%0 Journal Article %A Anbarian, Mehrdad %A Sepehrian, Mostafa %A Nazem, Farzad %A Hajiloo, Behrooz %T The Effect of Pedaling and Fatigue on Changes of Knee Muscles Co-contraction During Running in Triathletes %J Journal of Sport Biomechanics %V 1 %N 1 %U http://biomechanics.iauh.ac.ir/article-1-27-en.html %R %D 2015 %K Triathlon, Fatigue, Cycling, Running, Electromyography, %X Objective: The purpose of this study was to determine the effect of cycling fatigue on co-activation of knee muscles during running in novice triathletes. Methods: Twelve novice male triathletes aged 23.7±2.1 years participated in this quasi experimental study. Surface electromyographic activity from gastrocnemius, rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus were recorded during support and non-support phases of running before and after cycling fatigue protocol. General and directed co-activation of the knee muscles were calculated. Paired t-test was used to analyze the data(p<0.05). Results: General co-activation was significantly reduced in propulsion sub-phase, total support and non-support phases after fatigue (p=0.001), but there were not any differences in heel contact and midstance sub-phases. Fatigue only altered directed co-activation of medial and lateral knee muscles during heel contact sub-phase (p=0.034). Extensor and flexor directed co-activation during non-support phase of running significantly decreased after fatigue (p=0.011). Conclusion: Changes in the co-activation during running after cycling fatigue can alter running pattern and reduce the knee function consequently, causing injuries to the lower limbs in novice triathletes. %> http://biomechanics.iauh.ac.ir/article-1-27-en.pdf %P 5-13 %& 5 %! %9 Research %L A-10-39-1 %+ Bu Ali Sina University, Hamedan, Iran. %G eng %@ 2476-4906 %[ 2015