title: History-dependent changes in the recovery process of the middle latency cutaneous reflex gain after ankle sprain injury.
abstract: OBJECTIVE
  We previously reported that suppressive middle latency cutaneous reflexes (MLRs) in the peroneus longus (PL) are exaggerated in subjects with chronic ankle instability, and the changes are related to functional instability. However, the time-varying history of these neurophysiological changes after an ankle sprain is yet to be elucidated. Therefore, in the present study, we investigated the time course of the changes in the PL MLR after an ankle sprain in relation to the number of sprain recurrences.
  
  
  METHODS
  Twenty-three subjects with ankle sprain were classified into 3 groups according to their history of ankle sprain: first ankle sprain, 2-3 ankle sprains, and ≥4 ankle sprains. Twenty-three age-matched control subjects also participated. The PL MLRs were elicited by stimulating the sural nerve while the subjects performed different levels of isometric ankle eversion. Gain of MLR was estimated using linear regression analysis (slope value) of the amplitude modulation of MLRs obtained from graded isometric contractions.
  
  
  RESULTS
  The gain of MLRs first increased 4 weeks after the injury. In subjects with their first ankle sprain, the MLRs returned to almost baseline levels after 3 months. In contrast, the increase in MLR gain persisted even after 3 months in subjects with recurrent ankle sprains. In addition, the MLR gains were closely related to functional recovery of the ankle joint.
  
  
  CONCLUSIONS
  Our findings suggest that the recovery process of MLR gains were strongly affected by the history of ankle sprains as well as the functional recovery of the ankle joint.
authors.affiliation: The United Graduate School of Education, Tokyo Gakugei University, Koganei, Tokyo, Japan. futatsubashi@ic.jobu.ac.jp.|Faculty of Business and Information Sciences, Jobu University, 634-1 Toyatsukamachi, Isesaki, Gunma, 372-8588, Japan. futatsubashi@ic.jobu.ac.jp.
authors.forename: Genki
authors.initials: G
authors.lastname: Futatsubashi
authors.affiliation: Department of Food and Nutrition Science, Sagami Women's University, Sagamihara, Kanagawa, Japan.
authors.forename: Syusaku
authors.initials: S
authors.lastname: Sasada
authors.affiliation: Department of Physical Therapy, Health Sciences University of Hokkaido, Sapporo, Hokkaido, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohtsuka
authors.affiliation: The United Graduate School of Education, Tokyo Gakugei University, Koganei, Tokyo, Japan.|Department of Integrative Physiology, Kyorin University, School of Medicine, Mitaka, Tokyo, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: The United Graduate School of Education, Tokyo Gakugei University, Koganei, Tokyo, Japan.|Faculty of Education, Chiba University, Chiba, Chiba, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Komiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D016512:Ankle Injuries / Q000473:pathology / Q000503:physiopathology* / Q000534:rehabilitation; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010543:Peroneal Nerve / Q000502:physiology; D020127:Recovery of Function; D012008:Recurrence; D012018:Reflex
keywords: Cutaneous reflex; History of ankle sprain; Recurrent ankle sprain; The recovery process