ABSTRACT
The aim of this study was to review the literature to see how the protocols are designed to induce kneejoint muscles fatigue using an isokinetic dynamometer. Materials and Methods: This study consisted of asystematic review and the search for the theoretical composition was performed in the PubMed databaseusing as descriptors the words muscle fatigue, knee, and isokinetic, and as filters the words Abstract available,Humans, Randomized Controlled Trial, and English language. It was not set limits for year of publications.Results: twenty nine studies were found, from which, seventeen were excluded due to exclusion criteria.Conclusion: It became evident in the present review that the greatest reduction in the peak torque occurs inprotocols that use series of trials without determining the number of repetitions, requiring that the movementbe executed until attaining exhaustion. However, if there is a need to determine a number of repetitionsto decrease the the knee joint torque to the levels close to the one attained in the exhaustion protocol, theprotocol that most reduced the knee joint flexor and extensor torque was the one that used five series of 30repetitions with interval of one minute between series, independent of the angular speed and the type ofcontraction, concentric or excentric.
Subject(s)
Humans , Male , Female , Knee Joint/physiology , Pliability , Guidelines as Topic/methods , Range of Motion, Articular , Reproducibility of ResultsABSTRACT
In numerous motor tasks, muscles around a joint act coactively to generate opposite torques. A variety of indexes based on electromyography signals have been presented in the literature to quantify muscle coactivation. However, it is not known how to estimate it reliably using such indexes. The goal of this study was to test the reliability of the estimation of muscle coactivation using electromyography. Isometric coactivation was obtained at various muscle activation levels. For this task, any coactivation measurement/index should present the maximal score (100% of coactivation). Two coactivation indexes were applied. In the first, the antagonistic muscle activity (the lower electromyographic signal between two muscles that generate opposite joint torques) is divided by the mean between the agonistic and antagonistic muscle activations. In the second, the ratio between antagonistic and agonistic muscle activation is calculated. Moreover, we computed these indexes considering different electromyographic amplitude normalization procedures. It was found that the first algorithm, with all signals normalized by their respective maximal voluntary coactivation, generates the index closest to the true value (100%), reaching 92 ± 6%. In contrast, the coactivation index value was 82 ± 12% when the second algorithm was applied and the electromyographic signal was not normalized (P < 0.04). The new finding of the present study is that muscle coactivation is more reliably estimated if the EMG signals are normalized by their respective maximal voluntary contraction obtained during maximal coactivation prior to dividing the antagonistic muscle activity by the mean between the agonistic and antagonistic muscle activations.
Subject(s)
Adult , Female , Humans , Male , Electromyography/methods , Muscle Contraction/physiology , Muscle, Skeletal/innervation , Muscle, Skeletal/physiology , Reproducibility of ResultsABSTRACT
Martial arts are practiced in both amateur and in high professional level, stimulating scientific research in several areas of knowledge, including biomechanics. The main purpose of this review is to present the biomechanics methods used in the study of martial arts. The great importance of this study is the compilation of information science of what has already been analyzed under the biomechanics aspects related to martial arts and how this has been done. The methodology was directed to the revision of literature starting from articles, books, and seminars. From the collection of bibliographic surveys, it has been concluded that depending on the parameters studied e.g.: reaction time, speed, strength, power, among others, there is the need to apply one or more methods since there are situations in which only one biomechanical method will not be enough to answer the pointed question. It is also concluded that the investigated studies in the presented review showed the character of a descriptive examination, not directly applied to the development of techniques used on different modalities.