Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction.

BACKGROUND: Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. METHODS: Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA). RESULTS: Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. CONCLUSIONS: Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF.

Does increased arterial stiffness increase the risk for postural hypotension?

This study tests the hypothesis that increased arterial stiffness is associated with postural hypotension in older adults. Aortic pulse wave velocity and postural blood pressure (BP) response were assessed in 49 nondiabetic community-dwelling normotensive (n=27) and hypertensive (n=22) older adults (mean age+/-SD, 71+/-6.7 years) who were not receiving vasoactive medications. During the 5-minute period of upright posture, 13 subjects had no change or a postural increase in systolic BP (SBP)(+10.6+/-14.6 mm Hg), 27 had a postural decrease of <20 mm Hg (-9.3+/-4.2 mm Hg), and nine had a postural decrease of >20 mm Hg (-29.1+/-8.1 mm Hg). Contrary to the proposed hypothesis, pulse wave velocity was significantly greater in subjects with a postural increase in SBP than in those with a postural decrease in SBP<20 mm Hg (10.2+/-0.68 m/sec vs. 8.3+/-0.37 m/sec; p=0.03) and tended to be greater than in those with a postural decrease in SBP>20 mm Hg (10.2+/-0.68 m/s vs. 8.5+/-0.73 m/sec; p=0.11). Higher pulse wave velocity was associated with a more positive postural SBP response at 1 minute (r=0.42; p=0.024), 3 minutes (r=0.38; p=0.007), and 5 minutes (r=0.45; p=0.001). This study does not support a relationship between arterial stiffness and a postural decrease in BP among healthy older adults; other age-related factors regulating BP homeostasis likely play a greater role.

Arterial stiffness is related to insulin resistance in nondiabetic hypertensive older adults.

Hypertension, diabetes, obesity, and aging are associated with increased arterial stiffness. Both insulin resistance and hyperglycemia may contribute to the development of arterial stiffness. Older nondiabetic hypertensive adults were recruited to test the following hypotheses: (1) insulin resistance is associated with arterial stiffness, and (2) this relationship is independent of glucose tolerance status. Aortic pulse wave velocity (PWV), pulse pressure (PP), insulin sensitivity index (S(I), measured by insulin-assisted frequently sampled iv glucose test), glucose tolerance status, and abdominal fat mass were assessed in 37 older (23 male, 14 female, mean age 69.4 +/- 5.9 yr), nondiabetic, hypertensive adults after a 4-wk antihypertensive medication withdrawal. Both PWV and PP were negatively correlated with S(I) (r = -0.49, P = 0.002, and r = -0.38, P = 0.02, respectively). The mean PWV and PP in those with normal glucose tolerance were not significantly different from those with impaired glucose tolerance (9.8 +/- 2.4 vs. 10.0 +/- 3.1 m/sec, P = 0.79 and 71 +/- 17 vs. 72 +/- 18 mm Hg, P = 0.80, respectively). In multiple regression analysis, PWV and PP remained independently correlated with S(I) (P < 0.05) after adjusting for age, gender, fasting glucose, glucose tolerance status, body mass index, or abdominal fat mass. These results suggest that in hypertensive, nondiabetic, older adults, insulin resistance is associated with arterial stiffness independent of glucose tolerance status.

Effects of aerobic exercise training in community-based subjects aged 80 and older: a pilot study.

OBJECTIVES: To assess the ability of sedentary, frail subjects aged 80 and older to train in a community-based exercise program and to evaluate clinical factors that predict improvements in peak oxygen consumption (VO2peak). DESIGN: Pretest, posttest. SETTING: Charlestown Retirement Community, Catonsville, Maryland PARTICIPANTS: Twenty-two (11 male, 11 female; mean age +/- standard deviation = 84 +/- 4.0, range 80-92) self-referred. INTERVENTION: Six months of moderate-intensity aerobic exercise training, two to three sessions/week, 20 to 30 minutes per session. Training modes included treadmill walking and/or stationary cycling. MEASUREMENTS: Baseline and follow-up maximal exercise treadmill tests (ETTs) with electrocardiogram monitoring and respiratory gas analysis. RESULTS: Six months of aerobic exercise training resulted in significant increases (mean +/- standard deviation) in ETT duration (11.9 +/- 3.3 vs 15.9 +/- 4.3 minutes; P =.01), VO2peak (1.23 +/- 0.37 vs 1.31 +/- 0.36 L/min; P =.04), and oxygen pulse (9.3 +/- 2.8 vs 10.1 +/- 3.2; P =.03). Mean heart rate was significantly lower during submaximal ETT stages 1 through 4 (P <.05), and resting systolic blood pressure decreased (146 +/- 18 vs 133 +/- 14 mmHg; P =.01) after training. Multiple regression analysis indicated that baseline VO2peak (r = 0.75, P =.002) and the total amount of time spent in exercise training (r = 0.55, P =.008) were independent predictors of the training-related improvements in VO2peak. CONCLUSION: Subjects aged 80 and older can increase aerobic capacity and reduce systolic blood pressure in a community-based exercise program of moderate intensity. The most important predictors of change in VO2peak were baseline VO2peak and the time spent in exercise training. Subjects with a lower baseline VO2peak had the greatest improvements in VO2peak after training.

Correlates of aortic stiffness in elderly individuals: a subgroup of the Cardiovascular Health Study.

BACKGROUND: Arterial stiffness has been associated with aging, hypertension, and diabetes; however, little data has been published examining risk factors associated with arterial stiffness in elderly individuals. METHODS: Longitudinal associations were made between aortic stiffness and risk factors measured approximately 4 years earlier. Aortic pulse wave velocity (PWV), an established index of arterial stiffness, was measured in 356 participants (53.4% women, 25.3% African American), aged 70 to 96 years, from the Pittsburgh site of the Cardiovascular Health Study during 1996 to 1998. RESULTS: Mean aortic pulse wave velocity (850 cm/sec, range 365 to 1863) did not differ by ethnicity or sex. Increased aortic stiffness was positively associated with higher systolic blood pressure (SBP), age, fasting and 2-h postload glucose, fasting and 2-h insulin, triglycerides, waist circumference, body mass index, truncal fat, decreased physical activity, heart rate, and common carotid artery wall thickness (P < .05). After controlling for age and SBP, the strongest predictors of aortic stiffness in men were heart rate (P = .001) and 2-h glucose (P = .063). In women, PWV was positively associated with heart rate (P = .018), use of antihypertensive medication (P = .035), waist circumference (P = .030), and triglycerides (P = .081), and was negatively associated with physical activity (P = .111). Results were similar when the analysis was repeated in nondiabetic individuals and in those free of clinical or subclinical cardiovascular disease in 1992 to 1993. CONCLUSIONS: In these elderly participants, aortic stiffness was positively associated with risk factors associated with the insulin resistance syndrome, increased common carotid intima-media thickness, heart rate, and decreased physical activity measured several years earlier.