title: A preliminary study of subsymptom threshold exercise training for refractory post-concussion syndrome.
abstract: OBJECTIVE
  To evaluate the safety and effectiveness of subsymptom threshold exercise training for the treatment of post-concussion syndrome (PCS).
  
  
  METHODS
  Prospective case series.
  
  
  METHODS
  University Sports Medicine Concussion Clinic.
  
  
  METHODS
  Twelve refractory patients with PCS (6 athletes and 6 nonathletes).
  
  
  METHODS
  Treadmill test to symptom exacerbation threshold (ST) before and after 2 to 3 weeks of baseline. Subjects then exercised 5 to 6 days per week at 80% ST heart rate (HR) until voluntary peak exertion without symptom exacerbation. Treadmill testing was repeated every 3 weeks.
  
  
  METHODS
  Adverse reactions to exercise, PCS symptoms, HR, systolic blood pressure (SBP), achievement of maximal exertion, and return to work/sport.
  
  
  RESULTS
  Pretreatment, ST occurred at low exercise HR (147 + or - 27 bpm) and SBP (142 + or - 6 mm Hg). After treatment, subjects exercised longer (9.75 + or - 6.38 minutes to 18.67 + or - 2.53 minutes, P = .001) and achieved peak HR (179 + or - 17 bpm) and SBP (156 + or - 13 mm Hg), both P < .001 versus pretreatment, without symptom exacerbation. Time series analysis showed significant change in rate of symptom reduction for all subjects and reduced mean symptom number in 8/11. Rate of PCS symptom improvement was related to peak exercise HR (r = -0.55, P = .04). Athletes recovered faster than nonathletes (25 + or - 8.7 vs 74.8 + or - 27.2 days, P = .01). No adverse events were reported. Athletes returned to sport and nonathletes to work.
  
  
  CONCLUSIONS
  Treatment with controlled exercise is a safe program that appears to improve PCS symptoms when compared with a no-treatment baseline. A randomized controlled study is warranted.
authors.affiliation: Department of Orthopaedics, University at Buffalo, The State University of New York, Buffalo, NY 14214, USA. leddy@buffalo.edu
authors.forename: John J
authors.initials: JJ
authors.lastname: Leddy
authors.forename: Karl
authors.initials: K
authors.lastname: Kozlowski
authors.forename: James P
authors.initials: JP
authors.lastname: Donnelly
authors.forename: David R
authors.initials: DR
authors.lastname: Pendergast
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Epstein
authors.forename: Barry
authors.initials: B
authors.lastname: Willer
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001265:Athletic Injuries / Q000150:complications / Q000534:rehabilitation / Q000628:therapy*; D005080:Exercise Test; D005081:Exercise Therapy; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D038223:Post-Concussion Syndrome / Q000150:complications / Q000534:rehabilitation / Q000628:therapy*; D011446:Prospective Studies; D013223:Statistics as Topic; D013997:Time Factors; D055815:Young Adult