Heart rate and thermal responses to power yoga.

BACKGROUND: and Purpose: Yoga has grown in popularity and may offer a viable alternative form of physical activity. The purpose of this study was to examine heart rate, hydration, and thermal responses to a power yoga sequence. MATERIALS AND METHODS: Twenty-seven men and women (n = 4/23; Mean ±â€¯SD age = 23.3 ±â€¯3.3 years; BMI = 23 ±â€¯3 kg m-2) underwent ∼45 min of power yoga. Heart rate and skin temperature were recorded. Mass was measured before and after exercise to estimate fluid loss. Time spent in light, moderate, and vigorous heart rate zones was calculated. RESULTS: Heart rate and skin temperature increased (p < 0.0001). Participants spent more time in moderate and vigorous heart rate zones than in light intensity (p < 0.0001). There was a reduction in body mass (-0.28 ±â€¯0.13 kg, p < 0.0001). CONCLUSION: Power yoga may be considered moderate-vigorous intensity exercise, based on heart-rate.

Effect of High-Calcium Diet on Coronary Artery Disease in Ossabaw Miniature Swine With Metabolic Syndrome.

BACKGROUND: Calcium is a shortfall essential nutrient that has been a mainstay of osteoporosis management. Recent and limited findings have prompted concern about the contribution of calcium supplementation to cardiovascular risk. A proposed mechanism is through the acceleration of coronary artery calcification. Determining causality between calcium intake and coronary artery calcification has been hindered by a lack of sensitive methodology to monitor early vascular calcium accumulation. The primary study aim was to assess the impact of high calcium intake on coronary artery calcification using innovative calcium tracer kinetic modeling in Ossabaw swine with diet-induced metabolic syndrome. Secondary end points (in vitro wire myography, histopathology, intravascular ultrasound) assessed coronary disease. METHODS AND RESULTS: Pigs (n=24; aged ≈15 months) were fed an atherogenic diet with adequate calcium (0.33% by weight) or high calcium (1.90% from calcium carbonate or dairy) for 6 months. Following 5 months of feeding, all pigs were dosed intravenously with (41)Ca, a rare isotope that can be measured in serum and tissues at a sensitivity of 10(-18) mol/L by accelerator mass spectrometry. Kinetic modeling evaluated early coronary artery calcification using (41)Ca values measured in serial blood samples (collected over 27 days) and coronary artery samples obtained at sacrifice. Serum disappearance of (41)Ca and total coronary artery (41)Ca accumulation did not differ among groups. Secondary end points demonstrated no treatment differences in coronary artery disease or function. CONCLUSION: There was no detectable effect of high calcium diets (from dairy or calcium carbonate) on coronary artery calcium deposition in metabolic syndrome swine.

Vitamin C prevents the acute decline of flow-mediated dilation after altered shear rate patterns.

Oscillatory and retrograde shear rate (SR) impairs endothelial function, potentially through shear-induced oxidative stress. We tested the hypothesis that acute vitamin C supplementation would prevent the attenuation of brachial artery flow-mediated dilation (FMD) after a period of augmented oscillatory and retrograde SR. Twelve healthy men (aged 26 ± 3 years) participated in two 30-min study visits in which one arm was subjected to increased oscillatory and retrograde SR, using 60 mm Hg of forearm cuff compression, and the contralateral arm served as the control. Subjects ingested capsules containing either placebo (sucrose) or vitamin C at 90 and 120 min (1000 mg total vitamin C) prior to cuff compression periods in a randomized placebo-controlled double-blind crossover study. Oscillatory and retrograde SR in the cuffed arms increased during the compression periods in the placebo and vitamin C study visits (p < 0.01 for both), with no difference between studies (p > 0.05). Antegrade SR remained unchanged throughout the compression periods (p > 0.05), and mean SR was lower in the cuffed arm than in the control arm for both study visits (p < 0.05). FMD decreased after cuff compression in the placebo cuffed arm (precompression vs. postcompression, 5.2% ± 1.4% vs. 3.5% ± 1.4%; p < 0.05), but remained unchanged after vitamin C therapy in the cuffed arm (precompression vs. postcompression, 5.3% ± 2.4% vs. 5.7% ± 2.6%; p > 0.05). No FMD changes were observed in the control arm for either study visit (p > 0.05). These data demonstrate that acute vitamin C supplementation prevents the attenuation of FMD due to altered SR patterns, suggesting that oxidative stress contributes to the oscillatory and retrograde SR-induced impairment of FMD.

Brachial artery flow-mediated dilation following exercise with augmented oscillatory and retrograde shear rate.

BACKGROUND: Acute doses of elevated retrograde shear rate (SR) appear to be detrimental to endothelial function in resting humans. However, retrograde shear increases during moderate intensity exercise which also enhances post-exercise endothelial function. Since SR patterns differ with the modality of exercise, it is important to determine if augmented retrograde SR during exercise influences post-exercise endothelial function. This study tested the hypothesis that (1) increased doses of retrograde SR in the brachial artery during lower body supine cycle ergometer exercise would attenuate post-exercise flow-mediated dilation (FMD) in a dose-dependent manner, and (2) antioxidant vitamin C supplementation would prevent the attenuated post-exercise FMD response. METHODS: Twelve men participated in four randomized exercise sessions (90 W for 20 minutes) on separate days. During three of the sessions, one arm was subjected to increased oscillatory and retrograde SR using three different forearm cuff pressures (20, 40, 60 mmHg) (contralateral arm served as the control) and subjects ingested placebo capsules prior to exercise. A fourth session with 60 mmHg cuff pressure was performed with 1 g of vitamin C ingested prior to the session. RESULTS: Post-exercise FMD following the placebo conditions were lower in the cuffed arm versus the control arm (arm main effect: P < 0.05) and without differences between cuff pressures (20 mmHg: 5.7 ± 2.2%; 40 mmHg: 4.7 ± 1.3%; 60 mmHg: 5.4 ± 2.4%) (P > 0.05). Following vitamin C treatment, post-exercise FMD in the cuffed and control arm increased from baseline (P < 0.05) but were not different (control: 7.1 ± 3.5% vs. cuffed: 6.6 ± 3.3%) (P > 0.05). CONCLUSIONS: These results indicate that augmented oscillatory and retrograde SR in non-working limbs during lower body exercise attenuates post-exercise FMD without an evident dose-response in the range of cuff pressures evaluated. Vitamin C supplementation prevented the attenuation of FMD following exercise with augmented oscillatory and retrograde SR suggesting that oxidative stress contributes to the adverse effects of oscillatory and retrograde shear during exercise on FMD.