TY - JOUR
T1 - Bilateral deficit in plantar flexion
T2 - Relation to knee joint position, muscle activation, and reflex excitability
AU - Kawakami, Yasuo
AU - Sale, Digby G.
AU - MacDougall, J. Duncan
AU - Moroz, John S.
N1 - Funding Information:
Acknowledgements The authors thank the subjects who took part in the study, and Drs. A.A. Vandervoort, T. Ohtsuki, and H. Kanehisa, for their comments on the manuscript. The present study was supported in part by grants from the Natural Science and Engineering Research Council (NSERC) of Canada and the Ministry of Education of Japan.
PY - 1998/2
Y1 - 1998/2
N2 - Six male subjects made maximal isometric plantar flexions unilaterally (UL) and bilaterally (BL), with the knee joint angle positioned at 90°and 0°(full extension) and the ankle joint kept at 90°. Plantar flexion torque and electromyogram (EMG) of the lateral gastrocnemius (LG) and the soleus (Sol) muscles were recorded. There was a deficit in torque in BL compared to UL (P < 0.05), and the deficit was greater when the knee was extended than when bent to 90°(13.9% vs 6.6%). The integrated EMG (iEMG) of UL and BL did not differ when the knee was at 90°. On the other hand, when the knee was extended iEMG of LG was smaller for BL than for UL, suggesting that the larger bilateral deficit when the knee was extended was due to a reduced activity of the LG motor units. In addition, the H-reflex recorded from Sol when the contralateral leg was performing a maximal unilateral plantarflexion was reduced. This would indicate that the force deficit was associated with a reduction of motoneuron excitability.
AB - Six male subjects made maximal isometric plantar flexions unilaterally (UL) and bilaterally (BL), with the knee joint angle positioned at 90°and 0°(full extension) and the ankle joint kept at 90°. Plantar flexion torque and electromyogram (EMG) of the lateral gastrocnemius (LG) and the soleus (Sol) muscles were recorded. There was a deficit in torque in BL compared to UL (P < 0.05), and the deficit was greater when the knee was extended than when bent to 90°(13.9% vs 6.6%). The integrated EMG (iEMG) of UL and BL did not differ when the knee was at 90°. On the other hand, when the knee was extended iEMG of LG was smaller for BL than for UL, suggesting that the larger bilateral deficit when the knee was extended was due to a reduced activity of the LG motor units. In addition, the H-reflex recorded from Sol when the contralateral leg was performing a maximal unilateral plantarflexion was reduced. This would indicate that the force deficit was associated with a reduction of motoneuron excitability.
KW - Gastrocnemius and soleus muscles
KW - H-reflex
KW - Unilateral and bilateral contractions
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U2 - 10.1007/s004210050324
DO - 10.1007/s004210050324
M3 - Article
C2 - 9535581
AN - SCOPUS:0031884625
SN - 1439-6319
VL - 77
SP - 212
EP - 216
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 3
ER -
