A New Index to Evaluate Running Coordination Based on Notational Analysis.

The aim of this study was 1) to define a new index to describe running coordination, named % of coordination, and 2) to examine whether it could represent an order parameter in relation to running velocity. Twelve international middle-distance athletes (six males and six females) performed three trials at easy, 5000 m pace and sprint velocities while filmed from a lateral view at 240 Hz. Notational analysis of six lower-limb key events corresponding to touchdown, mid-stance and flight phases was performed with high values of intra- (maximum standard deviation = 7 ms) and inter-operator (maximum systematic bias = 6 ms) reliability. Running velocity manipulations resulted in substantial and progressive increases in stride length, stride frequency (all p's < 0.001) and % of coordination (p < 0.001; η²p = 0.77), while duty factor showed a progressive reduction (p < 0.001, R2c = 0.86). However, % of coordination depended on the stride phase (p < 0.001; η²p = 0.78), with greater time gaps between key events in touchdown and mid-stance than in the flight phase. Results confirmed that % of coordination can illustrate changes in movement organisation, representing an easy tool for evaluating the running technique of competitive athletes.

Inflammatory biomarkers and academic performance in youth. The UP & DOWN Study.

Inflammation influences cognitive development in infants and older adults, however, how inflammation may affect academic development during childhood and adolescence remains to be elucidated. This study aimed to examine the association between inflammatory biomarkers and academic performance in children and adolescents. A total of 494 youth (238 girls) aged 10.6 ± 3.4 years participated in the study. Four inflammatory biomarkers were selected: C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and white blood cell (WBC) count. An inflammatory index was created using the above mentioned biomarkers. Academic performance was assessed through schools records. Results showed that three of the four inflammatory biomarkers (CRP, IL-6 and WBC) and the inflammatory index were negatively associated with all academic indicators (ß values ranging from -0.094 to -0.217, all P<0.05) independent of confounders including body fat percentage. Indeed, youth in the highest tertile of the inflammatory index had significantly lower scores in all academic indicators compared with youth in the middle tertile (scores ranging from -0.578 to -0.344) and in the lowest tertile (scores ranging from -0.678 to -0.381). In conclusion, inflammation may impair academic performance independently of body fat levels in youth. Our results are of importance because the consequences of childhood and adolescence inflammation tend to continue into adulthood. Lifestyle interventions in youth may be promising in reducing levels of inflammation beyond the reduction in body fat in order to achieve cognitive benefits.

Seasonal strength performance and its relationship with training load on elite runners.

The aim of this study was to analyze the time-course of force production of elite middle and long-distance runners throughout an entire season and at the end of the off-season, as well as its relationships with training load and hormonal responses. Training load was recorded daily throughout an entire season by measuring and evaluating the session distance (km), training zone and session-RPE in a group of 15 elite middle and long-distance runners (12 men, 3 women; age = 26.3 ± 5.1yrs, BMI = 19.7 ± 1.1). Also, basal salivary-free cortisol levels were measured weekly, and 50-metre sprints, mean propulsive velocity (MPV), mean propulsive power (MPP), repetition maximum (RM) and peak rate of force development (RFD) of half-squats were measured 4 times during the season, and once more after the off-season break. There were no significant variations in force production during the season or after the off-season break, except for the RFD (-30.2%, p = 0.005) values, which changed significantly from the beginning to the end of the season. Significant correlations were found between session-RPE and MPV (r = -0.650, p = 0.004), MPP (r = -0.602, p = 0.009), RM (r = -0.650, p = 0.004), and the 50-metre sprint (r = 0.560, p = 0.015). Meanwhile, salivary-free cortisol correlated significantly with the 50-metre sprint (r = 0.737, p < 0.001) and the RM ( r = -0.514, p = 0.025). Finally, the training zone correlated with the 50-metre sprint (r = -0.463, p = 0.041). Session-RPE, training zone and salivary-free cortisol levels are related to force production in elite middle and long-distance runners. Monitoring these variables could be a useful tool in controlling the training programs of elite athletes. Key pointsSession-RPE, training zone and salivary free cortisol levels correlate significantly with strength-related variables in middle and long-distance elite runners.A month of active rest during the off-season break is enough to prevent decreases in force production of such athletes.Monitoring training loads through session-RPE is a suitable and simple method for controlling the training process in elite middle and long-distance runners.

[Health-related quality of life in Latin American adolescents]. / Calidad de vida relacionada con la salud de adolescentes latinoamericanos.

OBJECTIVE: The objective of the present study was to find out if there are differences in terms of sex, age, or country of origin for the components of health-related quality of life (HRQL) in samples of adolescents from three cities-in Argentina, Brazil, and Chile, respectively-using data collected through an internationally recognized and validated survey questionnaire, KIDSCREEN-52. METHODS: The KIDSCREEN-52 questionnaire was administered to 1 357 adolescents between 12 and 17 years of age (48.6% of them male) in selected samples in the three countries. Univariate analysis of variation (ANCOVA) was used. Not only sex and age differences, but also differences for each component of HRQL, were found between the three country groups. RESULTS: The data showed significant differences between the three countries for each of the specific components of HRQL. Males scored significantly higher than females in the following components: Physical Well-being (P < 0.001), Psychological Well-being (P = 0.019), Moods and Emotions (P < 0.001), Self-perception (P = 0.001), Autonomy (P < 0.001), and Parent Relations and Home Life (P = 0.008). Furthermore, the average scores for Physical Well-being (P = 0.001), Psychological Well-being (P = 0.001), Self-Perception (P = 0.038), Autonomy (P = 0.001), Parent Relations and Home Life (P = 0.001), School Environment (P = 0.001), and Financial Resources (P = 0.022) showed a significantly declining trend with each advancing year, while average scores for the component Social Acceptance (Bullying) increased significantly with age (P < 0.001). CONCLUSIONS: The evidence suggests that interventions in disease prevention and health promotion should be developed for specific target groups, using appropriate actions depending on the sex and age of the adolescents.

The concurrent validity and reliability of a low-cost, high-speed camera-based method for measuring the flight time of vertical jumps.

Flight time is the most accurate and frequently used variable when assessing the height of vertical jumps. The purpose of this study was to analyze the validity and reliability of an alternative method (i.e., the HSC-Kinovea method) for measuring the flight time and height of vertical jumping using a low-cost high-speed Casio Exilim FH-25 camera (HSC). To this end, 25 subjects performed a total of 125 vertical jumps on an infrared (IR) platform while simultaneously being recorded with a HSC at 240 fps. Subsequently, 2 observers with no experience in video analysis analyzed the 125 videos independently using the open-license Kinovea 0.8.15 software. The flight times obtained were then converted into vertical jump heights, and the intraclass correlation coefficient (ICC), Bland-Altman plot, and Pearson correlation coefficient were calculated for those variables. The results showed a perfect correlation agreement (ICC = 1, p < 0.0001) between both observers' measurements of flight time and jump height and a highly reliable agreement (ICC = 0.997, p < 0.0001) between the observers' measurements of flight time and jump height using the HSC-Kinovea method and those obtained using the IR system, thus explaining 99.5% (p < 0.0001) of the differences (shared variance) obtained using the IR platform. As a result, besides requiring no previous experience in the use of this technology, the HSC-Kinovea method can be considered to provide similarly valid and reliable measurements of flight time and vertical jump height as more expensive equipment (i.e., IR). As such, coaches from many sports could use the HSC-Kinovea method to measure the flight time and height of their athlete's vertical jumps.

Rating of perceived exertion and velocity loss as variables for controlling the level of effort in the bench press exercise.

There is a growing interest in the analysis of different methods for monitor fatigue during resistance training sessions. This study aimed to (1) analyse the relationships between the percentage of performed repetitions with respect to the maximum possible number (%REP), RPE and magnitude of velocity loss (VL), and (2) examine whether a multiple regression analysis with the RPE and VL as predictor variables could improve the goodness of fit to predict %REP in the bench press exercise performed in a Smith machine. Seven men performed a repetition maximum test, on 3 separate testing sessions, against 3 different absolute loads based on a target mean velocity (MV) according to an individual load-velocity profile (≈1.00, ≈0.70, and ≈0.50 m/s). MV, VL, %REP and RPE were collected and used for analysis. Based upon quadratic polynomial regression analysis strong relationships were reported between the RPE and %REP (r2 = 0.89 and SEE = 9.85%) and between the VL and %REP (r2 = 0.91 and SEE = 9.85%). Multiple regression analysis with the RPE and VL as predictor variables improved the goodness of fit (r2 = 0.94 and SEE = 7.18%) of the model to predict %REP. These results suggest that both RPE and VL are useful variables to accurately estimate %REP in the bench press exercise.

Effects of an eccentric overload and small-side games training in match accelerations and decelerations performance in female under-23 soccer players.

BACKGROUND: The aims of this study were: 1) to investigate the impacts that an eccentric overload training (EOT) and a small-side game training (SSGT) have on the characteristics of the accelerations (ACC) and decelerations (DCC) of the players in a soccer match; and 2) to determine if EOT and SSGT could affect the ACC and DCC reduction over time in a soccer match. METHODS: Twenty-three female soccer players from a Spanish professional club were split into three groups: a small-sided game training group (SGG), an eccentric overload training group (EOG) and a control group (CG). RESULTS: The SSG improved the high intensity distance performed (ES [CI]=0.72 [0.22; 1.22]), the number of high intensity actions (ES [CI]=0.65 [0.01; 1.29]), the percentage of repeated high intensity actions (ES [CI]=0.54 [-0.17; 1.25]), the initial velocity of the ACC (ES [CI]=0.55 [-0.08; 1.17]) and the percentage of repeated accelerations (ES [CI]=0.87 [-0.18; 1.91]) with respect to the control group. The EOG obtained better results in distance travelling accelerating (ES [CI]=0.84 [0.09; 1.60]) and decelerating (ES [CI]=0.87 [0.23; 1.51]) above 3 m/s2, maximum ACC (ES [CI]=1.92 [0.90; 2.94]) and DCC (ES [CI]=1.29 [0.44; 2.14]) and the average of maximum ACC (ES [CI]=0.89 [0.23; 1.54]) and DCC (ES [CI]=1.08 [0.62; 1.55]) with respect to the CG. A decrement in the ACC and DCC performance was observed between the first and last 15 minutes of the competition, except for the EOG. CONCLUSIONS: The SSG obtained mainly improvements in variables related with efforts repetitions and the capacity of maintaining the ACC and the DCC over time, while improvements in the EOG were related to intensity in the ACC and DCC.

Relationships between training load, salivary cortisol responses and performance during season training in middle and long distance runners.

PURPOSE: Monitoring training from a multifactorial point of view is of great importance in elite endurance athletes. This study aims to analyze the relationships between indicators of training load, hormonal status and neuromuscular performance, and to compare these values with competition performance, in elite middle and long-distance runners. METHOD: Fifteen elite middle and long-distance runners (12 men, 3 women; age = 26.3±5.1 yrs) were measured for training volume, training zone and session rate of perceived exertion (RPE) (daily), countermovement jump (CMJ) and salivary free cortisol (weekly) for 39 weeks (i.e., the whole season). Competition performance was also observed throughout the study, registering the season best and worst competitions. RESULTS: Season average salivary free cortisol concentrations correlate significantly with CMJ (r = -0.777) and RPE (r = 0.551). Also, weekly averages of CMJ significantly correlates with RPE (r = -0.426), distance run (r = -0.593, p<0.001) and training zone (r = 0.437, p<0.05). Finally, it was found that the CMJ (+8.5%, g = 0.65) and the RPE (-17.6%, g = 0.94) measured the week before the best competition performance of the season were significantly different compared with the measurement conducted the week before the season's worst competition performance. CONCLUSIONS: Monitoring weekly measurements of CMJ and RPE could be recommended to control training process of such athletes in a non-invasive, field-based, systematic way.

Hormonal and neuromuscular responses to high-level middle- and long-distance competition.

PURPOSE: The purpose of this study was to analyze the effects of high-level competition on salivary free cortisol, countermovement jump (CMJ), and rating of perceived exertion (RPE) and the relationships between these fatigue indicators in a group of elite middle- and long-distance runners. METHOD: The salivary free cortisol levels and CMJ height of 10 high-level middle- and long-distance runners (7 men, 3 women; age 27.6 ± 5.1y) competing in 800-m, 1500-m, 3000-m, or 5000-m events in the 2013 Spanish National Championships were measured throughout a 4-wk baseline period, then again before and after their respective races on the day of the competition. Athletes' RPE was also measured after their races. RESULTS: Cortisol increased significantly after the race compared with the value measured 90 min before the race (+98.3%, g = 0.82, P < .05), while CMJ height decreased significantly after the race (-3.9%, g = 0.34, P < .05). The decrease in CMJ height after the race correlates significantly with the postcompetition cortisol increase (r = .782, P < .05) and the RPE assessment (r = .762, P < .01). CONCLUSIONS: Observed differences in CMJ height correlate significantly with salivary free cortisol levels and RPE of middle- and long-distance runners. These results show the suitability of the CMJ for monitoring multifactorial competition responses in high-level middle- and long-distance runners.

The effects of a maximal power training cycle on the strength, maximum power, vertical jump height and acceleration of high-level 400-meter hurdlers.

The aim of this study was to determine the effects of a power training cycle on maximum strength, maximum power, vertical jump height and acceleration in seven high-level 400-meter hurdlers subjected to a specific training program twice a week for 10 weeks. Each training session consisted of five sets of eight jump-squats with the load at which each athlete produced his maximum power. The repetition maximum in the half squat position (RM), maximum power in the jump-squat (W), a squat jump (SJ), countermovement jump (CSJ), and a 30-meter sprint from a standing position were measured before and after the training program using an accelerometer, an infra-red platform and photo-cells. The results indicated the following statistically significant improvements: a 7.9% increase in RM (Z=-2.03, p=0.021, δc=0.39), a 2.3% improvement in SJ (Z=-1.69, p=0.045, δc=0.29), a 1.43% decrease in the 30-meter sprint (Z=-1.70, p=0.044, δc=0.12), and, where maximum power was produced, a change in the RM percentage from 56 to 62% (Z=-1.75, p=0.039, δc=0.54). As such, it can be concluded that strength training with a maximum power load is an effective means of increasing strength and acceleration in high-level hurdlers.

Calidad de vida relacionada con la salud de adolescentes latinoamericanos / Health-related quality of life in Latin American adolescents

OBJETIVO: El objetivo del presente trabajo es determinar diferencias en relación con el sexo, la edad y el país de origen, en los componentes de la calidad de vida relacionada con la salud (CVRS), en una muestra de adolescentes de tres ciudades localizadas en Argentina, Brasil y Chile, utilizando datos recogidos mediante un cuestionario validado y reconocido internacionalmente: el KIDSCREEN-52. MÉTODOS: Se aplicó el cuestionario KIDSCREEN-52 a 1 357 adolescentes con edades comprendidas entre 12 y 17 años (48,6% varones) en muestras seleccionadas en los tres países. Se utilizó el análisis de varianza univariada (ANCOVA) y se identificaron diferencias entre países de los adolescentes, sexo y edad en cada componente de CVRS. RESULTADOS: Los datos indican diferencias significativas en componentes específicos de CVRS entre los tres países. Los varones consiguieron puntuaciones significativamente más elevadas que las mujeres en los componentes Bienestar físico (P < 0,001), Bienestar psicológico (P = 0,019), Estado de ánimo y emociones (P < 0,001), Autopercepción (P = 0,001), Autonomía (P < 0,001) y Relación con los padres y vida familiar (P = 0,008). Las puntuaciones medias atribuidas a los componentes Bienestar físico (P = 0,001), Bienestar psicológico (P = 0,001), Autopercepción (P = 0,038), Autonomía (P = 0,001), Relación con los padres y vida familiar (P = 0,001), Entorno escolar (P = 0,001) y Recursos económicos (P = 0,022) muestran un descenso significativo con el avance de la edad; en cuanto al componente Rechazo (social/bullying), los puntajes medios encontrados aumentaron significativamente con la edad (P < 0,001). CONCLUSIONES: Las evidencias encontradas sugieren que las intervenciones en prevención y promoción de la salud deberían ser concebidas para llegar a los grupos-objetivo específicos y tendrían que contemplar acciones de acuerdo con el sexo y la edad de los adolescentes.

OBJECTIVE: The objective of the present study was to find out if there are differences in terms of sex, age, or country of origin for the components of health-related quality of life (HRQL) in samples of adolescents from three cities-in Argentina, Brazil, and Chile, respectively-using data collected through an internationally recognized and validated survey questionnaire, KIDSCREEN-52. METHODS: The KIDSCREEN-52 questionnaire was administered to 1 357 adolescents between 12 and 17 years of age (48.6% of them male) in selected samples in the three countries. Univariate analysis of variation (ANCOVA) was used. Not only sex and age differences, but also differences for each component of HRQL, were found between the three country groups. RESULTS: The data showed significant differences between the three countries for each of the specific components of HRQL. Males scored significantly higher than females in the following components: Physical Well-being (P < 0.001), Psychological Well-being (P = 0.019), Moods and Emotions (P < 0.001), Self-perception (P = 0.001), Autonomy (P < 0.001), and Parent Relations and Home Life (P = 0.008). Furthermore, the average scores for Physical Well-being (P = 0.001), Psychological Well-being (P = 0.001), Self-Perception (P = 0.038), Autonomy (P = 0.001), Parent Relations and Home Life (P = 0.001), School Environment (P = 0.001), and Financial Resources (P = 0.022) showed a significantly declining trend with each advancing year, while average scores for the component Social Acceptance (Bullying) increased significantly with age (P < 0.001). CONCLUSIONS: The evidence suggests that interventions in disease prevention and health promotion should be developed for specific target groups, using appropriate actions depending on the sex and age of the adolescents.