Objective:

To analyze and compare the effect of temperature on the average velocity of the linear phase and the exponential phase stages produced by periodic stimulation with simple twitching or with tetanus in the toad sartorius.

Methods:

an in vitro experimental study with a sample of 46 toad sartorius muscles randomly selected. At the temperatures studied, peak tension produced with two stimulus patterns (twitching and tetanus) were measured until reaching the corresponding muscle fatigue in each case. The tension velocity drop in the linear phase and the exponential phase for each type of fatigue were calculated, and the regression slopes obtained with the Arrhenius equation were compared.

Results:

The temperatures used (1 to 12°C) significantly affected the velocity of fatigue in the stages of linear and exponential phases of both types of fatigue (p <0.05). The function of which the fatigue curves were adjusted to the temperatures used was similar to the function used with the curves at room temperature. When comparing the slopes of Arrhenius regression in the exponential phase and the different stages of the linear phase of each fatigue and between both fatigues, no significant differences were found (p>0.05).

Conclusions:

The temperature significantly affected average development velocity of fatigue in the different phases of the two types of fatigue, but when comparing slopes of most regressions corresponding to Arrhenius there were no significant differences, suggesting that the mechanisms underlying the different stages of fatigue have equal sensitivity to temperature.

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