comparison of the effects of two fatigue protocols on triceps surae musculotendinoes stiffness in healthy students

background : previous studies have investigated different effects of muscle fatigue on body systems. however, there are no reports on the effect of fatigue protocol and its level on musculotendinous stiffness (mts) of the tricep-surae. this study was designed to compare the effects of 2 levels of submaximal fatigue contraction on mts of triceps-surae. methods: twenty female students by simple randomized sampling participated in this study. triceps-surae musculotendinous stiffness was measured before and after two fatigue protocols. the fatigue protocols were comprised of a continuous isometric voluntary plantar flexion contraction (25% and 70% maximum voluntary contraction) until the contraction could no longer be maintained. the free oscillation technique was used to measure mts of the triceps-surae. a kistler force plate was used to measure the force applied. results: musculotendinous stiffness decreased immediately after both fatigue protocols (p value ≤ 0.05). data analysis with rm anova showed that there was no significant difference between the two protocols with respect to the decrease in mts stiffness of the triceps-surae. moreover, the decrease in stiffness did not change for 15 min after the two fatigue protocols (p>0.05). conclusion: musculotendinous stiffness of the triceps-surae decreased significantly after both fatigue protocols, and there was no significant difference between the two protocols with respect to change in triceps-surae musculotendinous stiffness. this result may be due to similar type of contraction in protocols, the learning effect, or the effect of central fatigue.