Early explosive force reduction associated with exercise-induced muscle damage.

This study was aimed to analyze the loss of muscle explosive force in the early phase of eccentric exercise-induced damage, and its possible relationships with muscle soreness and blood creatine kinase (CK) levels. Squat jump (SJ) and countermovement jump (CMJ) heights decreased in response to an eccentric exercise (120 eccentric actions of the knee extensors), with reductions that persisted at least for 24 h. The SJ/CMJ ratio was not significantly modified. Blood CK levels changed significantly over time and CK activity was significantly higher at 6 and at 24 h when compared to values obtained immediately after the eccentric exercise. Muscle soreness perceived at 6 h was slightly higher than that experienced just after finalizing the exercise and reached a clearly upper value at 24 h. A highly significant relationship between SJ and CMJ height loss was observed. CK activity at 24 h was significantly related to the SJ height loss at 6 h and to both the SJ height loss and the CMJ height loss immediately after the exercise. In summary, eccentric exercise induced a reduction in the explosive force generating capacity that affected in a similar way the pure concentric jump (SJ) and the jump eliciting the stretch-shortening cycle (CMJ). Results obtained suggest that CK activity is a better predictor of explosive force reduction than soreness, at least when values close to the peak are used.

Sweat lactate, ammonia, and urea in rugby players.

The purpose of this study was to investigate sweat lactate, ammonia, and urea excretion in rugby players. Fifteen elite amateur rugby players volunteered to participate. The study was conducted during competitive matches in the official season. Plasma and sweat concentrations of lactate, ammonia, and urea were measured before and after the matches. Peak values for creatine kinase activity were observed 24 h after the match. There was no significant change between time points for blood lactate concentration but secretion rate per unit surface and time was significantly reduced after the match. Sweat ammonia concentration increased significantly during the match; values were significantly reduced after 24 h and still remained low at 72 h. Secretion rate was also reduced from 24 h. Urea concentration was significantly reduced at 48 h, while secretion rates decreased at 24 h and 48 h. Lactate in blood was significantly elevated during the match but not thereafter. Blood ammonia was significantly elevated during the match and did not differ from the resting values at 24 or 48 h. Urea in blood tended to decrease during the match, with a significant reduction at 24 h. Significant positive correlations were observed between blood and sweat concentrations for urea and ammonia but not for lactate. Sweat rate correlated positively with sweat lactate secretion. The fact that part of the ammonia formed during exercise is lost with sweat indicates the importance of the purine nucleotide cycle during rugby matches. Our data also confirm that sweat lactate concentration is not influenced by circulatory blood lactate in rugby players.

Valoración isocinética del hombro en jóvenes nadadores mediante un patrón diagonal / Isokinetic assessment of the shoulder in young swimmers with a diagonal pattern

La evaluación isocinética del hombro de la manera más funcional posible, es mediante la reproducción de patrones diagonales semejantes a los aplicados durante procedimientos de facilitación neuro-muscular propioceptiva. El objetivo de nuestro trabajo es el estudio comparativo de la valoración isocinética del hombro, según género, mediante el patrón diagonal D2, en jóvenes nadadores promesas. 18 nadadores (9 mujeres y 9 varones), diestros, y entrenados por el mismo entrenador fueron valorados mediante el dispositivo dinamómetro Biodex System 3® según modo concéntrico a 180°/s y a 60°/s de velocidad, de acuerdo al patrón diagonal D2. Se utilizaron los accesorios específicos para evaluación de diagonales, y el eje de rotación orientado a través de la articulación glenohumeral. En el análisis estadístico de los grupos de datos se aplicó el programa informático Statgraphics Plus 4.0®. La magnitud de todas las variables isocinéticas estudiadas (peak torque, peak torque/peso corporal, trabajo y potencia) fue mayor durante el movimiento de E/AD/RI, con diferencias estadísticamente significativas con el movimiento de F/AB/RE. Esto se observó en el lado dominante y no dominante, en las dos velocidades estudiadas y en ambos géneros. La natación se presenta como un deporte que logra un desarrollo armónico de ambos segmentos y en ambos géneros, a diferencia de otros deportes asimétricos

Reproduction of diagonal patterns, similar to those applied during procedures of propioceptive neuromuscular facilitation, represent the most functional approach for isokinetic evaluation of the shoulder. The objective of our work is the comparative study of the isokinetic evaluation of the shoulder according to gender in young swimmers promises, by means of the diagonal pattern D2. 18 swimmers (9 women and 9 men), skillful, and trained by the same coach were evaluated by means of a Biodex System 3 Isokinetic Dynamometer® device, according to concentric way, at 180°/s and 60°/s of speed and following the diagonal pattern D2. Specific accessories were used for evaluation of diagonals, and the rotation axis guided through the glenohumeral joint. Statistical analysis of the groups of data was performed using Statgraphics Plus 4.0®. The magnitude of all the isokinetic variable studied (peak torque, peak torque/body weight, work and power) was significantly higher for the E/AD/IR, in comparison with the F/AB/ER movement. This was observed in the dominant and not dominant side, in the two studied speeds and in both gender. Swimming represents a sport in which, contrary to other asymmetric sports, a harmonic development of both segments and in both gender is achieved

Early explosive force reduction associated with exercise-induced muscle damage

This study was aimed to analyze the loss of muscle explosive force in the early phase of eccentric exercise-induced damage, and its possible relationships with muscle soreness and blood creatine kinase (CK) levels. Squat jump (SJ) and counter-movement jump (CMJ) heights decreased in response to an eccentric exercise (120 eccentric actions of the knee extensors), with reductions that persisted at least for 24 h. The SJ/CMJ ratio was not significantly modified. Blood CK levels changed significantly over time and CK activity was significantly higher at 6 and at 24 h when compared to values obtained immediately after the eccentric exercise. Muscle soreness perceived at 6 h was slightly higher than that experienced just after finalizing the exercise and reached a clearly upper value at 24 h. A highly significant relationship between SJ and CMJ height loss was observed. CK activity at 24 h was significantly related to the SJ height loss at 6 h and to both the SJ height loss and the CMJ height loss immediately after the exercise. In summary, eccentric exercise induced a reduction in the explosive force generating capacity that affected in a similar way the pure concentric jump (SJ) and the jump eliciting the stretch-shortening cycle (CMJ). Results obtained suggest that CK activity is a better predictor of explosive force reduction than soreness, at least when values close to the peak are used (AU)

En el presente estudio se analiza la pérdida de fuerza explosiva en la fase temprana del daño inducido por un ejercicio excéntrico, y su posible relación con el dolor muscular y los niveles plasmáticos de creatina quinasa (CK). La altura de salto, tanto estático (SJ) como reactivo (CMJ), disminuyó en respuesta al ejercicio excéntrico (120 contracciones excéntricas de los extensores de la rodilla), con reducciones que persistieron durante al menos 24 h. La relación SJ/CMJ no experimentó modificación alguna. Los niveles plasmáticos de CK cambiaron significativamente a lo largo del tiempo, siendo mayores a las 6 y a las 24 horas que al finalizar el ejercicio excéntrico. El dolor muscular percibido a las 6 horas fue significativamente mayor que el experimentado justo al finalizar el ejercicio y alcanzó un valor claramente superior a las 24 h. Se observó una alta correlación entre la pérdida de altura de SJ y la pérdida de altura CMJ. La concentración plasmática de CK a las 24 h mostró una correlación significativa con la pérdida de altura SJ a las 6 h, así como con la pérdida de altura SJ y CMJ inmediatamente después del ejercicio. En resumen, el ejercicio excéntrico indujo una reducción en la capacidad del músculo de generar fuerza de forma explosiva, que afectó en igual medida al salto concéntrico puro (SJ) y al salto que incluye ciclo, estiramiento-acortamiento (CMJ). Los resultados obtenidos sugieren que la concentración plasmática de CK predice mejor la reducción de fuerza explosiva inducida por el ejercicio excéntrico que el dolor muscular, principalmente cuando se usan valores cercanos al pico (AU)