Activity of Motor Units During Concentric and Eccentric Contractions

Moritani, Toshio; Muramatsu, Shigeru; Muro, Masuo

doi:10.1097/00002060-198812000-00003

Cited by 127 publications

(87 citation statements)

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“…De Luca 27) reported that different muscles showed different motor unit recruitment and different proportions of discharge frequency. Our results may have arisen from muscle contraction (concentric or eccentric) 25) , motor unit recruitment, and proportions of discharge frequency 27) , in contrast to the report by Yao et al 26) . Hof et al 28) and Otter et al 29) conducted a detailed analysis of the relationship between gait speed profile and muscle action in each phase of the gait cycle.…”

Section: Discussioncontrasting

confidence: 86%

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Quantitative and Qualitative Evaluation of Knee Electromyograms by a Bluetooth-communication Gait Analyzer: Integration and Power Spectral Analysis of Surface Electromyograms

et al. 2010

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Abstract. [Purpose] We observed the action of muscles during gait using a Bluetooth Gait Analyzer (sampling frequency 1 kHz), by integrating electromyograms and performing power spectral analysis. Analyzer was described in the quantitative and qualitative evaluation of these muscles.[Subjects] The subjects were 15 healthy adult males.[Methods] A Bluetooth electromyography gait analyzer was used to observe the action of the vastus medialis muscle (Quad muscle) and the long head of the biceps femoris muscle (Hamstrings) during slow, medium, and fast gait. Electromyograms were subjected to integration and power spectral analysis evaluation.[Results] The integrated electromyograms of the Quad muscles and the Hamstrings increased significantly with increases in gait speed. Power spectral analysis showed the mean power frequency of the Quad muscles tended to decrease, and the high frequency component (81-250 Hz) was significantly reduced. The mean power frequency of the Hamstrings increased with increases in gait speed, but the high frequency component was significantly increased.[Conclusion] The observed tendencies might have resulted from the induction of positive action in type I muscle fibers in the Quad muscles with increased gait speed and of the muscle action of type II fibers in the Hamstrings. We suggest that, as the gait speed increases, the Quad muscles are forced to play the role of a braking muscle.

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Section: Discussioncontrasting

confidence: 86%

“…The vastus medialis muscle exhibits an eccentric contraction upon heel contact in the gait cycle to absorb impact with the floor. The mode of muscle contraction at this moment 25) and exercise may be influential factors. Yao et al 26) noted that the low frequency component became dominant with increased synchronization of the motor units.…”

Section: Discussionmentioning

confidence: 99%

Quantitative and Qualitative Evaluation of Knee Electromyograms by a Bluetooth-communication Gait Analyzer: Integration and Power Spectral Analysis of Surface Electromyograms

et al. 2010

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“…Previous studies demonstrated that motor unit firing/recruitment properties are influenced by the contraction speed and/or contraction type, i.e., isometric, concentric, or eccentric (De Luca et al 1982;Moritani et al 1987). In order to apply our findings to actual human movements, the further studies are needed to clarify the motor unit firing properties in the elderly during motor tasks under various conditions.…”

Section: Limitationsmentioning

confidence: 84%

Age-related changes in motor unit firing pattern of vastus lateralis muscle during low-moderate contraction

Watanabe

Holobar

Kouzaki

et al. 2016

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Age-related changes in motor unit activation properties remain unclear for locomotor muscles such as quadriceps muscles, although these muscles are preferentially atrophied with aging and play important roles in daily living movements. The present study investigated and compared detailed motor unit firing characteristics for the vastus lateralis muscle during isometric contraction at low to moderate force levels in the elderly and young. Fourteen healthy elderly men and 15 healthy young men performed isometric ramp-up contraction to 70 % of the maximal voluntary contractions (MVC) during knee extension. Multichannel surface electromyograms were recorded from the vastus lateralis muscle using a two-dimensional grid of 64 electrodes and decomposed with the convolution kernel compensation technique to extract individual motor units. Motor unit firing rates in the young were significantly higher (~+29.7 %) than in the elderly (p < 0.05). There were significant differences in firing rates among motor units with different recruitment thresholds at each force level in the young (p < 0.05) but not in the elderly (p > 0.05). Firing rates at 60 % of the MVC force level for the motor units recruited at <20 % of MVC were significantly correlated with MVC force in the elderly (r = 0.885, p < 0.0001) but not in the young (r = 0.127, p > 0.05). These results suggest that the motor unit firing rate in the vastus lateralis muscle is affected by aging and muscle strength in the elderly and/or age-related strength loss is related to motor unit firing/ recruitment properties.

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“…I Surveys about the effect of elastic-band on muscle damages have been rare now. In previous studies, muscle damage following intensive resistant exercise same elastic-band mode has been attributed to the mechanical stress on the contractile apparatus during eccentric contraction 14 . In other hand other mechanism are that elastic-band exercise may induce muscle damage because of the forces produced during ground impact and associated eccentric contraction 5 .…”

Section: Discussionmentioning

confidence: 99%

Effect of elastic-band exercise on muscle damage and inflammatory responses in Taekwondo athletes

Gadruni

Mahmmadpour

Gadruni

2015

Rev Bras Med Esporte

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Introduction: Elastic bands offer variable elastic resistance (ER) throughout a range of motion and their incorporation with exercise movements has been used for variable strength training and rehabilitation purposes. Objective: Investigate the effect of acute bout of progressive elastic-band exercise on muscle damage and inflammatory response in Taekwondo athletes (TKD) compared with untrained ones. Methods: Fourteen (TKD, n = 7 and untrained, n = 7) men performed 3 sets of progressive resistance elastic exercise. Blood samples were taken pre-exercise and also immediately and 24h post exercise. Delayed onset muscle soreness (DOMS), creatine kinase (CK) and lactate dehydrogenase (LDH) activity, total leukocyte counts, interleukin-6 and C-reactive protein (CRP) were analyzed. Results: Only DOMS increased in untrained group, but elevation of DOMS was observed in both groups (TKD and untrained) at 24h after exercise (p<0.05). CK and LDH activity increased in both groups significantly. Also TKD group only showed CK increasing 24h post exercise (p<0.05). Total circulating leukocyte counts increased immediately in post exercise experiments and decreased in 24h ones in both groups (p<0.05). Serum IL-6 immediately increased in both groups and 24h post exercises but there was no significant difference between immediate and 24h post exercise experiments in TKD group. Furthermore, CRP just increased 24h after exercise in both groups (p<0.05). Conclusion: Progressive resistance elastic exercise induced muscle damage and inflammation in TKD athletes, but also had smaller changes in comparison with untrained group and other forms of exercise.

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Activity of Motor Units During Concentric and Eccentric Contractions

Cited by 127 publications

References 0 publications

Quantitative and Qualitative Evaluation of Knee Electromyograms by a Bluetooth-communication Gait Analyzer: Integration and Power Spectral Analysis of Surface Electromyograms

Quantitative and Qualitative Evaluation of Knee Electromyograms by a Bluetooth-communication Gait Analyzer: Integration and Power Spectral Analysis of Surface Electromyograms

Age-related changes in motor unit firing pattern of vastus lateralis muscle during low-moderate contraction

Effect of elastic-band exercise on muscle damage and inflammatory responses in Taekwondo athletes

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