Effects Of Age And Conditioning Status On Rest And Exerc

Aging

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Abstract

Summary:Our laboratory utilizes multiple techniques to determine the effects of age, gender and lifestyle habits on cardiovascular (CV) performance at rest and during exercise. (A) We examined whether age affects midwall systolic left ventricular (LV) performance, a more sensitive marker for determining myocardial dysfunction than standard endocardial measures. In 330 normal BLSA men (n=141) and women (n=189), those older than the median age of 50 years had smaller LV cavities, greater wall thickness, and higher endocardial fractional shortening than younger subjects. However, midwall shortening was not significantly age-related in either sex. Furthermore, the relationship between midwall shortening and end-systolic stress was similar in older versus younger groups. Thus, normative aging appears to have minimal effect on LV systolic performance whether measured at the LV endocardium or the midwall. (B) Longitudinal changes of maximal aerobic capacity (VO2max) were determined in nearly 1,400 Baltimore Longitudinal Study of Aging (BLSA) volunteers without evident cardiac disease, using mixed effects statistical analysis. Per decade, longitudinal declines in VO2max were generally greater than cross-sectional declines, especially in older decades. Gender differences in both absolute VO2max and rates of decline (men>women) are markedly attenuated when VO2max was normalized for fat-free mass rather than body weight. (C) The longitudinal decline in VO2max was determined in 42 older male endurance athletes, initially 64 (plus or minus) 6 years old. Over a mean follow-up of 7.8 years, VO2max declined by 22%, triple the decrease predicted by the baseline cross-sectional data. Within the overall sample, training status during follow-up had a major effect on the change in VO2max: the 6 men who continued to train vigorously had no significant decline in VO2max (0.28%/yr.), the 20 that trained at a lower intensity declined by 2.6% / yr, and the 14 who stopped training declined 4.6% / yr. Thus, physical activity patterns have a major impact on the long-term changes in maximal aerobic capacity in older athletes. (D) Left ventricular thickness, mass and chamber dimensions were measured in 336 healthy, normotensive adults (mean age 56+/-18 years, 200 women, 136 men) by magnetic resonance imaging (MRI). We found that the left ventricle becomes more spherical with age in normal adults because of reduced length. In women, this is associated with an increased wall thickness which offsets the decrease in length, resulting in left ventricular mass not changing with age. In men, wall thickness does not compensate for the increased sphericity, resulting in decreased left ventricular mass with age (Am J Cardiol 2002;90:1231-1236). (E) Ejection fraction (EF) acutely increases during exercise, but the EF reserve decreases with advancing age. EF is inversely related to the index of the interaction between arterial and ventricular properties, defined by the ratio of arterial elastance (EaI) to left ventricular systolic elastance (ELVI). We noninvasively characterized the arterial-ventricular coupling index EaI/ELVI and its two determinants at rest and during graded exercise in 136 healthy men and 103 healthy women (age range 21-87 years) from the Baltimore Longitudinal Study of Aging. We found that age-associated differences in EaI/ELVI occur in both genders during exercise, with less optimal coupling in older compared to younger subjects, which may help to explain the age deficit in maximal exercise EF. We also found that the mechanisms underlying the sub-optimal coupling in older adults differed between men and women (J Am Coll Cardiol. 2004;44(3):611-617).