An Annotated Checklist of Monogeneans (Platyhelminthes, Monogenea) from Aquatic Vertebrates in Peru: A Review of Diversity, Hosts and Geographical Distribution.

Monogeneans are flatworm parasites that infest fish gills primarily but can also infect various other vertebrates, including amphibians, aquatic reptiles, mammals like hippos, and occasionally invertebrates like copepods, isopods, and cephalopods. Despite their remarkable diversity, our knowledge of monogenean parasites in Peru remains significantly limited, resulting in substantial gaps in our comprehension of their taxonomic identities, host associations, and geographic distribution. To address these knowledge deficits, we present an extensively curated checklist of monogeneans associated with aquatic vertebrates in Peru. This comprehensive compilation is derived from meticulous literature surveys, the examination of specimens deposited in both international and national collections, and the inclusion of additional freshly collected specimens. The checklist offers a thorough repository of data encompassing the diversity, host associations, and geographical distribution of these parasites. Taxonomic discrepancies are addressed through a critical review of the existing literature, supplemented by the direct examination of specimens, including type or voucher specimens, deposited within scientific collections. Additionally, we provide data on the DNA sequences of individual taxa. The compiled list comprises records of 358 monogenean species, including 270 valid species and 88 taxa identified at the family or generic level, all reported across 145 host species in Peru. Predominantly, these parasitic species exhibit associations within fish, with 335 infecting teleosts and 20 affecting chondrichthyans. Three monogenean species have been documented as infecting amphibians, namely Mesopolystoma samiriensis, Polistoma sp. and Wetapolystoma almae. Among the monogeneans reported, 141 were found in marine environments and 214 in freshwater environments. The most diverse families were Dactylogyridae and Diplectanidae, comprising 217 and 24 species, respectively. The hosts that harbored the highest number of monogeneans were Pygocentrus nattereri (with 23 species), followed by Stellifer minor (13 spp.) and Triportheus angulatus (11 spp.). We detected many species that do not have any material deposited in a scientific collection due to the loss or deactivation of the collection. These findings represent only a fraction of the potential diversity, considering the wide variety of aquatic vertebrate hosts inhabiting the tropical and subtropical regions of Peru.

Molecular identification and prevalence of plerocercoid larvae (Cestoda: Diphyllobothriidae) in some commercial fish species from Peru.

Diphyllobothriosis, a fish-borne zoonosis in South America, is mainly caused by the Pacific broad tapeworm Adenocephalus pacificus Nybelin, 1931, a parasite of considerable concern in fishery resources due to its impact on public health. A new diphyllobothrid, Diphyllobothrium sprakeri Hernández-Orts et al. Parasites Vectors 14:219, 2021, was recently described from sea lions from the Pacific Coast, but marine fish acting as intermediate hosts are unknown. The objective of this study was to confirm the presence of plerocercoid larvae of Diphyllobothriidae Lühe, 1910 (Cestoda: Diphyllobothriidea) in nine fish species of commercial importance in Peru. Of a total of 6999 fish (5861 Engraulis ringens, 853 Sciaena deliciosa, 6 Sciaena callaensis, 171 Scomber japonicus, 40 Trachurus murphyi, 40 Ariopsis seemanni, 18 Merluccius peruanus, 5 Sarda chiliensis, and 5 Coryphaena hippurus), 183 were infected with plerocercoid larvae, representing a total prevalence of 2.61% and a mean intensity of 3.2. Based on mtDNA cox1 sequences of 43 plerocercoids, a phylogenetic analysis revealed that 41 belong to A. pacificus and two to D. sprakeri. These findings are first molecular data for D. sprakeri larvae, and the infections of E. ringens and T. murphyi by plerocercoid larvae represent the first records of intermediate/paratenic hosts for this species. Hence, the findings of the current study enhance our understanding of the presence of diphyllobothriid species in commercial fish from the Southeastern Pacific Ocean and their potential impact on seafood safety for local human populations.

The male reproductive cycle of the brown basilisk Basiliscus vittatus (Squamata: Corytophanidae) from Tabasco, Southern Mexico.

We used histological and morphometric methods to study the testis and associated glands, including the epididymis, ductus deferens, and renal sexual segment (RSS), of specimens of Basiliscus vittatus sampled from Tabasco, Mexico (17.5926° N, 92.5816° W). Samples were collected throughout 1 year, which included the dry (February to May) and rainy (June to January) seasons. Spermatogenesis in B. vittatus is active throughout the year, but a significant increase in the testicular volume, diameters of seminiferous tubules, height of the germinal epithelium, spermiogenesis, and released spermatozoa occur in the dry season. During the rainy season, all aforementioned parameters decreased except the secretory activity of the epididymis and the RSS, which increased concomitant with an increase of the spermatozoa population within the ductus deferens. These data strongly suggest that B. vittatus reproduce year-round, but males exhibit a peak in spermatogenic activity during the dry season and a peak in insemination and/or copulation at the beginning of the rainy season. We highlight the importance of analyzing not only the testis but also accessory ducts and glands when determining the reproductive cycles of reptiles. The reproductive cycle of B. vittatus is discussed in relation to the environmental conditions of Southern Mexico and is compared to that of other squamates.

Temperature- and genotype-dependent stress response and activation of the hypothalamus-pituitary-interrenal axis during temperature-induced sex reversal in pejerrey Odontesthes bonariensis, a species with genotypic and environmental sex determination.

In the pejerrey Odontesthes bonariensis (Atheriniformes, Atherinopsidae), exposure to high and low temperatures during the critical period of sex determination (CPSD) induce testicular and ovarian differentiation, respectively, regardless of the presence or not of the sex determining gene amhy, which is crucial for testis formation only at intermediate, sexually neutral temperatures. In this study we explored the existence of genotype-specific signaling of Crh (Corticotropin Releasing Hormone) family genes and their associated carrier protein, receptors, and other stress-related genes in response to temperature during the CPSD and the potential involvement of the central nervous system via the hypothalamus-pituitary-interrenal (HPI) axis in the sex determination of this species. The Crh family genes crhb, uts1, ucn3, the receptor crhr1 and the stress-related genes gr1, gr2, nr3c2 were transiently upregulated in the heads of pejerrey larvae during the CPSD by high temperature alone or in combination with other factors. Only crhr2 transcript abundance was not influenced by temperature but independently by time and genotype. In most cases, mRNA abundance was higher in the XX heads compared to that of XY individuals. The mRNAs of some of these genes were localized in the hypothalamus of pejerrey larvae during the CPSD. XX larvae also showed higher whole-body cortisol titers than the XY, downregulation of cyp19a1a and upregulation of the testis-related genes amhy/amha in trunks (gonads) and were 100% masculinized at the high temperature. In contrast, at the low temperature, crhbp and avt were upregulated in the heads, particularly the former in XY larvae. cyp19a1a and amhy/amha were up- and downregulated, respectively, in the gonads, and fish were 100% feminized. Signaling via the HPI axis was observed simultaneously with the first molecular signs of ongoing sex determination/differentiation in the gonads. Overall, the results strongly suggest a temperature-dependent, genotype-specific regulatory action of the brain involving the Crh family of stress-related genes on the process of environmental sex determination of pejerrey.

Using DNA barcoding to link cystacanths and adults of the acanthocephalan Corynosoma australe of the Southeastern Pacific Ocean (off Peru coast).

The objective of this study is to use DNA barcoding to link cystacanths and adults belonging to the acanthocephalans Corynosoma australe found in the Southeastern Pacific Ocean off the coast central from Peru. We sampled three species of commercial fish (Paralichthys adspersus (Steindachner), Paralabrax humeralis (Valenciennes), and Cheilodactylus variegatus (Valenciennes)) and two South American sea lions, Otaria byronia, stranded on the beaches of the city of Huacho and Barranca, Lima province. A total of 509 acanthocephalan larvae were found in the body cavity of 95 fish (prevalence 54.28%, total mean intensity 8.64). A total of 127 adult worms were found in the large intestine from two South American sea lions (P= 100%, MI= 63.5). A total of 203 larvae from P. humeralis were isolates (P=65.71%; MI= 8.83; MA=5.8), 235 (P=54.29%; MI= 12.37; MA= 6.71) from C. variegatus, and 71 (P=42.86%; MI= 4.73; MA= 2.03) from P. adspersus. All adult and larval specimens were morphologically identified as C. australe. They were generated cytochrome c oxidase subunit 1 (cox1) gene sequences of specimens and were compared with available data from GenBank. Molecular phylogenetic analysis supported our morphological identification, where the Peruvian isolates formed a clade with other isolates of C. australe from other countries of the American continent. Of the sequences obtained, two haplotypes were detected and were not identical with previous reports. Based on both DNA barcoding and morphological analyses, our finding represents the first molecular data of C. australe from Peru and the report of Cheilodactylus variegatus as a new paratenic host on the central coast, extending the knowledge and distribution range of this acanthocephalan in Southeastern Pacific Ocean.

Vector Correlations in the 225 nm Photodissociation of Co(CO)3NO.

Metal nitrosyls are fascinating compounds because they undergo significant geometry changes in the excited state. The volatile compound, Co(CO)3NO, is a model for understanding the excited-state behavior. In this experiment, Co(CO)3NO was photodissociated in a DC-sliced velocity mapping ion imaging apparatus with 1 + 1' resonance-enhanced multiphoton ionization (REMPI) detection of the nascent NO. Ion images were collected for different linear polarization of the dissociation and probe lasers to determine the vector correlations in the photodissociation. The fastest NO products arise from an excitation parallel to the dissociating Co-NO bond. The Co-NO bond bends in the excited state, producing an NO photoproduct with angular momentum that is also aligned in the laboratory frame. The µ-v-J vector correlations were measured and are consistent with the orientation µ||v⊥J caused by an excited-state Co-NO bend prior to dissociation. Slower NO photoproducts emerge with smaller vector correlations stemming from fragmentation, parent or fragment rotation, or intersystem crossing.

Simple foot strike angle calculation from three-dimensional kinematics: A methodological comparison.

A simple and accurate method of determining foot strike angle (FSA) during running can simplify data collections and validations of wearable sensors. The purpose of this study was to determine the validity of two simplified methods for estimating FSA and foot angle (throughout the ground contact) from three-dimensional kinematics. Markers were placed on the heel and head of the second metatarsal (HEEL-TOE) or on the lateral side of the head of the fifth metatarsal (HEEL-MET5). When compared to the reference foot segment, the HEEL-TOE method performed similarly with a minimal mean difference (0.28° [0.19°,0.36°], p < 0.001), a high Pearson's r (r = 0.994; p < 0.001), and low bias (-0.20°±1.05°). Alternatively, the HEEL-MET5 method underestimated FSA: mean difference = 4.28° [4.07°,4.91°] (p < 0.001), Pearson's r = 0.968 (p < 0.001), and bias = -4.58°±2.61°. Throughout the contact phase, significant SPM cluster regions were identified, indicating that the HEEL-MET5 method underestimated the angle of the foot for all foot strike patterns in the first 23-34% of the stance (p < 0.025). This study supports the idea that the HEEL-TOE method can be used as a simplified method for determining FSA from 3D kinematics. Researchers should proceed with caution when employing the HEEL-MET5 method, as it is likely underestimating FSA due to foot inversion in the early stance phase.

Connected skiing: Validation of edge angle and radial force estimation as motion quality parameters during alpine skiing.

Recent studies have developed wearable sensor systems to detect, classify and evaluate performance during alpine skiing. In order to enrich skiing data to provide motion quality feedback, edge angle (EA) and radial force (Fr) are parameters of interest. However, the estimation of these parameters via calibration-free wearable technologies has not been validated. The purpose of this study was to develop and validate a wearable method to estimate EA and Fr. Participants completed simulated skiing trials on an indoor skiing carpet. Two IMU's mounted to the ski boots estimated EA and Fr and compared to reference values measured with a 3D motion capture system. The performance of the wearable system was quantified by accuracy and precision. The overall accuracy and precision of the wearable system was 97.6 ± 12.4% and 15.5 ± 17.6% for EA, and 105.5 ± 5.7% and 29.8 ± 10.0%, respectively for Fr. The developed wearable system was accurate for the estimation of EA and Fr, but was highly variable with low precision for both metrics. Further research is needed to improve the precision of field-relevant skiing metrics during in-field studies using simple measurement setups that can easily be implemented by recreational and expert skiers alike.Highlights IMU's mounted on the boots are sufficient tools for accurate estimation of edge angle and radial force during both long and short style turns on a skiing simulator.As the estimation of edge angle and radial force are dependent on other estimated parameters (i.e. turn switch), the precision of these metrics is relatively low.The results of the current study apply only to simulated alpine skiing on a treadmill, and further work is required to prove the accuracy and precision of this system on snow.

Molecular identification and epidemiological data of Anisakis spp. (Nematoda: Anisakidae) larvae from Southeastern Pacific Ocean off Peru.

The objective of this study is to determine the infection status of nematode larvae and record epidemiological molecular data in commercial fish from the southeast Pacific off the central coast of Peru. Anisakiasis is a fish-borne zoonosis caused by Anisakis larvae, parasites of relevance in the fishery resources that have negative impact on public health. Between January 2012 to December 2014, 345 specimens of four fish species (Trachurus symmetricus murphyi, Scomber japonicus peruanus, Merluccius gayi peruanus and Seriolella violacea) were examined for Anisakis sp. larvae. A total of 997 Anisakis sp. larvae were found in the body cavity of 196 fish (total prevalence 53.7%, total mean intensity 5.08). After morphological analysis, 958 (96.08%) larvae were identified as Type I and 39 (3.92%) as Type II. Specimens were identified by molecular analysis of the mitochondrial cytochrome c oxidase subunit II (cox2) gene, confirming that A. pegreffii is the predominant species and the most important agent of human anisakiasis off the Peru Central Coast. In addition, we revealed the occurrence of A. physeteris (s.l.) in S. japonicus peruanus (P = 18.0%; MI = 2.17). Therefore, the results obtained in the present study improve the knowledge of the occurrence of Anisakis species in the commercial fish from the Southeastern Pacific Ocean, highlighting the importance of considering a potential hazard for humans and the necessity of further research in other fishes of greater preference by the Peruvian population.

Biomechanical Response of the Lower Extremity to Running-Induced Acute Fatigue: A Systematic Review.

Objective: To investigate (i) typical protocols used in research on biomechanical response to running-induced fatigue, (ii) the effect of sport-induced acute fatigue on the biomechanics of running and functional tests, and (iii) the consistency of analyzed parameter trends across different protocols. Methods: Scopus, Web of Science, Pubmed, and IEEE databases were searched using terms identified with the Population, Interest and Context (PiCo) framework. Studies were screened following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and appraised using the methodological index for non-randomized studies MINORS scale. Only experimental studies with at least 10 participants, which evaluated fatigue during and immediately after the fatiguing run were included. Each study was summarized to record information about the protocol and parameter trends. Summary trends were computed for each parameter based on the results found in individual studies. Results: Of the 68 included studies, most were based on in-lab (77.9%) protocols, endpoint measurements (75%), stationary measurement systems (76.5%), and treadmill environment (54.4%) for running. From the 42 parameters identified in response to acute fatigue, flight time, contact time, knee flexion angle at initial contact, trunk flexion angle, peak tibial acceleration, CoP velocity during balance test showed an increasing behavior and cadence, vertical stiffness, knee extension force during MVC, maximum vertical ground reaction forces, and CMJ height showed a decreasing trend across different fatigue protocols. Conclusion: This review presents evidence that running-induced acute fatigue influences almost all the included biomechanical parameters, with crucial influence from the exercise intensity and the testing environment. Results indicate an important gap in literature caused by the lack of field studies with continuous measurement during outdoor running activities. To address this gap, we propose recommendations for the use of wearable inertial sensors.

Connected Skiing: Motion Quality Quantification in Alpine Skiing.

Recent developments in sensing technology have made wearable computing smaller and cheaper. While many wearable technologies aim to quantify motion, there are few which aim to qualify motion. (2) To develop a wearable system to quantify motion quality during alpine skiing, IMUs were affixed to the ski boots of nineteen expert alpine skiers while they completed a set protocol of skiing styles, included carving and drifting in long, medium, and short radii. The IMU data were processed according to the previously published skiing activity recognition chain algorithms for turn segmentation, enrichment, and turn style classification Principal component models were learned on the time series variables edge angle, symmetry, radial force, and speed to identify the sources of variability in a subset of reference skiers. The remaining data were scored by comparing the PC score distributions of variables to the reference dataset. (3) The algorithm was able to differentiate between an expert and beginner skier, but not between an expert and a ski instructor, or a ski instructor and a beginner. (4) The scoring algorithm is a novel concept to quantify motion quality but is limited by the accuracy and relevance of the input data.

A Comprehensive Comparison and Validation of Published Methods to Detect Turn Switch during Alpine Skiing.

The instant of turn switch (TS) in alpine skiing has been assessed with a variety of sensors and TS concepts. Despite many published methodologies, it is unclear which is best or how comparable they are. This study aimed to facilitate the process of choosing a TS method by evaluating the accuracy and precision of the methodologies previously used in literature and to assess the influence of the sensor type. Optoelectronic motion capture, inertial measurement units, pressure insoles, portable force plates, and electromyography signals were recorded during indoor treadmill skiing. All TS methodologies were replicated as stated in their respective publications. The method proposed by Supej assessed with optoelectronic motion capture was used as a comparison reference. TS time differences between the reference and each methodology were used to assess accuracy and precision. All the methods analyzed showed an accuracy within 0.25 s, and ten of them within 0.05 s. The precision ranged from ~0.10 s to ~0.60 s. The TS methodologies with the best performance (accuracy and precision) were Klous Video, Spörri PI (pressure insoles), Martinez CTD (connected boot), and Yamagiwa IMU (inertial measurement unit). In the future, the specific TS methodology should be chosen with respect to sensor selection, performance, and intended purpose.

Antiviral activity of the sea cucumber tegument extract (Pattalus mollis) on human rotavirus A (RVA).

The antiviral effect against RVA in cell culture was evaluated by using an aqueous extract of Patallus mollis sea cucumber, applying the titration methodology. This technique is used to measures the ability of the extract dilutions to inhibit the cytopathic effect (CPE) of the virus, expressed as percentage of inhibition (IP). The mean extract cytotoxic concentration (CC50) used in the antiviral assay was 27,042.10 µg/mL and the PI of the antiviral activity extract was greater than 99.9% for each concentration. To determine the viral action mode, the cells were previously treated with the extracts in different stages during the viral infection cycle. The result analysis suggests that the extract inhibits 99% of the virus during the absorption and viral inactivation phase. These results show the P. mollis extract has a remarkable antiviral effect against the RVA in cell culture. So that, it is crucial to investigate its action mechanisms.

A New Species of Mymarothecium tantaliani n. sp (Monogenea: Dactylogiridae) in the Gills of Gamitana Colossoma macropomum (Cuvier) from Madre de Dios, Peru.

INTRODUCTION: Members of the genus Mymarothecium Kritsky, Boeger & Jégu, 1996 infect characiform fish in the Amazon River Basin. Although the Peruvian Amazon hosts rich fauna of fish, the taxonomic diversity of parasitic organisms such as Mymarothecium has been few explored. A new species of Mymarothecium in Colossoma macropomum Cuvier, from the southeast of the Peruvian Amazon, is described. METHODS: Monogeneans were isolated from gills of C. macropomum, fixed in formaldehyde in 4% solution. For morphological examinations were stained with Gomori's trichrome and others were clarified with Hoyer's medium. RESULTS: Mymarothecium is the third species of the genus recorded in C. macropomum. These new species have been characterized by a slightly sigmoid male copulatory organ (MCO) and the accessory piece with sinuous distal rod with hook-shaped process and a bifurcation in the middle part. Furthermore, the anteromedial projection of the ventral rod has a small conspicuous filament in both anchors. CONCLUSIONS: With the description of this new species, eight species of Mymarothecium have been reported in fish of the Serrasalmidae family originating in the Amazon.

Comparison of the Turn Switch Time Points Measured by Portable Force Platforms and Pressure Insoles.

Several methods to determine turn switch points during alpine skiing using the vertical GRF exist in the literature. Although comparative studies between pressure insoles (PI) and force platforms (FP) have been conducted, there are no reports comparing the detected time points. Yet, these sensors and methods have been used interchangeably. This study aims to compare the turn switch time points with both sensors and various methods. Twenty skiers performed turns with FP and PI for two different ski styles (high and low dynamic turns). Three different assessment methodologies were compared: minima, functional minima, and crossings. Bland Altman and repeated measures ANOVA were used to assess statistical differences. Main effects of sensor and method were observed (p < 0.001). Although there was a low effect size ( η p 2 = 0.013) between FP and PI, the 95% CI yielded values representing >30% of the turn duration. A large effect size (η2 = 0.153) was found between the crossing method and the minima and functional minima methods. This indicates that those methods assess different events during the turn switch phase. In conclusion, the sensors and assessment methodologies compared in this study are not interchangeable with the possible exception of the minima and functional minima assessed with FP.

Molecular Identification of Adenocephalus pacificus (Cestoda) from Three Human Cases in Lima Province, Peru.

The Pacific tapeworm Adenocephalus pacifcus (syn. Diphyllobothrium pacificum) is a causative agent of diphyllobothriosis occurred in Pacific coast of South America, mainly in Peru. Source of infections are traditional meal from raw or undercooked marine fish such as "cebiche". We confirmed 3 new cases, one including scolex and the other two headless. A strobila 46 cm long without scolex was discharged from an 8-year-old boy before treatment. Specimens were confirmed morphologically by presence of tegumental protuberances on proglottids and small sized eggs. Partial sequence of cytochrome c oxidase subunit 1 gene was congruent with A. pacificus sequences.

Caracterización del patrón proteico y perfil antigénico de larvas L 3 de anisákidos de importancia médica aisladas de peces comerciales de la costa peruana / Characterization of the protein pattern and antigen profile of L 3 larvae of medical importance in anisakids isolated from commercial fish of the peruvian coast

RESUMEN Introducción. La anisakidosis es una zoonosis causada por la ingestión accidental de larvas (L3) de anisákidos. Objetivo. Caracterizar el patrón proteico y perfil antigénico de la L3 de Anisakis simplex s.l. (tipo I), A. physeteris s.l. (tipo II) y Contracaecum osculatum s.l. aisladas de peces comerciales. Métodos. Se realizó una corrida electroforética en SDS-PAGE de los antígenos somáticos. Se inmunizó conejos experimentalmente y se evaluó por EITB. Resultados. El patrón proteico de Anisakis tipo I mostró 12 bandas, 18 Anisakis tipo II y C. osculatum 13, con las bandas 10 y 35 kDa específicas para Anisakis tipo II, 28 y 77 para C. osculatum no presentes en Anisakis tipo I. Conclusión. Se determinó bandas inmunogénicas específicas para Anisakis tipo I con las proteínas de peso molecular 11, 14, 25 y 40 kDa, para el tipo II de 9, 10, 12, 35 y 41 kDa, y C. osculatum 13, 15, 17, 30 y 47 kDa.

ABSTRACT Introduction. Anisakidosis is a zoonosis caused by accidental ingestion of anisakid larvae (L3). Objective. To characterize the protein pattern and antigenic profile of the L3 of Anisakis simplex s.l. (type I), A. physeteris s.l. (type II) and Contracaecum osculatum s.l. commercial3 fish isolated. Methods. An SDS-PAGE electrophoretic run of the somatic antigens was performed. Rabbits were immunized experimentally and evaluated by EITB. Results. The protein pattern of Anisakis type I showed 12 bands, 18 Anisakis type II and C. osculatum 13, with bands 10 and 35 kDa specific for Anisakis type II, 28 and 77 for C. osculatum, not present in Anisakis type I. Conclusion. Specific immunogenic bands were determined for Anisakis type I with the molecular weight proteins 11, 14, 25 and 40 kDa, for type II of 9, 10, 12, 35 and 41 kDa and C. osculatum 13, 15, 17, 30 and 47 kDa.

Biomechanics of graded running: Part II-Joint kinematics and kinetics.

Compared to level running (LR), different strategies might be implemented by runners to cope with specific challenges of graded running at different speeds. The changes in joint kinetics and kinematics associated with graded running have been investigated, but their interactions with speed are unknown. Nineteen participants ran on an instrumented treadmill at five grades (0°, ±5° and ± 10°) and three speeds (2.50, 3.33 and 4.17 m/s), while 3D motion and forces were recorded. Three speed × five-grade repeated-measures ANOVA was used to analyze kinetic and kinematic variables. A speed × grade interaction was observed for hip range of motion (ROM). Downhill running (DR) at fastest speed did not reduce ROM at the hip, compared to LR. Compared to LR, it was observed that the hip joint was responsible for a greater contribution of energy generation while running at the fastest speed at +10°. Speed × grade interactions were also observed for the energy absorption, peak moment, and peak power at the knee. Contrary to LR, running faster during UR did not require higher peak power at the knee. Finally, DR at the fastest speed did not increase peak negative power at the knee compared to LR. This study demonstrates that ankle, knee, and hip joint kinetics depend on speed and grade of running, while the effect of grade on joint kinematics was not substantially modulated by speed.

Biomechanics of graded running: Part I - Stride parameters, external forces, muscle activations.

Biomechanical alterations with graded running have only been partially quantified, and the potential interactions with running speed remain unclear. We measured spatiotemporal parameters, ground reaction forces, and leg muscle activations (EMG) in nineteen adults (10F/9M) running on an instrumented treadmills at 2.50, 3.33, and 4.17 m·s-1 and 0, ±5°, and ±10°. Step frequency illustrated a significant speed × grade interaction (P < .001) and was highest (+3%) at the steepest grade (+10°) and fastest speed (4.17 m·s-1 ) when compared to level running (LR) at the same speed. Significant interaction was also observed for ground reaction forces (all P ≤ .047). Peak ground reaction forces in the normal direction increased with running speed during downhill running (DR) only (+9% at -10° and 4.17 m·s-1 ). Impulse in the normal direction decreased at fastest speed and steepest DR (-9%) and uphill running (UR) (-17%) grades. Average normal loading rate increased and decreased at fastest speed and steepest DR (+52%) and UR (-28%) grades, respectively. Negative parallel impulse increased and decreased at fastest speed and steepest DR (+166%) and UR (-90%), respectively. Positive parallel impulse decreased and increased at fastest speed and steepest DR (-75%) and UR (+111%), respectively. EMG showed comparable u-shaped curves across the grades investigated, although only a change in vastus lateralis and tibilias anterior activity was detectable at the steepest grades and fastest speed. Overall, running grade and speed significantly influences spatiotemporal parameters, ground reaction forces, and muscle activations.