RESUMO
Biomechanical studies of rugby union scrummaging have focused on kinetic and kinematic analyses, while muscle activation strategies employed by front-row players during scrummaging are still unknown. The aim of the current study was to investigate the activity of spinal muscles during machine and live scrums. Nine male front-row forwards scrummaged as individuals against a scrum machine under "crouch-touch-set" and "crouch-bind-set" conditions, and against a two-player opposition in a simulated live condition. Muscle activities of the sternocleidomastoid, upper trapezius, and erector spinae were measured over the pre-engagement, engagement, and sustained-push phases. The "crouch-bind-set" condition increased muscle activity of the upper trapezius and sternocleidomastoid before and during the engagement phase in machine scrummaging. During the sustained-push phase, live scrummaging generated higher activities of the erector spinae than either machine conditions. These results suggest that the pre-bind, prior to engagement, may effectively prepare the cervical spine by stiffening joints before the impact phase. Additionally, machine scrummaging does not replicate the muscular demands of live scrummaging for the erector spinae, and for this reason, we advise rugby union forwards to ensure scrummaging is practiced in live situations to improve the specificity of their neuromuscular activation strategies in relation to resisting external loads.
Assuntos
Músculos do Dorso/fisiologia , Futebol Americano/fisiologia , Músculos do Pescoço/fisiologia , Coluna Vertebral/fisiologia , Fenômenos Biomecânicos , Eletromiografia , Humanos , Masculino , Adulto JovemRESUMO
We investigated the effect of a "PreBind" engagement protocol on the biomechanics of contested Rugby Union scrummaging at different playing levels. "PreBind" requires front-row props to take a bind on opposing players prior to the engagement, and to maintain the bind throughout the scrum duration. Twenty-seven teams from five different playing levels performed live scrums under realistic conditions. Video analysis, pressures sensors, and inertial measurement units measured biomechanical outcomes as teams scrummaged following different engagement protocols: the CTPE (referee calls "crouch-touch-pause-engage"), the CTS ("crouch-touch-set"), and the PreBind ("crouch-bind-set") variants. PreBind reduced the set-up distance between the packs (-27%) and the speed at which they came into contact by more than 20%. The peak biomechanical stresses acting on front rows during the engagement phase were decreased in PreBind by 14-25% with respect to CTPE and CTS, without reducing the capability to generate force in the subsequent sustained push. No relevant main effects were recorded for playing level due to within-group variability and there were no interaction effects between playing level and engagement protocol. Pre-binding reduced many mechanical quantities that have been indicated as possible factors for chronic and acute injury, and may lead to safer engagement conditions without affecting subsequent performance.
Assuntos
Futebol Americano/lesões , Pressão , Estresse Mecânico , Suporte de Carga , Adulto , Traumatismos em Atletas , Fenômenos Biomecânicos , Estudos Transversais , Humanos , Masculino , Gravação em Vídeo , Adulto JovemRESUMO
Skyscraper running is here analyzed in terms of mechanical and metabolic requirements, both at the general and at the individual level. Skyscraper runners' metabolic profile has been inferred from the total mechanical power estimated in 36 world records (48-421 m tall buildings), ranked by gender and age range. Individual athlete's performance (n=13) has been experimentally investigated during the Pirelli Vertical Sprint, with data loggers for altitude and heart rate (HR). At a general level, a non-linear regression of Wilkie's model relating maximal mechanical power to event duration revealed the gender and age differences in terms of maximum aerobic power and anaerobic energy resources particularly needed at the beginning of the race. The total mechanical power was found to be partitioned among: the fraction devolved to raise the body center of mass , the need to accelerate the limbs with respect to the body , and running in turns between flights of stairs . At the individual level, experiments revealed that these athletes show a metabolic profile similar to middle-distance runners. Furthermore, best skyscraper runners maintain a constant vertical speed and HR throughout the race, while others suddenly decelerate, negatively affecting the race performance.
Assuntos
Fenômenos Biomecânicos/fisiologia , Corrida/fisiologia , Adulto , Fatores Etários , Idoso , Altitude , Desempenho Atlético , Feminino , Frequência Cardíaca , Humanos , Ácido Láctico/metabolismo , Masculino , Pessoa de Meia-IdadeAssuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Doenças dos Genitais Femininos/tratamento farmacológico , Naproxeno/uso terapêutico , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Doença Inflamatória Pélvica/tratamento farmacológico , Peritonite/tratamento farmacológico , Salpingite/tratamento farmacológico , Cervicite Uterina/tratamento farmacológicoRESUMO
PIP: Controlled experiments confirmed the therapeutic usefulness in gynecology of a phlebokinetic drug, in which EPL (polyunsaturated phosphatidylcholine) was combined with escine and rutine. The drug is particularly recommended for the prophylaxis and treatment of vein disorders caused by oral contraceptives. A total of 75 patients were treated with the drug (Essaven), in addition to the usual treatment (such as anticoagulants), while 75 controls received the usual treatment only. Results were excellent in cases of varicose veins, where the symptoms were eliminated in almost all cases. In cases of phlebitis and thrombophlebitis, the response was less univocal, but a definite improvement was evident in a good number of cases treated with Essaven; the drug also favored the return to normal conditions after thrombophlebitis attacks, reducing the duration of their painful aftereffects. The drug can be used daily for very long periods without side effects. It can also be used safely during pregnancy, without adverse effects on the fetus and on delivery. It is regarded as ideal to avoid the side effects of contraceptives on the venous system.^ieng