Turbulence Unsteadiness Drives Extreme Clustering.

We show that the unsteadiness of turbulence has a drastic effect on turbulence parameters and in particle cluster formation. To this end we use direct numerical simulations of particle laden flows with a steady forcing that generates an unsteady large-scale flow. Particle clustering correlates with the instantaneous Taylor-based flow Reynolds number, and anticorrelates with its instantaneous turbulent energy dissipation constant. A dimensional argument for these correlations is presented. In natural flows, unsteadiness can result in extreme particle clustering, which is stronger than the clustering expected from averaged inertial turbulence effects.

Efficacy of antimicrobial and nutraceutical treatment for canine acute diarrhoea: A systematic review and meta-analysis for European Network for Optimization of Antimicrobial Therapy (ENOVAT) guidelines.

Systemic antimicrobial treatments are commonly prescribed to dogs with acute diarrhoea, while nutraceuticals (prebiotics, probiotics, and synbiotics) are frequently administered as an alternative treatment. The aim of this systematic review and meta-analysis was to assess the effectiveness of antimicrobials and nutraceutical preparations for treatment of canine acute diarrhoea (CAD). The results of this study will be used to create evidence-based treatment guidelines. PICOs (population, intervention, comparator, and outcome) were generated by a multidisciplinary expert panel taking into account opinions from stakeholders (general practitioners and dog owners). The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to evaluate the certainty of the evidence. The systematic search yielded six randomised controlled trials (RCT) for antimicrobial treatment and six RCTs for nutraceutical treatment meeting the eligibility criteria. Categories of disease severity (mild, moderate, and severe) were created based on the presence of systemic signs and response to fluid therapy. Outcomes included duration of diarrhoea, duration of hospitalization, progression of disease, mortality, and adverse effects. High certainty evidence showed that antimicrobial treatment did not have a clinically relevant effect on any outcome in dogs with mild or moderate disease. Certainty of evidence was low for dogs with severe disease. Nutraceutical products did not show a clinically significant effect in shortening the duration of diarrhoea (based on very low to moderate certainty evidence). No adverse effects were reported in any of the studies.

Enhancing physicians' radiology diagnostics of COVID-19's effects on lung health by leveraging artificial intelligence.

Introduction: This study aimed to develop an individualized artificial intelligence model to help radiologists assess the severity of COVID-19's effects on patients' lung health. Methods: Data was collected from medical records of 1103 patients diagnosed with COVID-19 using RT- qPCR between March and June 2020, in Hospital Madrid-Group (HM-Group, Spain). By using Convolutional Neural Networks, we determine the effects of COVID-19 in terms of lung area, opacities, and pulmonary air density. We then combine these variables with age and sex in a regression model to assess the severity of these conditions with respect to fatality risk (death or ICU). Results: Our model can predict high effect with an AUC of 0.736. Finally, we compare the performance of the model with respect to six physicians' diagnosis, and test for improvements on physicians' performance when using the prediction algorithm. Discussion: We find that the algorithm outperforms physicians (39.5% less error), and thus, physicians can significantly benefit from the information provided by the algorithm by reducing error by almost 30%.

Physiological demands and motion analysis of elite foil fencing.

The aim of this study was to determine the physiological demands and motion analysis of a simulated fencing competition. Eighteen fencers each completed 5 'poule' (5 touches) and 'direct elimination (DE)' (15 touches) fights. Expired gases were measured during 1 poule and DE fight. Heart rate (HR), ratings of perceived exertion (RPE) and movement data were recorded throughout all fights. Motion analysis was undertaken using the software LINCE PLUS. Differences between poule and DE fights were determined by either a paired t-test or a one-way repeated measures ANOVA. HR and RPE were significantly greater during DE compared to poule (170 ±10 vs 163 ±13 beats·min-1; P<0.05). A greater distance was covered during a DE fight compared to a poule fight (459.9 ± 117.7 m vs 162.6 ± 74.2 m; P<0.05). The average values of [Formula: see text] were 42.5 ±5.6 ml·kg-1·min-1 in men and 34.4 ±3.2 ml·kg-1·min-1 in women. Work-to-rest ratios reduced during the DE fights along with a lower average speed and increased max speed (11.7 ± 2.8 km∙h-1 vs 9.6 ± 1.6 km∙h-1; P<0.05). In conclusion, there is an increased physiological demand during a DE fight accompanied by a reduction in average speed and decreased work-to-rest ratio.

Maximum aerobic speed, maximum oxygen consumption, and running spatiotemporal parameters during an incremental test among middle- and long-distance runners and endurance non-running athletes.

Background: Maximal aerobic speed (MAS) is a useful parameter to assess aerobic capacity and estimate training intensity in middle- and long-distance runners. However, whether middle- and long-distance runners reach different levels of MAS compared to other endurance athletes with similar V̇O2max has not been previously studied. Therefore, we aimed to compare V̇O2max, MAS and spatiotemporal parameters between sub-elite middle- and long-distance runners (n = 6) and endurance non-runners (n = 6). In addition, we aimed to compare the maximal blood lactate concentration [BLa] experienced by participants after conducting these tests. Methods: Telemetric portable respiratory gas analysis, contact and flight time, and stride length and rate were measured using a 5-m contact platform during an incremental test at a synthetic athletics track. V̇O2, heart rate, respiratory quotient values in any 15 s average period during the test were measured. [BLa] was analyzed after the test . Running spatiotemporal parameters were recorded at the last two steps of each 400 m lap. A coefficient of variation (%CV) was calculated for each spatiotemporal variable in each participant from 8 km h-1 onwards. Results: Whereas runners reported faster MAS (21.0 vs. 18.2 km h-1) than non-runners (p  =  0.0001, ES = 3.0), no differences were found for V̇O2max and maximum blood lactate concentration during the running tests (p > 0.05). While significant increases in flight time and stride length and frequency (p < 0.001, 0.52 ≤ η p 2 ≤ 0.8) were observed throughout the tests, decreases in contact time (p < 0.001, η p 2 = 0 . 9 ) were reported. Runners displayed a greater %CV (p = 0.015) in stride length than non-runners. We conclude that middle- and long-distance runners can achieve a faster MAS compared to non-running endurance athletes despite exhibiting a similar V̇O2max. This superior performance may be associated to a greater mechanical efficiency. Overall, runners displayed a greater ability to modify stride length to achieve fast speeds, which may be related to a more mechanically efficient pattern of spatiotemporal parameters than non-runners.

Role of Innate and Adaptive Cytokines in the Survival of COVID-19 Patients.

SARS-CoV-2 is a new coronavirus characterized by a high infection and transmission capacity. A significant number of patients develop inadequate immune responses that produce massive releases of cytokines that compromise their survival. Soluble factors are clinically and pathologically relevant in COVID-19 survival but remain only partially characterized. The objective of this work was to simultaneously study 62 circulating soluble factors, including innate and adaptive cytokines and their soluble receptors, chemokines and growth and wound-healing/repair factors, in severe COVID-19 patients who survived compared to those with fatal outcomes. Serum samples were obtained from 286 COVID-19 patients and 40 healthy controls. The 62 circulating soluble factors were quantified using a Luminex Milliplex assay. Results. The patients who survived had decreased levels of the following 30 soluble factors of the 62 studied compared to those with fatal outcomes, therefore, these decreases were observed for cytokines and receptors predominantly produced by the innate immune system-IL-1α, IL-1α, IL-18, IL-15, IL-12p40, IL-6, IL-27, IL-1Ra, IL-1RI, IL-1RII, TNFα, TGFα, IL-10, sRAGE, sTNF-RI and sTNF-RII-for the chemokines IL-8, IP-10, MCP-1, MCP-3, MIG and fractalkine; for the growth factors M-CSF and the soluble receptor sIL2Ra; for the cytokines involved in the adaptive immune system IFNγ, IL-17 and sIL-4R; and for the wound-repair factor FGF2. On the other hand, the patients who survived had elevated levels of the soluble factors TNFß, sCD40L, MDC, RANTES, G-CSF, GM-CSF, EGF, PDGFAA and PDGFABBB compared to those who died. Conclusions. Increases in the circulating levels of the sCD40L cytokine; MDC and RANTES chemokines; the G-CSF and GM-CSF growth factors, EGF, PDGFAA and PDGFABBB; and tissue-repair factors are strongly associated with survival. By contrast, large increases in IL-15, IL-6, IL-18, IL-27 and IL-10; the sIL-1RI, sIL1RII and sTNF-RII receptors; the MCP3, IL-8, MIG and IP-10 chemokines; the M-CSF and sIL-2Ra growth factors; and the wound-healing factor FGF2 favor fatal outcomes of the disease.

Impact of the Innate Inflammatory Response on ICU Admission and Death in Hospitalized Patients with COVID-19.

OBJECTIVE: To describe the capacity of a broad spectrum of cytokines and growth factors to predict ICU admission and/or death in patients with severe COVID-19. DESIGN: An observational, analytical, retrospective cohort study with longitudinal follow-up. SETTING: Hospital Universitario Príncipe de Asturias (HUPA). PARTICIPANTS: 287 patients diagnosed with COVID-19 admitted to our hospital from 24 March to 8 May 2020, followed until 31 August 2020. MAIN OUTCOME MEASURES: Profiles of immune response (IR) mediators were determined using the Luminex Multiplex technique in hospitalized patients within six days of admission by examining serum levels of 62 soluble molecules classified into the three groups: adaptive IR-related cytokines (n = 19), innate inflammatory IR-related cytokines (n = 27), and growth factors (n = 16). RESULTS: A statistically robust link with ICU admission and/or death was detected for increased serum levels of interleukin (IL)-6, IL-15, soluble (s) RAGE, IP10, MCP3, sIL1RII, IL-8, GCSF and MCSF and IL-10. The greatest prognostic value was observed for the marker combination IL-10, IL-6 and GCSF. CONCLUSIONS: When severe COVID-19 progresses to ICU admission and/or death there is a marked increase in serum levels of several cytokines and chemokines, mainly related to the patient's inflammatory IR. Serum levels of IL-10, IL-6 and GCSF were most prognostic of the outcome measure.

The Effect of Health and Economic Costs on Governments' Policy Responses to COVID-19 Crisis under Incomplete Information.

The COVID-19 pandemic has become an unprecedented health, economic, and social crisis. The present study has built a theoretical model and used it to develop an empirical strategy, analyzing the drivers of policy-response agility during the outbreak. Our empirical results show that national policy responses were delayed, both by government expectations of the healthcare system capacity and by expectations that any hard measures used to manage the crisis would entail severe economic costs. With decision-making based on incomplete information, the agility of national policy responses increased as knowledge increased and uncertainty decreased in relation to the epidemic's evolution and the policy responses of other countries.

Cirugía en directo: estudio de seguridad tras 17 ediciones de cirugía retroperitoneoscópica / Live surgery: Safety study after 17 editions of retroperitoneoscopic surgery

Introducción: La cirugía en directo se ha convertido en una excelente herramienta para la formación médica. Pese a ello, existe controversia sobre la seguridad de los pacientes que participan.ObjetivoAnalizar los resultados de las cirugías en directo realizadas en 17 cursos consecutivos de retroperitoneoscopia organizados en nuestro centro, en los cuales se intervinieron nefrectomías parciales (NP), nefrectomías radicales (NR) y nefroureterectomías (NU).Material y métodosRevisión realizada desde enero del 2010 a octubre del 2017 de todas las cirugías en directo ejecutadas por un equipo quirúrgico experto en los cursos de retroperitoneoscopia, comparadas con un grupo control de cirugías llevadas a cabo de forma ordinaria y que fue emparejado en relación con la edad, el índice de masa corporal y las comorbilidades (1:1 por cada NR y 1:2 por cada NP y NU).ResultadosSe analizaron 21 cirugías en directo (ocho NP, siete NR y seis NU) con una mediana de seguimiento global de 38 meses. No se observaron diferencias significativas entre las cirugías de los cursos y los controles en cuanto a las variables perioperatorias (tiempo quirúrgico, sangrado operatorio y complicaciones intraoperatorias) ni en las complicaciones postoperatorias y los días de ingreso. Tampoco encontramos diferencias en la tasa de recidiva en los tres grupos (NP: 0% vs. 6,3%, p = 0,47, NU: 33,3% vs. 66,7%, p = 0,180, NR: 0% vs. 28,6%, p = 0,127).ConclusiónLa cirugía en directo realizada, por cirujanos expertos, en un ambiente adecuado y con pacientes idóneos no representa un riesgo añadido de complicaciones para estos y permite mantener los mismos resultados oncológicos. (AU)

Introduction: Live surgery has become an excellent tool for medical training. Despite this, there is controversy about the safety of the patients involved.ObjectiveTo analyze the results of live surgeries performed in 17 consecutive retroperitoneoscopy courses organized in our center. Procedures performed were partial nephrectomy (PN), radical nephrectomy (RN) and nephroureterectomy (NU).Material and methodsReview from January 2010 to October 2017 of all live surgeries carried out by an expert surgical team in the retroperitoneoscopy courses, compared with a control group of surgeries performed in standard conditions. A matching (1:1 for each RN and 1:2 for each PN and NU) according to age, body mass index and comorbidities was performed.ResultsTwenty-one live surgeries were analyzed (eight PN, seven RN and six NU) with a global median follow-up of 38 months. No significant differences were observed between both groups in terms of perioperative variables (operative time, operative bleeding and intraoperative complications) or of postoperative complications and length of hospital stay. Likewise, there were no differences between recurrence rates (PN: 0% vs. 6.3%, p = 0.47, NU: 33.3% vs. 66.7%, p = 0.180, RN: 0% vs. 28.6%, p = 0,127).ConclusionsLive surgery in the hands of expert surgeons in a suitable environment and with well-selected patients does not increase the risk of complications and allows maintaining the same oncological outcomes. (AU)

Live surgery: Safety study after 17 editions of retroperitoneoscopic surgery. / Cirugía en directo: estudio de seguridad tras 17 ediciones de cirugía retroperitoneoscópica.

INTRODUCTION: Live surgery has become an excellent tool for medical training. Despite this, there is controversy about the safety of the patients involved. OBJECTIVE: To analyze the results of live surgeries performed in 17 consecutive retroperitoneoscopy courses organized in our center. Procedures performed were partial nephrectomy (PN), radical nephrectomy (RN) and nephroureterectomy (NU). MATERIAL AND METHODS: Review from January 2010 to October 2017 of all live surgeries carried out by an expert surgical team in the retroperitoneoscopy courses, compared with a control group of surgeries performed in standard conditions. A matching (1:1 for each RN and 1:2 for each PN and NU) according to age, body mass index and comorbidities was performed. RESULTS: Twenty-one live surgeries were analyzed (eight PN, seven RN and six NU) with a global median follow-up of 38 months. No significant differences were observed between both groups in terms of perioperative variables (operative time, operative bleeding and intraoperative complications) or of postoperative complications and length of hospital stay. Likewise, there were no differences between recurrence rates (PN: 0% vs. 6.3%, p = 0.47, NU: 33.3% vs. 66.7%, p = 0.180, RN: 0% vs. 28.6%, p = 0,127). CONCLUSIONS: Live surgery in the hands of expert surgeons in a suitable environment and with well-selected patients does not increase the risk of complications and allows maintaining the same oncological outcomes.

A Predictive Model and Risk Factors for Case Fatality of COVID-19.

This study aimed to create an individualized analysis model of the risk of intensive care unit (ICU) admission or death for coronavirus disease 2019 (COVID-19) patients as a tool for the rapid clinical management of hospitalized patients in order to achieve a resilience of medical resources. This is an observational, analytical, retrospective cohort study with longitudinal follow-up. Data were collected from the medical records of 3489 patients diagnosed with COVID-19 using RT-qPCR in the period of highest community transmission recorded in Europe to date: February-June 2020. The study was carried out in in two health areas of hospital care in the Madrid region: the central area of the Madrid capital (Hospitales de Madrid del Grupo HM Hospitales (CH-HM), n = 1931) and the metropolitan area of Madrid (Hospital Universitario Príncipe de Asturias (MH-HUPA) n = 1558). By using a regression model, we observed how the different patient variables had unequal importance. Among all the analyzed variables, basal oxygen saturation was found to have the highest relative importance with a value of 20.3%, followed by age (17.7%), lymphocyte/leukocyte ratio (14.4%), CRP value (12.5%), comorbidities (12.5%), and leukocyte count (8.9%). Three levels of risk of ICU/death were established: low-risk level (<5%), medium-risk level (5-20%), and high-risk level (>20%). At the high-risk level, 13% needed ICU admission, 29% died, and 37% had an ICU-death outcome. This predictive model allowed us to individualize the risk for worse outcome for hospitalized patients affected by COVID-19.

Validity of Heart Rate-Based Models for Estimating Oxygen Uptake During Tennis Play.

Baiget, E, Iglesias, X, and Rodríguez, FA. Validity of heart rate-based models for estimating oxygen uptake during tennis play. J Strength Cond Res 34(11): 3208-3216, 2020-This study aimed to assess the validity of an on-court tennis test (specific endurance tennis test [SET-Test]) and 2 heart rate (HR)-based methods for estimating oxygen uptake (V[Combining Dot Above]O2) in competitive tennis players. Thirty-five male players performed a SET-Test to relate test duration (minutes) and V[Combining Dot Above]O2. Two weeks later, 16 players performed a simulated match play set where HR and V[Combining Dot Above]O2 (V[Combining Dot Above]O2-PLAY, criterion value) were measured and then compared with V[Combining Dot Above]O2 values predicted from the HR/V[Combining Dot Above]O2 linear regression equations derived from the SET-Test (pV[Combining Dot Above]O2-TEST) and from the one set match play (pV[Combining Dot Above]O2-PLAY). Test duration and V[Combining Dot Above]O2-TEST were strongly correlated (r = 0.821, p < 0.001, SEE = 5.6 ml·kg·min), indicating that SET-Test outcome is a somewhat good indicator of aerobic fitness in tennis players, likely to be useful for training purposes. pV[Combining Dot Above]O2-PLAY and V[Combining Dot Above]O2-PLAY (criterion value) were strongly correlated (r = 0.832, p < 0.001) and SEE was moderate (3.5 ml·kg·min = 11.5%). pV[Combining Dot Above]O2-TEST differed from the criterion (32.4 ± 10.7 vs. 30.8 ± 8.6 ml·kg·min, p < 0.001) and, although strongly correlated (r = 0.689, p < 0.001), an overestimation occurred (mean Δ = 1.6 ml·kg·min = 4.9%), yielding a high SEE (4.8 ml·kg·min = 15.6%). We conclude that (a) SET-Test performance is a valid and moderately accurate predictor of V[Combining Dot Above]O2; and (b) the individual HR-V[Combining Dot Above]O2 regression equation generated during tennis match play predicts V[Combining Dot Above]O2 with greater accuracy than the regression derived from the SET-Test.

Modeling chlordecone toxicokinetics data in growing pigs using a nonlinear mixed-effects approach.

The use of chlordecone (CLD), a chlorinated polycyclic pesticide used in the French West Indies banana fields between 1972 and 1993, resulted in a long-term pollution of agricultural areas. It has been observed that this persistent organic pollutant (POP) can transfer from contaminated soils to food chain. Indeed, CLD is considered almost fully absorbed after involuntary ingestion of contaminated soil by outdoor reared animals. The aim of this study was to model toxicokinetics (TKs) of CLD in growing pigs using both non-compartmental and nonlinear mixed-effects approaches (NLME). In this study, CLD dissolved in cremophor was intravenously administrated to 7 Creole growing pigs and 7 Large White growing pigs (1 mg kg-1 body weight). Blood samples were collected from time t = 0 to time t = 84 days. CLD concentrations in serum were measured by GCMS/MS. Data obtained were modeled using Monolix (2019R). Results demonstrated that a bicompartmental model best described CLD kinetics in serum. The influence of covariates (breed, initial weight and average daily gain) was simultaneously evaluated and showed that average daily gain is the main covariate explaining inter-individual TKs parameters variability. Body clearance was of 76.7 mL kg-1 d-1 and steady-state volume of distribution was of 6 L kg-1. This modeling approach constitutes the first application of NLME to study CLD TKs in farm animals and will be further used for rearing management practices in contaminated areas.

Physiological demands of standing and wheelchair fencing in able-bodied fencers.

BACKGROUND: The purpose of this study was to determine the cardiorespiratory demands of standing and wheelchair (seated) fencing in a group of able-bodied fencers during simulated competitive bouts. METHODS: Participants were ten male able-bodied fencers of regional level with previous training experience in wheelchair fencing. After a standardized warm-up, participants performed two series of simulated competitive épée bouts (5 and 15 touches) in a random order, either while standing or while sitting in a wheelchair. Expired gas was analyzed for oxygen consumption (V̇O2) and respiratory exchange ratio (RER) and heart rate were continually monitored. Energy expenditure (EE) was subsequently calculated. RESULTS: V̇O2, HR and EE peak responses were greater during standing than seated fencing (P<0.05). Mean V̇O2 during all ST bouts (5- and 15-touch) was 43% greater than in wheelchair fencing (44.2±7.8 vs. 25.1±5.4 mL/kg/min). Mean HR during the standing 5- and 15-touch bouts was 91±20% and 84±7%, respectively, of that recorded during the seated bouts. HR, V̇O2 and EE data also indicated that the 15-touch bouts were more physiologically demanding than the 5-touch bouts (P<0.01). The HR-V̇O2 relationship was similar between both fencing modes. The duration of the 5- and 15-touch bouts were shorter for the seated than the standing bouts (P<0.01). CONCLUSIONS: The physiological demands of wheelchair fencing are lower than those for standing fencing. Furthermore, the physiology of 5 versus 15-touch bouts, similar to those undertaken in fencing competition, also differs.

Dues efemèrides: 90 anys de Pediatria Catalana i centenari de la pandèmia de grip del 1918 / No disponible

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Bioelectrical impedance vector analysis (BIVA) in sport and exercise: Systematic review and future perspectives.

BACKGROUND: Bioelectrical impedance vector analysis (BIVA) is a general concept that includes all methodologies used in the analysis of the bioelectrical vector, whereas the "classic" BIVA is a patented methodology included among these methods of analysis. Once this was clarified, the systematic review of the literature provides a deeper insight into the scope and range of application of BIVA in sport and exercise. OBJECTIVE: The main goal of this work was to systematically review the sources on the applications of BIVA in sport and exercise and to examine its usefulness and suitability as a technique for the evaluation of body composition, hydration status, and other physiological and clinical relevant characteristics, ultimately to trace future perspectives in this growing area, including a proposal for a research agenda. METHODS: Systematic literature searches in PubMed, SPORTDiscus and Scopus databases up to July, 2017 were conducted on any empirical investigations using phase-sensitive bioimpedance instruments to perform BIVA within exercise and sport contexts. The search included healthy sedentary individuals, physically active subjects and athletes. RESULT: Nineteen eligible papers were included and classified as sixteen original articles and three scientific conference communications. Three studies analysed short-term variations in the hydration status evoked by exercise/training through whole-body measurements, eleven assessed whole-body body composition changes induced by long-term exercise, four compared athletic groups or populations using the whole-body assessment, and two analysed bioelectrical patterns of athletic injuries or muscle damage through localised bioimpedance measurements. CONCLUSIONS: BIVA is a relatively new technique that has potential in sport and exercise, especially for the assessment of soft-tissue injury. On the other hand, the current tolerance ellipses of "classic" BIVA are not a valid method to identify dehydration in individual athletes and a new approach is needed. "Specific" BIVA, a method which proposes a correction of bioelectrical values for body geometry, emerges as the key to overcome "classic" BIVA limitations regarding the body composition assessment. Further research establishing standardised testing procedures and investigating the relationship between physiology and the bioelectrical signal in sport and exercise is needed.

Blood lactate accumulation during competitive freediving and synchronized swimming.

A number of competitive water sports are performed while breath-holding (apnea). Such performances put large demands on the anaerobic system, but the study of lactate accumulation in apneic sports is limited. We therefore aimed to determine and compare the net lactate accumulation (NLA) during competition events in six disciplines of competitive freediving (FD) and three disciplines of synchronized swimming (SSW). The FD disciplines were: static apnea (STA; n = 14); dynamic apnea (DYN; n = 19); dynamic apnea no fins (DNF; n = 16); constant weight (CWT; n = 12); constant weight no fins (CNF; n = 8); free immersion (FIM; n =10). The SSW disciplines were solo (n = 21), duet (n = 31) and team (n = 34). Capillary blood lactate concentration was measured before and three minutes after competition performances, and apneic duration and performance variables were recorded. In all nine disciplines NLA was observed. The highest mean (SD) NLA (mmol·L-1) was found in CNF at 6.3 (2.2), followed by CWT at 5.9 (2.3) and SSW solo at 5 (1.9). STA showed the lowest NLA 0.7 (0.7) mmol·L-1 compared to all other disciplines (P ⟨ 0.001). The NLA recorded shows that sports involving apnea involve high levels of anaerobic activity. The highest NLA was related to both work done by large muscle groups and long apneic periods, suggesting that NLA is influenced by both the type of work and apnea duration, with lower NLA in SSW due to shorter apneic episodes with intermittent breathing.

Oxidative stress in elite athletes training at moderate altitude and at sea level.

Using a controlled parallel group longitudinal trial design, we investigated the effects of different training interventions on the prooxidant/antioxidant status of elite athletes: living and training at moderate altitude for 3 (Hi-Hi3) and 4 weeks (Hi-Hi), and for 4 weeks too, living high and training high and low (Hi-HiLo) and living and training at sea level (Lo-Lo). From 61 swimmers, 54 completed the study. Nitrites, carbonyls, and lipid peroxidation (LPO) levels were assessed in plasma. Enzymatic antioxidants glutathione peroxidase (GPx) and glutathione reductase (GRd), and non-enzymatic antioxidants total glutathione (GST), reduced glutathione (GSH) and oxidized glutathione (GSSG) were analysed in the erythrocyte fraction. At the end of the intervention, nitrites levels were similar in all altitude groups but higher than in the Lo-Lo controls (P = .02). Hi-HiLo had greater GPx activity than Hi-Hi and Hi-Hi3 during most of the intervention (P ≤ .001). GRd activity was higher in Lo-Lo than in Hi-Hi at the end of the training camp (P ≤ .001). All groups showed increased levels of LPO, except Lo-Lo, and carbonyls at the end of the study (P ≤ .001). Training at altitude for 3 or 4 weeks drives oxidative stress leading to cellular damage mainly by worsening the antioxidant capacities. The GSSG/GSH ratio appears to be related to perceived exertion and fatigue. The stronger antioxidant defence showed by the Hi-HiLo group suggests an inverse relationship between redox alterations and performance. Further studies are required to investigate the role of oxidative stress in acclimatization, performance, and health.

Dynamics of the Metabolic Response During a Competitive 100-m Freestyle in Elite Male Swimmers.

PURPOSE: To compare the dynamics of maximal oxygen uptake ([Formula: see text]), blood lactate ([La]b), total energy expenditure (Etot), and contributions of the aerobic (Eaer), alactic anaerobic (Ean,al), and lactic anaerobic (Ean,lac) metabolic energy pathways over 4 consecutive 25-m laps (L0-25, L25-50, etc) of a 100-m maximal freestyle swim. METHODS: Elite swimmers comprising 26 juniors (age = 16 [1] y) and 23 seniors (age = 24 [5] y) performed 100 m at maximal speed and then 3 trials (25, 50, and 75 m) at the same pace as that of the 100 m. [La]b was collected, and [Formula: see text] was measured 20 s postexercise. RESULTS: The estimated energetic contributions for the 100-m trial are presented as mean (SD): Eaer, 51% (8%); Ean,al, 18% (2%); Ean,lac, 31% (9%). [Formula: see text] increased from L0-25 to L25-50 (mean = 3.5 L·min-1; 90% confidence interval [CI], 3.4-3.7 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.3 L·min-1) and then stabilized in the 2nd 50 m (mean = 4.1 L·min-1; 90% CI, 3.9-4.3 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.4 L·min-1). Etot (juniors, 138 [18] kJ; seniors, 168 [26] kJ), Ean,al (juniors, 27 [3] kJ; seniors, 30 [3] kJ), and Ean,lac (juniors, 38 [12] kJ; seniors, 62 [24] kJ) were 11-58% higher in seniors. Faster swimmers (n = 26) had higher [Formula: see text], 90% CI 4.4-4.8 L·min-1 [Formula: see text] L·min-1, 90% CI 3.6-4.2 L·min-1), and Eaer power was associated with fast performances (P < .001). CONCLUSION: Faster swimmers were characterized by higher [Formula: see text] and less time to reach the highest [Formula: see text] at ∼50 m of the 100-m swim. Anaerobic qualities become more important with age.