Neuro-Immune Cell Units: A New Paradigm in Physiology.

The interplay between the immune and nervous systems has been acknowledged in the past, but only more recent studies have started to unravel the cellular and molecular players of such interactions. Mounting evidence indicates that environmental signals are sensed by discrete neuro-immune cell units (NICUs), which represent defined anatomical locations in which immune and neuronal cells colocalize and functionally interact to steer tissue physiology and protection. These units have now been described in multiple tissues throughout the body, including lymphoid organs, adipose tissue, and mucosal barriers. As such, NICUs are emerging as important orchestrators of multiple physiological processes, including hematopoiesis, organogenesis, inflammation, tissue repair, and thermogenesis. In this review we focus on the impact of NICUs in tissue physiology and how this fast-evolving field is driving a paradigm shift in our understanding of immunoregulation and organismal physiology.

Neuro-mesenchymal units control ILC2 and obesity via a brain-adipose circuit.

Signals from sympathetic neurons and immune cells regulate adipocytes and thereby contribute to fat tissue biology. Interactions between the nervous and immune systems have recently emerged as important regulators of host defence and inflammation1-4. Nevertheless, it is unclear whether neuronal and immune cells co-operate in brain-body axes to orchestrate metabolism and obesity. Here we describe a neuro-mesenchymal unit that controls group 2 innate lymphoid cells (ILC2s), adipose tissue physiology, metabolism and obesity via a brain-adipose circuit. We found that sympathetic nerve terminals act on neighbouring adipose mesenchymal cells via the ß2-adrenergic receptor to control the expression of glial-derived neurotrophic factor (GDNF) and the activity of ILC2s in gonadal fat. Accordingly, ILC2-autonomous manipulation of the GDNF receptor machinery led to alterations in ILC2 function, energy expenditure, insulin resistance and propensity to obesity. Retrograde tracing and chemical, surgical and chemogenetic manipulations identified a sympathetic aorticorenal circuit that modulates ILC2s in gonadal fat and connects to higher-order brain areas, including the paraventricular nucleus of the hypothalamus. Our results identify a neuro-mesenchymal unit that translates cues from long-range neuronal circuitry into adipose-resident ILC2 function, thereby shaping host metabolism and obesity.

Remote monitoring of cardiac implantable electronic devices to predict acute clinical decompensation events.

BACKGROUND: Heart failure (HF) patients are at constant risk of decompensation, and urgent hospital admissions can be life-threatening events. Monitoring biological variables has been proved to be an important mechanism to anticipate decompensations. TriageHF is a validated diagnostic algorithm tool available on Medtronic® cardiac implantable electronic devices that combines physiological data to stratify a patient's risk of HF hospitalization in the following 30 days in low, medium or high risk. We aimed to evaluate the utility of TriageHF algorithm to predict the occurrence of acute clinical decompensation events (ACDE), including HF and non-HF cardiovascular events, within a 30-day period in a population of HF patients with reduced ejection fraction. METHODS: We reviewed the transmissions received by the Medtronic® Carelink™ Network between August 2022 and July 2023. The heart failure risk status (HFRS) and the device parameters contributing to that risk, from the previous 30 days, were collected, along with the occurrence of ACDEs within 30 days. RESULTS: We retrospectively assessed 207 transmissions from the 64 patients included in the study. Among the 93 medium HFRS transmissions, 16 (17.2%) resulted in ACDEs. For the 21 high HFRS transmissions, 10 (47.6%) resulted in ACDEs. Considering the ACDEs, 60.7% were preceded by an alarm-initiated transmission. Except for heart rate variability, each diagnostic parameter demonstrated effectiveness in stratifying risk for ACDEs. Optivol® and the Combined Heart Rhythm showed independent association with ACDEs (p < .001). Patients with medium and high HFRS were, respectively, 8.6 and 29.1 times more likely to experience an ACDE in the next 30 days than low risk patients. A medium-high HFRS conferred a sensitivity of 92.9% and a NPV of 97.8% for an ACDE. CONCLUSION: TriageHF is a useful method for predicting ACDEs and has the potential to trigger medical actions to prevent hospitalizations.

Assessment of Cardiorespiratory and Metabolic Contributions in an Extreme Intensity CrossFit® Benchmark Workout.

Our purpose was to characterize the oxygen uptake kinetics (VO2), energy systems contributions and total energy expenditure during a CrossFit® benchmark workout performed in the extreme intensity domain. Fourteen highly trained male CrossFitters, aged 28.3 ± 5.4 years, with height 177.8 ± 9.4 cm, body mass 87.9 ± 10.5 kg and 5.6 ± 1.8 years of training experience, performed the Isabel workout at maximal exertion. Cardiorespiratory variables were measured at baseline, during exercise and the recovery period, with blood lactate and glucose concentrations, including the ratings of perceived exertion, measured pre- and post-workout. The Isabel workout was 117 ± 10 s in duration and the VO2 peak was 47.2 ± 4.7 mL·kg-1·min-1, the primary component amplitude was 42.0 ± 6.0 mL·kg-1·min-1, the time delay was 4.3 ± 2.2 s and the time constant was 14.2 ± 6.0 s. The accumulated VO2 (0.6 ± 0.1 vs. 4.8 ± 1.0 L·min-1) value post-workout increased substantially when compared to baseline. Oxidative phosphorylation (40%), glycolytic (45%) and phosphagen (15%) pathways contributed to the 245 ± 25 kJ total energy expenditure. Despite the short ~2 min duration of the Isabel workout, the oxygen-dependent and oxygen-independent metabolism energy contributions to the total metabolic energy release were similar. The CrossFit® Isabel requires maximal effort and the pattern of physiological demands identifies this as a highly intensive and effective workout for developing fitness and conditioning for sports.

Kinematical Effects of a Mandibular Advancement Occlusal Splint on Running until Exhaustion at Severe Intensity.

The effects of occlusal splints on sport performance have already been studied, although their biomechanical impacts are often overlooked. We investigated the kinematical changes during running until exhaustion at severe intensity while wearing a mandibular advancement occlusal splint. Twelve trained runners completed (i) an incremental protocol on a track to determine their velocity corresponding to maximal oxygen uptake and (ii) two trials of square wave transition exercises at their velocity corresponding to maximal oxygen until exhaustion, wearing two occlusal splints (without and with mandibular advancement). Running kinematics were compared within laps performed during the square wave transition exercises and between splint conditions. The mandibular advancement occlusal splint increased the running distance covered (~1663 ± 402 vs. 1540 ± 397 m, p = 0.03), along with a noticeable lap effect in decreasing stride frequency (p = 0.04) and increasing stride length (p = 0.03) and duty factor (p < 0.001). No spatiotemporal differences were observed between splints, except for improved balance foot contact times in the mandibular advancement condition. An increased knee flexion angle at initial contact (p = 0.017) was noted along laps in the non-advancement condition, despite the fact that no differences between splints were found. Running patterns mainly shifted within laps rather than between conditions, indicating that a mandibular advancement occlusal splint had a trivial kinematical effect.

Assessment of Angular and Straight Linear Rowing Ergometers at Different Intensities of Exercise.

We aimed to conduct a biophysical comparison of angular (Biorower) and linear (Concept2) rowing ergometers across a wide spectrum of exercise intensities. Sixteen (eleven male) skilled rowers, aged 29.8 ± 8.6 and 23.6 ± 1.5 years, with international competitive experience, performed 7 × 3 min bouts with 30 W increments and 60 s intervals, plus 1 min of all-out rowing on both machines with 48 h in between. The ventilatory and kinematical variables were measured breath-by-breath using a telemetric portable gas analyzer and determined using a full-body markerless system, respectively. Similar values of oxygen uptake were observed between ergometers across all intensity domains (e.g., 60.36 ± 8.40 vs. 58.14 ± 7.55 mL/min/kg for the Biorower and Concept2 at severe intensity). The rowing rate was higher on the Biorower vs. Concept2 at heavy and severe intensities (27.88 ± 3.22 vs. 25.69 ± 1.99 and 30.63 ± 3.18 vs. 28.94 ± 2.29). Other differences in kinematics were observed across all intensity domains, particularly in the thorax angle at the finish (e.g., 19.44 ± 4.49 vs. 27.51 ± 7.59° for the Biorower compared to Concep2 at heavy intensity), likely due to closer alignment of the Biorower with an on-water rowing technique. The overall perceived effort was lower on the Biorower when compared to the Concept2 (14.38 ± 1.76 vs. 15.88 ± 1.88). Rowers presented similar cardiorespiratory function on both rowing ergometers, while important biomechanical differences were observed, possibly due to the Biorower's closer alignment with an on-water rowing technique.

Ventilatory and Perceived Ergogenic Effects of Mandibular Forward Repositioning During Running at Maximal Oxygen Uptake Intensity.

ABSTRACT: Cardoso, F, Costa, MJ, Colaço, P, Vilas-Boas, JP, Pinho, JC, Pyne, DB, and Fernandes, RJ. Ventilatory and perceived ergogenic effects of mandibular forward repositioning during running at maximal oxygen uptake intensity. J Strength Cond Res XX(X): 000-000, 2024-Wearing an intraoral dental splint may enhance ventilatory function and exercise performance. Nineteen runners performed on a 400-m outdoor track: (a) an incremental protocol to assess the velocity at maximal oxygen uptake (vV̇o2max) and (b) 2 square wave bouts wearing 2 intraoral splints (with and without mandibular forward repositioning). The time until exhaustion at vV̇o2max (TLimv V̇o2max), ventilatory variables, oxygen uptake (V̇o2) kinetics, energetic profiling, perceived exertion and kinematics, were all measured. Ventilatory data were assessed breath-by-breath and perceived exertion evaluated using the Borg 6-20-point scale at the end of TLimv V̇o2max bouts. Images were recorded by video cameras (120 Hz) and kinematic measures retrieved using Kinovea. A paired t test was computed for comparison of splints (p ≤ 0.05). With (vs. without) mandibular forward repositioning, runners increased their TLimv V̇o2max by ∼6% (p = 0.03), coupled with higher ventilation (151 ± 22 vs. 147 ± 23 L·min-1, p = 0.04), end-tidal oxygen tension (114.3 ± 3.7 vs. 112.9 ± 3.9 mm Hg, p = 0.003), and lower inspiratory time (0.526 ± 0.083 vs. 0.540 ± 0.090 seconds, p = 0.02), despite similar V̇o2 kinetics (e.g., 49.0 ± 8.7 vs. 47.7 ± 8.6 ml∙kg∙min-1 of fast component amplitude) being observed. The energy expenditure was ∼8% higher (p = 0.03) with the mandible forward, coupled with lower perceived exertion scores (p = 0.04). Mandibular forward repositioning was effective in acutely improving running performance at vV̇o2max with ergogenic effects on ventilatory and perceived variables.

Assessing cardiac resynchronization therapy response in heart failure patients: a comparative analysis of efficacy and outcomes between transvenous and epicardial leads.

Cardiac resynchronization therapy (CRT) is an effective treatment for selected heart failure (HF) patients. Although transvenous implantation is the standard method, it is not feasible in some patients, so the epicardial lead emerges as an alternative. We aim to compare CRT response, procedure-related complications, and the occurrence of clinical outcomes between patients with transvenous and epicardial leads. In a single-center retrospective study, we enrolled consecutive HF patients submitted to CRT implantation with a defibrillator between 2013 and 2022. Clinical response was defined as an improvement of at least one of the New York Heart Association classes with no occurrence of cardiovascular death or HF hospitalization in the first year of follow-up. Echocardiographic response was attained with an increase in left ventricular ejection fraction 10% or a reduction of left ventricular end-diastolic volume >15% at 6-12 months after CRT implantation. Major adverse cardiovascular events (MACE) (cardiovascular mortality and HF hospitalization) and all-cause mortality were evaluated. From a total of 149 patients, 38% (n=57) received an epicardial lead. Clinical (63% versus 60%, p=0.679) and echocardiographic (63% versus 60%, p=0.679) responses were similar between the transvenous and epicardial groups. Patients in the transvenous group had a shorter hospital stay (2 versus 7 days, p<0.001). Procedure-related complications were comparable between groups (24% versus 28%, p=0.572), but left ventricular lead-related complications were more frequent in the transvenous group (14% versus 2%). During a median follow-up of 4.7 years, the rate of MACE was 30% (n=44), with no differences in both groups (p=0.591), neither regarding HF hospitalization (p=0.917) nor cardiovascular mortality (p=0.060). Nevertheless, the epicardial group had a higher rate of all-cause mortality (35% versus 20%, p=0.005), the majority occurring during long-term follow-up (>12 months), with no deaths in the postoperative period. Considering the comparable rates of CRT response, procedure-related complications, and MACE between groups, we conclude that epicardial lead is a feasible alternative for CRT when transvenous lead implantation is not possible. The occurrence of a higher number of all-cause deaths in epicardial patients in the long-term follow-up was mainly due to infectious complications (unrelated to the lead) and the progression of oncological/chronic diseases.

Machine Learning Approach to Model Physical Fatigue during Incremental Exercise among Firefighters.

Physical fatigue is a serious threat to the health and safety of firefighters. Its effects include decreased cognitive abilities and a heightened risk of accidents. Subjective scales and, recently, on-body sensors have been used to monitor physical fatigue among firefighters and safety-sensitive professionals. Considering the capabilities (e.g., noninvasiveness and continuous monitoring) and limitations (e.g., assessed fatiguing tasks and models validation procedures) of current approaches, this study aimed to develop a physical fatigue prediction model combining cardiorespiratory and thermoregulatory measures and machine learning algorithms within a firefighters' sample. Sensory data from heart rate, breathing rate and core temperature were recorded from 24 participants during an incremental running protocol. Various supervised machine learning algorithms were examined using 21 features extracted from the physiological variables and participants' characteristics to estimate four physical fatigue conditions: low, moderate, heavy and severe. Results showed that the XGBoosted Trees algorithm achieved the best outcomes with an average accuracy of 82% and accuracies of 93% and 86% for recognising the low and severe levels. Furthermore, this study evaluated different methods to assess the models' performance, concluding that the group cross-validation method presents the most practical results. Overall, this study highlights the advantages of using multiple physiological measures for enhancing physical fatigue modelling. It proposes a promising health and safety management tool and lays the foundation for future studies in field conditions.

Impact of developmental exposure to methylphenidate on rat brain's immune privilege and behavior: Control versus ADHD model.

Attention deficit hyperactivity disorder (ADHD) is the most prevalent childhood mental disorders that often persists into adulthood. Moreover, methylphenidate (MPH) is the mainstay of medical treatment for this disorder. Yet, not much is known about the neurobiological impact of MPH on control versus ADHD conditions, which is crucial to simultaneously clarify the misuse/abuse versus therapeutic use of this psychostimulant. In the present study, we applied biochemical and behavioral approaches to broadly explore the early-life chronic exposure of two different doses of MPH (1.5 and 5 mg/kg/day) on control and ADHD rats (Wistar Kyoto and Spontaneously Hypertensive rats, respectively). We concluded that the higher dose of MPH promoted blood-brain barrier (BBB) permeability and elicited anxiety-like behavior in both control and ADHD animals. BBB dysfunction triggered by MPH was particularly prominent in control rats, which was characterized by a marked disruption of intercellular junctions, an increase of endothelial vesicles, and an upregulation of adhesion molecules concomitantly with the infiltration of peripheral immune cells into the prefrontal cortex. Moreover, both doses of MPH induced a robust neuroinflammatory and oxidative response in control rats. Curiously, in the ADHD model, the lower dose of MPH (1.5 mg/kg/day) had a beneficial effect since it balanced both immunity and behavior relative to vehicle animals. Overall, the contrasting effects of MPH observed between control and ADHD models support the importance of an appropriate MPH dose regimen for ADHD, and also suggest that MPH misuse negatively affects brain and behavior.

Type I IFN Inhibits Alternative Macrophage Activation during Mycobacterium tuberculosis Infection and Leads to Enhanced Protection in the Absence of IFN-γ Signaling.

Tuberculosis causes ∼1.5 million deaths every year, thus remaining a leading cause of death from infectious diseases in the world. A growing body of evidence demonstrates that type I IFN plays a detrimental role in tuberculosis pathogenesis, likely by interfering with IFN-γ-dependent immunity. In this article, we reveal a novel mechanism by which type I IFN may confer protection against Mycobacterium tuberculosis infection in the absence of IFN-γ signaling. We show that production of type I IFN by M. tuberculosis-infected macrophages induced NO synthase 2 and inhibited arginase 1 gene expression. In vivo, absence of both type I and type II IFN receptors led to strikingly increased levels of arginase 1 gene expression and protein activity in infected lungs, characteristic of alternatively activated macrophages. This correlated with increased lung bacterial burden and pathology and decreased survival compared with mice deficient in either receptor. Increased expression of other genes associated with alternatively activated macrophages, as well as increased expression of Th2-associated cytokines and decreased TNF expression, were also observed. Thus, in the absence of IFN-γ signaling, type I IFN suppressed the switching of macrophages from a more protective classically activated phenotype to a more permissive alternatively activated phenotype. Together, our data support a model in which suppression of alternative macrophage activation by type I IFN during M. tuberculosis infection, in the absence of IFN-γ signaling, contributes to host protection.

Systemic inflammation in early neonatal mice induces transient and lasting neurodegenerative effects.

BACKGROUND: The inflammatory mediator lipopolysaccharide (LPS) has been shown to induce acute gliosis in neonatal mice. However, the progressive effects on the murine neurodevelopmental program over the week that follows systemic inflammation are not known. Thus, we investigated the effects of repeated LPS administration in the first postnatal week in mice, a condition mimicking sepsis in late preterm infants, on the developing central nervous system (CNS). METHODS: Systemic inflammation was induced by daily intraperitoneal administration (i.p.) of LPS (6 mg/kg) in newborn mice from postnatal day (PND) 4 to PND6. The effects on neurodevelopment were examined by staining the white matter and neurons with Luxol Fast Blue and Cresyl Violet, respectively. The inflammatory response was assessed by quantifying the expression/activity of matrix metalloproteinases (MMP), toll-like receptor (TLR)-4, high mobility group box (HMGB)-1, and autotaxin (ATX). In addition, B6 CX3CR1(gfp/+) mice combined with cryo-immunofluorescence were used to determine the acute, delayed, and lasting effects on myelination, microglia, and astrocytes. RESULTS: LPS administration led to acute body and brain weight loss as well as overt structural changes in the brain such as cerebellar hypoplasia, neuronal loss/shrinkage, and delayed myelination. The impaired myelination was associated with alterations in the proliferation and differentiation of NG2 progenitor cells early after LPS administration, rather than with excessive phagocytosis by CNS myeloid cells. In addition to disruptions in brain architecture, a robust inflammatory response to LPS was observed. Quantification of inflammatory biomarkers revealed decreased expression of ATX with concurrent increases in HMGB1, TLR-4, and MMP-9 expression levels. Acute astrogliosis (GFAP(+) cells) in the brain parenchyma and at the microvasculature interface together with parenchymal microgliosis (CX3CR1(+) cells) were also observed. These changes preceded the migration/proliferation of CX3CR1(+) cells around the vessels at later time points and the subsequent loss of GFAP(+) astrocytes. CONCLUSION: Collectively, our study has uncovered a complex innate inflammatory reaction and associated structural changes in the brains of neonatal mice challenged peripherally with LPS. These findings may explain some of the neurobehavioral abnormalities that develop following neonatal sepsis.

Changing the Mandibular Position in Rowing: A Brief Report of a World-Class Rower.

We investigated the acute biophysical responses of changing the mandibular position during a rowing incremental protocol. A World-class 37-year-old male rower performed two 7 × 3 min ergometer rowing trials, once with no intraoral splint (control) and the other with a mandibular forward repositioning splint (splint condition). Ventilatory, kinematics and body electromyography were evaluated and compared between trials (paired samples t-test, p ≤ 0.05). Under the splint condition, oxygen uptake was lower, particularly at higher exercise intensities (67.3 ± 2.3 vs. 70.9 ± 1.5 mL·kg-1·min-1), and ventilation increased during specific rowing protocol steps (1st-4th and 6th). Wearing the splint condition led to changes in rowing technique, including a slower rowing frequency ([18-30] vs. [19-32] cycles·min-1) and a longer propulsive movement ([1.58-1.52] vs. [1.56-1.50] m) than the control condition. The splint condition also had a faster propulsive phase and a prolonged recovery period than the control condition. The splint reduced peak and mean upper body muscle activation, contrasting with an increase in lower body muscle activity, and generated an energetic benefit by reducing exercise cost and increasing rowing economy compared to the control condition. Changing the mandibular position benefited a World-class rower, supporting the potential of wearing an intraoral splint in high-level sports, particularly in rowing.

Tricellulin expression in brain endothelial and neural cells.

Tricellulin is a tight junction (TJ) protein, which is not only concentrated at tricellular contacts but also present at bicellular contacts between epithelial tissues. We scrutinized the brain for tricellulin expression in endothelial and neural cells by using real-time polymerase chain reaction, Western blot and immunohistochemical and immunocytochemical analysis of cultured brain cells and paraffin sections of brain. Tricellulin mRNA was detected in primary cultures and in a cell line of human brain microvascular endothelial cells. Protein expression was confirmed by Western blot and immunofluorescence analysis, which further highlighted the localization of tricellulin in the cell membrane at tricellular and along bicellular contacts, and in the nucleus and perinuclear region. Compared with the well-studied TJ protein, zonula occludens-1, tricellulin expression was less marked at the cell membrane but more evident in the nuclear and perinuclear regions. The presence of tricellulin in cultured endothelial cells was corroborated by immunohistochemical and immunofluorescence staining in brain blood vessels, where it was colocalized with another TJ protein, claudin-5. Tricellulin mRNA was detected in neurons and astrocytes, whereas protein expression was observed in astrocytes but not in neurons, as shown by immunofluorescence analysis. This study reveals the presence and subcellular distribution of tricellulin in brain endothelial cells, both in vitro and in situ and its colocalization with other relevant TJ proteins. Moreover, it demonstrates the expression of the protein in astrocytes opening new avenues for future research to establish the biological significance of tricellulin expression in glial cells.

Cardioneuroablation for severe neurocardiogenic syncope.

INTRODUCTION AND OBJECTIVES: Cardioneuroablation (CNA), a technique based on radiofrequency ablation of cardiac vagal ganglia, was developed to treat recurrent vasovagal syncope (VVS) with a predominant cardioinhibitory component, as an alternative to pacemaker implantation. The aim of our study was to evaluate the safety and success rate of CNA guided by extracardiac vagal stimulation in patients with highly symptomatic cardioinhibitory VVS. METHODS: Prospective study of patients who underwent anatomically guided CNA at two cardiology centers. All patients had a history of recurrent syncope with a predominant cardioinhibitory component and refractory to conventional measures. Acute success was determined by the absence or significant reduction of cardiac parasympathetic response to extracardiac vagal stimulation. The primary endpoint was the recurrence of syncope during follow-up. RESULTS: In total, 19 patients (13 males; mean age 37.8±12.9 years) were included. Ablation was acutely successful in all patients. One patient had a convulsive episode after the procedure, which was deemed unrelated to the ablation, requiring admission to intensive care but without sequelae. No other complications occurred. At a mean follow-up of 21.0±13.2 months (range 3-42 months), 17 patients remained free of syncope. The remaining two patients had recurrence of syncope and, despite undergoing a new ablation procedure, required pacemaker implantation during follow-up. CONCLUSION: Cardioneuroablation, confirmed by extracardiac vagal stimulation, appears to be an effective and safe treatment option for highly symptomatic patients with refractory VVS with a predominant cardioinhibitory component, providing a new potential approach as an alternative to pacemaker implantation.

Physical Fitness Profile of High-Level Female Portuguese Handball Players.

We characterized the physical and physiological profiles of high-level female Portuguese handball players and examined the relationships between their anthropometric characteristics, general motor performance and cardiopulmonary fitness. Twenty-four high-level female handball players with an average age of 23.6 ± 5.5 years, height of 173.6 ± 5.1 cm and body mass of 72.6 ± 9.1 kg volunteered to participate. A Pearson correlation test was used to assess the relationship between variables. Direct relationships were observed between the players' height and arm span (r = 0.741), as well as between their squat jump and countermovement jump performances with regard to body mass (r = 0.448 and 0.496, respectively). The 9 m jump shot has a large relationship with the 7 m standing throw (r = 0.786) and between left hand dynamometry and body mass index (r = 0.595). The 30 m sprint has a relationship with the 7 m standing throw (r = -0.526) and the 9 m jump throw (r = -0.551). Oxygen uptake has a relationship with the players' height (r = -0.482) and time limit (r = 0.513), while the fitness index has a relation to the players' height (r = -0.488) and arm span (r = -0.422). Our results should be considered when using physical testing to plan optimal physical training regimens in elite team handball.

The brain-fat connection.

Type 2 innate lymphoid cells shape metabolism through a brain-body circuit.

Effects of Wearing a 50% Lower Jaw Advancement Splint on Biophysical and Perceptual Responses at Low to Severe Running Intensities.

Acute ergogenic effects of wearing occlusal splints have been reported for aerobic and anaerobic exercises, but the literature centered on performance improvement by using jaw repositioning splints is scarce. We aimed to analyze the effect of wearing a 50% lower jaw advancement splint on biophysical and perceptual responses at low to severe running intensities. Sixteen middle- and long-distance runners performed twice a 7 × 800 m intermittent running protocol (with 1 km·h-1 increments and 30 s rest periods) in an outdoor track field using two lower intraoral splints (a placebo and a lower jaw advancer). These devices were custom manufactured for each participant and a randomized and repeated measure design was used to compare conditions. No differences between placebo and lower jaw advancer were found (e.g., 52.1 ± 9.9 vs. 53.9 ± 10.7 mL·kg-1·min-1 of oxygen uptake, 3.30 ± 0.44 vs. 3.29 ± 0.43 m of stride length and 16 ± 3 vs. 16 ± 2 Borg scores), but small effects were sometimes observed (e.g., 109.2 ± 22.5 vs. 112.7 ± 25.2 L·min-1 of ventilation, ES = -0.42). Therefore, this jaw advancement splint had no substantial ergogenic effect on biophysical and perceptual responses when running at different intensities.

Case Study: A Jaw-Protruding Dental Splint Improves Running Physiology and Kinematics.

Wearing an intraoral jaw-protruding splint could enhance respiratory function in clinical settings and eventually exercise performance. PURPOSE: The authors studied the acute effect of wearing a lower-jaw-forwarding splint at different protruding percentages (30% and 50%) across a wide range of running exercise intensities. METHODS: A case study was undertaken with a highly trained and experienced 27-year-old female triathlete. She performed the same incremental intermittent treadmill running protocol on 3 occasions wearing 3 different intraoral devices (30% and 50% maximum range and a control device) to assess running physiological and kinematic variables. RESULTS: Both the 30% and 50% protruding splints decreased oxygen uptake and carbon dioxide production (by 4%-12% and 1%-10%, respectively) and increased ventilation and respiratory frequency (by 7%-12% and 5%-16%, respectively) along the studied running intensities. Exercise energy expenditure (approximately 1%-14%) and cost (7.8, 7.4, and 8.0 J·kg-1·m-1 for 30%, 50%, and placebo devices, respectively) were also decreased when using the jaw-protruding splints. The triathlete's lower limbs' running pattern changed by wearing the forwarding splints, decreasing the contact time and stride length by approximately 4% and increasing the stride rate by approximately 4%. CONCLUSIONS: Wearing a jaw-protruding splint can have a positive biophysical effect on running-performance-related parameters.