Salty Subjects: Unpacking Racial Differences in Salt-Sensitive Hypertension.

PURPOSE OF REVIEW: To review underlying mechanisms and environmental factors that may influence racial disparities in the development of salt-sensitive blood pressure. RECENT FINDINGS: Our group and others have observed racial differences in diet and hydration, which may influence salt sensitivity. Dietary salt elicits negative alterations to the gut microbiota and immune system, which may increase hypertension risk, but little is known regarding potential racial differences in these physiological responses. Antioxidant supplementation and exercise offset vascular dysfunction following dietary salt, including in Black adults. Furthermore, recent work proposes the role of racial differences in exposure to social determinants of health, and differences in health behaviors that may influence risk of salt sensitivity. Physiological and environmental factors contribute to the mechanisms that manifest in racial differences in salt-sensitive blood pressure. Using this information, additional work is needed to develop strategies that can attenuate racial disparities in salt-sensitive blood pressure.

Exploring heated exercise as a means of preventing the deleterious effects of high-sodium intake in Black women.

The purpose of this study was to examine whether hot yoga could attenuate sodium-induced pressor responses and endothelial dysfunction in Black females. Fourteen participants (ages 20-60 yr old) completed 3 days of low-sodium intake (≤31 mmol/day) followed by 3 days of high-sodium intake (201 mmol/day). Ambulatory blood pressure (BP), 24-h urinary sodium excretion, flow-mediated dilation (FMD), urine-specific gravity, and hematocrit were measured during/after each dietary phase. Participants were randomly assigned to 4 wk of hot yoga or a wait-list control condition. Wait-listed participants were rerandomized to the yoga group after week 4. Blood pressure and FMD in response to low- and high-sodium diet conditions were assessed again at week 4. Sodium loading significantly increased body mass, laboratory systolic and mean arterial BP and urinary sodium excretion in the group overall (P < 0.05 for all). A significant time-by-group interaction was observed for sodium-induced changes in FMD (P < 0.05). In the yoga group, sodium loading tended to decrease FMD at baseline (P = 0.054), whereas sodium loading significantly increased FMD after 4 wk of hot yoga (P < 0.05). In conclusion, results suggest that a brief heated exercise intervention can alter sodium's effects on endothelial function in Black female adults.NEW & NOTEWORTHY Hot yoga significantly altered endothelial function responses to high-sodium intake in Black female adults. Blood pressure responses were unaltered by the yoga intervention in this population.

Device-guided slow breathing alters postprandial oxidative stress in young adult males: A randomized sham-controlled crossover trial.

BACKGROUND AND AIMS: Slow, deep breathing (SDB) lowers blood pressure (BP) though the underlying mechanisms are unknown. Redox improvements could facilitate hemodynamic adjustments with SDB though this has not been investigated. The purpose of this randomized, sham-controlled trial was to examine the acute effects of SDB on oxidative stress and endothelial function during a physiological perturbation (high-fat meal) known to induce oxidative stress. METHODS AND RESULTS: Seventeen males (ages 18-35 years) were enrolled, and anthropometric measurements and 7-day physical activity monitoring were completed. Testing sessions consisted of 24-h diet recalls (ASA24), blood sample collection for superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS) analysis, and flow-mediated dilation (FMD). High-fat meals were ingested and 2-min breathing exercises (SDB or sham control breathing) were completed every 15 min during the 4-h postprandial phase. Blood sample collection and FMD were repeated 1-, 2-, and 4-h post meal consumption. Mean body mass index and step counts were 25.6 ± 4.3 kg/m2 and 8165 ± 4405 steps per day, respectively. Systolic and diastolic BP and nutrient intake 24 h prior were similar between conditions. No time or time by condition interaction effects were observed for FMD. The total area under the curve (AUC) for SOD was significantly lower during SDB compared to the sham breathing condition (p < 0.01). No differences were observed in TBARS AUC (p = 0.538). CONCLUSIONS: Findings from the current investigation suggest that SDB alters postprandial redox in the absence of changes in endothelial function in young, healthy males. CLINICAL TRIAL REGISTRATION NUMBER: NCT04864184. CLINICAL TRIALS IDENTIFIER: NCT04864184.

Effects of yoga interventions practised in heated and thermoneutral conditions on endothelium-dependent vasodilatation: The Bikram yoga heart study.

NEW FINDINGS: What is the central question of this study? Does the heated practice environment enhance the effects of Bikram yoga on endothelium-dependent vasodilatation in healthy, middle-aged adults? What is the main finding and its importance? The primary finding from this investigation is that the hatha yoga postures in the Bikram yoga series produce similar enhancements in endothelium-dependent vasodilatation in healthy, middle-aged adults regardless of environmental temperature. These findings highlight the efficacy of yoga postures in producing improvements in vascular health and downplay the necessity of the heated practice environment in inducing vascular adaptations. ABSTRACT: We have previously documented improvements in endothelium-dependent vasodilatation with a Bikram (hot) yoga intervention in middle-aged adults. At present, the effect of environmental temperature in hot yoga on endothelial function is unknown. The purpose of this investigation was to determine the effects of Bikram yoga interventions performed in heated or thermoneutral conditions on endothelium-dependent vasodilatation. Fifty-two sedentary but apparently healthy adults aged 40-60 years were randomly assigned to one of three groups: Bikram yoga practised at 40.5°C (n = 19), Bikram yoga practised at 23°C (n = 14) or sedentary time control (n = 19). The yoga interventions consisted of 90 min Bikram yoga classes three times a week for 12 weeks. Endothelium-dependent vasodilatation was measured non-invasively using brachial artery flow-mediated dilatation (FMD). Body fat percentage determined via dual-energy X-ray absorptiometry was significantly lower in the hot yoga group after the intervention than in the thermoneutral yoga and control conditions. Brachial artery FMD increased (P < 0.05) in the thermoneutral yoga group and tended to increase in the hot yoga group (P = 0.056). No changes occurred in the control group. There were no significant differences in FMD change scores between groups. We conclude that Bikram yoga practised in thermoneutral conditions improved endothelium-dependent vasodilatation in healthy, middle-aged adults. These new findings highlight the effectiveness of hatha yoga postures alone, in the absence of a heated practice environment, in improving vascular health and are of clinical significance given the increased propensity for heat intolerance in ageing adults.

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.

Exploring mechanisms of blood pressure regulation in response to device-guided and non-device-guided slow breathing: A mini review.

BACKGROUND: Hypertension is a widespread disease that, if persistent, increases the risks of coronary heart disease mortality and morbidity. Slow breathing is a recommended blood pressure-lowering strategy though the mechanisms mediating its effects are unknown. OBJECTIVE: This review aims to evaluate autonomic and vascular function as potential mediators driving BP adaptive responses with slow breathing. METHODS: We searched EBSCO host, Web of Science, Cochrane Central Register of Controlled Trials, and PubMed using key words for optimized search results. RESULTS: Nineteen studies were included in this review (11 device-guided; 8 non-device-guided breathing). Though some studies showed increased vagally mediated components of heart rate variability during slow breathing, results from acute and long-term studies were incongruent. Increases in baroreflex sensitivity (BRS) following a single device-guided slow breathing bout were noted in normotensive and hypertensive adults. Long-term (4 weeks to 3 months) effects of slow breathing on BRS were absent. Device-guided breathing resulted in immediate reductions in muscle sympathetic nerve activity (MSNA) in normo- and hyper-tensive adults though results from long-term studies yielded inconsistent findings. Non-device-guided slow breathing posed acute and chronic effects on vascular function with reductions in arterial stiffness in adults with type I diabetes and increases in microvascular endothelial function in adults with irritable bowel syndrome. Non-device guided breathing also reduced pro-inflammatory cytokines in healthy and hypertensive adults in acute and chronic studies. No adverse effects or non-adherence to treatment were noted in these trials. CONCLUSION: Device-guided slow breathing is a feasible and effective modality in improving BRS, HRV, and arterial stiffness though its long-term effects are obscure. Though less evidence exists supporting the efficacy of non-device-guided slow breathing, acute and chronic studies demonstrate improvements in vascular function and inflammatory cytokines. More studies are needed to further explore the long-term effects of slow breathing in general and non-device-guided breathing in particular.

Slow Breathing Reduces Biomarkers of Stress in Response to a Virtual Reality Active Shooter Training Drill.

Tactical occupations regularly encounter life-threatening situations while on duty. Although these occupations are often trained to utilize slow breathing (SB) during intense stress, there is no evidence supporting the effects on markers of stress in response to a virtual reality active shooter training drill (VR-ASD). The purpose of the study was to determine the impact of acute SB on biomarkers of stress in response to a VR-ASD. Seventy-nine (n = 79) subjects performed either slow breathing method 1 (SB1), slow breathing method 2 (SB2), or normal breathing (control) for five minutes, both pre- and post-VR-ASD. Saliva samples were analyzed for stress markers, including α-amylase (sAA) and secretory immunoglobulin-A (SIgA). Both methods of SB resulted in significantly lower sAA concentrations at 5 (p < 0.001) and 30 min post-VR-ASD (SB1: p = 0.008; SB2: p < 0.001) compared to the control. In the control condition, the sAA concentrations were significantly elevated 5 min post-VR-ASD (p < 0.001) but did not change across time in SB1 or SB2 (p > 0.05). Thus, both SB1 and SB2 reduced the sAA response and resulted in lower concentrations post-VR-ASD. This study was pre-registered as a clinical trial ("Impact of Breathing Interventions on Stress Markers"; NCT05825846).

The effects of slow deep breathing on microvascular and autonomic function and symptoms in adults with irritable bowel syndrome: A pilot study.

BACKGROUND: Irritable bowel syndrome (IBS) is linked to disruptions in sympathovagal balance, which could impair vascular homeostasis and cause IBS symptoms. Studies have shown reductions in sympathetic activity following a single slow, deep breathing (SDB) bout in healthy adults; however, no studies have investigated its chronic effects in IBS. The purpose of this study was to evaluate the feasibility and impact of a SDB intervention on microvascular and autonomic function and symptoms in adults with IBS. METHODS: Fourteen participants (ages 18-65 years) with IBS were randomly assigned to 4-week SDB or control conditions. The SDB group completed a 20-min video 5 times weekly while the control group maintained their normal activities. Microvascular endothelial function was measured using laser Doppler in response to thermal provocation and expressed as cutaneous vascular conductance at 39°C relative to a maximum response at 43.5°C (%CVCmax ). Heart rate variability (HRV) and post-exercise heart rate recovery (HRR) were employed as surrogate measures of autonomic function. IBS symptoms were assessed using the IBS-Severity Scale (IBS-SS). KEY RESULTS: Thirteen participants (6 controls and 7 SDB) completed the study. Age (p = 0.541) and body mass index (p = 0.157) were similar between groups. In the SDB group, %CVCmax increased from 45% to 59% (p < 0.00001) after the 4-week intervention. HRV, HRR, and IBS-SS scores were unaltered. CONCLUSIONS: and Inferences. These results demonstrate the feasibility of a SDB intervention in adults with IBS and suggest improvements in microvascular function in the absence of changes in symptoms or autonomic function in this population.

Adherence to and changes in mental and physiological health during an 8-week yoga intervention: A pilot study.

BACKGROUND: Participating in yoga may be ideal for college students to increase physical activity and improve mental health. PURPOSE: To investigate the feasibility and impact of an 8-week yoga intervention within a university setting on mental and physiologic heath. METHODS: This 8-week yoga intervention included twelve yoga-naïve adults, (23.8 ± 4.6 years; 71% female). Participants attended two 60-min yoga classes/week in addition to baseline, mid- and post-lab visits. RESULTS: 83% of participants attended ≥75% of yoga classes. Stress and depression symptoms decreased by 11% and 25%, respectively and erythrocyte sedimentation rate (ESR) reduced by 28%. Participants who did not meet physical activity recommendations observed greater improvements in stress, depression symptoms, ESR, and C-reactive protein compared to participants who met recommendations. CONCLUSION: The majority of participants attended ≥12 of 16 yoga classes. Exploratory analyses provide preliminary support for the impact of yoga on reducing stress, symptoms of depression, and ESR. Participants who were not meeting physical activity guidelines prior to starting the intervention received greater benefits.

Endothelial ischemia-reperfusion injury in humans: association with age and habitual exercise.

Advancing age is a major risk factor for coronary artery disease. Endothelial dysfunction accompanied by increased oxidative stress and inflammation with aging may predispose older arteries to greater ischemia-reperfusion (I/R) injury. Because coronary artery ischemia cannot be induced safely, the effects of age and habitual endurance exercise on endothelial I/R injury have not been determined in humans. Using the brachial artery as a surrogate model of the coronary arteries, endothelial function, assessed by brachial artery flow-mediated dilation (FMD), was measured before and after 20 min of continuous forearm occlusion in young sedentary (n = 10, 24 ± 2 yr) and middle-aged (n = 9, 48 ± 2 yr) sedentary adults to gain insight into the effects of primary aging on endothelial I/R injury. Young (n = 9, 25 ± 1 yr) and middle-aged endurance-trained (n = 9, 50 ± 2 yr) adults were also studied to determine whether habitual exercise provides protection from I/R injury. Fifteen minutes after ischemic injury, FMD decreased significantly by 37% in young sedentary, 35% in young endurance-trained, 68% in middle-aged sedentary, and 50% in middle-aged endurance-trained subjects. FMD returned to baseline levels within 30 min in young sedentary and endurance-trained subjects but remained depressed in middle-aged sedentary and endurance-trained subjects. Circulating markers of antioxidant capacity and inflammation were not related to FMD. In conclusion, advancing age is associated with a greater magnitude and delayed recovery from endothelial I/R injury in humans. Habitual endurance exercise may provide partial protection to the endothelium against this form of I/R injury with advancing age.

The acute effects of vinyasa flow yoga on vascular function, lipid and glucose concentrations, and mood.

While the chronic effects of certain styles of yoga on cardiometabolic factors have been investigated, little is known about the acute effects of a single yoga session on these outcomes. Moreover, vinyasa yoga's potential to modulate cardiometabolic outcomes has not been established. The purpose of this study is to determine the acute effects of a vinyasa yoga session on arterial stiffness, wave reflection, lipid and glucose concentrations, and mood in adults with prior yoga experience. Thirty yoga practitioners with a minimum of 3 months of practice experience were enrolled into the study. Carotid-femoral pulse wave velocity (cf-PWV), augmentation index (AIx), lipid profile, glucose concentrations, and mood (Positive and Negative Affect Scale) were assessed at baseline and immediately following a 1 -h vinyasa yoga session. After the yoga session, participants had significantly lower AIx (p < 0.001), non-HDL cholesterol (p < 0.05), and negative affect (p < 0.01) compared to baseline. These results highlight the efficacy of a single bout of yoga in altering wave reflection while improving mood and lipid concentrations in healthy adults with a history of yoga practice.

Range of Yoga Intensities From Savasana to Sweating: A Systematic Review.

BACKGROUND: There is limited research examining the intensity of yoga and intensity variations between different styles. The purpose of this review is to examine the intensity of yoga based on different physiologic responses both between different yoga styles and within styles of yoga. METHODS: Articles were searched for on the PubMed database in early 2019. Inclusion criteria were as follows: (1) written in English, (2) cite a specific style of yoga and include whole yoga session, and (3) measure metabolic or heart rate response. RESULTS: Ten articles were reviewed; articles reported oxygen consumption (n = 1), heart rate (n = 4), or both variables (n = 5). Yoga styles assessed included ashtanga (n = 2), Bikram (n = 3), gentle (n = 1), hatha (n = 3), Iyengar (n = 1), power (n = 1), and vinyasa (n = 1). Oxygen consumption commonly categorized yoga as a light-intensity activity, while heart rate responses classified different yoga into multiple intensities. CONCLUSION: This review demonstrates that large differences in intensity classifications are observed between different styles of yoga. Furthermore, metabolic and heart rate responses can be variable, leading to inconsistent intensity classifications. This is likely due to their nonlinear relationship during yoga. Thus, it is imperative that the field of yoga research works together to create a standard for reporting yoga.

A Comparison of Blood Viscosity and Hematocrit Levels between Yoga Practitioners and Sedentary Adults.

Elevations in whole blood viscosity (WBV) and hematocrit (Hct), have been linked with increased risk of cardiovascular disease (CVD). Endurance training has been demonstrated to lower WBV and Hct; however, evidence supporting the efficacy of yoga on these measures is sparse. A cross-sectional study was conducted examining WBV and Hct levels between yoga practitioners with a minimum of 3 years of consistent practice and sedentary, healthy adults. Blood samples were collected from a total of 42 participants: 23 sedentary adults and 19 regular yoga practitioners. Brachial arterial blood pressure (BP) was measured and the averages of 3 measures were reported. The yoga practitioner group had significantly lower WBV at 45 s-1 (p < 0.01), 90 s-1 (p < 0.01), 220 s-1 (p < 0.05), and 450 s-1 (p < 0.05) than sedentary participants. No significant group differences in Hct (p =0.38) were found. A tendency toward lower systolic BP (p=0.06) was observed in the yoga practitioner group; however, no significant group differences in BP were exhibited. A consistent yoga practice was associated with lower WBV, a health indicator related to CVD risk. These findings support a regular yoga practice as a valid form of exercise for improving rheological indicators of cardiovascular health.

Effects of heated and thermoneutral yoga interventions on arterial stiffness in middle-aged adults.

The study investigated the efficacy of 12 weeks of heated and thermoneutral Bikram yoga in reducing arterial stiffness in middle-aged adults. Fifty-four sedentary adults (ages 40-60 years) completed 12 weeks of yoga at 40.5 °C (n = 21), yoga at 23 °C (n = 14) or time control (n = 19). Brachial-ankle pulse wave velocity (PWV) was not significantly altered by hot or thermoneutral yoga interventions.

The effect of Bikram yoga on endothelial function in young and middle-aged and older adults.

The purpose of this investigation was to determine if Bikram yoga, a style of heated hatha yoga, would improve endothelial function in young and middle-aged and older, healthy adults. This trial was performed in 36 young (n = 17) and middle-aged and older adults (n = 19) who completed 3 weekly Bikram yoga classes for 8 weeks. Height, body weight and body composition were determined and endothelial function was measured noninvasively using brachial artery flow-mediated dilation (FMD) before and after the intervention. No changes in body weight, BMI or body fat percentage occurred as a result of the intervention in either group. Brachial artery FMD was significantly increased in middle-aged and older (P < 0.05) but not in young adults as a result of the intervention. The results demonstrate that a relatively short-term Bikram yoga practice might significantly improve vascular endothelial function in middle-aged and older adults. While apparently healthy individuals in this study experienced no adverse events, those with preexisting conditions should take caution and consult with a physician prior to engaging in this style of yoga.

Impact of Hot Yoga on Arterial Stiffness and Quality of Life in Normal and Overweight/Obese Adults.

BACKGROUND: Obesity is associated with arterial stiffening and diminished quality of life. Bikram yoga may be a feasible alternative to traditional exercise among obese individuals. Accordingly, the purpose of this study was to investigate the impact of Bikram yoga, a heated style of hatha yoga, on arterial stiffness in normal and overweight/obese adults. METHODS: Forty-three (23 normal body mass index or BMI; 20 overweight/obese) apparently healthy participants completed an 8-week Bikram yoga intervention. Body composition was estimated via dual energy x-ray absorptiometry, arterial stiffness was measured via brachialankle pulse wave velocity, and health-related quality of life was assessed via RAND 36-Item Short Form survey at baseline and at the end of the 8-week intervention. RESULTS: After the intervention, brachial-ankle pulse wave velocity decreased (P < .05) in overweight/obese participants while no such changes were observed in normal BMI participants. In the quality of life measures, emotional well-being improved (P < .05) in both groups, and general health improved (P < .05) only in the normal weight BMI group. CONCLUSION: Bikram yoga ameliorates arterial stiffness in overweight/obese adults and can positively impact quality of life regardless of BMI.

Improvements in glucose tolerance with Bikram Yoga in older obese adults: a pilot study.

Bikram yoga is an exotic form of physical activity combining hatha yoga and thermal therapy that could positively impact metabolic health. Although this increasingly popular alternative exercise may be ideal for obese adults due to its low impact nature, few studies have elucidated the health benefits associated with it. As an initial step, we determined the effect of Bikram yoga on glucose tolerance. Fourteen young lean and 15 older obese subjects completed an 8-week Bikram yoga intervention in which classes were completed 3 times per week. Glucose tolerance was assessed using a 75 g oral glucose tolerance test. The area under the glucose curve following the oral glucose tolerance test was significantly reduced as a result of the Bikram Yoga intervention in older obese (P < 0.05) but not in young lean subjects. We concluded that a short-term Bikram yoga intervention improved glucose tolerance in older obese, but not in young lean adults.

Hatha yoga and vascular function: results from cross-sectional and interventional studies.

The aim of this study was to determine the effect of hatha yoga on arterial elasticity and endothelial function. First, a cross-sectional study was performed to determine whether yoga practitioners would demonstrate greater arterial compliance and endothelium-dependent vasodilation than their sedentary peers. Second, an intervention study involving 13 sedentary middle-aged and older adults (51 ± 7 years) was performed to determine whether 12 weeks of hatha yoga would elicit increases in arterial compliance and endothelial function. In the cross-sectional study involving a total of 34 subjects, there were no group differences in body fatness, blood lipid and lipoprotein concentrations, carotid artery compliance or brachial artery flow-mediated dilation (FMD). Hemoglobin A1c was lower in yoga practitioners than in sedentary adults (P < 0.05). Total cholesterol and hemoglobin A1c decreased after the intervention (P < 0.05) while carotid artery compliance and brachial artery FMD did not change. The results of both cross-sectional and interventional studies indicate that regular practice of hatha yoga is not associated with improvements in vascular functions.

The effect of Bikram yoga on arterial stiffness in young and older adults.

BACKGROUND AND OBJECTIVE: Bikram yoga is the most popular form of hot yoga, despite the limited information available on its cardiovascular benefits. This study sought to determine the effect of Bikram yoga on arterial stiffness and insulin resistance in young and older adults. METHODS: Twenty-four young (mean age±standard deviation, 30±1 years) and 18 middle-aged and older (mean age, 53±2 years) adults completed an 8-week Bikram yoga intervention. Bikram yoga classes were performed for 90 minutes per session, three times per week, in a room heated to 40.5°C with 40%--60% relative humidity. RESULTS: Body mass, body fat percentage, blood pressure, and fasting blood glucose and triglyceride concentrations did not significantly change as a result of the intervention in either the young or the older group. Trunk flexibility, as measured by the sit-and-reach test, increased in both groups (p<0.01). Total (p<0.05) and low-density lipoprotein cholesterol (p<0.05) levels, plasma insulin concentrations (p<0.01), and scores on the homeostatic model of the assessment of insulin resistance (p<0.01) decreased in older adults, whereas total and high-density lipoprotein cholesterol concentrations were reduced in young adults (all p<0.05). Carotid artery compliance (p<0.05) was increased and ß-stiffness index decreased in young (p<0.05) but not in older adults. Carotid pulse pressure did not significantly change in either group. CONCLUSION: A relatively short-term Bikram yoga intervention improved arterial stiffness in young but not older adults and significantly reduced insulin resistance index in older but not young adults.

Habitual resistance exercise and endothelial ischemia-reperfusion injury in young adults.

Resistance exercise involves muscular contractions that can render downstream tissues ischemic and may precondition the vasculature against ischemia-reperfusion (IR) injury, but it is unknown if habitual resistance exercise protects against IR injury in humans. We determined the magnitude and recovery from endothelial IR injury induced by forearm occlusion in 22 healthy young sedentary and resistance-trained adults. After IR injury, brachial artery flow-mediated dilation (FMD) significantly decreased by 36% in sedentary, but not resistance-trained subjects and fully recovered within 45 min. Though HDL-cholesterol, handgrip strength and systolic blood pressure were significantly associated with FMD 15 min after IR injury, the change in FMD from before to 15 min after IR injury was not associated with any subject characteristics. These results are consistent with the notion that habitual resistance exercise may protect against endothelial IR injury in young adults, presumably through effects analogous to ischemic preconditioning.