title: The improvement of walking speed after cardiac rehabilitation is associated with the reduction in the metabolic cost of walking in older persons.
abstract: BACKGROUND
  To walk a given distance older persons consume more metabolic energy than younger adults across all speeds. As physical activity interventions improve a variety of physical performance measures in older persons, including walking speed, in this study we hypothesized that the improvement of walking speed might be associated with the reduction of the metabolic cost of walking and we tested our hypothesis in a selected sample of older patients receiving cardiac rehabilitation.
  
  
  METHODS
  In 120 patients (88 men and 32 women, mean age 74.1 years±SD 5.0) we assessed energy expenditure during the 6-min Walk Test (6mWT) before and after the rehabilitation using a portable system for direct calorimetry.
  
  
  RESULTS
  On the 6mWT performed after the rehabilitation patients significantly increased total energy expenditure (28.0 kcal±SD 8.3 vs. 25.7 kcal±SD 7.6, p<0.001), the distance walked (398 m±SD 93 vs. 343 m±SD 95, p<0.001) and, consequently, walking speed (1.11 m/s±SD 0.26 vs. 0.95m/s±SD 0.26, p<0.001) while the metabolic cost of walking, i.e. the amount of energy used to move a body mass of 1 kg for a distance of 1m, was significantly reduced (1.00 cal/kg/m±SD 0.19 vs. 1.11 cal/kg/m±SD 0.32, p<0.001).
  
  
  CONCLUSIONS
  In older patients receiving cardiac rehabilitation the improvement of walking speed is associated with the improvement of walking economy. This might be a contributory factor to the favourable effects of physical activity interventions on physical performance measures.
authors.affiliation: Cardiac Rehabilitation Unit, Don Gnocchi Foundation, Florence, Italy. raffmoli@tin.it
authors.forename: Raffaele
authors.initials: R
authors.lastname: Molino-Lova
authors.forename: Guido
authors.initials: G
authors.lastname: Pasquini
authors.forename: Federica
authors.initials: F
authors.lastname: Vannetti
authors.forename: Anita
authors.initials: A
authors.lastname: Paperini
authors.forename: Tatiana
authors.initials: T
authors.lastname: Forconi
authors.forename: Renato
authors.initials: R
authors.lastname: Zipoli
authors.forename: Paola
authors.initials: P
authors.lastname: Polcaro
authors.forename: Francesca
authors.initials: F
authors.lastname: Cecchi
authors.forename: Claudio
authors.initials: C
authors.lastname: Macchi
mesh_terms: D000054:Acceleration; D000367:Age Factors; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures / Q000379:methods / Q000534:rehabilitation*; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000601:surgery; D015331:Cohort Studies; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011182:Postoperative Care / Q000379:methods; D011788:Quality of Life; D012047:Rehabilitation Centers; D018570:Risk Assessment; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology*