Peripheral and central fatigue cause similar decreases on dynamic postural stability in male recreational runners.

Decreased dynamic postural stability could be linked to a great number of injuries. Moreover, fatigue -both central and peripheral- may diminish dynamic postural stability and have an impact on injuries. Therefore, the main objectives of our study were to identify and compare the effects of central and peripheral fatigue on dynamic postural stability. The Modified Star Excursion Balance Test (mSEBT) in anterior, posterolateral and posteromedial directions was performed in eighteen male recreational runners before and after a central or peripheral fatigue protocol. Central fatigue was induced by a 30-minute run at 85% of maximal aerobic speed on a treadmill, while a localized fatigue protocol in quadriceps and hamstrings muscles using an isokinetic dynamometer was performed to cause peripheral fatigue. Our results indicate that the maximum and average reached distance in anterior, posterolateral, posteromedial and summation of three directions were decreased by both central and peripheral fatigue (p 0.05). Thus, dynamic postural stability was decreased by peripheral and central fatigue in recreational runners, and both have similar effects on mSEBT performance

Effects of a training program on stable vs unstable surfaces on postural stability.

The training surface can modulate the body's response to training stimuli. The purpose of the article was to determine the influence of two types of training programs on stable/unstable surfaces on postural stability. 20 physically active participants with no history of lower limb injuries were randomly assigned to 3 groups (Control, Unstable Training, Stable Training), and performed supervised training in 16 sessions. Dynamic postural stability and static stability were assessed and tests were performed at baseline after completion of the training and 1, 2 and 4 weeks after the training process. The stable surface training group improved dynamic stability between the pre-test and the two first retention tests performed (p = .037, d = .780; p = .011, d = .989). The unstable training group significantly improved its dynamic stability level between the post-test and the retention test (2). The improvements found after the training session for the unstable training group do not mean an increase in stability higher than that obtained by the stable surface training group. The dynamic postural stability test seems more appropriate than the static tests for analyzing small changes related to the training of postural stability in healthy young people

Impact acceleration during prolonged running while wearing conventional versus minimalist shoes.

Purpose: In recent years a sub-group of minimalist runners have emerged who aim to perform physical exercise more naturally in an attempt to reduce running-related injuries. Here we aimed to determine the effect that running with minimalist footwear in a prolonged run has on footimpact accelerations. Method: Seventeen runners ran with minimalist and conventional shoes (MS and CS, respectively) in two separate sessions; the participants had experience with both footwear types. We measured the length and frequency of each stride, as well as the tibial and head impact acceleration every 5 minutes during a prolonged run (30 minutes at 80% of each individual's maximum aerobic speed). Results: There were significant differences in the acceleration rate in the tibia (CS: 516.1 ± 238.47 G/s and MS: 786.6 ± 238.45 G/s; p = .009) and head (CS: 73.3 ± 23.65 G/s and MS: 120.7 ± 44.13 G/s; p = .000). Our data indicate that the type of footwear increased the stride frequency and decreased length and that the impact acceleration is increased with MS compared to CS (p < .05 in both cases). However, the effect of prolonged run was not significantly different between CS and MS (p < .05). Conclusions: The peak tibia acceleration and headtibia acceleration rate indicate that the use of MS may be related to a higher risk of injury. These differences remained independently of the runners' fatigue stat

Effects of central and peripheral fatigue on impact characteristics during running

Fatigue and impact can represent an injury risk factor during running. The objective of this study was to compare the impact transmission along the locomotor system between the central and peripheral fatigued states during running. Tibial and head acceleration as well as shock attenuation in the time- and frequency-domain were analyzed during 2-min of treadmill running in the pre- and post-fatigue state in eighteen male popular runners (N = 18). The impact transmission was measured before and after a 30-min central fatigue protocol on the treadmill or a peripheral fatigue protocol in the quadricep and hamstring muscles using an isokinetic dynamometer. The time-domain acceleration variables were not modified either by peripheral or central fatigue (p > 0.05). Nevertheless, central fatigue increased the maximum (p = 0.006) and total (p = 0.007) signal power magnitude in the high-frequency range in the tibia, and the attenuation variable in the low- (p = 0.048) and high-frequency area (p = 0.000), while peripheral fatigue did not cause any modifications in the frequency-domain variables (p > 0.05). Furthermore, the attenuation in the low (p = 0.000)- and high-frequency area was higher with central fatigue than peripheral fatigue (p = 0.003). The results demonstrate that central fatigue increases the severity of impact during running as well as the attenuation of low and high components

Methodology to quantify the effect of policies and measures in emission reductions from road transport

Atmospheric emissions from road transport have increased all around the world since 1990 more rapidly than from other pollution sources. Moreover, they contribute in more than 25% to total emissions, in the majority of European countries. This situation confirms the importance of road transport when complying with emission ceilings (e.g. Kyoto Protocol and National Emissions Ceilings Directive). The developed methodology illustrates the effect on transport emissions of the most influential variables and their relationships. Therefore, it would be a policy instrument to design emission reduction measures. Firstly, the influence of the main variables was studied: mileage or mobility (passengers or tonnes) per vehicle type (cars, buses, light duty vehicles, heavy duty vehicles, mopeds, and motorcycles); fuel used (diesel, petrol, biofuels, natural gas, and LPG); driving mode (urban, rural, and highway) and vehicle speed; technology used (Euro types, hybrid vehicles, and electric vehicles by power); vehicle characteristics (power, load factor, age, operational life, etc.). The second step consisted of defining several scenarios, changing the variables in order to analyze both the individual and combined effect of these on emissions (sensitivity analysis). These scenarios evaluate the effect of changes in the previous factors, according to realistic policies and measures (e.g. penetration of Euro 5 and 6, increase of biofuel use, scrapping systems, etc.) The third step included the development of an holistic model to estimate emissions which allows the quantification of the effect of both technical and non technical measures. The model is called EmiTRANS and it estimates the emissions in a flexible and coherent way. It contributes to incorporate scientific data on decision making process. Finally, this methodology has been successfully proven for the calculation of emission projections from road transport in Spain, up to 2020 under several scenarios

Quantification of the effect of both technical and non-technical measures from road transport on Spain's emissions projections

Atmospheric emissions from road transport have increased all around the world since 1990 more rapidly than from other pollution sources. Moreover, they contribute to more than 25% of total emissions in the majority of the European Countries. This situation confirms the importance of road transport when complying with emission ceilings (e.g. Kyoto Protocol and National Emissions Ceilings Directive). A methodology has been developed to evaluate the effect of transport measures on atmospheric emissions (EmiTRANS). Its application to Spain in the horizon of 2020 allows the quantification of the effect of several measures on emission reductions. This quantification was done through scenario development. Several scenarios were calculated considering technical measures (e.g. vehicle scrapping systems, higher penetration of hybrid and electric vehicles, fuel substitution, etc.) and non-technical measures (mileage reduction, implementation of Low Emission Zones and/or Congestion Charges in main cities, reduction of average speeds, logistical improvements that affects heavy duty vehicle load factors, etc.). The scenarios show the effect of each measure on NOx, SO2, CO, PM10, PM2.5, VOC, CO2 and CH4 emissions. The main conclusion is the necessity to combine both technical and non-technical measures to increase global effectiveness. In the analysis of specific pollutants, there is a great dispersion on reductions effect: technical measures are more effective to reduce air pollutants while non-technical measures are better options to reduce greenhouse effect gases (even though they also reduce air pollutants in a less efficient way)

Efectos de la lazada de la zapatilla del corredor/a sobre las variables espaciotemporales, el confort, la frecuencia cardiaca y la percepción subjetiva del esfuerzo.

El objetivo fue analizar los efectos del tipo de lazada en las variables espaciotemporales, la frecuencia cardiaca, el confort y la percepción subjetiva del esfuerzo, así como también el efecto del tiempo/fatiga. Se analizaron 24 sujetos, empleando dos tipos de lazadas; a) lazada cruzada convencional y b) lazada 'heel lock'. Todos los participantes realizaron 2 pruebas en días separados y distribuidos de manera aleatoria sobre cinta rodante. La prueba de carrera consistió en un calentamiento previo de 5 min a 8 km/h y posteriormente una prueba de 20 min de carrera a 10 km/h con 1% de pendiente. Los valores de frecuencia cardiaca (p =0.029, ES= 0.199) y el esfuerzo percibido (p<0,001, ES= 0.745) en relación con el instante y el sexo eran mayores hacia el final de la prueba y en mujeres. Por otro lado, en referencia al confort, encontramos diferencias significativas en la lazada, donde los valores fueron significativamente mayores con la 'heel lock'. Finalmente, en las variables espaciotemporales se observan diferencias significativas en función del instante, se incrementó la cadencia (p=0.018, ES=0.183) y descendió la longitud de paso (p=0.019, ES=0.166). Y en función de la lazada en el tiempo de vuelo (p=0.019, ES=0.227), de contacto (p=0.013, ES=0.248), altura (p=0.022, ES=0.217) y ángulo de paso (p=0.024, ES=0.212). En conclusión, la variabilidad de resultados de este estudio muestra que el cambio de tipo de lazada puede variar en gran medida la técnica de carrera y su estudio puede ayudar a reducir el riesgo de lesiones en carrera

Evaluation of impact-shock on gait after the implementation of two different training programs in older adults

Gait is negatively affected with increasing age. It is widely accepted that training produces physical-functional improvements in older adults, which can be assessed with numerous physical-functional tests. However, very few studies have been carried out using accelerometry to analyse the training effect on kinetic and kinematic variables in older adults, and there is no one that investigate the effects of two different training programs. Therefore, the aim of this study is to analyse the effects of an interval-walking program and a multicomponent program on the acceleration impacts, shock attenuation, step-length, stride frequency, and gait speed in older adults. Methods: 23 participants were divided into multicomponent training group [n = 12, 7 female, 71.58 (4.56) years] and interval-walking group [n = 11, 6 female, 69.64 (3.56) years]. We evaluated the participants using three triaxial accelerometers, placing one on the distal end of each tibia and one on the forehead. Findings: After 14 weeks' of training, the maximum acceleration values both for the head accelerometer and for the non-dominant tibia, as well as the attenuation in the same leg, increased in the multicomponent training group. The maximum acceleration values for the head and the stride frequency also increased in the intervalwalking group. Lower limb strength improved in both groups. Interpretation: Given the benefits we found for each of these programs, we encourage their consideration when planning older adults training programs and suggest that multicomponent programs should be introduced prior to the start of walking-based programs

New Echinoid (Spatangoida: Toxasterinidae) from the Campanian of Coahuila, Northeastern Mexico

ABSTRACT Three specimens corresponding to a new echinoid species from the Upper Cretaceous (Lower Campanian) from Austin Formation in the northeastern of Mexico are reported here. The morphology of the specimens (test with a cordiform aboral region) as well as the sedimentary environment reported at the Austin Formation, suggests that this species represents an infaunal and detritivorous dweller living in a shallow water environment within the continental shelf. This is consistent with the more actual knowledge for other species of Diplodetus Keywords: Echinoids, Diplodetus, Upper Cretaceous, Campanian, Austin Formation, NE Mexico. ESUMEN Se reportan tres especímenes de Diplodetus brisenoi, una nueva especie de equinoideo del Campaniano Inferior (Cretácico Superior) de la Formación Austin, en Jiménez, Coahuila, noreste de México. Tanto su morfología (testa con ámbito cordiforme) como el ambiente de depósito reportado para la Formación Austin sugieren que esta especie representa un elemento de la infauna con hábitos detritívoros en ambientes de plataforma, lo cual es consistente con lo reportado para otras especiesdel género Diplodetus. Palabras clave: Equinoideos, Diplodetus, Cretácico Superior, Campaniano, Formación Austin, NE de México

Cambios producidos en ciclistas amateurs sobre la percepción del esfuerzo, confort, cinemática angular y presiones en función del retroceso del sillín e intensidad del ejercicio.

El ciclismo es uno de los deportes más populares en todo el mundo y, uno de los más practicados en España. En este sentido, diferentes estudios han analizado el efecto de la altura del sillín sobre el rendimiento del ciclista, sin embargo, son escasos los estudios que analizan el efecto del retroceso del sillín. El presente trabajo de investigación pretende estudiar el efecto producido sobre el esfuerzo y confort percibido, las presiones en el sillín y en la cinemática angular de la extremidad inferior. Se llevó a cabo una prueba en cicloergómetro empleando 3 retrocesos del sillín (RS): libre, +10%, -10% y dos intensidades del ejercicio (baja y alta). La muestra estuvo compuesta por 34 ciclistas amateurs. El esfuerzo percibido solo fue significativamente mayor por el efecto de la intensidad durante la intensidad alta (p< 0.001, ES= 0.728) En cambio, el confort percibido y la cinemática mostraron diferencias significativas (p< 0.05) en función del retroceso del sillín, la intensidad y el sexo de los ciclistas. Además, también se encontraron diferencias significativas (p< 0.05) en función del retroceso y sexo en las presiones sobre el sillín. Una posición del sillín retrasada (+10%) produce una reducción de los niveles de confort, mayores niveles de extensión de cadera, rodilla y tobillo, así como una mayor presión máxima y media en la región del pubis. En cuanto a la intensidad de pedaleo, una intensidad alta aumenta la percepción del esfuerzo y disminuye los niveles de flexión en las extremidades inferiores