. The key findings indicate that in the acceleration phase (0-20 m), stride length and contact time symmetry were crucial, while in the maximal speed phase (20-50 m), the symmetry of stride frequency was important. A higher sports level was associated with a more optimized running technique, as evidenced by lower kinematic asymmetry. The results suggest that minimizing kinematic asymmetry may be a crucial factor in optimizing the sprinting technique and enhancing performance, offering practical insights for coaches and athletes and empowering them to make informed decisions in their training programs.
Objectives To investigate the associations of training exposure and limb-specific postural stability with previous running-related injury (RRI) in recreational runners and determine whether postural stability provides additional information beyond training-related variables. Design Cross-sectional study. Methods A total of 146 recreational runners (104 with and 42 without a history of RRI) completed a questionnaire on training characteristics and injury history, underwent Functional Movement Screen (FMS) assessment, and performed single-leg postural stability testing using the Biodex Balance System. Postural stability was quantified using the Overall Stability Index (OSI), with higher values indicating poorer stability. Hierarchical logistic regression examined associations with previous RRI. Results Runners with previous RRI reported higher training frequency (6.4 ± 2.0 vs. 5.3 ± 1.9 sessions/week; p = 0.001) and longer running experience (4.5 ± 1.9 vs. 3.4 ± 2.1 years; p = 0.003). Training frequency (OR 2.47, 95% CI 1.35–4.51), running experience (OR 2.76, 95% CI 1.40–5.45), and their interaction (OR 0.87, 95% CI 0.77–0.98) were independently associated with injury history. After adjustment, only non-dominant limb OSI remained independently associated with injury history (OR 0.80, 95% CI 0.64–0.99; p = 0.042). Including non-dominant limb OSI improved model discrimination (AUC 0.74–0.76) and explained variance (Nagelkerke R² 0.21–0.29). FMS score was not associated with injury history. Conclusions Training frequency, running experience, and non-dominant limb postural stability were independently associated with previous RRI. Limb-specific postural stability provided additional information beyond training-related variables, although prospective studies are needed to determine its relationship with future running-related injury.
BackgroundCognitive impairment (CI) is common in multiple sclerosis (MS) yet poorly captured by conventional disability scales. Although neuropsychological assessment and magnetic resonance imaging (MRI) are routinely used separately, there is no simple clinically applicable framework integrating cognitive performance with structural brain changes to identify patients at increased risk of cognitive decline. Integrating neuropsychological testing with MRI-based atrophy metrics may yield clinically useful cognitive phenotypes with differential patterns of brain atrophy measures.MethodsData were collected from 79 patients with multiple sclerosis (PwMS) who underwent comprehensive neuropsychological assessment and brain MRI. Neuropsychological variables were subjected to a feature selection procedure based on variance and quartile coefficient of dispersion filtering, followed by Pearson correlation and mutual information (MI) analyses to generate reduced feature sets. These feature sets were used as input for unsupervised clustering with the Partitioning Around Medoids (PAM) algorithm to identify cognitive phenotypes. Differences between the resulting groups in the degree of brain atrophy measures were subsequently evaluated using appropriate statistical tests—one-way ANOVA or the Kruskal–Wallis test. Post hoc analysis was performed using a pairwise t-test, Welch's t-test, or Wilcoxon test with the Holm-Bonferroni correction, depending on the data distribution and variance.ResultsThe feature selection procedure based on variance and mutual information identified neuropsychological features that were subsequently used for clustering. Based on these features, the PAM algorithm identified three distinct groups of PwMS that differed in their clinical characteristics, degree of brain atrophy measures, and cognitive phenotype, ranging from preserved cognition to global cognitive impairment.ConclusionThree cognitive phenotypes with differential patterns of brain atrophy measures integrate neuropsychological testing with MRI measures into a clinically applicable framework that may help bridge the gap between structural imaging findings and everyday cognitive assessment in PwMS. This approach may improve screening, enable earlier detection of CI, improve monitoring, and provide valuable information for rehabilitation planning.
Background: Vitamin D is involved in musculoskeletal function, but evidence that supplementation improves athletic performance remains inconsistent, particularly in athletes with sufficient baseline vitamin D status. Methods: In this double-blind randomized controlled trial, 18 professional female soccer players were randomized during the autumn preparatory period (August-September) to receive vitamin D3 (4000 IU/day; n = 9) or placebo (n = 9) for eight weeks. Outcomes included total serum 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] concentrations, hematological variables, RAST total sprint time, 5- and 30-m sprint performance, and countermovement-jump outcomes. Results: At baseline, after summer exposure, 25% of participants had insufficient or deficient 25(OH)D concentrations (≤30 ng/mL). The remaining cohort (75%) had sufficient 25(OH)D concentrations (>30 ng/mL). After eight weeks, no statistically significant between-group differences were observed in vitamin D metabolites, hematological variables, or performance outcomes (Δ25(OH)D: SG +12.4 ± 8.2 ng/mL vs. PG +3.1 ± 6.5 ng/mL; p = 0.12). RAST total sprint time (p = 0.001) and 30-m sprint performance (p = 0.005) improved over time. Conclusions: Vitamin D3 supplementation at 4000 IU/day for eight weeks was not associated with additional improvements in muscle strength, sprint performance, or countermovement-jump outcomes compared with placebo. Because most participants had sufficient baseline 25(OH)D concentrations, larger trials in female athletes with confirmed vitamin D insufficiency or deficiency are needed to determine whether individualized supplementation or longer intervention periods provide additional physiological or performance-related benefits. The trial was retrospectively registered at ClinicalTrials.gov (NCT07641075) on 8 June 2026.
