Comparison of greenhouse gas emissions from sheep measured using both respiration and portable accumulation chambers.

Methane (CH4) is a potent gas produced by ruminants, and new measurement techniques are required to generate large datasets suitable for genetic analysis. One such technique are portable accumulation chambers (PAC), a short-term sampling method. The objectives of the current study were to explore the relationship between CH4 and carbon dioxide (CO2) output measured using both PAC and respiration chambers (RC) in growing lambs, and separately investigate the relationship among CH4, CO2 and measured ad libitum DM intake (DMI). Methane, CO2 and DMI were measured on 30 Suffolk and 30 Texel ewe lambs (age 253 ± 12 days) using the RC and PAC sequentially. The experiment was conducted over a 14-day period, with DMI measured from days 1 to 14; measurements in RC were conducted from days 10 to 12, while measurements in PAC were taken twice, the day immediately prior to the lambs entering the RC (day 9; PAC Pre-RC) and on the day lambs exited the RC (day 13; PAC Post-RC). Greater CH4 and CO2 output was measured in the RC than in the PAC (P < 0.01); similarly mean CH4 yield was greater when measured in the RC (15.39 ± 0.452 g CH4/kg DMI) compared to PAC (8.01 ± 0.767 g CH4/kg DMI). A moderate correlation of 0.37 was found between CH4 output measured in PAC Pre-RC and the RC, the corresponding regression coefficient of CH4 output measured in the RC regressed on CH4 output measured in PAC Pre-RC was close to unity (0.74; SE 0.224). The variance of CH4 and CO2 output within the measurement technique did not differ from each other (P > 0.05). Moderate to strong correlations were found between CH4 and CO2 per kg of live weight and CH4 and CO2 yield. Results from this study highlight the suitability of PAC as a ranking tool to rank animals based on their gaseous output when compared to the RC. However, repeated measurements separated by several days may be beneficial if precise rankings are required. Given the close to unity regression coefficient of CH4 output measured in the RC regressed on CH4 output measured in PAC Pre-RC suggests that PAC could also be potentially used to estimate absolute CH4 output; however, further research is required to substantiate this claim. When DMI is unknown, CH4 and CO2 per kg of live weight are a suitable alternative to the measurement of CH4 and CO2 yield.

Machine learning to improve the interpretation of intercalating dye-based quantitative PCR results.

This study aimed to evaluate the contribution of Machine Learning (ML) approach in the interpretation of intercalating dye-based quantitative PCR (IDqPCR) signals applied to the diagnosis of mucormycosis. The ML-based classification approach was applied to 734 results of IDqPCR categorized as positive (n = 74) or negative (n = 660) for mucormycosis after combining "visual reading" of the amplification and denaturation curves with clinical, radiological and microbiological criteria. Fourteen features were calculated to characterize the curves and injected in several pipelines including four ML-algorithms. An initial subset (n = 345) was used for the conception of classifiers. The classifier predictions were combined with majority voting to estimate performances of 48 meta-classifiers on an external dataset (n = 389). The visual reading returned 57 (7.7%), 568 (77.4%) and 109 (14.8%) positive, negative and doubtful results respectively. The Kappa coefficients of all the meta-classifiers were greater than 0.83 for the classification of IDqPCR results on the external dataset. Among these meta-classifiers, 6 exhibited Kappa coefficients at 1. The proposed ML-based approach allows a rigorous interpretation of IDqPCR curves, making the diagnosis of mucormycosis available for non-specialists in molecular diagnosis. A free online application was developed to classify IDqPCR from the raw data of the thermal cycler output ( http://gepamy-sat.asso.st/ ).

Effect of rumen fluke on feed digestibility and methane emissions in sheep.

Thirty-six ewes aged 18 months were assigned to one of three groups (n = 12) on the basis of faecal egg count (FEC) for rumen fluke; C: control (FEC = 0-5 epg), T: affected (FEC ≥ 6 epg) and treated, NT: affected (FEC ≥ 6 epg) and not treated. T ewes were treated with oxyclozanide 14 days prior to the trial commencing. Ewes were fed grass silage ad libitum. Digestibility crates and respiration chambers were used to measure feed digestibility and methane production. Dry matter intake (DMI), feed digestibility and CH4/DMI did not differ (P > 0.05) between treatments. However, CH4/live weight (LW) was significantly greater (P < 0.001) for NT ewes, while that of C and T ewes were similar. This study indicates that a high rumen fluke burden can increase methane emissions but only when expressed on a body weight basis (per kg LW). As the link between rumen fluke infection and methane production has not previously been investigated within the literature, these findings demonstrate the need for further research to better understand these relationships.

Drug resistance in leprosy: An update following 70years of chemotherapy.

Leprosy is one of the oldest infectious diseases, reported for more than 2000years. Leprosy elimination goal as a public health problem set by the World Health Organization, aiming for a global prevalence rate<1 patient in a population of 10,000, was achieved in 2000 mainly thanks to the worldwide use of leprosy drugs starting in the 1980s and their access at no cost for patients since 1995. However, around 200,000 new cases are still reported each year, particularly in India, Brazil, and Indonesia. As with other bacteria of medical interest, antimicrobial resistance is observed in Mycobacterium leprae strains in several parts of the world, despite multidrug therapy being the recommended standard leprosy treatment to avoid resistance selection since 1982. Therefore, identifying and monitoring resistance is necessary. We provide an overview of the historical facts that led to the current drug resistance situation, the antibiotics effective against M. leprae, their mechanisms of action and resistance, and resistance detection methods. We also discuss therapeutic management of the resistant cases, new genes with potential roles in drug resistance and bacterial adaptation, new drugs under investigation, and the risk for resistance selection with the chemoprophylaxis measures.

Dual nature of magnetic nanoparticle dispersions enables control over short-range attraction and long-range repulsion interactions.

Competition between attractive and repulsive interactions drives the formation of complex phases in colloidal suspensions. A major experimental challenge lies in decoupling independent roles of attractive and repulsive forces in governing the equilibrium morphology and long-range spatial distribution of assemblies. Here, we uncover the 'dual nature' of magnetic nanoparticle dispersions, particulate and continuous, enabling control of the short-range attraction and long-range repulsion (SALR) between suspended microparticles. We show that non-magnetic microparticles suspended in an aqueous magnetic nanoparticle dispersion simultaneously experience a short-range depletion attraction due to the particulate nature of the fluid in competition with an in situ tunable long-range magnetic dipolar repulsion attributed to the continuous nature of the fluid. The study presents an experimental platform for achieving in situ control over SALR between colloids leading to the formation of reconfigurable structures of unusual morphologies, which are not obtained using external fields or depletion interactions alone.

Drug resistance in leprosy: an update following 70 years of chemotherapy

Leprosy is one of the oldest infectious diseases, reported for more than 2000 years. Leprosy elimination goal as a public health problem set by the World Health Organization, aiming for a global prevalence rate < 1 patient in a population of 10,000, was achieved in 2000 mainly thanks to the worldwide use of leprosy drugs starting in the 1980s and their access at no cost for patients since 1995. However, around 200,000 new cases are still reported each year, particularly in India, Brazil, and Indonesia. As with other bacteria of medical interest, antimicrobial resistance is observed in Mycobacterium leprae strains in several parts of the world, despite multidrug therapy being the recommended standard leprosy treatment to avoid resistance selection since 1982. Therefore, identifying and monitoring resistance is necessary. We provide an overview of the historical facts that led to the current drug resistance situation, the antibiotics effective against M. leprae, their mechanisms of action and resistance, and resistance detection methods. We also discuss therapeutic management of the resistant cases, new genes with potential roles in drug resistance and bacterial adaptation, new drugs under investigation, and the risk for resistance selection with the chemoprophylaxis measures.

Sampling strategy for bacteriological diagnosis of intrathoracic tuberculosis.

BACKGROUND: Pulmonary tuberculosis (TB) is the most frequent site of TB and the one leading its spread worldwide. Multiple specimens are commonly collected for TB diagnosis including those requiring invasive procedures. This study aimed to review the sampling strategy for the microbiological diagnosis of pulmonary TB. METHODS: A retrospective analysis of collected samples from September 1st 2014 to May 1st 2016 in the Bacteriology laboratory of Pitié-Salpêtrière Hospital (Paris, France) was performed. All the samples collected in patients aged over 18 years for the bacteriological diagnosis of pulmonary TB were included. RESULTS: A total of 6267 samples were collected in 2187 patients. One hundred and twenty-six patients (6%) had a culture confirmed pulmonary TB. Among them, multiple sputum collections were sufficient for TB diagnosis in 63.5%, gastric lavages permitted to avoid bronchoscopy in only 7.1%, and bronchoscopy was necessary in 29.4%. The culture positivity of sputa (8.6%) was higher than that of bronchial aspirations (3.1%), bronchiolo-alveolar lavages (BAL) (2.3%) or gastric lavages (4.8%) (P<0.001). From its 70.0% theoretical PPV value, the 46.1% selection in bronchial aspirations allocated to molecular test increased PPV up to 88.9%. CONCLUSIONS: Based on our data, we suggest to collect sputum consistently. If smear negative a bronchoscopy should be performed and molecular diagnosis be performed on a subset of bronchial aspirations based on expertise of the bronchoscopist.

Comparison of polysaccharide glycoconjugates as candidate vaccines to combat Clostridiodes (Clostridium) difficile.

Two known Clostridiodes (Clostridium) difficile surface antigens, a lipoteichoic acid (LTA) and a polysaccharide (PS-II) were isolated and purified in order to prepare glycoconjugate vaccines to the carrier protein human serum albumin utilising a reductive amination strategy. Mice and rabbits were immunized with a prime and two boost strategy and the resulting sera were examined for their ability to recognise the purified homologous antigens and subsequently killed whole cells of C. difficile strains and other Clostridia species. Immunisation derived antisera from rabbits and mice, recognised all strains of C. difficile vegetative cells examined, with generally similar titers from animals that received the LTA or the PS-II conjugates. Sera raised to the LTA conjugates were able to recognise other Clostridia species C. butyricum, C. bifermentans and C. subterminale whereas sera raised to the PS-II conjugates were not. These LTA and PS-II sera recognised live cells in an immunofluorescence assay and were also able to recognise the spore form of the bacterium. This study has confirmed that the LTA and PS-II polysaccharides are both highly conserved surface polymers of C. difficile that are easily accessible to the immune system and as such may have potential as vaccine antigens or as targets for therapeutics to combat C. difficile infection.

First evaluation of the automated-multiplex-PCR Unyvero ITI G2 cartridge for rapid diagnosis of osteo-articular infections.

OBJECTIVE: Conventional microbiological methods (CMM), including long-term culture, for the diagnosis of osteo-articular infections (OAI) fail in at least 5% of all cases. Only one IOA dedicated molecular method has been commercialized, and only the first version of this kit has been studied. The aim of this work was to evaluate the concordance between test results obtained with the second version of the Unyvero ITI G2 cartridge (Curetis) and CMM. The cartridge, combining one-step automated lysis/DNA extraction with multiplex PCR and amplicon detection by array hybridization, allows for the detection of 102 prevalent pathogens and their antibiotic resistance markers directly in clinical specimens (liquid [n=8] or solid [n=32]). MATERIAL AND METHODS: Frozen samples from 40 patients who underwent orthopedic surgery at Pitié-Salpêtrière hospital were tested retrospectively with the cartridge: 5 were culture-negative, 25 revealed monomicrobial and 10 polymicrobial OAI. The 2 main surgical sites were hip (22.5%) and knee (17.5%). RESULTS: Extraction, amplification and hybridization reactions were completed in 28 of the 40 cases, failed in all cartridge chambers in 6 cases, and in 1 or 2 chambers in an additional 6 cases. Overall sensitivity and specificity for microorganism identification were estimated at 67.6% and 98.2%, when complete and partial failures were excluded. CONCLUSIONS: These results show that the performances of the second version of the Unyvero ITI G2 cartridge should be further enhanced before considering avoiding conventional microbiological methods.

[Cervicofacial nontuberculous mycobacteria in children: Clinical, microbiological and therapeutic features. A retrospective study and literature review]. / Adénites cervico-faciales à mycobactéries atypiques de l'enfant : caractéristiques cliniques, microbiologiques et thérapeutiques. Étude rétrospective et revue de la littérature.

BACKGROUND: Nontuberculous mycobacteria (NTM) is a common cause of lymphadenitis. A rise in incidence has been reported. Our main aim was to describe the clinical features, microbiological aspects and treatment of the disease. METHODS: We conducted a retrospective, monocentric study between January 2008 and December 2017 (University Hospital of Nantes). INCLUSION CRITERIA: age<18 years, 1 positive lymph node specimen with identification of the species in culture, head-and-neck localization. RESULTS: Forty-nine patients were enrolled from 2008 to 2017. Median age was 28 months (range: 6-141 months). Median time to confirmation of diagnosis was 2.1 months (range: 0.7-6 months). The sites encountered were mandibular (45%), cervical (33%), and parotid (16%). The main clinical signs were a tender nodule (70%), purplish nodule (59%) or painless nodule (83%), without fever (88%). The species identified were: Mycobacterium avium (n=26), M. lentiflavum (n=13), M. intracellulare (n=7), M. malmoense (n=2) and M. scrofulaceum (n=1). Antibiotic treatment was frequent (77% of cases). DISCUSSION: This study is the second largest French cohort of NTM lymphadenitis in children with microbiological confirmation. The most frequent presentation was a tender, purplish, and painless mandibular nodule. The predominant species was M. avium. M. lentiflavum, which emerged during our study, does not figure in any European studies before 2014 but appears in the most recent studies. The effects of discontinuation of mandatory BCG immunization in France in NMT is not statistically demonstrable here due to lack of relevant data prior to 2007. CONCLUSION: A possible diagnosis of NTM lymphadenitis should not be overlooked in children presenting painless, purplish, cervicofacial tumefaction.

A single psychotomimetic dose of ketamine decreases thalamocortical spindles and delta oscillations in the sedated rat.

BACKGROUND: In patients with psychotic disorders, sleep spindles are reduced, supporting the hypothesis that the thalamus and glutamate receptors play a crucial etio-pathophysiological role, whose underlying mechanisms remain unknown. We hypothesized that a reduced function of NMDA receptors is involved in the spindle deficit observed in schizophrenia. METHODS: An electrophysiological multisite cell-to-network exploration was used to investigate, in pentobarbital-sedated rats, the effects of a single psychotomimetic dose of the NMDA glutamate receptor antagonist ketamine in the sensorimotor and associative/cognitive thalamocortical (TC) systems. RESULTS: Under the control condition, spontaneously-occurring spindles (intra-frequency: 10-16 waves/s) and delta-frequency (1-4 Hz) oscillations were recorded in the frontoparietal cortical EEG, in thalamic extracellular recordings, in dual juxtacellularly recorded GABAergic thalamic reticular nucleus (TRN) and glutamatergic TC neurons, and in intracellularly recorded TC neurons. The TRN cells rhythmically exhibited robust high-frequency bursts of action potentials (7 to 15 APs at 200-700 Hz). A single administration of low-dose ketamine fleetingly reduced TC spindles and delta oscillations, amplified ongoing gamma-(30-80 Hz) and higher-frequency oscillations, and switched the firing pattern of both TC and TRN neurons from a burst mode to a single AP mode. Furthermore, ketamine strengthened the gamma-frequency band TRN-TC connectivity. The antipsychotic clozapine consistently prevented the ketamine effects on spindles, delta- and gamma-/higher-frequency TC oscillations. CONCLUSION: The present findings support the hypothesis that NMDA receptor hypofunction is involved in the reduction in sleep spindles and delta oscillations. The ketamine-induced swift conversion of ongoing TC-TRN activities may have involved at least both the ascending reticular activating system and the corticothalamic pathway.

[Molecular diagnosis of tuberculosis]. / Place de la biologie moléculaire dans le diagnostic de la tuberculose.

Tuberculosis is caused by the M. tuberculosis complex. Its slow growth delays the bacteriological diagnosis based on phenotypic tests. Molecular biology has significantly reduced this delay, notably thanks to the deployment of the Xpert® MTB/RIF test (Cepheid), which detects the M. tuberculosis complex and rifampicin resistance in 2hours. Other tests detecting isoniazid and second-line antituberculous drugs resistance have been developed. However, the performances of molecular tests are significantly reduced if the acid-fast bacilli microscopy screening is negative. It is therefore crucial to limit their indication to strong clinical suspicions. Resistance detection tests only explore certain characterized positions; however, not all drug-resistance mutations are known. Moreover, the performances vary for different antituberculous drugs. The advent of genomic sequencing is promising. Its integration into routine workflow still needs to be evaluated and the data analysis remains to be standardized. The rise of molecular biology techniques has revolutionized the diagnosis of tuberculosis and drug resistance. However, they remain screening tests; results still have to be confirmed by phenotypic reference methods.

Effects of interactions between feeding practices, animal health and farm infrastructure on technical, economic and environmental performances of a pig-fattening unit.

European pig production faces economic and environmental challenges. Modelling can help farmers simulate and understand how changes in their management practices affect the efficiency of their production system. We developed an individual-based model of a pig-fattening unit that considers individual variability in performance among pigs, farmers' feeding practices and animal management and estimates environmental impacts (using life cycle assessment) and economic results of the unit. We previously demonstrated that this model provides reliable estimates of farm performance for different combinations of management practices, pig types and building characteristics. The objectives of this study were to quantify how interactions between feeding practices and animal management influence fattening unit results in healthy or impaired health conditions using the model. A virtual experiment was designed to evaluate effects of interactions between feeding practices, health status of the pig herd and infrastructure constraints on the technical performance, economic results and environmental impacts of the unit. The virtual experiment consisted of 96 scenarios, which combined chosen values of 6 input parameters of the model: batch interval (35 days and 7 days), use or non-use of a buffer room to manage the lightest pigs, feed rationing (ad libitum and restricted) and sequence plans (two-phase (2P), daily-phase (DP)), scale at which the feeding plan is applied (i.e. room, pen and individual) and health status of the pig herd (i.e. healthy v. impaired). Variance analysis was used to test effects of the factors in these 96 scenarios, and multivariate data analyses were used to classify the scenarios. Healthy populations obtained on average higher economic results (e.g. gross margin of 11.20 v. 1.50 €/pig) and lower environmental impacts (e.g. 2.24 v. 2.38 kg CO2-eq/kg pig live weight gain) than the population with impaired health. With 35 days batch interval and DP feeding, populations with impaired health reached gross margin similar to healthy populations with 2P ad libitum feeding and 7 days batch interval. Restricted, DP and individual feeding plans improved the economic and environmental performances of the unit for both health statuses. This study highlighted that health status of the pig herd is the main factor that affects technical, economic and environmental performances of a pig-fattening unit, and that adequate feeding strategies and animal management can compensate, to some extent, the effects of impaired health on environmental impacts but not on gross margin.

[Cor pulmonale]. / Cœur pulmonaire.

Cor pulmonale is a disease of the heart characterised by dilatation of the right ventricle and paradoxical movement of the interventricular septum. The diagnosis depends on echocardiography even if pulmonary artery catheterisation suggests it. It is secondary to pulmonary disease or a disorder of the pulmonary circulation. These two mechanisms, which are often connected, involve pulmonary hypertension as the origin of a systolic and diastolic overload of the right ventricle, which then leads to the alterations of its structure and performance. Acute cor pulmonale is usually secondary to an acute respiratory distress syndrome or to a pulmonary embolism but it can also be seen in primary lactic acidosis, a vaso-occlusive crisis in a patient with sickle cell anaemia, severe acute asthma, and entry of air or injected crushed tablets into the circulation. Chronic cor pulmonale is the terminal stage of pulmonary hypertension. Clinically these patients are dyspnoeic with signs of chronic right heart failure. They should have an echocardiogram confirming the cardiac involvement. Certain precipitating factors, such as infection of any origin, have been reported, leading to acute on chronic cor pulmonale that has a particularly high mortality.

Updating maintenance energy requirement for the current sheep flocks and the associated effect of nutritional and animal factors.

There is evidence indicating that using the current UK energy feeding system to ration the present sheep flocks may underestimate their nutrient requirements. The objective of the present study was to address this issue by developing updated maintenance energy requirements for the current sheep flocks and evaluating if these requirements were influenced by a range of dietary and animal factors. Data (n = 131) used were collated from five experiments with sheep (5 to 18 months old and 29.0 to 69.8 kg BW) undertaken at the Agri-Food and Biosciences Institute of the UK from 2013 to 2017. The trials were designed to evaluate the effects of dietary type, genotype, physiological stage and sex on nutrient utilization and energetic efficiencies. Energy intake and output data were measured in individual calorimeter chambers. Energy balance (Eg) was calculated as the difference between gross energy intake and a sum of fecal energy, urine energy, methane energy and heat production. Data were analysed using the restricted maximum likelihood analysis to develop the linear relationship between Eg or heat production and metabolizable energy (ME) intake, with the effects of a range of dietary and animal factors removed. The net energy (NEm) and ME (MEm) requirements for maintenance derived from the linear relationship between Eg and ME intake were 0.358 and 0.486 MJ/kg BW0.75, respectively, which are 40% to 53% higher than those recommended in energy feeding systems currently used to ration sheep in the USA and the UK. Further analysis of the current dataset revealed that concentrate supplement, sire type or physiological stage had no significant effect on the derived NEm values. However, female lambs had a significantly higher NEm (0.352 v. 0.306 or 0.288 MJ/kg BW0.75) or MEm (0.507 v. 0.441 or 0.415 MJ/kg BW0.75) than those for male or castrated lambs. The present results indicate that using present energy feeding systems in the UK developed over 40 years ago to ration the current sheep flocks could underestimate maintenance energy requirements. There is an urgent need to update these systems to reflect the higher metabolic rates of the current sheep flocks.

Multidisciplinary advisory teams to manage multidrug-resistant tuberculosis: the example of the French Consilium.

SETTING: The World Health Organization (WHO) recommends that multidrug-resistant tuberculosis (MDR-TB) treatment should be managed in collaboration with multidisciplinary advisory committees (consilia). A formal national Consilium has been established in France since 2005 to provide a centralised advisory service for clinicians managing MDR-TB and extensively drug-resistant (XDR-TB) cases.OBJECTIVE: Review the activity of the French TB Consilium since its establishment.DESIGN: Retrospective description and analysis of the activity of the French TB Consilium.RESULTS: Between 2005 and 2016, 786 TB cases or contacts of TB cases were presented at the French TB Consilium, including respectively 42% and 79% of all the MDR-TB and XDR-TB cases notified in France during this period. Treatment regimens including bedaquiline and/or delamanid were recommended for 42% of the cases presented at the French TB Consilium since 2009. Patients were more likely to be presented at the French TB Consilium if they were born in the WHO Europe Region, had XDR-TB, were diagnosed in the Paris region, or had resistance to additional drugs than those defining XDR-TB.CONCLUSION: The French TB Consilium helped supervise appropriate management of MDR/XDR-TB cases and facilitated implementation of new drugs for MDR/XDR-TB treatment.

Re-emergence of Corynebacterium diphtheriae.

BACKGROUND: Diphtheria is re-emerging in Europe. A total of 36 cases were reported in Europe in 2015 versus 53 cases between 2000 and 2009. PATIENTS: We report two cases of Corynebacterium diphtheriae infection in a French hospital in 2016: a cutaneous infection with negative toxin testing in a French traveller, and a respiratory diphtheria carriage with positive toxin testing in an Afghan refugee diagnosed with pulmonary tuberculosis. The vaccination history of the Afghan patient could not be retrieved.

Effects of a 6-Week Period of Polarized or Threshold Training on Performance and Fatigue in Elite Swimmers.

PURPOSE: To quantify the impact of a polarized distribution of training intensity on performance and fatigue in elite swimmers. METHODS: Twenty-two elite junior swimmers (12 males, age = 17 [3] y, and 10 females, age = 17 [3] y) participated in a crossover intervention study over 28 wk involving 2- × 6-wk training periods separated by 6 wk. Swimmers were randomly assigned to a training group for the first period: polarized (81% in zone 1, blood lactate concentration, [La]b ≤ 2 mmol·L-1; 4% in zone 2, 2 mmol·L-1 < [La]b ≤ 4 mmol·L-1; and 15% in zone 3, [La]b > 4 mmol·L-1) or threshold (65%/25%/10%). Before and after each period, they performed a 100-m maximal swimming test to determine performance, maximal [La]b, and oxygen consumption and an incremental swimming test to determine speed corresponding to [La]b = 4 mmol·L-1 (V4 mmol·L-1). Self-reported indices of well-being were collected with a daily questionnaire. RESULTS: Polarized training elicited small to moderately greater improvement than threshold training on 100-m performance (within-group change ± 90% confidence interval: 0.97% ± 1.02% vs 0.09% ± 0.94%, respectively) with less fatigue and better quality of recovery. There was no substantial gender effect. No clear differences were observed in physiological adaptations between groups. CONCLUSIONS: In elite junior swimmers, a 6-wk period of polarized training induced small improvements in 100-m time-trial performance and, in combination with less perceived fatigue, forms a viable option for coaches preparing such cohorts of swimmers for competition.