title: Quadriceps excitability is enhanced by a conditioning tap to the Achilles tendon.
abstract: In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time characteristics of the patellar tendon-tap reflex in ten college-age subjects. We also conditioned the tendon jerk with a tap to the contralateral Achilles tendon or the ipsilateral Achilles tendon. The results clearly demonstrated that a conditioning tap to the Achilles tendon produced a marked (greater than 200 percent) excitatory effect onto the quadriceps muscle. Also, this effect occurred sooner when the quadriceps was conditioned by an ipsilateral stimulus rather than a contralateral stimulus. It is concluded that in accord with other conditioning studies to date, the quadriceps muscle is characterized by a predominantly excitatory effect caused by a conditioning stimulus, and that this arousal is independent of the origin of the conditioning stimulus.
authors: Motor Control Laboratory, Indiana University, Bloomington.
authors: D M
authors: DM
authors: Koceja
authors: G
authors: G
authors: Kamen
authors: J R
authors: JR
authors: Burke
mesh_terms: D000125:Achilles Tendon / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D003214:Conditioning, Classical / Q000502:physiology*; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D009132:Muscles / Q000502:physiology*; D010329:Patella; D010474:Percussion; D011930:Reaction Time; D012026:Reflex, Stretch / Q000502:physiology*; D015203:Reproducibility of Results; D013848:Thigh