title: Lower rate-pressure product during submaximal walking: a link to fatigue improvement following a physical activity intervention among breast cancer survivors.
abstract: Research showing a link between exercise-induced changes in aerobic fitness and reduced fatigue after a cancer diagnosis has been inconsistent. We evaluated associations of fatigue and rate-pressure product (RPP), a reliable index of myocardial oxygen demand, at rest and during submaximal walking following a physical activity intervention among post-primary treatment breast cancer survivors (BCS).
  
  
  
  Secondary analyses of 152 BCS in a randomized controlled trial testing a physical activity intervention (INT) versus usual care (UC) were performed. The INT group completed counseling/group discussions along with supervised exercise sessions tapered to unsupervised exercise. Evaluations were made at baseline and immediately post-intervention (M3) on measures of physical activity (accelerometry), graded walk test, and average fatigue over the previous 7 days. RPP was calculated by dividing the product of heart rate and systolic blood pressure by 100.
  
  
  
  Resting and submaximal RPPs were significantly improved in both groups at M3; however, the magnitude of change (∆) was greater in the INT group from stage 1 (∆RPP1; INT -13 ± 17 vs. UC -7 ± 18; p = 0.03) through stage 4 (∆RPP4; INT -21 ± 26 vs. UC -9 ± 24; p < 0.01) of the walk test. The INT group reported significantly reduced fatigue (INT -0.7 ± 2.0 vs. UC +0.1 ± 2.0; p = 0.02) which was positively associated with ∆RPP during stages 2-4 of the walk test but not ∆aerobic fitness.
  
  
  
  Lower RPP during submaximal walking was significantly associated with reduced fatigue in BCS.
  
  
  
  Exercise/physical activity training programs that lower the physiological strain during submaximal walking may produce the largest improvements in reported fatigue.
authors.affiliation: Department of Human Studies, University of Alabama at Birmingham, Birmingham, AL, USA. carters@uab.edu.|Department of Nutrition Sciences, University of Alabama at Birmingham, 1675 University Blvd, Webb Building #248, Birmingham, AL, 35233-2432, USA. carters@uab.edu.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Carter
authors.affiliation: Department of Human Studies, University of Alabama at Birmingham, Birmingham, AL, USA.|Department of Nutrition Sciences, University of Alabama at Birmingham, 1675 University Blvd, Webb Building #248, Birmingham, AL, 35233-2432, USA.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Hunter
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: McAuley
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, Canada.
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Courneya
authors.affiliation: Department of Kinesiology, Southern Illinois University, Carbondale, IL, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Anton
authors.affiliation: Department of Nutrition Sciences, University of Alabama at Birmingham, 1675 University Blvd, Webb Building #248, Birmingham, AL, 35233-2432, USA.
authors.forename: Laura Q
authors.initials: LQ
authors.lastname: Rogers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000503:physiopathology / Q000628:therapy*; D018479:Early Intervention, Educational; D005081:Exercise Therapy; D005221:Fatigue / Q000517:prevention & control*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D011788:Quality of Life; D017741:Survivors; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Cardiovascular; Exercise; Heart rate; Systolic blood pressure