From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Wed Aug 04 1999 - 04:45:39 MDT
Authors
Lee CD. Blair SN. Jackson AS.
Institution
Division of Epidemiology & Clinical Applications, Cooper Institute for
Aerobics Research, Dallas, TX, USA.
Title
Cardiorespiratory fitness, body
composition, and all-cause and cardiovascular disease mortality in men.
Source
American Journal of Clinical Nutrition. 69(3):373-80, 1999 Mar.
Abstract
BACKGROUND: Cardiorespiratory fitness and
body fatness are both related to health, but their interrelation to all-cause
and cardiovascular disease (CVD) mortality is unknown. OBJECTIVE: We examined
the health benefits of leanness and the hazards of obesity while
simultaneously considering cardiorespiratory
fitness. DESIGN: This was an observational cohort study. We
followed 21925 men, aged 30-83 y, who had a body-composition assessment and a
maximal treadmill exercise test. There were 428 deaths (144 from CVD, 143
from cancer, and 141 from other causes) in an average of 8 y of follow-up
(176742 man-years). RESULTS: After adjustment for age, examination year,
cigarette smoking, alcohol intake, and parental history of ischemic heart
disease, unfit (low cardiorespiratory
fitness as determined by maximal exercise testing), lean men
had double the risk of all-cause mortality of fit, lean men (relative risk:
2.07; 95% CI: 1.16, 3.69; P = 0.01). Unfit, lean men also had a higher risk
of all-cause and CVD mortality than did men who were fit and obese. We
observed similar results for fat and fat-free mass in relation to mortality.
Unfit men had a higher risk of all-cause and CVD mortality than did fit men
in all fat and fat-free mass categories. Similarly, unfit men with low waist
girths (<87 cm) had greater risk of all-cause mortality than did fit men with
high waist girths (> or =99 cm). CONCLUSIONS: The health benefits of leanness
are limited to fit men, and being fit may reduce the hazards of obesity.
Additional quotes from the above research paper:
"The all-cause mortality rate of fit, obese men was not significantly
different from that of fit, lean men."
Table 3
Waist circumference category Multivariate RR
and cardiorespiratory fitness level of death
Low waist circumference (<87 cm)
Fit 1.0
Unfit 4.88
Moderate waist circumference (87 to <99 cm)
Fit 1.05
Unfit 2.05
High waist circumference (>99 cm)
Fit 0.95
Unfit 2.40
"In summary, we found that obesity did not appear to increase mortality
risk in fit men. For long-term health benefits we should focus on
improving fitness by increasing physical activity rather than relying
only on diet for weight control. Aerobic exercise improves IHD risk
factors, and increases in physical activity or fitness extend longevity.
Although some studies show that there is no difference between diet and
aerobic exercise in reducing IHD risk factors, or even report that diet
is better than aerobic exercise for improving IHD risk factors in
overweight men, our data show that fit men had greater longevity than
unfit men regardless of their body composition or risk factor status.
Obese men should be encouraged to increase their cardiorespiratory
fitness by engaging in regular, moderate intensity physical activity;
this should benefit them even if they remain overweight."
Additional note by poster:
Although weight loss through dieting is associated with improvements in
some IHD risk factors, what is not widely recognized is that other IHD
risk factors are worsened. These include increased homocysteine, lower
HDL, and reductions in intake of heart protective omega-3 fatty acids,
and possibly reduced dietary arginine (nut) intake. These are some of the
factors that may explain why most studies have found that dieting does
not lower mortality rates.
Although this is not a popular idea, body fatness in and of itself
appears to be neutral with respect to mortality. Other variables are the
key determining factors of human life expectancy, and cardiorespiratory
fitness as measured by a treadmill is one.
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:04:39 MST