title: The Relationships between Age and Running Biomechanics.
abstract: Running has high injury rates, especially among older runners. Most aging literature compares young with old runners without accounting for the progression of biomechanics throughout the lifespan. We used age as a continuous variable to investigate the continuum of age-related gait adaptations in running along with determining the chronology and rate of these adaptations.
  
  
  OBJECTIVE
  This study aimed to identify the relations among age and selected running biomechanics throughout the range of 18-60 yr.
  
  
  METHODS
  Experienced (n = 110) healthy runners (male, 54%) provided informed consent and ran at their training pace while motion and force data were captured. Kinematics, ground reaction forces (GRF), and lower limb joint torques and powers were correlated with age using Pearson product-moment correlations and linear regression.
  
  
  RESULTS
  Running velocity was inversely related to age (r = -0.27, P = 0.005) because of decreased stride length (r = -0.25, P = 0.008) but not rate. Peak vertical GRF (r = -0.23, P = 0.016) and peak horizontal propulsive GRF decreased with age (r = -0.38, P < 0.0001). Peak ankle torque (r = -0.32, P = 0.0007) and peak negative (r = 0.34, P = 0.0003) and positive (r = -0.37, P < 0.0001) ankle power decreased with age. Age-based regression equations and per-year reductions in all variables significantly related to age are reported.
  
  
  CONCLUSIONS
  Data support previous work showing lower GRF, stride length, and velocity in old runners. Results are novel in showing the rate of decline in running biomechanics on a per-year basis and that mechanical reductions at the ankle but not at the hip or knee were correlated with age, confirming a previous observation of biomechanical plasticity with age showing reduced ankle but not hip function in gait.
authors.affiliation: 1Department of Kinesiology, East Carolina University, Greenville, NC; 2Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, MA; 3Department of Biostatistical Sciences and Department of Social Sciences and Health Policy, Wake Forest School of Medicine, Winston-Salem, NC; and 4Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC.
authors.forename: Paul
authors.initials: P
authors.lastname: Devita
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Fellin
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Seay
authors.forename: Edward
authors.initials: E
authors.lastname: Ip
authors.forename: Nicole
authors.initials: N
authors.lastname: Stavro
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Messier
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012420:Running / Q000502:physiology*; D055815:Young Adult