title: Within-session responses to high-intensity interval training in chronic stroke.
abstract: Poststroke hemiparesis often leads to a vicious cycle of limited activity, deconditioning, and poor cardiovascular health. Accumulating evidence suggests that exercise intensity is a critical factor determining gains in aerobic capacity, cardiovascular protection, and functional recovery after stroke. High-intensity interval training (HIT) is a strategy that augments exercise intensity using bursts of concentrated effort alternated with recovery periods. However, there was previously no stroke-specific evidence to guide HIT protocol selection.
  
  
  OBJECTIVE
  This study aimed to compare within-session exercise responses among three different HIT protocols for persons with chronic (>6 months after) stroke.
  
  
  METHODS
  Nineteen ambulatory persons with chronic stroke performed three different 1-d HIT sessions in a randomized order, approximately 1 wk apart. HIT involved repeated 30-s bursts of treadmill walking at maximum tolerated speed, alternated with rest periods. The three HIT protocols were different on the basis of the length of the rest periods, as follows: 30 s (P30), 60 s (P60), or 120 s (P120). Exercise tolerance, oxygen uptake (V˙O2), HR, peak treadmill speed, and step count were measured.
  
  
  RESULTS
  P30 achieved the highest mean V˙O2, HR, and step count but with reduced exercise tolerance and lower treadmill speed than P60 or P120 (P30: 70.9% V˙O2peak, 76.1% HR reserve (HRR), 1619 steps, 1.03 m·s(-1); P60: 63.3% V˙O2peak, 63.1% HRR, 1370 steps, 1.13 m·s(-1); P120: 47.5% V˙O2peak, 46.3% HRR, 1091 steps, 1.10 m·s(-1)). P60 achieved treadmill speed and exercise tolerance similar to those in P120, with higher mean V˙O2, HR, and step count.
  
  
  CONCLUSIONS
  For treadmill HIT in chronic stroke, a combination of P30 and P60 may optimize aerobic intensity, treadmill speed, and stepping repetition, potentially leading to greater improvements in aerobic capacity and gait outcomes in future studies.
authors: 1Department of Rehabilitation Sciences, College of Allied Health Sciences, University of Cincinnati, Cincinnati, OH; 2Departments of Internal Medicine and Cardiology, College of Medicine, University of Cincinnati, Cincinnati, OH; 3Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; 4Department of Neurology, Physical Medicine and Rehabilitation, College of Medicine, University of Cincinnati, Cincinnati, OH.
authors: Pierce
authors: P
authors: Boyne
authors: Kari
authors: K
authors: Dunning
authors: Daniel
authors: D
authors: Carl
authors: Myron
authors: M
authors: Gerson
authors: Jane
authors: J
authors: Khoury
authors: Brett
authors: B
authors: Kissela
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D004562:Electrocardiography; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D005684:Gait; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010291:Paresis / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D020521:Stroke / Q000150:complications / Q000503:physiopathology; D000071939:Stroke Rehabilitation