TY - JOUR

T1 - Mathematical equation of fusion index of tetanic contraction of skeletal muscles

AU - Watanabe, S.

AU - Kitawaki, T.

AU - Oka, H.

N1 - Funding Information:
This research was partially supported by a Grant-in-Aid for Scientific Research (C) 19500388 from Japan Society for the Promotion of Science (JSPS).

PY - 2010/4

Y1 - 2010/4

N2 - The fusion index (FI) is an index that can evaluate the tetanic progression of the skeletal muscles. Although the FI-frequency curve (FFC), which is obtained by changing the stimulation frequency, is greatly affected by muscle fiber type and fiber compositions, there are no reports of a mathematical equation that can express the FFC. In this study, the FFC was measured for the gastrocnemius, vastus intermedius, and soleus muscles of rats, and the mathematical equation (FFC-equation) was proposed. The FFC-equation (FI(f)) was proportional to the h-th power of f, and was in inverse proportion to the sum of the h-th power of k and the h-th power of f. f was the stimulation frequency, k was the stimulation frequency at 50% of FI, and h reflected the gradient of FFC. As a result, the approximated curve produced by the FFC-equation corresponded with the measured FFC. k reflected the fiber compositions and h represented the ratio of relaxation time to contraction time of the twitch contraction. The calcium ion fluctuation in muscle plasma may be described by the FFC-equation obtained from the experimental data.

AB - The fusion index (FI) is an index that can evaluate the tetanic progression of the skeletal muscles. Although the FI-frequency curve (FFC), which is obtained by changing the stimulation frequency, is greatly affected by muscle fiber type and fiber compositions, there are no reports of a mathematical equation that can express the FFC. In this study, the FFC was measured for the gastrocnemius, vastus intermedius, and soleus muscles of rats, and the mathematical equation (FFC-equation) was proposed. The FFC-equation (FI(f)) was proportional to the h-th power of f, and was in inverse proportion to the sum of the h-th power of k and the h-th power of f. f was the stimulation frequency, k was the stimulation frequency at 50% of FI, and h reflected the gradient of FFC. As a result, the approximated curve produced by the FFC-equation corresponded with the measured FFC. k reflected the fiber compositions and h represented the ratio of relaxation time to contraction time of the twitch contraction. The calcium ion fluctuation in muscle plasma may be described by the FFC-equation obtained from the experimental data.

KW - Fiber type

KW - Fusion index

KW - Muscle force

KW - Tetanic contraction

KW - Twitch contraction

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U2 - 10.1016/j.jelekin.2009.02.007

DO - 10.1016/j.jelekin.2009.02.007

M3 - Article

C2 - 19332376

AN - SCOPUS:75049085827

VL - 20

SP - 284

EP - 289

JO - Journal of Electromyography and Kinesiology

JF - Journal of Electromyography and Kinesiology

SN - 1050-6411

IS - 2

ER -