While older adults can benefit from initiating a regular regimen of moderate-intensity exercise in terms of improved fitness levels and small improvements in HDL cholesterol levels, the time frame needed to achieve HDL cholesterol change (2 years) may be longer than that reported previously for younger populations. Frequency of participation may be particularly important for achieving such changes. Supervised home-based exercise regimens represent a safe, attractive alternative for achieving sustained participation.

Background-Endothelial function is impaired by hyperhomocyst(e)inemia. We have previously shown that homocyst(e)ine (Hcy) inhibits NO production by cultured endothelial cells by causing the accumulation of asymmetric dimethylarginine (ADMA). The present study was designed to determine if the same mechanism is operative in humans. Methods and Results-We studied 9 patients with documented peripheral arterial disease (6 men; 3 women; age, 64Ϯ3 years), 9 age-matched individuals at risk for atherosclerosis (older adults; 9 men; age, 65Ϯ1 years), and 5 young control subjects (younger adults; 5 men; age, 31Ϯ1 years) without evidence of or risk factors for atherosclerosis. Endothelial function was measured by flow-mediated vasodilatation of the brachial artery before and 4 hours after a methionineloading test (100 mg/kg body weight, administered orally). In addition, blood was drawn at both time points for measurements of Hcy and ADMA concentrations. Plasma Hcy increased after the methionine-loading test in each group (all, PϽ0.001). Plasma ADMA levels rose in all subjects, from 0.9Ϯ0.2 to 1.6Ϯ0.2 mol/L in younger adults, from 1.5Ϯ0.2 to 3.0Ϯ0.4 mol/L in older adults, and from 1.8Ϯ0.1 to 3.9Ϯ0.3 mol/L in peripheral arterial disease patients (all, PϽ0.001). Flow-mediated vasodilatation was reduced from 13Ϯ2% to 10Ϯ1% in younger adults, from 6Ϯ1% to 5Ϯ1% in older adults, and from 7Ϯ1% to 3Ϯ1% in peripheral arterial disease patients (all, PϽ0.001

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In patients with congestive heart failure (CHF), the poor relationship between systemic exercise performance and cardiac function, together with morphologic and metabolic abnormalities in skeletal muscle, raises the possibility that skeletal muscle function may be impaired and limit systemic exercise performance. We assessed strength and endurance of the knee extensors during static and dynamic exercise in 16 patients with Class I-IV CHF and eight age-matched sedentary controls and related these measurements to systemic exercise performance. To assess skeletal muscle function independent of peripheral blood flow, endurance was repeated under ischemic conditions. Strength was not significantly different in the two groups. Dynamic endurance, quantified as the decline in peak torque during 15 successive isokinetic knee extensions, was significantly reduced in the patients compared to controls during aerobic (peak torque 65 vs. 86% of initial for exercise at 90 deg/s and 60 vs. 85% for exercise at 180 deg/s; P < 0.002 for both), and during ischemic exercise (56 vs. 76% of initial torque; P < 0.01). Static endurance, defined as the time required for force during a sustained maximal voluntary contraction to decline to 60% of maximal, was reduced in the patients compared to controls (40±14 vs. 77±29 s; P < 0.02). There were highly significant relationships between systemic exercise performance and skeletal muscle endurance at 90 and 180 deg/s in the patients with CHF (r = 0.90 and 0.66, respectively). These findings indicate that skeletal muscle endurance is impaired in patients with CHF, that this abnormality is in part independent of limb blood flow, and that these changes may be important determinants of systemic exercise performance. (J. Clin. Invest. 1991.