Aim: Reliability of the assessment of peripheral fatigue induced in knee extensors by high-intensity intermittent running exercise (HIE) was established in ten amateur soccer players (age: 18±1, height: 178±5 cm, weight: 68±8 kg).
Methods: Transcutaneous electrical stimulations before and after HIE determined muscle contractile properties on three separate occasions (T1, T2 and T3), each separated by 7 days.
Results: No significant differences were noted for any of the parameters measured (P=0.101). The ICC values for peak torque (PT) varied from moderate to high, with the exception of PT at 10-Hz calculated comparing T2 vs. T1 (range PRE=0.78-0.92; POST=0.76-0.97). The ICC derived from PT percentage decrements data were all low, with the exception of PT decrements at 1 Hz calculated comparing T3 vs. T2 (ICC=0.85, moderate). The TE for all contractile parameters obtained using 1-Hz and 100-Hz electrical stimulations were below 10%, including some that demonstrated a TE lower than 5%. Muscle contractile properties determined using 10-Hz stimulations showed a higher level of TE (range: 3.2-15.1%). Similar results were obtained for maximal rate of torque development and torque relaxation.
Conclusion: From the results of this study it can be concluded that muscle contractile properties express a good level of reliability in baseline and postexercise measures following familiarization.