Arterial blood pressure and cardiovascular responses to yoga practice.

CONTEXT: Yoga is qualitatively different from any other mode of physical activity in that it consists of a unique combination of isometric muscular contractions, stretching exercises, relaxation techniques, and breathing exercises. In particular, yoga postures consist of systemic isometric contractions that are known to elicit marked increases in mean blood pressure that are not observed during dynamic exercise. Stretching can also induce increases in blood pressure and sympathetic nerve activity in the muscles. Currently, not much is known about changes in blood pressure and other cardiovascular responses to yoga practice. OBJECTIVE: The study intended to determine the acute effects of one session of hatha yoga practice on blood pressure and other cardiovascular responses. To gain insight into the long-term effects of yoga practice, both novice (n = 19) and advanced (n = 18) yoga practitioners were studied. DESIGN: The two groups were matched for age, gender, BMI, and blood pressure. SETTING: The setting was a research laboratory at a university. PARTICIPANTS: Thirty-six apparently healthy, nonobese, sedentary, or recreationally active individuals from the community participated in the study. Intervention The intervention comprised one session of yoga practice, in which participants followed a custom made instructional video providing a yoga routine that consisted of a series of 23 hatha-based yoga postures. OUTCOME MEASURES: Prior to arriving at the laboratory, each participant completed a research health questionnaire, a training-status questionnaire, and a yoga-experience questionnaire. Prior to the yoga practice, each participant's height, body fat percentage, trunk or lumbar flexibility, and arterial stiffness as assessed by carotid femoral pulse wave velocity (cfPWV) were measured. For each posture during the yoga practice, the study continuously measured systolic, mean, and diastolic blood pressures, heart rate, stroke volume, and cardiac output. RESULTS: Systolic, mean, and diastolic blood pressures increased significantly during the yoga practice. The magnitude of these increases in blood pressure was greatest with standing postures. Heart rate and cardiac output increased significantly during yoga practice, especially with standing postures. Overall, no differences existed in cardiovascular responses between the novice and advanced practitioners throughout the yoga testing session; cfPWV velocity was significantly and inversely associated with lumbar flexion but not with sit-and-reach test scores. CONCLUSIONS: The research team concluded that a variety of hatha yoga postures, especially standing postures, evoked significant increases in blood pressure. The elevation in blood pressure due to yoga practice was associated with increases in cardiac output and heart rate, which are responses similar to those observed in isometric exercise. The lack of obvious differences in blood pressure and other cardiovascular responses between novice and advanced yoga practitioners suggests that long-term yoga practice does not attenuate acute yoga responses.

Elevated cerebral glutamate and myo-inositol levels in cognitively normal middle-aged adults with metabolic syndrome.

Metabolic syndrome (MetS) is a cluster of risk factors associated with significant cardiovascular morbidity and mortality and diminished cognitive function. Given that the cerebral mechanisms mediating the relationship between peripheral metabolic dysfunction and cognitive impairment are unknown, we set out to examine the relationship between diagnosis of metabolic syndrome and cerebral metabolism. Thirteen participants with MetS (aged 48 ± 6 years) and 25 healthy adults (aged 51 ± 6 years) underwent neuropsychological assessment, health screen and proton magnetic resonance spectroscopy ((1)H MRS) examining N-acetyl-aspartate (NAA), myo-inositol (mI), creatine (Cr), choline (Cho), and glutamate (Glu) concentrations in occipitoparietal grey matter. Cerebral metabolite ratios (NAA/Cr, Cho/Cr, mI/Cr, and Glu/Cr) of participants with MetS, defined by the International Diabetes Federation criteria, were compared with controls matched for age, education, cognition, and emotional function. There were no significant differences in global cognitive function, memory, language, and psychomotor performance between the groups. Diagnosis of MetS was associated with significantly higher mI/Cr (F(1,36) = 5.02, p = 0.031) and Glu/Cr ratio (F(1,36) = 4.81, p = 0.035). Even in cognitively normal adults, MetS is related to cerebral metabolic disturbances, a possible indication of early brain vulnerability. Longitudinal studies that begin in mid-life can help validate the use of (1)H MRS markers as indicators of long-term cognitive outcomes.

Insulin sensitivity as a mediator of the relationship between BMI and working memory-related brain activation.

Midlife obesity is associated with cognitive deficits and cerebral atrophy in older age. However, little is known about the early signs of these deleterious brain effects or the physiological mechanisms that underlie them. Functional magnetic resonance imaging (fMRI) allows us to detect early changes in brain response to cognitive challenges while behavioral performance is still intact. Accordingly, we examined the impact of obesity on functional activation during a 2-Back task in 32 cognitively normal middle-aged adults, who were classified into normal, overweight, and obese groups according to BMI. Additionally, we examined insulin sensitivity as a potential mediator of the relationship between BMI and brain activation. Insulin sensitivity is of special interest because insulin is strongly associated with both obesity and central nervous system functioning. Group differences in task-related brain activation were examined in a priori regions of interest (ROIs) using ANOVA. The obese BMI group displayed significantly lower task-related activation in the right parietal cortex, BA 40/7, (F(2,29) = 5.26, P = 0.011) than the normal (P = 0.016) and overweight (P = 0.047) BMI groups. Linear regression and bootstrapping methods for assessing indirect effects indicated that insulin sensitivity fully mediated the relationship between task-related activation in the right parietal cortex and BMI ((F(3,28) = 9.03, P = 0.000), ß = 0.611, P = 0.001, 95% confidence interval: -2.548 to -0.468). In conclusion, obesity in middle age was related to alterations in brain activation during a cognitive challenge and this association appeared to be mediated by insulin sensitivity.