Chris Lockhart

Short-Term Aerobic Exercise Reduces Arterial Stiffness in Older Adults With Type 2 Diabetes, Hypertension, and Hypercholesterolemia

OBJECTIVE The relationship between increased arterial stiffness and cardiovascular mortality is well established in type 2 diabetes. We examined whether aerobic exercise could reduce arterial stiffness in older adults with type 2 diabetes complicated by comorbid hypertension and hyperlipidemia. RESEARCH DESIGN AND METHODS A total of 36 older adults (mean age 71.4 ± 0.7 years) with diet-controlled or oral hypoglycemic–controlled type 2 diabetes, hypertension, and hypercholesterolemia were recruited. Subjects were randomly assigned to one of two groups: an aerobic group (3 months vigorous aerobic exercise) and a nonaerobic group (no aerobic exercise). Exercise sessions were supervised by a certified exercise trainer three times per week, and a combination of cycle ergometers and treadmills was used. Arterial stiffness was measured using the Complior device. RESULTS When the two groups were compared, aerobic training resulted in a decrease in measures of both radial (−20.7 ± 6.3 vs. +8.5 ± 6.6%, P = 0.005) and femoral (−13.9 ± 6.7 vs. +4.4 ± 3.3%, P = 0.015) pulse-wave velocity despite the fact that aerobic fitness as assessed by Vo2max did not demonstrate an improvement with training (P = 0.026). CONCLUSIONS Our findings indicate that a relatively short aerobic exercise intervention in older adults can reduce multifactorial arterial stiffness (type 2 diabetes, aging, hypertension, and hypercholesterolemia).

Aerobic training restores arterial baroreflex sensitivity in older adults with type 2 diabetes, hypertension, and hypercholesterolemia.

Objective: Lowered baroreflex sensitivity (BRS) predicts mortality and occurs with increasing age and diabetes. We examined whether aerobic exercise could restore arterial BRS in adults at high cardiovascular risk (diabetes, geriatric age group, hypercholesterolemia, and hypertension). Design: Randomized, controlled, single-blind study. Setting: VITALiTY (Vancouver Initiative to Add Life to Years) Research Laboratory. Participants: Thirty-nine older adults (mean age, 71.5 ± 0.7 years) with diet-controlled or oral hypoglycemic-controlled type 2 diabetes, hypertension, and hypercholesterolemia. Interventions: Subjects were recruited to each of 2 groups: an aerobic group (3 months of vigorous aerobic exercise as defined by 80% to 85% of maximal heart rate), and a nonaerobic (no aerobic exercise) group. Exercise sessions were supervised by a certified exercise trainer 3 times per week. Main Outcome Measures: Baroreflex function was assessed using the spontaneous baroreflex method. Main outcome measures included BRS, BRSup, BRSdown, and &OV0312;o2max. Results: The aerobic group demonstrated an increase in BRS that was not demonstrated in the nonaerobic group (+60.9 ± 23.5 vs +2.2 ± 7.9%; P = 0.010). Conclusions: Our findings indicate that a relatively short aerobic exercise intervention can reverse functional impairments of the arterial baroreflex function in older adults at high cardiovascular risk.

Aerobic training-induced improvements in arterial stiffness are not sustained in older adults with multiple cardiovascular risk factors

There is a well-established relationship between increased arterial stiffness and cardiovascular mortality. We examined whether a long-term aerobic exercise intervention (6 months) would increase arterial compliance in older adults with hypertension complicated by Type 2 diabetes (T2DM) and hyperlipidemia. A total of 52 older adults (mean age 69.3±0.6 years, 30 males and 22 females) with diet/oral hypoglycemic-controlled T2DM, hypertension and hypercholesterolemia were recruited. Subjects were randomly assigned to one of two groups: an aerobic group (6 months vigorous aerobic exercise, AT group) and a non-aerobic group (6 months of no aerobic exercise, NA group). Arterial stiffness was measured as pulse-wave velocity (PWV) using the Complior device. Aerobic training decreased arterial stiffness as measured by both radial (P=0.001, 2-way analysis of variance with repeated measures) and femoral (P=0.002) PWV. This was due to a decrease in arterial stiffness in the AT group after 3 months of training, which was not maintained after 6-month training for either radial (P=0.707) or femoral (P=0.680) PWV. Our findings indicate that in older adults with multiple cardiovascular risk factors, short-term improvements in arterial stiffness became attenuated over the long term.

Sedentary behavior and sleep efficiency in active community-dwelling older adults

Objectives Previous studies have demonstrated that aerobic exercise interventions have a positive impact on sleep efficiency in older adults. However, little work has been done on the impact of sedentary behavior (sitting, watching television, etc.) on sleep efficiency. Methods 54 Community-dwelling men and women >65 years of age living in Whistler, British Columbia (mean 71.5 years) were enrolled in this cross-sectional observational study. Measures of sleep efficiency as well as average waking sedentary (ST), light (LT), and moderate (MT) activity were recorded with Sensewear accelerometers worn continuously for 7 days. Results From the univariate regression analysis, there was no association between sleep efficiency and the predictors LT and MT. There was a small negative association between ST and sleep efficiency that remained significant in our multivariate regression model containing alcohol consumption, age and gender as covariates. (standardized β correlation coefficient −0.322, p=0.019). Although significant, this effect was small (an increase in sedentary time of 3 hours per day was associated with an approximately 5% reduction in sleep efficiency). Conclusions This study found a small significant association between the time spent sedentary and sleep efficiency, despite high levels of activity in this older adult group.

Arterial stiffness and the response to carotid sinus massage in older adults

Background and aims: Carotid sinus hypersensitivity (CSH) is a common cause of fainting and falls in the older adult population and is diagnosed by carotid sinus massage (CSM). Previous work has suggested that age-related stiffening of blood vessels reduces afferent input from the carotid sinus leading to central upregulation of the overall arterial baroreflex response. We examined the differences in arterial stiffness and baroreflex function in older adults at high cardiovascular risk (advanced age, Type 2 diabetes, hypertension and hyperlipidemia) with and without CSH. Methods: Forty-three older adults (mean age 71.4±0.7) with Type 2 diabetes, hyperlipidemia and hypertension were recruited. After resting supine for 45 minutes prior to the start of data collection, each subject had arterial stiffness measured by pulse wave velocity (PWV, Complior SD), followed by spontaneous baroreflex measures (Baroreflex sensitivity, BRS) and CSM. Results: Of the 43 subjects tested, 10 subjects met the criteria for CSH (8 pure vasodepressor and 2 mixed CSH). CSH subjects had higher measures of arterial stiffness when compared to normal subjects for both radial PWV(11.5±0.6 vs 9.6±0.4 m/s, p=0.043) and femoral PWV(13.4±0.9 vs 11.0±0.5 m/s, p=0.036). The CSH group demonstrated significantly lower BRS as compared to the normal group (BRS, 6.73±0.58 vs 10.41±0.85 ms/mmHg, p=0.038). These results were unchanged when the analysis was repeated with only the VD subjects. Conclusions: Older adults with CSH have higher arterial stiffness and reduced arterial baroreflex sensitivity. There was no evidence to support upregulation of the arterial baroreflex in patients with CSH.

Short-term aerobic exercise reduces nitroglycerin-induced orthostatic intolerance in older adults with type 2 diabetes.

Aims/Hypothesis: Older adults are at a high risk for syncope due to orthostatic intolerance (OI), and this risk increases with comorbid type 2 diabetes and vasoactive medications. Despite many benefits, previous investigations have shown worsening OI with aerobic training. We examined whether aerobic exercise reduced OI in older adults with type 2 diabetes who were given a short-acting vasoactive agent (nitroglycerin). Methods: Forty older adults (25 males and 15 females, mean age 71.4 ± 0.7 years, ranging in age from 65 to 83 years) with type 2 diabetes were recruited. Subjects were randomized to each of 2 groups: an aerobic group (3 months of vigorous aerobic exercise) and a nonaerobic (no aerobic exercise) group. Exercise sessions were supervised by a certified exercise trainer 3 times per week. After being given 400 μg of sublingual nitroglycerin, each subject was placed in a 70° head-up tilt for 30 minutes. Results: When the 2 groups were compared using a Cox proportional hazards model, tilt table tolerance was significantly better in the aerobic group as compared to in the nonaerobic group (χ2MC = 7.271, P = 0.007). Conclusions: Our findings indicate that a relatively short aerobic exercise intervention can improve postnitroglycerin orthostatic tolerance in older adults with type 2 diabetes.

Euglycemic Hyperinsulinemia Alters the Response to Orthostatic Stress in Older Adults With Type 2 Diabetes

OBJECTIVE—Insulin has opposing influences on blood pressure by simultaneously increasing adrenergic activity and vasodilatating peripheral blood vessels. In this study, we sought to determine whether hyperinsulinemia affects tilt table responses in older adults with type 2 diabetes not complicated by orthostatic hypotension. RESEARCH DESIGN AND METHODS—Twenty-two older adults (mean age 71.7 ± 1.1) with diet-controlled or oral hypoglycemic drug–controlled type 2 diabetes were recruited. All subjects with orthostatic hypotension, diabetic nephropathy, and sensory neuropathy were excluded. Subjects underwent euglycemic-hyperinsulinemic clamp and placebo “sham clamp” sessions. Sequential euglycemic-hyperinsulinemic clamps were performed for 2 h at 40 mU · m−2 · min−1 (low dose) and 2 h at 80 mU · m−2 · min−1 (high dose), and each was followed by a head-up tilt table test at 70°C for 10 min. RESULTS—There were no incidents of presyncope during the sham clamp, whereas there were four presyncopal events during both the low-dose and high-dose tilts. Although the low-dose clamp showed no difference in the response between sessions (two-way ANOVA), subjects demonstrated a significantly larger decrease in mean arterial pressure (P = 0.005) and diastolic blood pressure (P = 0.08) during the high-dose tilt. Doppler measures of middle cerebral artery velocity were no different between the two sessions at either dose. CONCLUSIONS—The vasodilatory response to insulin can unmask orthostatic intolerance in older adults with type 2 diabetes, resulting in presyncopal symptoms. This could contribute to orthostatic hypotension in combination with other factors such as hyperthermia, hypovolemia, and adverse effects from medications.