Acute Effects of Static versus Dynamic Stretching on Isometric Peak Torque, Electromyography, and Mechanomyography of the Biceps Femoris Muscle

Abstract

The purpose of this study was to examine the acute effects of static versus dynamic stretching on peak torque (PT) and electromyographic (EMG), and mechanomyographic (MMG) amplitude of the biceps femoris muscle (BF) during isometric maximal voluntary contractions of the leg flexors at four different knee joint angles. Fourteen men ((mean +/- SD) age, 25 +/- 4 years) performed two isometric leg flexion maximal voluntary contractions at knee joint angles of 41 degrees , 61 degrees , 81 degrees , and 101 degrees below full leg extension. EMG (muV) and MMG (m x s(-2)) signals were recorded from the BF muscle while PT values (Nm) were sampled from an isokinetic dynamometer. The right hamstrings were stretched with either static (stretching time, 9.2 +/- 0.4 minutes) or dynamic (9.1 +/- 0.3 minutes) stretching exercises. Four repetitions of three static stretching exercises were held for 30 seconds each, whereas four sets of three dynamic stretching exercises were performed (12-15 repetitions) with each set lasting 30 seconds. PT decreased after the static stretching at 81 degrees (p = 0.019) and 101 degrees (p = 0.001) but not at other angles. PT did not change (p > 0.05) after the dynamic stretching. EMG amplitude remained unchanged after the static stretching (p > 0.05) but increased after the dynamic stretching at 101 degrees (p < 0.001) and 81 degrees (p < 0.001). MMG amplitude increased in response to the static stretching at 101 degrees (p = 0.003), whereas the dynamic stretching increased MMG amplitude at all joint angles (p </= 0.05). These results suggested that the decreases in strength after the static stretching may have been the result of mechanical rather than neural mechanisms for the BF muscle. Overall, an acute bout of dynamic stretching may be less detrimental to muscle strength than static stretching for the hamstrings.

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“…Nonetheless, in all studied indicators, the results of the study proved the substantially better preparedness and performance of the group of top-level ice hockey players prior to the speed and speed-strength load after the application of dynamic rather than static stretching. On the basis of the study in agreement with many authors (Fletcher & Jones, 2004;Herda et al, 2008;Jaggers et al, 2008;Cacek & Bubníková, 2009;Cacek, Hlavoňová & Michálek, 2009;Gelen, 2010) we consider dynamic stretching to be the most suitable warm-up method prior to speed-strength types of load.…”

“…After the static or no stretching, the power of 1788.5±85.7 W / 1784.8±108.4 W was recorded while after dynamic stretching it was 2022.3±121.0 W. Fletcher & Jones (2004) obtained similar results, ascribing them to the loss of elastic energy. Many other studies have come to the same conclusions (Herda et al, 2008;Cacek & Bubníková, 2009;Cacek, Hlavoňová & Michálek, 2009;Gelen, 2010). Nonetheless, Little & Williams came up with different results in this matter.…”

Efeito Agudo De Diferentes Métodos De Alongamento Sobre O Desempenho Da Força Em Séries Sucessivas

“…Simic et al 14 reportaram efeitos negativos significativamente maiores (P = 0,012) quando testes isométricos são utilizados como medida de força. Esse fato pode ser explicado pela mudança na relação comprimento/tesão (torque-ângulo) que o alongamento estático promove na unidade músculo-tendínea 35 . Uma vez que a redução na rigidez da unidade músculo-tendínea e o aumento do comprimento de repouso do sarcômero após o alongamento estático vai requerer que o músculo opere em um comprimento maior para exercer o mesmo nível de tensão antes do alongamento 36 , em testes isométricos, o músculo estaria operando em um comprimento menor após a rotina de alongamento, o que desfavoreceria seu melhor desempenho.…”

Efeito agudo dos exercícios de flexibilidade no desempenho de força máxima e resistência de força de membros inferiores e superiores

“…Isso pode ser consequência da inibição provocada pelos órgãos tendinosos de Golgi que teriam sido estimulados pela tensão desenvolvida na unidade músculo-tendão durante as atividades de flexibilidade e também da contribuição reflexa dos receptores de dor. No entanto, esse mecanismo é controverso, pois há estudos que observaram redução no desempenho de força máxima com o método estático de flexibilidade sem haver alteração do sinal eletromiográfico (HERDA et al, 2008;ESPOSITO et al, 2009;EVETOVICH et al, 2003). Esses estudos apontam que a principal causa dessa redução seria em função dos aspectos mecânicos que comprometem o tempo para atingir o pico de força, a taxa de desenvolvimento de força e até a aceleração do movimento.…”