intermittent handgrip
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2015 ◽  
Vol 16 (7) ◽  
pp. 764-772 ◽  
Author(s):  
Jiří Baláš ◽  
Michail Michailov ◽  
David Giles ◽  
Jan Kodejška ◽  
Michaela Panáčková ◽  
...  

2008 ◽  
Vol 40 (4) ◽  
pp. 684-690 ◽  
Author(s):  
YOKO SAITO ◽  
MOTOYUKI IEMITSU ◽  
TAKESHI OTSUKI ◽  
SEIJI MAEDA ◽  
RYUICHI AJISAKA

2006 ◽  
Vol 55 (4) ◽  
pp. 433-442
Author(s):  
YOKO SAITO ◽  
TAKESHI OTSUKI ◽  
MOTOYUKI IEMITSU ◽  
SEIJI MAEDA ◽  
RYUICHI AJISAKA

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S220
Author(s):  
Yoko Saito ◽  
Motoyuki Iemitsu ◽  
Takeshi Otsuki ◽  
Seiji Maeda ◽  
Ryuichi Ajisaka

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S220
Author(s):  
Yoko Saito ◽  
Motoyuki Iemitsu ◽  
Takeshi Otsuki ◽  
Seiji Maeda ◽  
Ryuichi Ajisaka

2003 ◽  
Author(s):  
Mireille C. P. van Beekvelt ◽  
Karin Orbon ◽  
Baziel G. M. van Engelen ◽  
Ron A. Wevers ◽  
Willy N. J. M. Colier

2003 ◽  
Vol 90 (1) ◽  
pp. 300-312 ◽  
Author(s):  
Jing Z. Liu ◽  
Zu Y. Shan ◽  
Lu D. Zhang ◽  
Vinod Sahgal ◽  
Robert W. Brown ◽  
...  

During prolonged submaximal muscle contractions, electromyographic (EMG) signals typically increase as a result of increasing motor unit activities to compensate for fatigue-induced force loss in the muscle. It is thought that cortical signals driving the muscle to higher activation levels also increases, but this has never been experimentally demonstrated. The purpose of this study was to quantify brain activation during submaximal fatigue muscle contractions using functional magnetic resonance imaging (fMRI). Twelve volunteers performed a sustained handgrip contraction for 225 s and 320 intermittent handgrip contractions (∼960 s) at 30% maximal level while their brain was imaged. For the sustained contraction, EMG signals of the finger flexor muscles increased linearly while the target force was maintained. The fMRI-measured cortical activities in the contralateral sensorimotor cortex increased sharply during the first 150 s, then plateaued during the last 75 s. For the intermittent contractions, the EMG signals increased during the first 660 s and then began to decline, while the handgrip force also showed a sign of decrease despite maximal effort to maintain the force. The fMRI signal of the contralateral sensorimotor area showed a linear rise for most part of the task and plateaued at the end. For both the tasks, the fMRI signals in the ipsilateral sensorimotor cortex, prefrontal cortex, cingulate gyrus, supplementary motor area, and cerebellum exhibited steady increases. These results showed that the brain increased its output to reinforce the muscle for the continuation of the performance and possibly to process additional sensory information.


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