EEG-based neurophysiological indices for expert psychomotor performance - a review.

A primary objective of current human neuropsychological performance research is to define the physiological correlates of adaptive knowledge utilization, in order to support the enhanced execution of both simple and complex tasks. Within the present article, electroencephalography-based neurophysiological indices characterizing expert psychomotor performance, will be explored. As a means of characterizing fundamental processes underlying efficient psychometric performance, the neural efficiency model will be evaluated in terms of alpha-wave-based selective cortical processes. Cognitive and motor domains will initially be explored independently, which will act to encapsulate the task-related neuronal adaptive requirements for enhanced psychomotor performance associating with the neural efficiency model. Moderating variables impacting the practical application of such neuropsychological model, will also be investigated. As a result, the aim of this review is to provide insight into detectable task-related modulation involved in developed neurocognitive strategies which support heightened psychomotor performance, for the implementation within practical settings requiring a high degree of expert performance (such as sports or military operational settings).

Acute and long-term sleep measurements produce opposing results on sleep quality in 8 and 12 hour shift patterns in law enforcement officers.

The occupational demands of law enforcement increase the risk of poor-quality sleep, putting officers at risk of adverse physical and mental health. This cross-sectional study aimed to characterise sleep quality in day workers, 8 and 12 h rotating shift pattern workers. One hundred eighty-six officers volunteered for the study (37 female, age: 41 ± 7). Sleep quality was assessed using the Pittsburgh sleep quality index, actigraphy and the Leeds sleep evaluation questionnaire. The maximal aerobic capacity (VO2max ) was measured on a treadmill via breath-by-breath analysis. There was a 70% overall prevalence of poor sleepers based on Pittsburgh sleep quality index scores, where 8 h shifts exhibited the worst prevalence (92%, p = 0.029), however, there was no difference between age, gender, or role. In contrast, 12 h shifts exhibited the poorest short-term measures, including awakening from sleep (p = 0.039) and behaviour following wakefulness (p = 0.033) from subjective measures, and poorer total sleep time (p = 0.024) and sleep efficiency (p = 0.024) from the actigraphy. High VO2max predicted poorer wake after sleep onset (Rsq = 0.07, p = 0.05) and poorer sleep latency (p = 0.028). There was no relationship between the Pittsburgh sleep quality index scores and any of the short-term measures. The prevalence of poor sleepers in this cohort was substantially higher than in the general population, regardless of shift pattern. The results obtained from the long- and short-term measures of sleep quality yielded opposing results, where long-term perceptions favoured the 12 h pattern, but short-term subjective and objective measures both favoured the 8 h pattern.

A bespoke sleep monitoring and sleep hygiene intervention improves sleep in an U18 professional football player: A case study.

This case study reports on a professional football player (age: 17.6 years) who was referred for sleep monitoring and intervention after reporting excessive night-time awakenings. The player undertook a series of subjective sleep assessments and objective sleep monitoring (activity monitor). Based on the data presented, a sleep hygiene intervention was prescribed. Numerical comparisons were made between pre-intervention (Pre) and post-intervention (Post) values. Objective values were also compared to reference data from a similarly aged professional cohort from the same club (n = 11). Wake episodes per night (Pre: 7.9 ± 3, Post: 4.5 ± 1.9; -43%) and wake after sleep onset (WASO; Pre: 74.3 ± 31.8 mins, Post: 50.0 ± 22.8 mins, -33%) were improved from Pre to Post. Compared to the reference data, mean wake episodes per night (Pre: 7.9 ± 3.0, reference: 4.6 ± 2.6; -42%) and WASO (Pre: 74.3 ± 31.8 mins, reference: 44.3 ± 36.5 mins; -40%) were all lower compared to Pre levels. Whilst causality cannot be proven, we observed multiple sleep metrics improving following an intervention. This provides a potential framework for practitioners looking to provide targeted sleep assessment and intervention.

The development and validation of an open-source accelerometery algorithm for measuring jump height and frequency in ballet.

The aim was to determine the validity of an open-source algorithm for measuring jump height and frequency in ballet using a wearable accelerometer. Nine professional ballet dancers completed a routine ballet class whilst wearing an accelerometer positioned at the waist. Two investigators independently conducted time-motion analysis to identify time-points at which jumps occurred. Accelerometer data were cross-referenced with time-motion data to determine classification accuracy. To determine the validity of the measurement of jump height, five participants completed nine jetés, nine sautés and three double tour en l'air from a force plate. The jump height predicted by the accelerometer algorithm was compared to the force plate jump height to determine agreement. Across 1440 jumps observed in time-motion analysis, 1371 true positives, 34 false positives and 69 false negatives were identified by the algorithm, resulting in a sensitivity of 0.98, a precision of 0.95 and a miss rate of 0.05. For all jump types, mean absolute error was 2.6 cm and the repeated measures correlation coefficient was 0.97. Bias was 1.2 cm and 95% limits of agreement were -4.9 to 7.2 cm. The algorithm may be used to manage jump load, implement periodization strategies, or plan return-to-jump pathways for rehabilitating athletes.

Collagen Gene Polymorphisms Previously Associated with Resistance to Soft-Tissue Injury Are More Common in Competitive Runners Than Nonathletes.

ABSTRACT: Dines, HR, Nixon, J, Lockey, SJ, Herbert, AJ, Kipps, C, Pedlar, CR, Day, SH, Heffernan, SM, Antrobus, MR, Brazier, J, Erskine, RM, Stebbings, GK, Hall, ECR, and Williams, AG. Collagen gene polymorphisms previously associated with resistance to soft-tissue injury are more common in competitive runners than nonathletes. J Strength Cond Res 37(4): 799-805, 2023-Single-nucleotide polymorphisms (SNPs) of collagen genes have been associated with soft-tissue injury and running performance. However, their combined contribution to running performance is unknown. We investigated the association of 2 collagen gene SNPs with athlete status and performance in 1,429 Caucasian subjects, including 597 competitive runners (354 men and 243 women) and 832 nonathletes (490 men and 342 women). Genotyping for COL1A1 rs1800012 (C > A) and COL5A1 rs12722 (C > T) SNPs was performed by a real-time polymerase chain reaction. The numbers of "injury-resistant" alleles from each SNP, based on previous literature (rs1800012 A allele and rs12722 C allele), were combined as an injury-resistance score (RScore, 0-4; higher scores indicate injury resistance). Genotype frequencies, individually and combined as an RScore, were compared between cohorts and investigated for associations with performance using official race times. Runners had 1.34 times greater odds of being rs12722 CC homozygotes than nonathletes (19.7% vs. 15.5%, p = 0.020) with no difference in the rs1800012 genotype distribution ( p = 0.659). Fewer runners had an RScore 0 of (18.5% vs. 24.7%) and more had an RScore of 4 (0.6% vs. 0.3%) than nonathletes ( p < 0.001). Competitive performance was not associated with the COL1A1 genotype ( p = 0.933), COL5A1 genotype ( p = 0.613), or RScore ( p = 0.477). Although not associated directly with running performance among competitive runners, a higher combined frequency of injury-resistant COL1A1 rs1800012 A and COL5A1 rs12722 C alleles in competitive runners than nonathletes suggests these SNPs may be advantageous through a mechanism that supports, but does not directly enhance, running performance.

Compression Garments for Recovery from Muscle Damage: Evidence and Implications of Dose Responses.

ABSTRACT: The use of compression garments (CG) has been associated with improved recovery following exercise-induced muscle damage. The mechanisms responsible are not well established, and no consensus exists regarding the effects of compression pressure (i.e., the "dose"), which until recently was seldom reported. With the increasing prevalence of studies reporting directly measured pressures, the present review aims to consolidate current evidence on optimal pressures for recovery from exercise-induced muscle damage. In addition, recent findings suggesting that custom-fitted garments provide greater precision and experimental control are discussed. Finally, biochemical data from human trials are presented to support a theoretical mechanism by which CG enhance recovery, with recommendations for future research. The effects of compression on adaptation remain unexplored. More studies are required to investigate the relationship between compression pressure and the recovery of performance and physiological outcomes. Furthermore, improved mechanistic understanding may help elucidate the optimal conditions by which CG enhance recovery.

The effects of normoxic endurance exercise on erythropoietin (EPO) production and the impact of selective ß1 and non-selective ß1 + ß2 adrenergic receptor blockade.

PURPOSE: Habitual endurance exercise results in increased erythropoiesis, which is primarily controlled by erythropoietin (EPO), yet studies demonstrating upregulation of EPO via a single bout of endurance exercise have been equivocal. This study compares the acute EPO response to 30 min of high versus 90 min of moderate-intensity endurance exercise and whether that response can be upregulated via selective adrenergic receptor blockade. METHODS: Using a counterbalanced, cross-over design, fifteen participants (age 28 ± 8) completed two bouts of running (30-min, high intensity vs 90-min, moderate intensity) matched for overall training stress. A separate cohort of fourteen participants (age 31 ± 6) completed three bouts of 30-min high-intensity cycling after ingesting the preferential ß1-adrenergic receptor (AR) antagonist bisoprolol, the non-preferential ß1 + ß2 antagonist nadolol or placebo. Venous blood was collected before, during, and after exercise, and serum EPO levels were determined by ELISA. RESULTS: No detectable EPO response was observed during or after high intensity running, however, in the moderate-intensity trial EPO was significantly elevated at both during-exercise timepoints (+ 6.8% ± 2.3% at 15 min and + 8.7% ± 2.2% at 60 min). No significant change in EPO was observed post-cycling or between the trials involving ßAR blockade. CONCLUSION: Neither training mode (running or cycling), nor beta-blockade significantly influenced the EPO response to 30 min of high-intensity exercise, however, 90 min of moderate-intensity running elevated EPO during exercise, returning to baseline immediately post-exercise. Identifying the optimal mode, duration and intensity required to evoke an EPO response to exercise may help tailor exercise prescriptions designed to maximize EPO response for both performance and clinical applications.

Medical encounters at community-based physical activity events (parkrun) in the UK.

OBJECTIVE: To determine the incidence, clinical correlates and exposure risk of medical encounters during community-based physical activity events in the UK. METHODS: An analysis of medical data from weekly, community-based physical activity events (parkrun) at 702 UK locations over a 6-year period (29 476 294 participations between 2014 and 2019) was conducted in order to define the incidence and clinical correlates of serious life-threatening, non-life-threatening and fatal medical encounters. RESULTS: 84 serious life-threatening encounters (overall incidence rate=0.26/100 000 participations) occurred including 18 fatalities (0.056/100 000 participations). Statistical modelling revealed that the probabilities of serious life-threatening encounters were exceptionally low, however, male sex, increasing age, slower personal best parkrun time and less prior running engagement/experience (average number of runs per year and number of years as a parkrun participant) were associated with increased probability of serious life-threatening encounters. These were largely accounted for by cardiac arrest (48/84, 57%) and acute coronary syndromes (20/84, 24%). Non-life-threatening medical encounters were mainly attributed to tripping or falling, with a reported incidence of 39.2/100 000 participations. CONCLUSIONS: Serious life-threatening and fatal medical encounters associated with parkrun participation are extremely rare. In the context of a global public health crisis due to inactivity, this finding underscores the safety and corollary public health value of community running/walking events as a strategy to promote physical activity.

Jumping in Ballet: A Systematic Review of Kinetic and Kinematic Parameters.

AIMS: Understanding the biomechanics of jumping in ballet dancers provides an opportunity to optimize performance and mitigate injury risk. This systematic review aimed to summarize research investigating kinetics and kinematics of jumping in ballet dancers. METHODS: PubMed (MEDLINE), SPORTDiscus, and Web of Science were systematically searched for studies published before December 2020. Studies were required to investigate dancers specializing in ballet, assess kinetics or kinematics during take-off or landing, and be published in English. RESULTS: A total of 3,781 articles were identified, of which 29 met the inclusion criteria. Seven studies investigated take-off (kinetics: n = 6; kinematics: n = 4) and 23 studies investigated landing (kinetics: n = 19; kinematics: n = 12). Included articles were categorized into six themes: Activity Type (n = 10), Environment and Equipment (n = 10), Demographics (n = 8), Physical Characteristics (n = 3), Injury Status (n = 2), and Skill Acquisition and Motor Control (n = 1). Peak landing vertical ground reaction force (1.4-9.6 times body weight) was most commonly reported. Limited evidence suggests greater ankle involvement during the take-off of ballet jumps compared to countermovement jumps. There is also limited evidence indicating greater sagittal plane joint excursions upon landing in ballet dancers compared to non-dancers, primarily through a more extended lower extremity at initial contact. Only 4 articles investigated male ballet dancers, which is a notable gap in the literature. CONCLUSIONS: The findings of this review can be used by dance science and medicine practitioners to improve their understanding of jumping in ballet dancers.

Variability in nitrate-reducing oral bacteria and nitric oxide metabolites in biological fluids following dietary nitrate administration: An assessment of the critical difference.

There is conflicting evidence on whether dietary nitrate supplementation can improve exercise performance. This may arise from the complex nature of nitric oxide (NO) metabolism which causes substantial inter-individual variability, within-person biological variation (CVB), and analytical imprecision (CVA) in experimental endpoints. However, no study has quantified the CVA and CVB of NO metabolites or the factors that influence their production. These data are important to calculate the critical difference (CD), defined as the smallest difference between sequential measurements required to signify a true change. The main aim of the study was to evaluate the CVB, CVA, and CD for markers of NO availability (nitrate and nitrite) in plasma and saliva before and after the ingestion of nitrate-rich beetroot juice (BR). We also assessed the CVB of nitrate-reducing bacteria from the dorsal surface of the tongue. It was hypothesised that there would be substantial CVB in markers of NO availability and the abundance of nitrate-reducing bacteria. Ten healthy male participants (age 25 ±â€¯5 years) completed three identical trials at least 6 days apart. Blood and saliva were collected before and after (2, 2.5 and 3 h) ingestion of 140 ml of BR (∼12.4 mmol nitrate) and analysed for [nitrate] and [nitrite]. The tongue was scraped and the abundance of nitrate-reducing bacterial species were analysed using 16S rRNA next generation sequencing. There was substantial CVB for baseline concentrations of plasma (nitrate 11.9%, nitrite 9.0%) and salivary (nitrate 15.3%, nitrite 32.5%) NO markers. Following BR ingestion, the CVB for nitrate (plasma 3.8%, saliva 12.0%) and salivary nitrite (24.5%) were lower than baseline, but higher for plasma nitrite (18.6%). The CD thresholds that need to be exceeded to ensure a meaningful change from baseline are 25, 19, 37, and 87% for plasma nitrate, plasma nitrite, salivary nitrate, and salivary nitrite, respectively. The CVB for selected nitrate-reducing bacteria detected were: Prevotella melaninogenica (37%), Veillonella dispar (35%), Haemophilus parainfluenzae (79%), Neisseria subflava (70%), Veillonella parvula (43%), Rothia mucilaginosa (60%), and Rothia dentocariosa (132%). There is profound CVB in the abundance of nitrate-reducing bacteria on the tongue and the concentration of NO markers in human saliva and plasma. Where these parameters are of interest following experimental intervention, the CD values presented in this study will allow researchers to interpret the meaningfulness of the magnitude of the change from baseline.

Quantification of aerobic determinants of performance in post-pubertal adolescent middle-distance runners.

PURPOSE: The use of oxygen cost ([Formula: see text]aero) parameters to predict endurance performance has recently been criticized. Instead, it is suggested that aerobic energy cost ([Formula: see text]) provides greater validity; however, a comparison of these quantification methods has not previously been made. METHODS: Fifty-six male (n = 34) and female (n = 22) competitive adolescent (17 ± 1 years) middle-distance runners participated in a sub-maximal and maximal incremental treadmill test. Running economy (RE) was measured at the speed corresponding to lactate turnpoint, and the three speeds prior. Maximal oxygen uptake ([Formula: see text]O2max), speed at [Formula: see text]O2max and fraction of [Formula: see text]O2max utilized across a range of intensities, and speeds from 0.8, 1.5 and 3 km races were also quantified. RE and fractional utilization were calculated in units of [Formula: see text]aero and [Formula: see text]aero. RESULTS: Multiple linear regression models demonstrated no discernible difference in the predictive capability of RE, fractional utilization and [Formula: see text]O2max when expressed as [Formula: see text]aero or [Formula: see text]aero in both sexes. When plotted as a function of running speed, [Formula: see text]aero displayed a stepwise decrease (F = 11.59, p < 0.001) whereas [Formula: see text]aero exhibited a curvilinear response (F = 4.74, p = 0.015). Differences were also evident in the slopes plotted for %[Formula: see text]O2max and %[Formula: see text]aeromax against running speed (F = 5.38, p = 0.021). CONCLUSIONS: Quantifying aerobic determinants of performance in units of [Formula: see text]aero provides no greater validity compared to [Formula: see text]aero-based measurement. Although both [Formula: see text]aero and [Formula: see text]aero are sensitive to changes in speed, [Formula: see text]aero provides the more valid reflection of the underlying metabolic cost of running. Physiologists should also be aware of the potential differences between expression of aerobic running intensity based upon %[Formula: see text]O2max compared to %[Formula: see text]aeromax.

Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A systematic review and meta-analysis.

PURPOSE: The aim of this study was to determine whether iron treatments improve the iron status and aerobic capacity of iron deficient non-anaemic endurance athletes. METHOD: A meta-analysis of studies that investigated the effects of iron treatment on serum ferritin (sFer), serum iron (sFe), transferrin saturation (Tsat), haemoglobin concentration ([Hb]) and (VO(2max)). Seventeen eligible studies were identified from online databases. RESULTS: Analysis of pooled data indicated that iron treatments had a large effect on improving sFer (Hedges' g=1.088, 95% CI 0.914 to 1.263, p<0.001), sFe (Hedges' g=1.004, 95% CI 0.828 to 1.181, p<0.001) and Tsat (Hedges g=0.741, 95% CI 0.564 to 0.919, p<0.001) and a moderate effect on improving [Hb] (Hedges' g=0.695, 95% CI 0.533 to 0.836, p<0.001) and (VO(2max)) (Hedges' g=0.610, 95% CI 0.399 to 0.821, p<0.001). Regression analysis revealed a significant interaction between the effect of iron treatment on sFer and treatment duration, suggesting treatments that lasted beyond 80 days appear to have the least effect on sFer. CONCLUSIONS: These results indicate iron treatments improve the iron status and aerobic capacity of iron deficient non-anaemic endurance athletes.

Eight weeks of intermittent hypoxic training improves submaximal physiological variables in highly trained runners.

It is unclear whether intermittent hypoxic training (IHT) results in improvements in physiological variables associated with endurance running. Twelve highly trained runners (VO2peak 70.0 ± 3.5 ml·kg-1·min-1) performed incremental treadmill tests to exhaustion in normobaric normoxia and hypoxia (16.0% FIO2) to assess submaximal and maximal physiological variables and the limit of tolerance (T-Lim). Participants then completed 8 weeks of moderate to heavy intensity normoxic training (control [CONT]) or IHT (twice weekly 40 minutes runs, in combination with habitual training), in a single blinded manner, before repeating the treadmill tests. Submaximal heart rate decreased significantly more after IHT (-5 ± 5 b·min-1; p = 0.001) than after CONT ( -1 ± 5 b·min-1; p = 0.021). Changes in submaximal V[Combining Dot Above]O2 were significantly different between groups (p ≤ 0.05); decreasing in the IHT group in hypoxia (-2.6 ± 1.7 ml·kg-1·min-1; p = 0.001) and increasing in the CONT group in normoxia (+1.1 ± 2.1 ml·kg-1·min-1; p = 0.012). There were no VO2peak changes within either group, and while T-Lim improved post-IHT in hypoxia (p = 0.031), there were no significant differences between groups. Intermittent hypoxic training resulted in a degree of enhanced cardiovascular fitness that was evident during submaximal, but not maximal intensity exercise. These results suggest that moderate to heavy intensity IHT provides a mean of improving the capacity for submaximal exercise and may be useful for pre-acclimatization for subsequent exercise in hypoxia, but additional research is required to establish its efficacy for athletic performance at sea level.

Influence of compression garments on recovery after marathon running.

Strenuous physical activity can result in exercise-induced muscle damage. The purpose of this study was to investigate the efficacy of a lower limb compression garment in accelerating recovery from a marathon run. Twenty four subjects (female, n = 7; male, n = 17) completed a marathon run before being assigned to a treatment group or a sham treatment group. The treatment group wore lower limb compression tights for 72 hours after the marathon run, the sham treatment group received a single treatment of 15 minutes of sham ultrasound after the marathon run. Perceived muscle soreness, maximal voluntary isometric contraction (MVIC), and serum markers of creatine kinase (CK) and C-reactive protein (C-RP) were assessed before, immediately after, and 24, 48, and 72 hours after the marathon run. Perceived muscle soreness was significantly lower (p ≤ 0.05) in the compression group at 24 hours after marathon when compared with the sham group. There were no significant group effects for MVIC, CK, and C-RP (p > 0.05). The use of a lower limb compression garment improved subjective perceptions of recovery; however, there was neither a significant improvement in muscular strength nor a significant attenuation in markers of exercise-induced muscle damage and inflammation.

Selective cortical adaptations associated with neural efficiency in visuospatial tasks - the comparison of electroencephalographic profiles of expert and novice artists.

Visuospatial cognition encapsulates an individual's ability to efficiently navigate and make sense of the multimodal cues from their surroundings, and therefore has been linked to expert performance across multiple domains, including sports, performing arts, and highly skilled tasks, such as drawing (Morrone and Minini, 2023). As neural efficiency posits a task-specific functional reorganization facilitated by long-term training, the present study employs a visuospatial construction task as a means of investigating the neurophysiological adaptations associated with expert visuospatial cognitive performance. Electroencephalogram (EEG) data acquisitions were used to evaluate the event-related changes (ER%) and statistical topographic maps of nine expert versus nine novice artists. The expert artists displayed overall higher global ER% compared to the novices within task-active intervals. Significant increases in relative ER% were found in the theta (t (10) = 3.528, p = 0.003, CI = [27.3,120.9]), lower-alpha (t (10) = 3.751, p = 0.002, CI = [28.2,110.5]), upper-alpha (t (10) = 3.829, p = 0.002, CI = [50.2,189.8]), and low beta (t (10) = 4.342, p < 0.001, CI = [37.0,114.9]) frequency bands, when comparing the experts to the novice participants. These results were particularly found in the frontal (t (14) = 2.014, p = 0.032, CI = [7.7,245.4]) and occipital (t (14) = 2.647, p = 0.010, CI = [45.0,429.7]) regions. Further, a significant decrease in alpha ER% from lower to upper activity (t (8) = 4.475, p = 0.001, CI = [21.0, 65.8]) was found across cortical regions in the novice group. Notably, greater deviation between lower and upper-alpha activity was found across scalp locations in the novice group, compared to the experts. Overall, the findings demonstrate potential local and global EEG-based indices of selective cortical adaptations within a task requiring a high degree of visuospatial cognition, although further work is needed to replicate these findings across other domains.

Injury Incidence, Severity, and Type Across the Menstrual Cycle in Female Footballers: A Prospective Three Season Cohort Study.

PURPOSE: The aim of the study was to assess the influence of menstrual cycle phase on injury incidence, severity, and type in elite female professional footballers over three seasons. METHODS: Time-loss injuries and menstrual cycle data were prospectively recorded for 26 elite female football players across three seasons. The menstrual cycle was categorized into four phases using a standardized model: menstruation (phase 1; P1), remainder of follicular phase (phase 2; P2), early luteal (phase 3; P3), and premenstrual phase (phase 4; P4). Injury incidence rates (IIR) and ratios (IIRR) were calculated for overall injuries, injury severity, type, contact vs noncontact, and game/training. RESULTS: A total of 593 cycles across 13,390 d were tracked during the study, and 74 injuries from 26 players were eligible for analysis. When comparing IIR between phases (reference: P1), overall injury rates were highest in P4 (IIRR, 2.30 (95% confidence interval, 0.99-5.34; P = 0.05)). When examining rates by injury severity and type, IIR values were also highest in P4 for ≤7 d' time-loss (4.40 (0.93-20.76; P = 0.06)), muscle-specific (6.07 (1.34-27.43; P = 0.02)), and noncontact (3.05 (1.10-8.50; P = 0.03)) injuries. Muscle-specific (IIRR P3/P1, 5.07 (1.16-22.07; P = 0.03)) and ≤7 d' time-loss (4.47 (1.01-19.68; P = 0.05)) injury risk was also significantly higher in P3. Muscle injuries were the most prevalent subtype ( n = 41). No anterior cruciate ligament injuries were recorded across the monitoring period. CONCLUSIONS: Injury risk was significantly elevated during the luteal phase of the menstrual cycle (P3 and P4) among elite female professional footballers. Further research is urgently needed to better understand the influence of the menstrual cycle on injury risk and to develop interventions to mitigate risk.

COVID-19 vaccination produces exercise-responsive SARS-CoV-2 specific T-cells regardless of infection history.

BACKGROUND: The mobilization and redistribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific T-cells and neutralizing antibodies (nAbs) during exercise is purported to increase immune surveillance and protect against severe coronavirus disease 2019 (COVID-19). We sought to determine if COVID-19 vaccination would elicit exercise-responsive SARS-CoV-2 T-cells and transiently alter nAb titers. METHODS: Eighteen healthy participants completed a 20-min bout of graded cycling exercise before and/or after receiving a COVID-19 vaccine. All major leukocyte subtypes were enumerated before, during, and after exercise by flow cytometry, and immune responses to SARS-CoV-2 were determined using whole blood peptide stimulation assays, T-cell receptor (TCR)-ß sequencing, and SARS-CoV-2 nAb serology. RESULTS: COVID-19 vaccination had no effect on the mobilization or egress of major leukocyte subsets in response to intensity-controlled graded exercise. However, non-infected participants had a significantly reduced mobilization of CD4+ and CD8+ naive T-cells, as well as CD4+ central memory T-cells, after vaccination (synthetic immunity group); this was not seen after vaccination in those with prior SARS-CoV-2 infection (hybrid immunity group). Acute exercise after vaccination robustly mobilized SARS-CoV-2 specific T-cells to blood in an intensity-dependent manner. Both groups mobilized T-cells that reacted to spike protein; however, only the hybrid immunity group mobilized T-cells that reacted to membrane and nucleocapsid antigens. nAbs increased significantly during exercise only in the hybrid immunity group. CONCLUSION: These data indicate that acute exercise mobilizes SARS-CoV-2 specific T-cells that recognize spike protein and increases the redistribution of nAbs in individuals with hybrid immunity.

Jumping Asymmetries and Risk of Injuries in Preprofessional Ballet.

BACKGROUND: Preprofessional ballet dancers are exposed to the risk of injuries, primarily in the lower extremities, with most injuries occurring during jumping and landing activities. Interlimb asymmetry during jumping and landing activities has been associated with the injury risk in adolescent athletes, but this has not been examined in dancers. PURPOSE: To investigate associations between interlimb asymmetry during a double-leg countermovement jump (DL-CMJ) and single-leg jump (SLJ) and the injury risk in adolescent preprofessional ballet dancers. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Adolescent preprofessional ballet dancers (N = 255) performed 3 DL-CMJs and 3 SLJs on force plates during annual screening. Absolute and directional (separate values for left and right limb dominance) asymmetries in a set of kinetic variables during a DL-CMJ and in jump height during an SLJ were calculated. Each variable was characterized as having "high" or "normal" asymmetry according to the percentage of asymmetry (greater than or less than or equal to, respectively, the mean ± 0.5 SD) based on the present sample. Risk ratios (RRs) and 95% CIs were calculated based on the injury incidence in the subsequent academic year. RESULTS: Of the 242 dancers that satisfied the inclusion criteria, 128 injuries were observed in the subsequent academic year. In the whole sample, 3 absolute, 7 left limb-dominant, and 1 right limb-dominant kinetic asymmetry in the eccentric, concentric, and landing phases of the DL-CMJ as well as left limb-dominant jump height asymmetry in the SLJ were associated with a significant (P < .001) increase in the injury risk (RR, 1.28-1.69 [95% CI, 1.02-2.37]). Separating by sex, asymmetries in the eccentric and landing phase of the DL-CMJ were not significant in boys, while in girls, RRs for asymmetries in the eccentric and landing phase of the DL-CMJ increased, and SLJ jump height asymmetry was not significant. CONCLUSION: Higher asymmetries in certain kinetic variables during the DL-CMJ and in jump height during the SLJ were associated with an elevated risk of injuries in elite preprofessional ballet dancers with some sex-specific differences. Associations were mainly identified for high left limb-dominant asymmetry in the takeoff phase, suggesting that the injury risk may be specific to a relative right limb deficit.

Ankle mechanics during jump landings across different foot positions in professional ballet dancers.

This study aimed to investigate the effect foot position on ankle joint mechanics and vertical ground reaction forces (vGRF) across jump landings in professional ballet dancers. Twenty-seven professional ballet dancers (men: 14; women: 13) attended one data collection session, completing five maximal countermovement jumps in parallel, first, second, fourth, and fifth positions. Three-dimensional ankle mechanics, landing vGRF variables, and jump height were recorded via a seven-camera motion capture system and one force platform. A repeated measures multivariate analysis of variance was used to assess the main effects foot position across all target variables. A linear discriminate analysis was conducted to investigate target variables across foot positions. Frontal and transverse plane ankle mechanics had the largest impact when discriminating between foot positions. Ankle power in the transverse plane during jump landing in fourth was double that of all other positions. Our findings suggest that ankle range of motion should be restored before returning to jumps in fourth and fifth positions following distal lower extremity injury. The multiplanar energy transfer observed indicates a need for specific exercises to develop multiplanar force and rate of force development of local structures around the ankle.