Paraspinal Precontraction Does Not Enhance Isokinetic Trunk Extension Performance

摘要

Study DesignThis study investigated the influence of isometric contraction of the trunk extensor muscles, immediately preceding maximum effort isokinetic trunk extension precontraction, on isokinetic performance variables and activation levels of the paraspinal muscles.ObjectivesTo determine whether agonist precontraction significantly imporved the concentric and eccontric isokinetic trunk extension contraction.Summary of Background DataAgonist precontraction has been reported to enhance agonist neural drive and forc output of the knee and ankle joints.Methodssubjects performed concentric and eccentric isokinetic trunk extension at 60, 90, and 120 deg/sec, each of which were preceded by isomatric trunk extension precontraction force equal to 0percnt;, 25percnt;, and 50percnt; body weight.ResultsConcentric and eccentric contractions showed general, but no statistically significant performance enhancement with paraspinal precontraction. Eccentric contractions tended to improve to a greater extent than concentric contractions.ConclusionsIt is possible that the addition of agonist precontraction increased the complexity of the trunk extension task, thus requiring a learning, period, as is the case with most novel motor skills. There may be meaningful rehabilitation-related implications of the qualitative tendencies observed int he data that merit further consideration.