title: Older Runners Retain Youthful Running Economy despite Biomechanical Differences.
abstract: OBJECTIVE
  Sixty-five years of age typically marks the onset of impaired walking economy. However, running economy has not been assessed beyond the age of 65 yr. Furthermore, a critical determinant of running economy is the spring-like storage and return of elastic energy from the leg during stance, which is related to leg stiffness. Therefore, we investigated whether runners older than 65 yr retain youthful running economy and/or leg stiffness across running speeds.
  
  
  METHODS
  Fifteen young and 15 older runners ran on a force-instrumented treadmill at 2.01, 2.46, and 2.91 m·s(-1). We measured their rates of metabolic energy consumption (i.e., metabolic power), ground reaction forces, and stride kinematics.
  
  
  RESULTS
  There were only small differences in running economy between young and older runners across the range of speeds. Statistically, the older runners consumed 2% to 9% less metabolic energy than the young runners across speeds (P = 0.012). Also, the leg stiffness of older runners was 10% to 20% lower than that of young runners across the range of speeds (P = 0.002), and in contrast to the younger runners, the leg stiffness of older runners decreased with speed (P < 0.001).
  
  
  CONCLUSIONS
  Runners beyond 65 yr of age maintain youthful running economy despite biomechanical differences. It may be that vigorous exercise, such as running, prevents the age related deterioration of muscular efficiency and, therefore, may make everyday activities easier.
authors.affiliation: 1Department of Integrative Physiology, University of Colorado, Boulder, CO; 2Department of Kinesiology and Recreation Administration, Humboldt State University, Arcata, CA; and 3Department of Veterans Affairs, Eastern Colorado Healthcare System, Denver, CO.
authors.forename: Owen N
authors.initials: ON
authors.lastname: Beck
authors.forename: Shalaya
authors.initials: S
authors.lastname: Kipp
authors.forename: Jaclyn M
authors.initials: JM
authors.lastname: Roby
authors.forename: Alena M
authors.initials: AM
authors.lastname: Grabowski
authors.forename: Rodger
authors.initials: R
authors.lastname: Kram
authors.forename: Justus D
authors.initials: JD
authors.lastname: Ortega
mesh_terms: D000367:Age Factors; D000368:Aged; D056352:Athletes; D001696:Biomechanical Phenomena; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D012420:Running / Q000502:physiology*; D055815:Young Adult