title: Stretch reflex and Hoffmann reflex responses to osteopathic manipulative treatment in subjects with Achilles tendinitis.
abstract: BACKGROUND
  Irvin M. Korr, PhD, hypothesized that sensitivity of the monosynaptic stretch reflex (ie, deep tendon reflex) plays a major role in the restriction-of-motion characteristic of somatic dysfunction, and that restoration of range of motion through osteopathic manipulative treatment (OMT) could be achieved by resetting of the stretch receptor gain.
  
  
  OBJECTIVE
  To test Korr's hypothesis in the context of Achilles tendinitis, examining whether OMT applied to patients with Achilles tendinitis reduces the strength of the stretch reflex.
  
  
  METHODS
  Subjects were recruited through public advertisements and referrals from healthcare professionals. There were no recruitment restrictions based on demographic factors. Amplitudes for stretch reflex and H-reflex (Hoffmann reflex) in the triceps surae muscles (the soleus together with the lateral and medial heads of the gastrocnemius) were measured in subjects with diagnosed Achilles tendonitis (n=16), both before and after OMT. These measurements were also made in asymptomatic control subjects (n=15) before and after sham manipulative treatment.
  
  
  RESULTS
  As predicated on the concepts of the strain-counterstrain model developed by Lawrence H. Jones, DO, the use of OMT produced a 23.1% decrease in the amplitude of the stretch reflex of the soleus (P<.05) in subjects with Achilles tendinitis. Similarly significant responses were measured in the lateral and medial heads of the gastrocnemius in OMT subjects. The H-reflex was not significantly affected by OMT. In control subjects, neither reflex was significantly affected by sham manipulative treatment. By using a rating scale on questionnaires before treatment and daily for 7 days posttreatment, OMT subjects indicated significant clinical improvement in soreness, stiffness, and swelling.
  
  
  CONCLUSIONS
  The reduction of stretch reflex amplitude with OMT, together with no change in H-reflex amplitude, is consistent with Korr's proprioceptive hypothesis for somatic dysfunction and patient treatment. Because subjects' soreness ratings also declined immediately after treatment, decreased nociceptor activity may play an additional role in somatic dysfunction, perhaps by altering stretch reflex amplitude.
authors.affiliation: Interdisciplinary Institute for Neuromuscular Research, Department of Biomedical Sciences, Irvine Hall, Ohio University College of Osteopathic Medicine, Athens, OH 45701-2979, USA. Howell@oucom.ohiou.edu
authors.forename: John N
authors.initials: JN
authors.lastname: Howell
authors.forename: Karen S
authors.initials: KS
authors.lastname: Cabell
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Chila
authors.forename: David C
authors.initials: DC
authors.lastname: Eland
mesh_terms: D000125:Achilles Tendon / Q000503:physiopathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008297:Male; D026301:Manipulation, Osteopathic; D008875:Middle Aged; D012026:Reflex, Stretch / Q000502:physiology*; D052256:Tendinopathy / Q000503:physiopathology* / Q000628:therapy*