Toxicity tests, bioaccumulation and residuality of pyrethroid insecticides commonly used to control conifer bark beetles in Mexico.

Effectiveness of pyrethroid insecticides against pests including bark beetles (Dendroctonus spp.) is well known, but little is known about their (a) residuality and persistence in forests after application to control an outbreak and (b) ability to bioaccumulate in insects, which could cause adverse effects on the trophic chains. The 24 h lethal toxicity, bioaccumulation factors, and lethal body burdens of the pyrethroid insecticides bifenthrin, deltamethrin, and cypermethrin were evaluated in the bark beetle Dendroctonus mexicanus. The residuality and persistence of the insecticide bifenthrin in the forest ecosystem (soil, water, and sediment) was also monitored after its application in a region infested by bark beetles. We determined whether contamination of soil, water, and sediments occurred near the sanitation site. For D. mexicanus, the most toxic insecticide for adults was bifenthrin for topical application (LC50 = 0.94 mg/L) and cypermethrin for bark application (LC50 = 5.04 mg/L). The insecticide that bioaccumulated the most in the insect body was deltamethrin (622.41 µg g-1 dw) and the insecticide that bioaccumulated the least amount was cypermethrin (183.09 µg g-1 dw). However, cypermethrin was the active substance that presented the lowest body burdens, and therefore required a lower dose to cause death of D. mexicanus adults. Our results demonstrate that prolonged presence of bifenthrin in the forest ecosystem could lead to bioaccumulation in soil, sediment, and insects.

Validity, Reliability, and Sensitivity to Exercise-Induced Fatigue of a Customer-Friendly Device for the Measurement of the Brain's Direct Current Potential.

ABSTRACT: Valenzuela, PL, Sánchez-Martínez, G, Torrontegi, E, Vázquez-Carrión, J, Montalvo, Z, and Kara, O. Validity, reliability, and sensitivity to exercise-induced fatigue of a customer-friendly device for the measurement of the brain's direct current potential. J Strength Cond Res 36(6): 1605-1609, 2022-This study aimed to determine the validity, reliability, and sensitivity to exercise-induced fatigue of the brain's direct current (DC) potential measured with a commercially available and customer-friendly electroencephalography (EEG) device and Omegawave (OW). The study was composed of 3 different experiments as follows: (a) we compared the DC potential values obtained simultaneously in 31 subjects with both OW and a research-quality EEG system; (b) 3 consecutive DC potential measurements with OW were taken at rest on the same day in 25 subjects for reliability analyses; and (c) sensitivity to fatigue was assessed in 9 elite badminton players through the measurement of the DC potential with OW-as well as other fatigue-related measures (e.g., Hooper's index, heart rate variability, jump ability, and simple and complex reaction times)-24 hours after both a day of rest and of strenuous exercise, which were performed in a crossover and randomized design. The DC potential measured with OW was reliable (intraclass correlation coefficient = 0.97) and significantly correlated to that of EEG (r = 0.55, p = 0.001), although significant differences were observed between systems (p < 0.001). Compared with the rest day, strenuous exercise resulted in an impaired Hooper's index (p = 0.010) and jump ability (p = 0.008), longer simple (p = 0.038) and complex reaction times (p = 0.011), and a trend toward sympathetic dominance (standard deviation of normal to normal R-R intervals, p = 0.042; root mean square of differences between consecutive R-R intervals, p = 0.068). In turn, no significant differences were found between sessions for the DC potential (p = 0.173). In summary, the DC potential measured with OW was reliable and modestly correlated to that measured with EEG, but no differences were observed in response to the delayed fatigue (after 24 hours) elicited by strenuous exercise in elite athletes.

Effects of COVID-19 Lockdown and a Subsequent Retraining Period on Elite Athletes' Workload, Performance, and Autonomic Responses: A Case Series.

PURPOSE: To describe the effects of COVID-19 lockdown and a subsequent retraining on the training workloads, autonomic responses, and performance of a group of elite athletes. METHODS: The training workloads and heart rate variability (assessed through the log-transformed root mean square of successive R-R intervals) of 7 elite badminton players were registered daily during 4 weeks of normal training (baseline), 7 to 10 weeks of lockdown, and 6 to 8 weeks of retraining. Physical performance was assessed at baseline and after each phase by means of a countermovement jump and the estimated squat 1-repetition maximum. RESULTS: A reduction in training workloads was observed in all participants during the lockdown (-63.7%), which was accompanied by a reduced heart rate variability in all but one participant (-2.0%). A significant reduction was also observed for countermovement jump (-6.5%) and 1-repetition maximum performance (-11.5%), which decreased in all but one participant after the lockdown. However, after the retraining phase, all measures returned to similar values to those found at baseline. At the individual level, there were divergent responses, as exemplified by one athlete who attenuated the reduction in training workloads and increased her performance during the lockdown and another one who markedly reduced his workload and performance, and got injured during the retraining phase. CONCLUSIONS: Although there seems to be a large interindividual variability, COVID-19 lockdown is likely to impose negative consequences on elite athletes, but these detrimental effects might be avoided by attenuating reductions in training workloads and seem to be overall recovered after 6 to 8 weeks of retraining.

Should We Base Training Prescription on the Force-Velocity Profile? Exploratory Study of Its Between-Day Reliability and Differences Between Methods.

PURPOSE: To analyze the differences in the force-velocity (F-v) profile assessed under unconstrained (ie, using free weights) and constrained (ie, on a Smith machine) vertical jumps, as well as to determine the between-day reliability. METHODS: A total of 23 trained participants (18 [1] y) performed an incremental load squat jump test (with ∼35%, 45%, 60%, and 70% of the subjects' body mass) on 2 different days using free weights and a Smith machine. Nine of these participants repeated the tests on 2 other days for an exploratory analysis of between-day reliability. F-v variables (ie, maximum theoretical force [F0], velocity [v0], and power, and the imbalance between the actual and the theoretically optimal F-v profile) were computed from jump height. RESULTS: A poor agreement was observed between the F-v variables assessed under constrained and unconstrained conditions (intraclass correlation coefficient [ICC] < .50 for all). The height attained during each single jump performed under both constrained and unconstrained conditions showed an acceptable reliability (coefficient of variation < 10%, ICC > .70). The F-v variables computed under constrained conditions showed an overall good agreement (ICC = .75-.95 for all variables) and no significant differences between days (P > .05), but a high variability for v0, the imbalance between the actual and the theoretically optimal F-v profile, and maximal theoretical power (coefficient of variation = 17.0%-27.4%). No between-day differences were observed for any F-v variable assessed under unconstrained conditions (P > .05), but all of the variables presented a low between-day reliability (coefficient of variation > 10% and ICC < .70 for all). CONCLUSIONS: F-v variables differed meaningfully when obtained from constrained and unconstrained loaded jumps, and most importantly seemed to present a low between-day reliability.

Ischemic Preconditioning and Muscle Force Capabilities.

ABSTRACT: Valenzuela, PL, Martín-Candilejo, R, Sánchez-Martínez, G, Bouzas Marins, JC, de la Villa, P, and Sillero-Quintana, M. Ischemic preconditioning and muscle force capabilities. J Strength Cond Res 35(8): 2187-2192, 2021-This study analyzed the effects of ischemic preconditioning (IPC) on muscle force capabilities. Sixteen male subjects participated in this randomized, crossover, sham-controlled study. They were assigned to either IPC (3 × 5 minutes at 220 mm Hg in both arms with 5-minute rests) or a sham intervention (SHAM) (occlusion pressure set at 10 mm Hg). Forty minutes later, their force capabilities on the bench press exercise were assessed (load-velocity relationship with light, moderate, and heavy loads [30, 50, and 70% body mass, respectively]; 1 repetition maximum [1RM]; and number of repetitions to failure in 3 sets with 60% RM). The skin temperature (Tsk) of the pectoral and biceps muscles was analyzed as a secondary endpoint by means of infrared thermography. A significant decrease in the Tsk of the pectoral and biceps muscles was observed after the intervention (p < 0.01) and before the warm-up (p < 0.05) in IPC, but not in SHAM. However, exercise resulted in a similar Tsk increase in the pectoral muscles in both conditions (p > 0.05). No significant differences (p > 0.05 for all) were observed between conditions in the mean velocity attained with light (1.11 ± 0.11 and 1.09 ± 0.14 m·s-1, respectively), moderate (0.83 ± 0.14 and 0.83 ± 0.16 m·s-1), nor heavy loads (0.56 ± 0.17 and 0.54 ± 0.16 m·s-1), in 1RM (75.0 ± 18.9 and 73.1 ± 15.0 kg for IPC and SHAM, respectively; p = 0.181), nor in the number of repetitions performed (52 ± 13 and 54 ± 16 repetitions, p = 0.492). In summary, IPC decreased Tsk locally (biceps) and remotely (pectoral). However, it did not alter muscle force capabilities nor the Tsk response to exercise.

Ecotoxicity of pesticides and semiochemicals used for control and prevention of conifer bark beetle (Dendroctonus spp.) outbreaks.

Application of pyrethroid pesticides and semiochemicals are two treatments used worldwide to control conifer bark beetles (Dendroctonus spp.); their residues can reach water reservoirs and water currents through run off and affect non-target organisms such as freshwater invertebrates. Therefore, we assessed the 48-h lethal toxicity, chronic toxicity (reproduction inhibition), and bioaccumulation of three pyrethroid pesticides (bifenthrin, cypermethrin, and deltamethrin) and two semiochemicals (verbenone and 3-methyl-2-cyclohexen-1-one) in two freshwater invertebrates: the cladoceran Alona guttata and the rotifer Lecane papuana. Bifenthrin was the most toxic of the five chemical compounds tested followed by deltamethrin and then cypermethrin, which was the least toxic pyrethroid for both species. Semiochemicals were far less toxic than pyrethroids and verbenone was most toxic than 3-methyl-2-cyclohexen-1-one for both species. For the rotifer Lecane papuana, the pyrethroid with the highest Bioconcentration Factor was bifenthrin, and for the semiochemicals it was 3-methyl-2-cyclohexen-1-one. For the cladoceran Alona guttata, the pyrethroid with the highest bioconcentration factor was cypermethrin and for the semiochemicals it was verbenone. The pyrethroid with highest body burdens both lethal and chronic was cypermethrin. Semiochemicals showed lethal and chronic body burdens 12-fold higher than pyrethroids and were therefore less toxic than pyrethroids. These results showed that the semiochemicals verbenone and 3-methyl-2-cyclohexen-1-one are a safe tool for the freshwater invertebrates tested when compared with pyrethroid pesticides. Cypermethrin was the least toxic of the pyrethroids tested and therefore could be considered as a good candidate to control outbreaks of the conifer bark beetle.

Reference power values for the jump squat exercise in elite athletes: A multicenter study.

The present study aimed to provide reference values for lower-limb muscle power assessed during the incremental jump squat (JS) test in elite athletes (i.e., professional athletes competing at international level). We pooled data from all JS tests performed by elite athletes of different sports in two high-performance centres between 2015 and 2019, and computed reference values (i.e., terciles) for mean power (MP), mean propulsive power (MPP), and peak power (PP). Reference values were obtained from 684 elite athletes (458 male and 226 female) of 16 different sports (boxing, judo, karate, fencing, taekwondo, wrestling, basketball, soccer, futsal, handball, rugby union, badminton, tennis, long distance running, triathlon, and sprinting). Significant differences (p < 0.001) were found between male and female athletes for MP (7.47 ± 1.93 and 6.15 ± 1.68 W·Kg-1, respectively), MPP (10.50 ± 2.75 and 8.63 ± 2.43 W·Kg-1), and PP (23.64 ± 6.12 and 19.35 ± 5.49 W·Kg-1). However, the velocity at which these power measures was attained seemed to be independent of sex (~0.95, 1.00 and 2.00 m·s-1 for mean, mean propulsive, and peak velocity, respectively) and homogeneous across different sport disciplines (coefficient of variation <10%). These data can be used to classify athletes' power capabilities, and the optimum velocity ranges provided here could be useful for training purposes.

Enhanced External Counterpulsation and Recovery From a Plyometric Exercise Bout.

OBJECTIVE: To analyze the effectiveness of enhanced external counterpulsation (EECP) on recovery from exercise-induced muscle damage (EIMD). DESIGN: This study followed a crossover, placebo-controlled, counterbalanced design. PARTICIPANTS: Ten healthy active subjects (7 male; 27 ± 4 years). INTERVENTIONS: Participants performed a plyometric exercise bout (10 sets of 10 jumps interspersed with 1-minute rests) and were then assigned to recover for 30 minutes with either EECP (cuff pressure = 80 mm Hg) or a Sham intervention (0 mm Hg) immediately after exercise and at 24 hours after exercise. Two weeks later, they repeated the protocol with the other recovery intervention. MAIN OUTCOME MEASURES: Muscle soreness, creatine kinase (CK) activity, jump performance, and tensiomyographic variables were measured before exercise, and 24 and 48 hours after exercise. RESULTS: The mean jump height of the plyometric bout did not differ between EECP and Sham (P > 0.05). Exercise resulted in increased muscle soreness (P < 0.001) and CK levels (P < 0.001), as well as in impaired jump performance (P < 0.05). No changes were observed in tensiomyographic variables. No significant differences were found between interventions for any of the study outcomes. CONCLUSIONS: No benefits on recovery from EIMD after a plyometric exercise bout were observed with EECP.

The Differential Expression of Mevalonate Pathway Genes in the Gut of the Bark Beetle Dendroctonus rhizophagus (Curculionidae: Scolytinae) Is Unrelated to the de Novo Synthesis of Terpenoid Pheromones.

Bark beetles commonly produce de novo terpenoid pheromones using precursors synthesized through the mevalonate pathway. This process is regulated by Juvenile Hormone III (JH III). In this work, the expression levels of mevalonate pathway genes were quantified after phloem feeding-to induce the endogenous synthesis of JH III-and after the topical application of a JH III solution. The mevalonate pathway genes from D. rhizophagus were cloned, molecularly characterized, and their expression levels were quantified. Also, the terpenoid compounds produced in the gut were identified and quantified by Gas Chromatography Mass Spectrometry (GC-MS). The feeding treatment produced an evident upregulation, mainly in acetoacetyl-CoA thiolase (AACT), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), phosphomevalonate kinase (PMK), and isopentenyl diphosphate isomerase (IPPI) genes, and males reached higher expression levels compared to females. In contrast, the JH III treatment did not present a clear pattern of upregulation in any sex or time. Notably, the genes responsible for the synthesis of frontalin and ipsdienol precursors (geranyl diphosphate synthase/farnesyl diphosphate synthase (GPPS/FPPS) and geranylgeranyl diphosphate synthase (GGPPS)) were not clearly upregulated, nor were these compounds further identified. Furthermore, trans-verbenol and myrtenol were the most abundant compounds in the gut, which are derived from an α-pinene transformation rather than de novo synthesis. Hence, the expression of mevalonate pathway genes in D. rhizophagus gut is not directed to the production of terpenoid pheromones, regardless of their frequent occurrence in the genus Dendroctonus.

Acute Responses to On-Court Repeated-Sprint Training Performed With Blood Flow Restriction Versus Systemic Hypoxia in Elite Badminton Athletes.

PURPOSE: Repeated-sprint training (RS) is commonly conducted in normoxia, but its completion with localized (blood-flow restriction [BFR]) or systemic hypoxia has been proven effective for performance enhancement. Yet, few studies have applied these types of RS sessions in racket sports. The authors aimed to determine the acute responses to these types of training in elite badminton players. METHODS: Eight male elite badminton players participated in this randomized crossover study. They performed 3 on-court RS sessions, each consisting of 3 sets of 10 repetitions of 10-s badminton-specific movements in normoxia (RSN), systemic normobaric hypoxia (RSH, FiO2 = 14%), or with BFR (RS-BFR, 40% arterial occlusion pressure). Performance, perceptual (ie, rating of perceived exertion), and physiological (ie, pulse saturation, muscle oxygenation, blood lactate, creatine kinase, heart-rate variability) responses were measured after each set and up to 48 h postsession. RESULTS: RS-BFR induced a greater performance impairment (lower distance and accelerations) and a higher local perceived exertion in the legs than RSN and RSH (P < .05), whereas greater overall fatigue was reported with RSH (P < .05). RSH induced a lower saturation (P < .001), but no differences were observed in muscle oxygenation between conditions. No differences in creatine kinase or heart-rate variability were observed at any time point (from baseline up to 48 h after the session). CONCLUSIONS: RS-BFR-and, to a lower extent, RSH-resulted in impaired performance and a higher perceived strain than RSN. However, these 2 hypoxic methods do not seem to induce a long-lasting (post 24-48 h) physiological stress in elite badminton players.

Enhancement of Mood but not Performance in Elite Athletes With Transcranial Direct-Current Stimulation.

PURPOSE: To determine if transcranial direct-current stimulation (tDCS) could be effective for the enhancement of swimming performance or mood state in elite athletes. METHODS: Eight male elite triathletes (age = 20 [2] y, maximal oxygen uptake = 71 [4] mL·kg-1·min-1) participated in this crossover, counterbalanced, sham-controlled, double-blind study. Participants received either actual (20 min of anodal stimulation of the motor cortex at 2 mA) or sham tDCS and performed an 800-m swimming test in which rating of perceived exertion and blood lactate response were measured. Mood state (Brunel Mood Scale) was assessed before and after each tDCS session and after the swimming test. Heart-rate variability and central nervous system readiness were assessed before and after each tDCS session. The chances of finding differences between conditions were determined using magnitude-based inferences. RESULTS: A significant and very likely higher Brunel Mood Scale-determined vigor self-perception was found with actual tDCS after the stimulation session (-0.1 [1.2] and 2.0 [2.3] for sham and actual tDCS, respectively; P = .018, effect size = 1.14) and after exercise (-4.1 [2.9] and -0.9 [3.6] for sham and actual tDCS, respectively; P = .022, effect size = 0.98). However, likely trivial and nonsignificant (P > .05) differences were found between conditions in performance (599 [38] s and 596 [39] s, respectively). Unclear and nonsignificant differences were observed between conditions for the rest of the study end points. CONCLUSIONS: tDCS elicited a marked increase in vigor self-perception that was maintained after exercise but failed to improve swimming performance in elite triathletes.

Enhanced External Counterpulsation and Short-Term Recovery From High-Intensity Interval Training.

PURPOSE: Enhanced external counterpulsation (EECP) is a recovery strategy whose use has increased in recent years owing to the benefits observed in the clinical setting in some cardiovascular diseases (ie, improvement of cardiovascular function). However, its claimed effectiveness for the enhancement of exercise recovery has not been analyzed in athletes. The aim of this study was to determine the effectiveness of EECP on short-term recovery after a fatiguing exercise bout. METHODS: Twelve elite junior triathletes (16 [2] y) participated in this crossover counterbalanced study. After a high-intensity interval training session (6 bouts of 3-min duration at maximal intensity interspersed with 3-min rest periods), participants were assigned to recover during 30 min with EECP (80 mm Hg) or sham (0 mm Hg). Measures of recovery included performance (jump height and mean power during an 8-min time trial), metabolic (blood lactate concentration at several time points), autonomic (heart-rate variability at several time points), and subjective (rating of perceived exertion [RPE] and readiness to compete) outcomes. RESULTS: There were no differences between EECP and sham in mean RPE or power output during the high-intensity interval training session, which elicited a significant performance impairment, vagal withdrawal, and increased blood lactate and RPE in both EECP and sham conditions (all P < .05). No significant differences were found in performance, metabolic, or subjective outcomes between conditions at any time point. A significantly lower high-frequency power (P < .05, effect size = 1.06), a marker of parasympathetic activity, was observed with EECP at the end of the recovery phase. CONCLUSION: EECP did not enhance short-term recovery after a high-intensity interval training session in healthy, highly trained individuals.

Enemies by accident, neutral on the rebound: diversity and contingency at the birth of war humanitarianism, 1862-1864 / Enemigos por accidente, neutrales de rebote: diversidad y contingencia en el nacimiento del humanitarismo de guerra, 1862-1864

The historiography of the origin and early years of the movement of societies of the Red Cross and the Red Crescent is, in general, highly pervaded by a narrative whose main architect was Henry Dunant himself. So much so, in fact, that there is no satisfactory explanation as to how the attempt to develop medical a technology ended up involving the implementation of a legal technology, namely, Humanitarian Law. In an attempt to critically revise this narrative, a description is made here of that journey, providing evidence on the way in which a technology, even one as highly regarded as the 1864 Geneva Convention, may arise contingently without being intended, not even imagined, within the circles in which it emerged, through diversity interplaying as a collective action, with no need to resort to any explanatory artifice that might demand that the outcomes should actually be the result of any successful intentional route (AU)

La historiografía sobre el origen y los primeros años del movimiento de sociedades de la Cruz Roja y la Media Luna Roja está, en general, muy contaminado por un relato cuyo principal artífice fue el propio Henry Dunant. Tanto, que no encuentra el modo de dar una explicación satisfactoria a cómo el intento de apuesta por una tecnología sanitaria acaba convertido en la constitución de una tecnología jurídica como es el Derecho Humanitario. Intentando evitar esa contaminación, se ofrece una descripción de ese recorrido dando evidencias de cómo una tecnología, incluso una tan respetada como la Convención de Ginebra de 1864, puede producirse contingentemente sin ser buscada, ni siquiera imaginada en los círculos en los que se produce, por la interacción de la diversidad como acción colectiva, sin tener que acudir al artificio de explicaciones que exigen que los resultados lo sean de recorridos intencionales exitosos (AU)

Humanitarian aid in peacetime: conflicting narratives in the international Red Cross movement, 1867-1884 / El socorro humanitario en tiempo de paz: divergencias iniciales en el movimiento internacional de la Cruz Roja, 1867-1884

When, scarcely five years after its advent, the movement of aid societies for the relief of soldiers wounded in battle in international wars, set out to examine what should their activities be in peacetime, many debates were opened up as to the feasibility of broadening their field of action to other warlike settings and disasters. The following is an examination of how these debates developed, providing evidence that (a) the International Committee of the Red Cross (ICRC) defended its position not to incorporate civil aims into the humanitarian purposes of the Red Cross international movement until after the First World War; and (b) different national societies and committees of the Red Cross, disagreeing with this position, defended, within the framework of emergent paradigms in hygiene and public health, the care of the sick poor, and were involved as early as the 1870s and 1880s in first-aid to the sick and wounded in everyday life as well as in relief of disasters both natural and caused by famine (AU)

Cuando, apenas cinco años después de su puesta en marcha, el movimiento de sociedades de socorro a los soldados heridos en campaña en caso de guerras internacionales se propuso examinar en qué deberían consistir sus actividades en tiempo de paz, se abrieron los debates sobre la posibilidad de ampliar su campo de actuación a otros escenarios y calamidades. Se analiza cómo fueron esos debates, ofreciendo muestras de cómo (a) el Comité Internacional de la Cruz Roja (CICR) defendió no añadir objetivos civiles entre los propósitos humanitarios del movimiento internacional hasta después de la Primera Guerra Mundial; y (b) diferentes sociedades nacionales y comités de la Cruz Roja, discrepando de esa posición, defendieron, en el marco de los paradigmas emergentes en la higiene y la salud pública, la asistencia a pobres enfermos y se implicaron, tan pronto como en las décadas de 1870 y 1880, tanto en la intervención rutinaria en socorro de enfermos y heridos en la vida diaria, como en la atención a catástrofes naturales y producidas por el hombre (AU)

Host preference and attack pattern of Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae): a bark beetle specialist on pine regeneration.

Pine seedlings and saplings are seldom attacked by bark beetles of the genus Dendroctonus. However, Dendroctonus rhizophagus (Coleoptera: Curculionidae: Scolytinae) Thomas and Bright specifically attacks pine seedlings and causes conspicuous mortality in naturally regenerated stands in the Sierra Madre Occidental, northern Mexico. We evaluated the host preference and attack of D. rhizophagus under field conditions. We tried to establish any relationship between tree growth or host size and the number of attacking beetles. Generally, only one pair of beetles attacked each of the seedlings regardless of host size; however, a significant positive linear relationship between host size and adult brood size was observed. We found that this species preferred the best growing seedlings in our study sites.