title: Agonist and antagonist muscle activation during maximal and submaximal isokinetic fatigue tests of the knee extensors.
abstract: The purpose of this study was to examine the differences in electromyographic activity of agonist and antagonist knee musculature between a maximal and a submaximal isokinetic fatigue protocol. Fourteen healthy males (age: 24.3+/-2.5 years) performed 25 maximal (MIFP) and 60 submaximal (SIFP) isokinetic concentric efforts of the knee extensors at 60 degrees s(-1), across a 90 degrees range of motion. The two protocols were performed a week apart. The EMG activity of vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) were recorded using surface electrodes. The peak torque (PT) and average EMG (aEMG) were expressed as percentages of pre-fatigue maximal value. One-way analysis of variance indicated a significant (p<0.05) decline of PT during the maximal (45.7%) and submaximal (46.8%) protocols. During the maximal test, the VM and VL aEMG initially increased and then decreased. In contrast, VM and VL aEMG continuously increased during submaximal testing (p<0.05). The antagonist (BF) aEMG remained constant during maximal test but it increased significantly and then declined during the submaximal testing. The above results indicate that agonist and antagonist activity depends on the intensity of the selected isokinetic fatigue test.
authors.affiliation: Laboratory of Coaching and Performance, Department of Physical Education and Sport Science, Aristotle University, Thessaloniki, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Hassani
authors.forename: D
authors.initials: D
authors.lastname: Patikas
authors.forename: E
authors.initials: E
authors.lastname: Bassa
authors.forename: K
authors.initials: K
authors.lastname: Hatzikotoulas
authors.forename: E
authors.initials: E
authors.lastname: Kellis
authors.forename: C
authors.initials: C
authors.lastname: Kotzamanidis
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D006801:Humans; D007717:Knee / Q000502:physiology*; D008297:Male; D009043:Motor Activity; D009119:Muscle Contraction; D018763:Muscle Fatigue; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance; D052097:Quadriceps Muscle / Q000502:physiology; D016059:Range of Motion, Articular; D012016:Reference Values; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D019415:Torque