Changes in rearfoot strike patterns over childhood: A 3-year prospective longitudinal cohort study.

Rearfoot strike (RFS) in children running produces impact forces that give rise to a transient stress wave traveling through the body. It could contribute to the development of injuries. The purpose of this study was to determine RFS prevalence during childhood while running at a self-selected velocity in a prospective longitudinal cohort study. A total of 175 children (68 girls), aged 6 to 14 years, participated in this study. The sample was divided into three age groups (age in 2016): 6-8 years, 9-11 years, and 12-14 years, which were analysed again three years later (2019). A 2D video-based analysis was used to record the RFS. Taking into account all samples, in the jogging trial the prevalence of RFS (an average of both feet) was 86.9% in 2016 and 94.7% three years later; in the running trial the prevalence was 82.6 and 94.4%, respectively. In all samples a significant increase of RFS prevalence was found in both the jogging and running trials for both feet over three years (jogging, left foot, p=.011, right foot, p=.023; running, left foot, p=.001, right foot, p<.001). In girls, there were no significant differences in any conditions. In boys, a significant increase of RFS prevalence was found after three years in both feet (p<.01) in the running trial. This study shows that RFS prevalence in children increases with age and the results may be used to characterize typical running development in children population

Dependencia al ejercicio físico e insatisfacción corporal en diferentes deportes de resistencia y su relación con la motivación al deporte

El objetivo de este estudio es analizar la dependencia al ejercicio físico e insatisfacción corporal de deportistas de resistencia y su relación con la motivación al ejercicio físico. Participaron 126 hombres (M = 36.02 ± 10.62 años) y 23 mujeres (M = 28.18 ± 8.65 años) que practican: carrera de fondo, natación, triatlón y ciclismo. En la muestra total, la prevalencia de dependencia al ejercicio físico fue de un 13.6% y de insatisfacción corporal de un 16.3 %. Los triatletas presentan mayor prevalencia de dependencia al ejercicio físico, con diferencias significativas en relación con los corredores. La regulación introyectada es un factor predictivo común a la dependencia al ejercicio físico y a la insatisfacción corporal.The objective of this study is to analyse dependence on exercise and body dissatisfaction in endurance athletes and its relation with motivation to do sports. 126 men (M= 36.02 ± 10.62 years) and 23 women (M = 28.18 ± 8.65 years) took part who did: long-distance running, swimming, triathlon and cycling. In the total sample, the prevalence of exercise dependence was 13.6% and body dissatisfaction was 16.3%. For exercise dependence, triathletes showed higher scores with significant differences when compared to the runners. Introjected regulation is a common predictor for exercise dependence and body dissatisfaction.O objectivo deste estudo é analisar a dependência do exercício físico e insatisfação corporal de desportistas de resistência e a sua relação com a motivação para o exercício físico. Participaram 126 homens (M = 36.02 ± 10.62 anos) y 23 mulheres (M = 28.18 ± 8.65 anos) que praticam: corrida de fundo, natação, triatlo e ciclismo. Na amostra total, a prevalência de dependência do exercício físico foi de 13.6% e de insatisfação corporal de 16.3%. Os triatletas apresentam maior prevalência de dependência do exercício físico, com diferenças significativas em relação aos corredores. A regulação introjectada é um factor preditivo comum à dependência do exercício físico e à insatisfação corporal

S-Like Ribonuclease T2 Genes Are Induced during Mobilisation of Nutrients in Cotyledons from Common Bean

Germination and seedling development are crucial phases in a plant’s life cycle with economical and agronomical implications. The RNA quality in seeds is linked to seed viability, being an important agronomic trait since this leads to a loss in germination efficiency. In addition, RNA can be an important phosphorous reservoir in seeds, affecting the efficiency of the mobilisation of nutrients towards the seedlings. However, knowledge about the physiological function of ribonucleases during germination and seedling development is scarce. We analysed the ribonuclease activities of cotyledons during these processes and the expression of S-like ribonucleases T2. Ribonuclease activity was detected in cotyledons at 1 day after imbibition and the specific activity increased during germination and seedling development, reaching a maximal value at 10 days after imbibition. At this stage, the levels of proteins and RNA in cotyledons were very low. Using in-gel assays, three ribonucleases were detected with apparent molecular masses of 16, 17 and 19 kDa along cotyledon ontogeny. The S-like ribonucleases T2 family consists of four genes in common bean (PvRNS1 to PvRNS4). The expression of PvRNS1, PvRNS2 and PvRNS4 increased in the phase of nutrient mobilisation in cotyledons. The expression of PvRNS1 increased 1000 fold in cotyledons, from 1 to 6 days after imbibition. The suppression of the induction of ribonuclease activity and gene expression in decapitated seedlings suggests that the regulatory signal comes from the developing axes. These results clearly state that S-like ribonucleases T2 are involved in RNA turnover in cotyledons during seedling development

Anaerobic Speed Reserve, Sprint Force–Velocity Profile, Kinematic Characteristics, and Jump Ability among Elite Male Speed-and Endurance-Adapted Milers

This study aimed to compare sprint, jump performance, and sprint mechanical variables between endurance-adapted milers (EAM, specialized in 1500–3000-m) and speed-adapted milers (SAM, specialized in 800–1500 m) and to examine the relationships between maximal sprint speed (MSS), anaerobic speed reserve (ASR), sprint, jump performance, and sprint mechanical characteristics of elite middle-distance runners. Fifteen participants (8 EAM; 7 SAM) were evaluated to obtain their maximal aerobic speed, sprint mechanical characteristics (force–velocity profile and kinematic variables), jump, and sprint performance. SAM displayed greater MSS, ASR, horizontal jump, sprint performance, and mechanical ability than EAM (p < 0.05). SAM also showed higher stiffness in the 40-m sprint (p = 0.026) and a higher ratio of horizontal-to-resultant force (RF) at 10 m (p = 0.003) and RFpeak (p = 0.024). MSS and ASR correlated with horizontal (r = 0.76) and vertical (r = 0.64) jumps, all sprint split times (r ≤ −0.85), stiffness (r = 0.86), and mechanical characteristics (r ≥ 0.56) during the 100-m sprint, and physical qualities during acceleration (r ≥ 0.66) and sprint mechanical effectiveness from the force–velocity profile (r ≥ 0.69). Season-best times in the 800 m were significantly correlated with MSS (r = −0.86). Sprint ability has a crucial relevance in middle-distance runners’ performance, especially for SA

The variability of strength production capacities during a judo contest

Background. The muscular response of athletes in a judo contest is one of the most important aspect to measure with precision. Objective. Our purpose was to obtain and analyse the variability of strength associated to muscular performance parameters during a judo contest. Methods. Thirty-five men performed five 5-minute bouts with 15 minutes of passive rest. Immediately after each bout, muscular performance parameters were tested: countermovement jump (CMJ), maximal dynamic strength capacities (mean power velocity (MPV), mean strength (MS), maximum strength (MXS), mean power (MP) and maximum power (MXP)) in upper body, dominant (DHS) and non-dominant handgrip isometric strength (NDHS). ANOVA to compare baseline test data and successive bouts was used. Results. ANOVA revealed significant differences in NDHS (p<0.001), DHS (p<0.001), CMJ (p<0.001), MPV (p<0.001), MXS (p<0.001), MP (p<0.001) and MXP (p<0.001). No significant differences in MS (p = 0.008) were found. Some significant correlations between NDHS and ΔPMX (r=0.368, p=0.050), MPV and ΔMXS (r=0.528, p=0.001) and ΔMXP (r=0.683, p<0.001), MPX and ΔMXS (r=0.528, p=0.001) and ΔMP (r=0.877, p<0.001) were found. Conclusion. Due to judo contest can be considered a high intensity exercise, it produces an amount of muscular fatigue and therefore significant loss strength that it cannot be recovery during rest-times between successive bouts. For this reason, it was a high variability in strength production capacities, which are modified during a judo contest

Geometry and kinematics of the Baza Fault (central Betic Cordillera, South Spain): insights into its seismic potential

The geometry and kinematics of active faults have a significant impact on their seismic potential. In this work, a structural characterization of the active Baza Fault (central Betic Cordillera, southern Spain) combining surface and subsurface data is presented. Two sectors are defined based on their surface geometry: a northern sector striking N–S to NNW–SSE with a narrow damage zone and a southern sector striking NW–SE with a wide damage zone. A kinematic analysis shows pure normal fault kinematics along most of the fault. Geometric differences between the northern and southern sectors are caused by i) a heterogeneous basement controlling the fault geometry at depth and in the cover; ii) different orientations of the Baza Fault in the basement with respect to the regional extension direction and iii) interaction with other active faults. We use this structural characterization to analyse the segmentation of the Baza Fault. According to segmentation criteria, the entire Baza Fault should be considered a single fault seismogenic segment. Consequently, the seismic potential of the fault is defined for a complete rupture. Magnitude for the Mmax event is calculated using several scale relationships, obtaining values ranging between Mw 6.6 and Mw 7.1. Recurrence times range between approximately 2,000 and 2,200 years for Mmax events and between 5,300 and 5,400 years for palaeo-events. A geodetic scenario modelled for an Mmax event of Mw 6.7 shows permanent vertical displacements of more than 0.40m and an overall WSW–ENE extension during entire ruptures of the Baza Fault.This work was funded by the research project TASCUB (RTI2018-100737-B-I00) of the Spanish Ministry of Science, Innovation and Universities, the research group VIGROB053 (University of Alicante), the research project AICO/2019/040 of the Generalitat Valenciana (Valencia regional government), and the research group RNM-325 of the Junta de Andalucía (Andalucia regional government). Iván Medina Cascales was funded by Ph.D. contract FPU16/00202 of the Spanish Ministry of Science, Innovation and Universities. Research partially funded by the Programa Operativo FEDER Andalucía 2014-2020-call made by the University of Jaén 2018

Force–velocity profiles in CrossFit athletes: A cross-sectional study considering sex, age, and training frequency

Introduction: The force–velocity profile has been analysed previously in different sports modalities; nevertheless, it has not been analysed in CrossFit. Objective: The aim of this study was to report neuromuscular characteristics of CrossFit athletes using their individual force-velocity profile, investigating differences according to sex, age, and training frequency. Materials and Meth-ods: 72 males (33.17 ± 6.86 years; BMI: 25.93 ± 3.64 kg/m2) and 18 females (30.11 ± 6.92 years; BMI: 23.53 ± 3.98 kg/m2) participated in this study. The force-velocity profile was calculated using Samo-zino’s method. Furthermore, neuromuscular characterization was completed with a squat jump and three drop jumps (20, 30, and 40 cm). Results: Regarding sex, significant differences in all analysed mechanical variables (p < 0.001) were found except for the theoretical maximal force (p = 0.944). No significant differences were found between age groups. Considering training frequency, athletes who train more than 5 days per week showed higher performance in all analysed mechanical variables (p < 0.05). Conclusion: CrossFit athletes have a force-velocity profile more oriented towards velocity than force. Males and females have different neuromuscular characteristics, also neuromus-cular improvements can be achieved at any age. Moreover, higher neuromuscular performance is developed with a training frequency of 5 days or more per week

Sponyloarthritis features forecasting the presence of HLA-B27 or sacroiliitis on magnetic resonance imaging in patients with suspected axial spondyloarthritis: Results from a cross-sectional study in the ESPeranza Cohort

Introduction: Chronic back pain (CBP) is frequently the presenting symptom in patients with suspected axial spondyloarthritis (axSpA). Presence of sacroiliitis on magnetic-resonance-imaging (MRI) or HLA-B27 adds to diagnostic certainty. However, these costly tests cannot be applied in all patients with CBP. This study aims to investigate which SpA features increase the likelihood of a positive HLA-B27 or positive MRI of the sacroiliac-joints (MRI-SI) in patients with suspected axSpA. Methods: Data from 665 patients with CBP within the ESPeranza Programme were analysed. Diagnostic utility measures (LR+, LR−) for a positive MRI-SI or HLA-B27 were calculated for various definitions of inflammatory back pain (IBP), their separate items and for other SpA features. Results: Pretest probabilityies of a positive result was 41 % for MRI-SI and 40 % for HLA-B27. For a positive MRI-SI result the most useful IBP characteristic was alternating buttock pain (LR + =2.6). Among the IBP-criteria, fulfillment of the ‘ASAS criteria’ (LR + =2.1) was most contributory. Interestingly, the addition of alternating buttock pain to the Calin/ASAS-IBP criteria (LR + =6.0 and 5.5, respectively) or the addition of awakening at second half of night to the Calin-IBP criteria (LR + =5.5) increased the pre-test probability of MRI-sacroiliitis from 41 % to 79–80 %. Dactylitis (LR + =4.1) and inflammatory bowel disease (IBD) (LR + =6.4) increased this probability to 73 % and 81 %, respectively. To forecast HLA-B27 positivity, awakening at the second half of the night, fulfillment of the ASAS-IBP definition and uveitis were the most useful, but only marginally predictive (LR + = 1.3, 1,6 and 2.6, respectively). Conclusions: If patients with suspected axial SpA have either 1) IBP according to Calin/ASAS definition plus alternating buttock pain, or 2) IBP according to Calin definition plus awakening at night, or 3) dactylitis or 4) IBD, the probability of finding a positive MRI-SI increases significantlyVNC received one of the ASAS research grants on call 2013 to perform this study. The Spanish Foundation of Rheumatology received funding from Pfizer to develop the Esperanza Programme. Nowadays, the programme is supported by a restricted grant of the Institute Carlos III (FIS PI13/02034)

Load that maximizes power output in countermovement jump

Introduction: One of the main problems faced by strength and conditioning coaches is the issue of how to objectively quantify and monitor the actual training load undertaken by athletes in order to maximize performance. It is well known that performance of explosive sports activities is largely determined by mechanical power. Objective: This study analysed the height at which maximal power output is generated and the corresponding load with which is achieved in a group of male-trained track and field athletes in the test of countermovement jump (CMJ) with extra loads (CMJEL). Methods: Fifty national level male athletes in sprinting and jumping performed a CMJ test with increasing loads up to a height of 16 cm. The relative load that maximized the mechanical power output (Pmax) was determined using a force platform and lineal encoder synchronization and estimating the power by peak power, average power and flight time in CMJ. Results: The load at which the power output no longer existed was at a height of 19.9 ± 2.35, referring to a 99.1 ± 1% of the maximum power output. The load that maximizes power output in all cases has been the load with which an athlete jump a height of approximately 20 cm. Conclusion: These results highlight the importance of considering the height achieved in CMJ with extra load instead of power because maximum power is always attained with the same height. We advise for the preferential use of the height achieved in CMJEL test, since it seems to be a valid indicative of an individual's actual neuromuscular potential providing a valid information for coaches and trainers when assessing the performance status of our athletes and to quantify and monitor training loads, measuring only the height of the jump in the exercise of CMJEL.Actividad Física y Deport