Background:
There is disagreement in the literature regarding whether the excessive excursion or velocity of rearfoot eversion is related to the development of 2 common running injuries: Achilles ...tendinopathy (AT) and medial tibial stress syndrome (MTSS). An alternative hypothesis suggests that the duration of rearfoot eversion may be an important factor. However, the duration of eversion has received relatively little attention in the biomechanics literature.
Hypothesis:
Runners with AT or MTSS will demonstrate a longer duration of eversion but not greater excursion or velocity of eversion compared with healthy controls.
Study Design:
Controlled laboratory study.
Methods:
Forty-two runners participated in this study (13 with AT, 8 with MTSS, and 21 matched controls). Participants were evaluated for lower extremity alignment and flexibility, after which a 3-dimensional kinematic and kinetic running gait analysis was performed. Differences between the 2 injuries and between injured and control participants were evaluated for flexibility and alignment, rearfoot kinematics, and 3 ground-reaction force metrics. Binary logistic regression was used to evaluate which variables best predicted membership in the injured group.
Results:
Injured participants, compared with controls, demonstrated higher standing tibia varus angles (8.67° ± 1.79° vs 6.76° ± 1.75°, respectively; P = .002), reduced static dorsiflexion range of motion (6.14° ± 5.04° vs 11.19° ± 5.10°, respectively; P = .002), more rearfoot eversion at heel-off (–6.47° ± 5.58° vs 1.07° ± 2.26°, respectively; P < .001), and a longer duration of eversion (86.02% ± 15.65% stance vs 59.12% ± 16.50% stance, respectively; P < .001). There were no differences in the excursion or velocity of eversion. The logistic regression (χ2 = 20.84, P < .001) revealed that every 1% increase in the duration of eversion during the stance phase increased the odds of being in the injured group by 1.08 (95% CI, 1.023-1.141; P = .006).
Conclusion:
Compared with healthy controls, runners currently symptomatic with AT or MTSS have a longer duration of eversion but not greater excursion or velocity of eversion.
Clinical Relevance:
Static measures of the tibia varus angle and dorsiflexion range of motion, along with dynamic measures of the duration of eversion, may be useful for identifying runners at risk of sustaining AT or MTSS.
Grid cells in the medial entorhinal cortex have spatial firing fields that repeat periodically in a hexagonal pattern. When animals move, activity is translated between grid cells in accordance with ...the animal's displacement in the environment. For this translation to occur, grid cells must have continuous access to information about instantaneous running speed. However, a powerful entorhinal speed signal has not been identified. Here we show that running speed is represented in the firing rate of a ubiquitous but functionally dedicated population of entorhinal neurons distinct from other cell populations of the local circuit, such as grid, head-direction and border cells. These 'speed cells' are characterized by a context-invariant positive, linear response to running speed, and share with grid cells a prospective bias of ∼50-80 ms. Our observations point to speed cells as a key component of the dynamic representation of self-location in the medial entorhinal cortex.
Achilles tendinopathy and patellofemoral pain are common running injuries associated with increased Achilles tendon (AT) forces and patellofemoral joint (PFJ) stresses. This study examined AT forces ...and PFJ stresses at different running speeds in high‐performing endurance runners. Twenty runners ran overground at four running speeds (3.3, 3.9, 4.8, and 5.6 m/s). AT forces and PFJ stresses were estimated from kinematic and kinetic data. Repeated measures ANOVA with partial eta squared effect sizes was conducted to assess differences between running speeds. Increased peak AT forces (19.5%; p < 0.001) and loading rates (57.3%; p < 0.001) from 3.3 m/s to 5.6 m/s were observed. Cumulative AT loading was greater in the faster speeds compared to the slower speeds. Faster running speeds resulted in increased peak plantar flexor moments, increased peak plantar flexion angles, and a more flexed knee and an anterior center of pressure position at touchdown. Peak PFJ stress was lower in the slowest speed (3.3 m/s) compared to the faster running speeds (3.9–5.6 m/s; p = 0.005). PFJ stress loading rate significantly increased (43.6%; p < 0.001). Greater AT loading observed could be associated with strategies such as increased plantar flexor moments and altered lower body position at touchdown which are commonly employed to generate greater ground contact forces. Greater AT and PFJ loading rates were likely due to shorter ground contact times and therefore less time available to reach the peak. Running at faster speeds could increase the risk of developing Achilles tendinopathy and patellofemoral pain or limit recovery from these injuries without sufficient recovery.
The health benefits from participation in half-marathon is challenged by a yearly running-related injury (RRI) incidence proportion exceeding 30%. Research in injury etiology is needed to ...successfully prevent injuries. The body’s load capacity is believed to play an essential role for injury development. Therefore, the purpose of ProjectRun21 was to investigate the association between load capacity defined as running experience and running pace, and RRI when following a specific half-marathon running schedule.
A 14-week prospective cohort study.
A cohort of 784 healthy runners followed a specific half-marathon running schedule. Data on running activity was collected objectively using a Global-Positioning-System watch or smartphone. RRI were collected using e-mail-based weekly questionnaires. Primary exposures were running experience and running pace, dichotomized into a high and a low group for runners running less or more than 15km/week and faster or slower than 6min/km, respectively. Data was analyses through time-to-event models with cumulative risk difference (RD) as measure of association.
A total of 136 participants sustained a RRI during follow-up. Although not statistically significant, all estimates indicate a tendency toward fewer injuries amongst runners categorized as having high experience (RD=−11.3% (−27.2% to 4.6%)) or high pace (RD=−17.4% (−39.0% to 4.5%)), and a combination of both high experience and high pace (RD=−8.1% (−22.3% to 6.1%)) compared with their counterpart peers.
Runners covering less than 15km per week, and/or runs slower than 6min/km, may sustain more RRI than their counterpart runners.
El objetivo del estudio fue determinar el efecto de la densidad de siembra en las características fitosanitarias y agronómicas de genotipos promisorios de maní, en Quevedo, Ecuador. Se utilizaron las ...líneas promisorias de maní CB-02, CB-16 y CB-23, tipo Runner, con distanciamiento estándar de 0,50 m entre hileras y una población de 3,6; 5 y 10 plantas m.sup.-1 para cada cultivar. Se cuantificó la intensidad de cercosporiosis y roya, así también las variables agronómicas altura de la planta, número de frutos y de semillas, peso de frutos por planta de 1000 semillas, frutos por parcela, y rendimiento de frutos (kg ha.sup.-1). Fue empleado un Diseño de Bloques Completos al Azar con nueve tratamientos y cuatro réplicas, con arreglo factorial 3 (líneas) x 3 (plantas m.sup.-1). Para la comparación entre las medias de los tratamientos se empleó la prueba de Tukey al 5 % de probabilidad del error. La línea de maní CB-23 obtuvo menor número de lesiones para cercosporiosis y roya. Con 3,6 y 5 plantas m.sup.-1 fue obtenido el mayor número de frutos por planta (321,83 y 286,50, respectivamente), y con 10 plantas m.sup.-1, la mayor altura de planta (47,24 cm), peso de frutos por parcela (2,00 kg) y rendimiento de frutos (1809,42 kg ha.sup.-1). Se observó interacciones entre los factores, solamente para el número de frutos por planta (p<0,05) y para el rendimiento (p<0,01), mostrando dependencias entre ellos. Palabras clave: Arachis hypogaea, densidad de plantas, cercosporiosis, roya, rendimiento The aim of this study was to determine the effect of seeding density on sanitary and agronomic characteristics of promising peanut genotypes, in Quevedo, Ecuador. The following promising peanut lines were used: CB-02, CB-16 and CB-23, Runner type, with a standard distance of 0,50 m between rows and 3,6; 5 and 10 plants m.sup.-1 for each cultivar. The disease intensity of leaf spot and rust were determined, furthermore, agronomic variables such as plant height, number of pods and seeds, pod weight per plant, weight of 1000 seeds, weight of pods per parcel and pod yield (kg ha.sup.-1). The experiment was carried on a Completely Randomized Block design with 9 treatments and four replications, using a factorial arrangement 3 (lines) x 3 (plants m.sup.-1). Tukey's test at 5% of significance level was used for separation of means. The smallest number of leaf spot and rust lesions was observed on the peanut line CB-23. On the one hand, at plant densities of 3,6 and 5 plants m.sup.-1 lead to the highest number of pods per plant (321,83 and 286,50 respectively). On the other hand, the highest plant height (47,24 cm), weight of pods per parcel (2,00 kg) and pod yield (1809,42 kg ha.sup.-1) were observed at 10 plants m.sup.-1. The interaction between factors was significant for the following variables: number of seeds per plant (p<0,05) and yield (p<0,01), showing the dependence between the analyzed factors. Key words: Arachis hypogaea, seed density, leaf spot, rust, yield
The speed is an essential physical ability for the futsal athlete, being related to various physical actions during the game. This can manifest in three ways: reaction speed; acceleration and ...acyclic. The speed training can occur in various ways and among them include training through repeated sprints and reduced games. The aim of this study was to investigate by reviewing the literature the influence of training with sprints and games reduced in relation to the improvement of the running speed of futsal players, represented by the development of the running speed. It was observed that both training methodologies potentiate the development of the running speed of futsal players, the most significant gains being related to the competitive period. Key words: Training. Speed. Futsal. A velocidade e uma capacidade fisica imprescindivel para o atleta de futsal, estando relacionada com varias acoes fisicas realizadas durante o jogo. Esta pode se manifestar de tres formas: velocidade de reacao; de aceleracao e aciclica. O treinamento da velocidade pode ocorrer de diversas maneiras e dentre elas destacamos o treinamento atraves de sprints repetidos e com jogos reduzidos. O objetivo do presente estudo foi investigar atraves da revisao da literatura a influencia do treinamento com sprints e jogos reduzidos na relacao com a melhora da velocidade de corrida de jogadores de futsal, representada pelo desenvolvimento da velocidade de corrida. Foi observado que ambas as metodologias de treinamento potencializam o desenvolvimento da velocidade de corrida de jogadores de futsal, sendo os ganhos mais expressivos estando relacionados ao periodo competitivo. Palavras-chave: Treinamento. Velocidade. Futsal.
The purpose of this study was to classify runners in sex-specific groups as either competitive or recreational based on center of mass (CoM) accelerations. Forty-one runners participated in the study ...(25 male and 16 female), and were labeled as competitive or recreational based on age, sex, and race performance. Three-dimensional acceleration data were collected during a 5-minute treadmill run, and 24 features were extracted. Support vector machine classification models were used to examine the utility of the features in discriminating between competitive and recreational runners within each sex-specific subgroup. Competitive and recreational runners could be classified with 82.63 % and 80.4 % in the male and female models, respectively. Dominant features in both models were related to regularity and variability, with competitive runners exhibiting more consistent running gait patterns, but the specific features were slightly different in each sex-specific model. Therefore, it is important to separate runners into sex-specific competitive and recreational subgroups for future running biomechanical studies. In conclusion, we have demonstrated the ability to analyze running biomechanics in competitive and recreational runners using only CoM acceleration patterns. A runner, clinician, or coach may use this information to monitor how running patterns change as a result of training.
A number of studies have shown that attentional focus instructions can effect running economy. This study assessed spiroergometry, as well as running kinematics as a possible mechanism to explain ...these effects. Twelve runners had to focus their attention on either their running movement, their breathing or on a video while running on a treadmill at a set, submaximum speed. Spiroergometry and running kinematics were measured. Results revealed worse running economy in both internal focus conditions (breathing and movement) compared to the external focus condition (video), replicating previous findings. In addition, vertical oscillation during the running movement was elevated in the movement compared to the video condition, indicating a less efficient running style. No changes in kinematics were found for the breathing compared to the video condition. Therefore, consciously focusing on the running movement moves runners away from their optimised running pattern and leads to detriments in economy. The decreases in running economy in the breathing condition can be better explained by changes in breathing patterns.
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