title: The relationship of walking intensity to total and cause-specific mortality. Results from the National Walkers' Health Study.
abstract: OBJECTIVE
  Test whether: 1) walking intensity predicts mortality when adjusted for walking energy expenditure, and 2) slow walking pace (≥24-minute mile) identifies subjects at substantially elevated risk for mortality.
  
  
  METHODS
  Hazard ratios from Cox proportional survival analyses of all-cause and cause-specific mortality vs. usual walking pace (min/mile) in 7,374 male and 31,607 female recreational walkers. Survival times were left censored for age at entry into the study. Other causes of death were treated as a competing risk for the analyses of cause-specific mortality. All analyses were adjusted for sex, education, baseline smoking, prior heart attack, aspirin use, diet, BMI, and walking energy expenditure. Deaths within one year of baseline were excluded.
  
  
  RESULTS
  The National Death Index identified 1968 deaths during the average 9.4-year mortality surveillance. Each additional minute per mile in walking pace was associated with an increased risk of mortality due to all causes (1.8% increase, P=10(-5)), cardiovascular diseases (2.4% increase, P=0.001, 637 deaths), ischemic heart disease (2.8% increase, P=0.003, 336 deaths), heart failure (6.5% increase, P=0.001, 36 deaths), hypertensive heart disease (6.2% increase, P=0.01, 31 deaths), diabetes (6.3% increase, P=0.004, 32 deaths), and dementia (6.6% increase, P=0.0004, 44 deaths). Those reporting a pace slower than a 24-minute mile were at increased risk for mortality due to all-causes (44.3% increased risk, P=0.0001), cardiovascular diseases (43.9% increased risk, P=0.03), and dementia (5.0-fold increased risk, P=0.0002) even though they satisfied the current exercise recommendations by walking ≥7.5 metabolic equivalent (MET)-hours per week.
  
  
  CONCLUSIONS
  The risk for mortality: 1) decreases in association with walking intensity, and 2) increases substantially in association for walking pace ≥24 minute mile (equivalent to <400 m during a six-minute walk test) even among subjects who exercise regularly.
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Williams
authors.forename: Paul D
authors.initials: PD
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000401:mortality*; D004032:Diet; D004522:Educational Status; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors; D016019:Survival Analysis; D014481:United States; D016138:Walking / Q000502:physiology*