Effects of different contextual interference programs in agility (Efectos producidos por diferentes programas de interferencia contextual en la agilidad)

En este estudio participaron 76 alumnos de 9-10 años de edad de un colegio público de educación primaria (44 chicos y 32 chicas). Los participantes fueron randomizados en función del resultado del pretest en cuatro grupos: interferencia contextual baja (ICB, n=19), interferencia contextual moderada (ICM, n=19) interferencia contextual alta (ICA, n=19) y Grupo Control (GC, n=19). El objetivo de este estudio fue conocer que método de entrenamiento de la agilidad en función de la interferencia contextual baja, moderada o alta (ICB, ICM e ICA) es más efectivo en escolares de cuarto curso de educación primaria, con el fin de dilucidar qué método de desarrollo de esta capacidad resultó el idóneo en esta etapa de escolarización. La agilidad fue evaluada mediante el test MAT2. Salvo en el grupo control (CG), se obtuvieron diferencias significativas en la agilidad (test MAT2), en todos los grupos después de un programa de intervención de 4 semanas de duración en alumnos del cuarto curso de primaria. Estas diferencias han sido superiores en el grupo de ICM (p<0,01, ES=1,12). Se encontraron diferencias significativas (p<0,05, ES=0,79) en el postest entre el grupo de ICM e ICB. This study involved 76 students from 9-10 years old in a public elementary school (44 boys and 32 girls). Participants were randomized to the outcome of the pretest into four groups: low contextual interference (ICB, n = 19), moderate contextual interference (ICM, n = 19) high contextual interference (ICA, n = 19) and Control Group (GC, n = 19). The aim of this study was to determine which method of agility training (ICB, ICM or ICA) is more effective in primary school children (9-10 years), in order to figure out what method of development of this capacity was the appropriate at this stage of schooling. The agility was evaluated by MAT2 test. Except in the control group (GC), there were significant differences in agility (MAT2 test) in all groups (ICB, ICM and ICA) after an intervention program of 4-week fourth-year students of elementary school. These differences have been higher in the ICM group (p<0.01, ES=1.12). We found significant differences (p<0.05, ES=0.79) in the posttest between the ICM and ICB group

Psychological characteristics of waterpolo referees in Spain

El objetivo de este estudio es evaluar diferentes habilidades psicológicas en los árbitros de waterpolo. Para ello se utilizó el “Cuestionario de Características Psicológicas Relacionadas con el Rendimiento Deportivo (CPRD) (Gimeno, Buceta y Pérez Llanta, 2001) con el fin de medir diferentes factores (control del estrés, influencia de la evaluación del rendimiento, motivación, habilidad mental y cohesión de equipo). La muestra utilizada estaba formada por 40 árbitros de waterpolo que forman parte del Comité Nacional de Árbitros de la Real Federación Española de Natación. Los resultados muestran que la experiencia, edad o internacionalidad del árbitro no influyen en ninguno de los factores psicológicos estudiados. Además, el grupo de árbitros que declaró “entrenar” obtuvo una media mayor en el factor motivación que el grupo que no lo hacía. Por último, sí hemos encontrado una alta correlación entre los factores “influencia de la evaluación del rendimiento” y “control del estrés”

Description of physical activity, motor skills and body composition in children and young with autistic spectrum. Gender differences

El objetivo de este estudio es describir los niveles de práctica de actividad física, habilidades motrices básicas y la composición corporal en niños y jovenes con Trastornos de Espectro Autista que se encuentran escolarizados en centros de educación especial en la Comunidad de Madrid y analizar diferencias entre sexos, por ser una población de la que existe una carencia de información sobre estos parámetros. Participaron 53 niños y jóvenes (11.9 + 3.4 años) y sus familias. Se empleó un diseño descriptivo y comparativo entre sexos donde se utilizó acelerometría para medir su actividad física, test motores para las habilidades motrices y bioimpedancia para la composición corporal. Los niños presentan mayores tasas de actividad moderada frente a las niñas, tanto en los días laborables (62.8±33.5 vs 36.1±34.1 minutos respectivamente; p=.02) como en los días festivos, donde estas diferencias se incrementan (75.4±56.0 vs 31.5±36.7; p=.02). Los festivos incrementan el tiempo que dedican a la televisión (40.9±45.0 vs 87.7±102.8 min. en las niñas; 59.7±80.2 vs 88.8±144.0 en los niños; p=.01), sin diferencias entre sexos (p>.05). En el total de la muestra, se ha encontrado un 27.3% de incidencia de sobrepeso siendo más elevada en las niñas (55.6% niñas vs 20.0% niños; p=.03). Igualmente, las niñas han mostrado menores niveles de habilidad motriz. Se hace necesario implementar programas de actividad física para este colectivo, prestando especial atención a las niña

Interindividual variability in sweat electrolyte concentration in marathoners

Background: Sodium (Na+) intake during exercise aims to replace the Na+ lost by sweat to avoid electrolyteimbalances, especially in endurance disciplines. However, Na+ needs can be very different among individuals because of the great inter-individual variability in sweat electrolyte concentration. The aim of this investigation was to determine sweat electrolyte concentration in a large group of marathoners. Methods: A total of 157 experienced runners (141 men and 16 women) completed a marathon race (24.4 ± 3.6 °C and 27.7 ± 4.8 % of humidity). During the race, sweat samples were collected by using sweat patches placed on the runners’ forearms. Sweat electrolyte concentration was measured by using photoelectric flame photometry. Results: As a group, sweat Na+ concentration was 42.9 ± 18.7 mmol·L−1 (minimal-maximal value = 7.0–95.5 mmol·L−1), sweat Cl− concentration was 32.2 ± 15.6 mmol·L−1 (7.3–90.6 mmol·L−1) and sweat K+ concentration was 6.0 ± 0.9 mmol·L−1 (3.1–8.0 mmol·L−1). Women presented lower sweat Na+ (33.9 ± 12.1 vs 44.0 ± 19.1 mmol·L−1; P = 0.04) andsweat Cl− concentrations (22.9 ± 10.5 vs 33.2 ± 15.8 mmol·L−1; P = 0.01) than men. A 20 % of individuals presented asweat Na+ concentration higher than 60 mmol·L−1 while this threshold was not surpassed by any female marathoner. Sweat electrolyte concentration did not correlate to sweat rate, age, body characteristics, experience or training. Although there was a significant correlation between sweat Na+ concentration and running pace (r = 0.18; P = 0.03), this association was weak to interpret that sweat Na+ concentration increased with running pace. Conclusions: The inter-individual variability in sweat electrolyte concentration was not explained by any individual characteristics except for individual running pace and sex. An important portion (20 %) of marathoners might need special sodium intake recommendations due to their high sweat salt losses

Myosin Light Chain Kinase (MLCK) Gene Influences Exercise Induced Muscle Damage during a Competitive Marathon

Myosin light chain kinase (MLCK) phosphorylates the regulatory light chain (RLC) of myosin producing increases in force development during skeletal muscle contraction. It has been suggested that MLCK gene polymorphisms might alter RLC phosphorylation thereby decreasing the ability to produce force and to resist strain during voluntary muscle contractions. Thus, the genetic variations in the MLCK gene might predispose some individuals to higher values of muscle damage during exercise, especially during endurance competitions. The aim of this investigation was to determine the influence of MLCK genetic variants on exercise-induced muscle damage produced during a marathon. Sixty-seven experienced runners competed in a marathon race. The MLCK genotype (C37885A) of these marathoners was determined. Before and after the race, a sample of venous blood was obtained to assess changes in serum myoglobin concentrations and leg muscle power changes were measured during a countermovement jump. Self-reported leg muscle pain and fatigue were determined by questionnaires. A total of 59 marathoners (88.1%) were CC homozygotes and 8 marathoners (11.9%) were CA heterozygotes. The two groups of participants completed the race with a similar time (228 ± 33 vs 234 ± 39 min; P = 0.30) and similar self-reported values for fatigue (15 ± 2 vs 16 ± 2 A.U.; P = 0.21) and lower-limb muscle pain (6.2 ± 1.7 vs 6.6 ± 1.8 cm; P = 0.29). However, CC marathoners presented higher serum myoglobin concentrations (739 ± 792 vs 348 ± 144 μg·mL-1; P = 0.03) and greater pre-to-post- race leg muscle power reduction (-32.7 ± 15.7 vs -21.2 ± 21.6%; P = 0.05) than CA marathoners. CA heterozygotes for MLCK C37885A might present higher exercise-induced muscle damage after a marathon competition than CC counterparts

Pre-exercise Caffeine Intake Enhances Bench Press Strength Training Adaptations

Previous research has identified acute caffeine intake as an effective ergogenic aid to enhance velocity and power during bench press exercise. However, no previous investigation has analyzed the effects of chronic intake of caffeine on training adaptations induced by bench press strength training. Thus, the aim of this investigation was to determine the effects of pre-exercise caffeine intake on training adaptations induced by a bench press training protocol. Using a double-blind, randomized experimental design, 16 healthy participants underwent a bench press training protocol for 4 weeks (12 sessions). Seven participants ingested a placebo and nine participants ingested 3 mg/kg/BM of caffeine before each training session. Three days before, and 3 days after the completion of the training protocol, participants performed a one-repetition maximum (1RM) bench press and force-velocity test (from 10 to 100% 1RM). From comparable pre-training values, the strength training similarly increased 1RM in the caffeine and placebo groups (+13.5 ± 7.8% vs. +11.3 ± 5.3%, respectively; p = 0.53). In the caffeine group, the strength training induced a higher mean velocity at 40%, (0.81 ± 0.08 vs. 0.90 ± 0.14 m/s), 60% (0.60 ± 0.06 vs. 0.65 ± 0.06 m/s), 70% (0.47 ± 0.05 vs. 0.55 ± 0.06 m/s), 80% (0.37 ± 0.06 vs. 0.45 ± 0.05 m/s), 90% (0.26 ± 0.07 vs. 0.34 ± 0.06 m/s), and 100% 1RM (0.14 ± 0.04 vs. 0.25 ± 0.05 m/s; p < 0.05) while the increases in the placebo group were evident only at 30 (0.95 ± 0.06 vs. 1.03 ± 0.07 m/s), 70% (0.51 ± 0.03 vs. 0.57 ± 0.05 m/s) and 80% 1RM (0.37 ± 0.06 vs. 0.45 ± 0.05 m/s) (p < 0.05). The placebo group only increased peak velocity at 60 and 70% 1RM (p < 0.05) while peak velocity increased at 10%, and from 30 to 100% 1RM in the caffeine group (p < 0.05). The use of 3 mg/kg/BM of caffeine before exercise did not modify improvements in 1RM obtained during a 4 week bench press strength training program but induced more muscle performance adaptations over a wider range of load

Elevation of Cardiac Troponins After Endurance Running Competitions

In the present investigation, we selected 63 healthy runners (in triplets) from a group of 322 nonprofessional finishers because of their similarities in age (mean±SD age, 37±7 years), anthropometry (66.9±12.8 kg), and running experience (3.3±0.2 years). The triplets also had similar 10-year absolute cardiovascular risks (2.8±2.1%) calculated by the non–laboratory-based Framingham function.5 In each group, there were 13 women and 8 men. From each triplet, 1 runner competed in a 10-km race, another in a half-marathon race, and the third in a full marathon race. As would be expected, as a result of the different training patterns for each distance, training volume in the month before the race increased with the competition distance (23.9±9.0, 34.8±8.0, and 40.6±16.4 km/wk for 10-km runners, half-marathoners, and marathoners, respectively; P<0.01). Before and 10 minutes after the race, body mass was measured to assess dehydration. Blood samples were obtained to measure cardiac biomarkers, including high-sensitivity cardiac troponins I and T, NT-proBNP (N-terminal pro-B-type natriuretic peptide), and the cardiac (creatine kinase-MB) and skeletal muscle (creatine kinase-MM) isoenzymes of creatine kinase and myoglobin at the end of the races. The between-group differences in these variables were analyzed by a 2-way ANOVA. The study was approved by the Ethics Committee for Research of the Camilo Jose Cela University. All the research protocols described here were carried out in accordance with the Declaration of Helsinki, and all subjects gave informed consent to participate in the study

Physical activity and leisure habits and relation with Ruffier index in adolescents

El objetivo del estudio fue medir y correlacionar la práctica de actividad física y con el Índice de Ruffier (IR) en adolescentes. A un total de 884 alumnos (edad=16,4±0,8 años) se les midió la actividad física con la Versión modificada del Assessment of Physical Activity Level Questionnaire (APALQ) y se evaluó la capacidad de adaptación al esfuerzo mediante el Test Ruffier. La media del Índice de Ruffier fue 11,1±4,6 y el Índice de actividad física (IAF) 13,8±4,4. Las relaciones entre IAF y el IR, y entre horas de ocio sedentario e IR resultaron ser significativas aunque débiles (r=-0,31; p=0,000). En el IR los chicos presentaron valores superiores (t= -8,78; p= 0,000) a las chicas. También destinan más tiempo a la práctica de AF y estas diferencias fueron significativas en AF reglada y no reglada y en participación en competición (p=0,000), mientras que las chicas destinan más tiempo a actividades sedentarias como leer y estudiar (p=0,000). Es necesario promover la práctica de actividades físico-deportivas, especialmente entre las chicas

The use of compression stockings during a marathon competition to reduce exercise-induced muscle damage: are they really useful?

OBJECTIVES: To examine the efficacy of wearing compression stockings to prevent muscle damage and to maintain running performance during a marathon competition. BACKGROUND: Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance found during marathon races. METHODS: Thirty-four experienced runners were pair-matched for age, anthropometric data, and best race time in the marathon, and randomly assigned to a control group (n = 17) of runners who wore conventional socks or to a group of runners who wore foot-to-knee graduated compression stockings (n = 17). Before and after the race, a sample of venous blood was obtained, and jump height and leg muscle power were measured during a countermovement jump. Serum myoglobin and creatine kinase concentrations were determined as blood markers of muscle fiber damage

A caffeinated energy drink improves jump performance in adolescent basketball players

This study aimed at investigating the effects of a commercially available energy drink on shooting precision, jump performance and endurance capacity in Young basketball players. Sixteen young basketball players (first division of a junior national league; 14.9 ± 0.8 years; 73.4 ± 12.4 kg; 182.3 ± 6.5 cm) volunteered to participate in the research. They ingested either (a) an energy drink that contained 3 mg of caffeine per kg of body weight or (b) a placebo energy drink with the same appearance and taste. After 60 min for caffeine absorption, they performed free throw shooting and three-point shooting tests. After that, participants performed a maximal countermovement jump (CMJ), a repeated maximal jumps test for 15 s (RJ-15), and the Yo–Yo intermittent recovery test level 1 (Yo–Yo IR1). Urine samples were obtained before and 30 min after testing. In comparison to the placebo, the ingestion of the caffeinated energy drink did not affect precision during the free throws (Caffeine = 70.7 ± 11.8 % vs placebo = 70.3 ± 11.0 %; P = 0.45), the three-point shooting test (39.9 ± 11.8 vs 38.1 ± 12.8 %; P = 0.33) or the distance covered in the Yo–Yo IR1 (2,000 ± 706 vs 1,925 ± 702 m; P = 0.19). However, the energy drink significantly increased jump height during the CMJ (38.3 ± 4.4 vs 37.5 ± 4.4 cm; P\0.05) mean jump height during the RJ-15 (30.2 ± 3.6 vs 28.8 ± 3.4 cm; P\0.05) and the excretion of urinary caffeine (1.2 ± 0.7 vs 0.1 ± 0.1 lg/mL; P\0.05). The intake of a caffeine-containing energy drink (3 mg/kg body weight) increased jump performance although it did not affect basketball shooting precision