ABSTRACT
At present, fatigue state monitoring of upper limb movement generally relies solely on surface electromyographic signal (sEMG) to identify and classify fatigue, resulting in unstable results and certain limitations. This paper introduces the sEMG signal recognition and motion capture technology into the fatigue state monitoring process and proposes a fatigue analysis method combining an improved EMG fatigue threshold algorithm and biomechanical analysis. In this study, the right upper limb load elbow flexion test was used to simultaneously collect the biceps brachii sEMG signal and upper limb motion capture data, and at the same time the Borg Fatigue Subjective and Self-awareness Scale were used to record the fatigue feelings of the subjects. Then, the fatigue analysis method combining the EMG fatigue threshold algorithm and the biomechanical analysis was combined with four single types: mean power frequency (MPF), spectral moments ratio (SMR), fuzzy approximate entropy (fApEn) and Lempel-Ziv complexity (LZC). The test results of the evaluation index fatigue evaluation method were compared. The test results show that the method in this paper has a recognition rate of 98.6% for the overall fatigue state and 97%, 100%, and 99% for the three states of ease, transition and fatigue, which are more advantageous than other methods. The research results of this paper prove that the method in this paper can effectively prevent secondary injury caused by overtraining during upper limb exercises, and is of great significance for fatigue monitoring.
Subject(s)
Humans , Electromyography/methods , Fatigue , Muscle Fatigue , Muscle, Skeletal , Upper ExtremityABSTRACT
O objetivo deste estudo foi analisar o efeito da combinação de diferentes percentuais de cargas na determinação do limiar de fadiga eletromiográfi co (EMGLF) dos músculos eretores da espinha (ER). Participaram deste estudo oito voluntários do sexo masculino. Os eletrodos foram posicionados sobre o músculo ER bilateralmente (L1). O voluntário executou contrações isométricas até a exaustão com 30%, 40%, 50% e 60% da contração isométrica voluntária máxima. O EMGLF-C4 é aquele obtido com a utilização das quatro cargas; o EMGLF-C3/4/5, combinando cargas de 30, 40 e 50%; o EMGLF-C3/4/6, combinando cargas de 30, 40 e 60%; o EMGLF-C3/5/6, combinando cargas de 30, 50 e 60%, e o EMGLF-C4/5/6 combinando cargas de 40, 50 e 60%. Para a comparação entre as combinações de carga utilizou-se o teste de Friedman (p<0,05), e para a comparação entre os lados utilizou-se o teste de Wilcoxon (p<0,05). Observou-se que ao comparar o EMGLF-C4 com as outras combinações de cargas, não há diferenças signifi cativas no ER do lado direito, já no ER do lado esquerdo esta semelhança não ocorre somente com o EMGLF-C4/5/6. Concluiu-se que as combinações propostas para determinação do EMGLF apresentam índices semelhantes bilateralmente e que unilateralmente apenas para o lado esquerdo a combinação de cargas entre 40%, 50% e 60% não apresenta semelhança, permitindo com isso otimizar o presente protocolo quanto ao percentual de carga utilizado e o número de percentuais.
The objective of this study was to analyze the effect of load combination on the electromyographic fatigue threshold (EMGFT) of the erector spinae muscle (ES). Eight male subjects have participated of this study. Surface electrodes were attached bilaterally on the ES (L1). The subjects executed isometric contractions with loads of 30%, 40%, 50% and 60% of the maximum voluntary isometric contraction until the exhaustion. The EMGLF-C4 was obtained throughout four loads and then was obtained the EMGLF-C3/4/5, throughout loads of 30, 40 e 50%, the EMGLF-C3/4/6, throughout loads of 30, 40 e 60%, the EMGLF-C3/5/6, throughout loads of 30, 50 e 60%, and the EMGLF-C4/5/6 throughout loads of 40, 50 e 60%. To the comparison among the combinations it was used a Friedman test (p<0,05), and to the comparison between sides it was used a Wilcoxon test (p<0,05). When comparing the EMGLF-C4 with the combinations of loads, there are no signifi cant differences in the ES of the right side, but in the ES of the left side similar results didnt happened with the EMGLF-C4/5/6. The present study concluded that the ES presented similar indexes bilaterally and that unilaterally just to the left side the combination of loads among 40%, 50% and 60% didnt present similar results, allowing us to optimize the percent of load and the number of loads of the present protocol.