Publications (2)8.31 Total impact
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Article: The Effect of Age-related Differences in Body Size and Composition on Cardiovascular Determinants of VO2max.
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ABSTRACT: BACKGROUND: A reduction in maximal stroke volume (SV(max)) and total blood volume (TBV) has been hypothesized to contribute to the decline in maximal oxygen uptake (VO(2)max) with healthy aging. However, these variables have rarely been collected simultaneously in a board age range to support or refute this hypothesis. It is also unclear to what extent scaling size-related cardiovascular determinants of VO(2)max affects the interpretation of age-related differences. METHODS: A retrospective analysis of VO(2)max, maximal cardiac output (Q(C)max), TBV, and body composition including fat-free mass (FFM) in 95 (51% M) healthy adults ranging from 19-86 years. RESULTS: Absolute and indexed VO(2)max, Q(C)max, and maximal heart rate decreased in both sexes with age (p ≤ .031). SV(max) declined with age when scaled to total body mass or body surface area (p ≤ .047) but not when expressed in absolute levels (p = .120) or relative to FFM (p = .464). Absolute and indexed TBVs (mL/kg; mL/m(2)) were not significantly affected by age but increased with age in both sexes when scaled to FFM (p ≤ .013). A lower arteriovenous oxygen difference (a-vO(2)diff) contributed to the reduction in VO(2)max with age in treadmill exercisers (p = .004) but not in the entire cohort (p = .128). CONCLUSION: These results suggest (a) a reduction in absolute SV(max), and TBV do not contribute substantially to the age-related reduction in VO(2)max, which instead results from a smaller Q(C)max due to a lower maximal heart rate, and (b) body composition scaling methods should be used to accurately describe the effect of aging on physical function and cardiovascular variables.The Journals of Gerontology Series A Biological Sciences and Medical Sciences 11/2012; · 4.60 Impact Factor -
Article: Effect of healthy aging on left ventricular relaxation and diastolic suction.
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ABSTRACT: Doppler ultrasound measures of left ventricular (LV) active relaxation and diastolic suction are slowed with healthy aging. It is unclear to what extent these changes are related to alterations in intrinsic LV properties and/or cardiovascular loading conditions. Seventy carefully screened individuals (38 female, 32 male) aged 21-77 were recruited into four age groups (young: <35; early middle age: 35-49; late middle age: 50-64 and seniors: ≥65 yr). Pulmonary capillary wedge pressure (PCWP), stroke volume, LV end-diastolic volume, and Doppler measures of LV diastolic filling were collected at multiple loading conditions, including supine baseline, lower body negative pressure to reduce LV filling, and saline infusion to increase LV filling. LV mass, supine PCWP, and heart rate were not affected significantly by aging. Measures of LV relaxation, including isovolumic relaxation time and the time constant of isovolumic pressure decay increased progressively, whereas peak early mitral annular longitudinal velocity decreased with advancing age (P < 0.001). The propagation velocity of early mitral inflow, a noninvasive measure of LV suction, decreased with aging with the greatest reduction in seniors (P < 0.001). Age-related differences in LV relaxation and diastolic suction were not attenuated significantly when PCWP was increased in older subjects or reduced in the younger subjects. There is an early slowing of LV relaxation and diastolic suction beginning in early middle age, with the greatest reduction observed in seniors. Because age-related differences in LV dynamic diastolic filling parameters were not diminished significantly with significant changes in LV loading conditions, a decline in ventricular relaxation is likely responsible for the alterations in LV diastolic filling with senescence.AJP Heart and Circulatory Physiology 06/2012; 303(3):H315-22. · 3.71 Impact Factor
