A New Approach to Evaluate Neuromuscular Fatigue of Extensor Elbow Muscles

Abstract

Neuromuscular fatigue evaluation is widely performed on different muscles through the conventional protocol using maximum voluntary contraction (MVC) with electrical stimuli in the analyzed muscle. In an attempt to use this protocol on elbow extensor musculature, previous studies and pilot studies showed co-contraction effects from antagonist musculature during muscular stimulations. The aim of this study was to propose a new neuromuscular fatigue protocol evaluation on elbow extensor musculature. Twenty participants preformed exercises to induce central (CenFat) and peripheral fatigue (PerFat). Neuromuscular fatigue was evaluated on knee extensor muscles by a conventional protocol that provides Twitch Superimposed (TS K) and Twitch Potentiated (TP K), central and peripheral parameters respectively. For elbow extensor muscles, the protocol used sustained submaximal contraction at 10, 20, 30, 40, and 50% of MVC. The neuromuscular fatigue in upper limbs was identified by Twitch Potentiated (TP E) and multiple Twitch Superimposed (TS E) parameters. Using the relationship between MVC (%) and evoked force, the proposed protocol used several TS E to provide slope, y-intercept and R 2. It is proposed that slope, R 2 , and y-intercept change may indicate peripheral fatigue and the identified relationship between y-intercept and R 2 may indicate central fatigue or both peripheral and central fatigue. The results were compared using the non-parametric analyzes of Friedmann and Wilcoxon and their possible correlations were verified by the Spearmann test (significance level set at p < 0.05). After PerFat a decrease in TP E (57.1%, p < 0.001) was found but not in any TS E , indicating only peripheral fatigue in upper limbs. After CenFat a decrease in TP E (21.4%, p: 0.008) and TP K (20.9%, p < 0.001) were found but not in TS K , indicating peripheral fatigue in upper and lower limbs but not central fatigue. A non-significant increase of 15.3% after CenFat and a statistical reduction (80.1%, p: 0.001) after PerFat were found by slope. Despite R 2 showing differences after both exercises (p < 0.05), it showed a recovery behavior after CenFat (p: 0.016). Although PerFat provided only peripheral fatigue, CenFat did not provide central fatigue. Considering the procedural limitations of CenFat, parameters resulting from the proposed protocol are sensitive to neuromuscular alteration, however, further studies are required.

Proposal of a Conditioning Activity Model on Sprint Swimming Performance

“…In the upper limbs, self-adhesive electrodes (5 × 5 cm, Valutrode, Arkts, Santa Tereza, Paraná, Brazil) were positioned on the belly of the long head of the triceps brachii (cathode) and the distal tendon of the triceps brachii (anode) to receive the electrical stimulus charge. In contrast, the stimulation threshold assumed for this musculature was the intensity corresponding to the highest torque produced without apparently influencing the contraction of the biceps brachii (Norberto et al, 2020). Once the stimulation thresholds were determined, the intensity of the electrical stimulus was assumed for both limbs.…”

Using a System-Based Monitoring Paradigm to Assess Fatigue during Submaximal Static Exercise of the Elbow Extensor Muscles

“…Consequently, they lack valuable insight regarding the progression of fatigue during the task itself, including the underlying physiological processes that contribute to the degraded performance of the neuromuscular system. Neuromuscular fatigue can be identified by measuring the evoked force from twitch responses after electrically stimulating muscles during maximal or submaximal voluntary contractions [ 16 ]. However, this technique is also applied before and after a fatiguing exercise.…”

Efeito da fadiga sobre o desempenho no goalball

“…Embora a aplicação da técnica Twitch Interpolation em membros inferiores esteja validada (Gandevia, 2001) e nos membros superiores ainda apresente limitações (Norberto et al, 2020), um método simples e de fácil execução como o da dinamometria de preensão manual (Gunha et al, 2020) poderia ter sido utilizado. De fato, como demostrado por De Campos e colaboradores (2020), atletas que apresentam maior força nos membros superiores tendem a arremessar bolas mais rápidas, o que permite sugerir que a fadiga muscular é maior nos membros superiores do que nos membros inferiores devido à grande quantidade de arremessos executados pelos jogadores em uma partida, que pode exceder 40 em atletas da elite (Alves et al, 2018), especificamente entre os alas (Monezi et al, 2018).…”

“…Evidências indicam que indivíduos sem experiência prévia com a técnica podem não ser capazes de exercer a força máxima na musculatura avaliada devido a expectativa de desconforto da eletroestimulação que, consequentemente, prejudica seu desempenho na execução do teste (Button & Behm, 2008). Além disso, a literatura indica que é inerente a aplicação da técnica na musculatura extensora do cotovelo o "fenômeno de co-contração", quando há contração simultânea dos músculos agonistas e antagonistas da musculatura braquial durante a estimulação, um processo comumente identificado como uma limitação (Norberto, de Arruda, & Papoti, 2020).…”