title: Is There a Gradient of Mortality Risk among Men with Low Cardiorespiratory Fitness?
abstract: OBJECTIVE
  A low level of cardiorespiratory fitness (CRF) is a strong and independent predictor of all-cause mortality in men; however, it is unknown whether a gradient of mortality risk exists within the lowest CRF category.
  
  
  METHODS
  A total of 6251 apparently healthy men (mean age, 48.7 ± 6.3 yr) completed a comprehensive baseline clinical examination, including a maximal treadmill exercise test at Cooper Clinic between 1971 and 2006. In accord with previous studies using this cohort, low CRF was defined as a treadmill time in the first quintile within each age category of 40-49, 50-59, and 60-69 yr. The low CRF cohort was then grouped by tertiles (low/low, LL; mid/low, ML; and high/low, HL) using the same age categories.
  
  
  RESULTS
  After a mean follow-up period of 19.1 ± 10.4 yr, 1259 deaths occurred. Adjusted all-cause mortality rates were 57.0, 31.1, and 34.4 deaths per 10,000 man-years across LL, ML, and HL CRF categories for the 40- to 49-yr-old age group (P trend = 0.007). Similar trends were seen across low CRF categories for the 50- to 59-yr-old and 60- to 69-yr-old age groups (P trend = 0.02 and 0.09, respectively). When using treadmill time as a continuous variable, each 1-min increment in treadmill time was associated with a 9%, 11%, and 15% reduction in risk of all-cause mortality among low-CRF men in the 40-49, 50-59, and 60-69 age groups, respectively.
  
  
  CONCLUSIONS
  An inverse trend in all-cause mortality exists among men across LL, ML, and HL CRF groups. Although all low-fit men should be targeted for physical activity intervention, it is especially important to target the LL CRF group.
authors.affiliation: 1Research Division, Cooper Institute, Dallas, TX; 2Department of Medicine, Stanford University, Palo Alto, CA; and 3Center for Human Nutrition, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Farrell
authors.forename: Carrie E
authors.initials: CE
authors.lastname: Finley
authors.forename: William L
authors.initials: WL
authors.lastname: Haskell
authors.forename: Scott M
authors.initials: SM
authors.lastname: Grundy
mesh_terms: D000368:Aged; D002320:Cardiovascular Physiological Phenomena; D005500:Follow-Up Studies; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D010809:Physical Fitness; D011446:Prospective Studies; D012143:Respiratory Physiological Phenomena; D012307:Risk Factors