Exercise intensity and blood pressure during sleep

Exercise, of appropriate intensity and duration, could help maintain normotension if post-exercise hypotension persists over subsequent everyday activities. Therefore, we monitored ambulatory blood pressure (BP) for 24 h following four separate exercise bouts which differed in intensity, duration and total work completed. At 08:00 h, six normotensive males completed a no exercise control and, in two further trials, 30 min of cycling at 70 % V O (2 peak) and 40 % V O (2 peak). A fourth trial involved cycling at 40 % V O (2 peak) for a time which equated total work with that in the most intense exercise trial. Between 20 min and 24 h after exercise, ambulatory BP, heart rate (HR) and wrist-activity were compared between trials using general linear models. Participants slept normally at night. Post-exercise changes in BP and HR were not affected by exercise intensity or total work completed from 20 min after exercise until nocturnal sleep-onset (p > 0.21). During sleep, mean arterial BP was lower following exercise at 70 % V O (2 peak) compared to the other trials (p = 0.03), including the 40 % V O (2 peak) trial equated for total work (90 % CI for difference = - 22.1 to - 0.1). We conclude that daytime exercise can elicit a physiologically meaningful lower BP during sleep and exercise intensity is the most important factor in this phenomenon.     

Effect of static and dynamic exercise on heart rate and blood pressure variabilities

PURPOSE: This study examines the effect of static and dynamic leg exercises on heart rate variability (HRV) and blood pressure variability (BPV) in humans. METHODS: 10 healthy male subjects were studied at rest, during static exercise performed at 30% of maximal voluntary contraction (SX30), and during dynamic cycling exercises done at 30% of VO2max (DX30) and at 60% of VO2max (DX60). Respiration, heart rate, and blood pressure signals were digitized to analyze temporal and spectral parameters involving short and overall indexes (SD, deltaRANGE, RMSSD, Total power), power of the low (LF), middle (MF), and high (HF) frequency components, and the baroreceptor sensitivity by the alphaMF index. RESULTS: During SX30, indexes of HRV as SD, deltaRANGE, Total power, and MF in absolute units increased in relation with rest values and were significantly higher (P < 0.001) than during DX30 and DX60; HF during SX30, in normalized and absolute units, was not different of the rest condition but was higher (P < 0.001) than HF during DX30 and DX60. Parameters of BPV as SD and deltaRANGE increased (P < 0.001) during both type of exercises, and significant (P < 0.01) increments were observed on MF during SX30 and DX30; systolic HF was attenuated during DX30 (P < 0.05), whereas diastolic HF was augmented during DX60 (P < 0.001). Compared with rest condition, the alphaMF index decreased (P < 0.01) only during dynamic exercises. CONCLUSION: Because HRV and BPV response is different when induced by static or dynamic exercise, differences in the autonomic activity can be advised. Instead of the vagal withdrawal and sympathetic augmentation observed during dynamic exercise, the increase in the overall HRV and the MF component during static exercise suggest an increased activity of both autonomic branches.     

Automated blood pressure measurements during exercise

One of the critical parameters measured during exercise is blood pressure. However, the accurate measurement of systolic and diastolic blood pressure during exercise is difficult with auscultation and impractical with direct arterial techniques. The purpose of this study was to compare an automated system (Colin, Inc. STBP-680) with auscultation in humans during rest and exercise and to compare the automated system with direct arterial blood pressure measurement in a canine model during pharmacological challenges that resulted in a wide range of blood pressure values. Compared with direct arterial blood pressure taken in the canine model, the STBP-680 gave good estimates of diastolic blood pressure and adequately monitored relative changes in systolic blood pressure, diastolic blood pressure, and mean arterial pressure (mean arterial pressures in all instances were calculated as one-third systolic plus two-thirds diastolic blood pressures). Compared with auscultation methods in humans, the STBP-680 gave similar estimates of resting diastolic blood pressure and monitored relative changes in resting systolic blood pressures, diastolic blood pressures, and mean arterial pressures. During both treadmill and cycle ergometer exercise in humans, the STBP-680 monitored changes in systolic blood pressure, phase IV diastolic blood pressure, and mean arterial pressure. Further, the STBP-680 estimated exactly and noted relative changes in heart rate in every test. However, during exercise, quantitative estimations of systolic blood pressure by the STBP-680 were higher than those found using auscultation. Where exact, quantitative measures of blood pressure are needed, direct arterial measurement continues to be the most accurate method. However, where indirect methods can be used, the STBP-680 may provide a suitable alternative that reduces many of the technical concerns of auscultation in young, healthy individuals.     

高龄高血压患者晨峰时段血压变化的临床观察及护理

 目的 观察76例患者晨间血压的变化,探讨预防高龄高血压患者晨峰时段血压骤变导致意外的护理措施,以加强预见性护理。方法 选择住院治疗行动态血压检查的患者76例,均为男性,60~97岁,平均（80.28±7.23）岁,并以80岁为界,＜80岁为低龄组35例,≥80岁为高龄组41例,观察晨间血压变化及进餐、服用降压药后对血压的影响,分析年龄、临床症状与血压变化的关系。结果 76例晨峰时段服药、进餐后血压均呈下降趋势;高龄高血压患者服药、进餐后各时间段收缩压与服药进餐前比较均有明显统计学差异（P＜0.01,P＜0.05）,且临床症状发生率较高。结论 高龄高血压患者晨峰时段是病情观察的重点时段,因此,进行晨峰时段防止进餐、服药后血压下降所致意外的健康教育非常必要。     

Chemoreflex and metaboreflex responses to static hypoxic exercise in aging humans

PURPOSE: We tested the hypothesis that aging decreases the contribution of metaboreceptors to sympathetic responses during exercise in hypoxia. METHODS: We recorded sympathetic nerve traffic to muscle circulation (MSNA), heart rate (HR), blood pressure (BP), minute ventilation (VE), and blood lactate (BL) in 12 older (55 +/- 10 yr) and 12 younger (22 +/- 2 yr) normal subjects during three randomized interventions: isocapnic hypoxia (chemoreflex activation), isometric handgrip exercise (HG) in normoxia (metaboreflex activation), and HG during isocapnic hypoxia (concomitant metaboreflex and chemoreflex activation). All interventions were followed by a forearm circulatory arrest period to allow metaboreflex activation in the absence of exercise and chemoreflex activation. RESULTS: Older subjects had higher resting MSNA (38 +/- 12 vs 23 +/- 9 bursts per minute; P < 0.01) and BP (P < 0.001). Heart rate, minute ventilation, and blood lactate did not differ (all P > 0.5). MSNA responses to HG in normoxia (P < 0.05) and in hypoxia (P < 0.05) were smaller in the older subjects, but were similar during hypoxia alone. The increase in HR was smaller in the older subjects for all interventions (all P < 0.05). In contrast, the increase in systolic and diastolic BP, VE, and BL were similar in both groups (P > 0.05). During the local circulatory arrest, MSNA and BP remained elevated in both groups after HG in normoxia (P < 0.01) and in hypoxia (P < 0.01), but MSNA changes were smaller in the older subjects (P < 0.05). CONCLUSION: Aging reduces sympathetic reactivity to isometric handgrip, but does not prevent the metaboreceptors to remain the main determinant of sympathetic activation during exercise in hypoxia.     

Adaptation of blood flow during the rest to work transition in humans.

Beat-by-beat measurements show that limb blood flow rises rapidly and in a biphasic manner at the onset of rhythmic exercise in humans. In this review the time course of change in limb flow with the onset of exercise is described and the mechanisms that may or may not contribute to its regulation are discussed. The pumping action of contracting skeletal muscle appears to form an important regulator of increasing flow with the first contraction. However, evidence from human studies suggests that vasodilation begins with the first contraction. Whether this early dilation is regulated by neural recruitment of motor fibers and/or muscle contraction per se is discussed, but the mechanism(s) remains unclear. Finally, the contribution of endothelial-derived relaxation factors to the exponential increase in flow at the exercise onset is examined. Based on studies in humans with intra-arterial infusion of blocking drugs, neither acetylcholine, nitric oxide, nor prostaglandins appear to be essential for a normal dynamic flow response on going from rest to exercise. Overall, evidence from human studies supports the hypothesis that the rate of increase in blood flow during rhythmic voluntary exercise is closely coupled to motor unit recruitment with dilation beginning at the first contraction.     

Phlebohemodynamics in the femoral vein and postcava during a voluntary quick single contraction of shin muscles in supine and standing humans]

Effects of a voluntary single quick shin contraction on quantitative parameters of the venous outflow in the femoral vein and postcava were investigated in 65 normal males and females with the Doppler ultrasonic and duplex blood pool scanning techniques. Measured were linear spontaneous blood flow, mean linear and peak velocites of the transport of blood after the muscle contraction, baseline linear cross sections of the femoral vein and postcava cross section, and their extension in the course of mobilized blood evacuation. Based on these measurements calculated were weight power space velocities of the spontaneous blood flow and volumes of mobilized venous blood The investigations were made in supine and standing subjects. According to our data, hemodynamic productivity of the muscle contraction in vertical subjects was much higher than in horizontal with the peak and mean linear blood evacuation outrunning the mean spontaneous outflow from the femoral vein in 25.7 and 10.3 times, respectively. Besides, the weight power space velocity of the contraction-induced outflow exceeded that of the spontaneous blood flow 12.5 times. Simultaneous contraction of the muscles on both legs increased four times the weight power space velocity in the subdiaphragmatic part of the postcava.     

Intracarotid blood pressure changes during contrast medium injection.

PURPOSETo investigate changes in blood pressure during intracarotid injection of contrast material.METHODSTwo catheters were inserted into the ipsilateral common carotid artery of dogs. The proximal catheter was used for injection of contrast material and the other was positioned distally to monitor blood pressure.RESULTSDistal intracarotid pressure rose significantly during injection of contrast material at all rates (5, 7, and 10 mL/s) and at all doses (0.2, 0.5, 0.7, and 1.0 mL/kg). In addition, these blood pressure elevations were shown to be correlated with injection rates and doses. Even when the pressure-monitoring coaxial catheter was advanced into smaller arteries, no decline in the impact of injection was observed.CONCLUSIONIntracarotid injection of contrast material causes a temporal elevation of cerebral blood pressure in dogs.     

Validity of predicting mean arterial blood pressure during exercise

PURPOSE: Mean arterial blood pressure (mean arterial pressure (MAP)) at rest is conventionally estimated as the product of the diastolic pressure plus one-third of the pulse pressure. Since pulse wave forms and the duration of diastole change during exercise, one might question the validity of this prediction equation for the exercise state. Our purpose was to test this by directly measuring blood pressure over a wide range of exercise intensities. METHODS: Pressure was recorded by arterial catheterization in 29 subjects performing progressive exercise and/or constant-load exercise at different intensities. Actual MAP was measured by integrating the area under the pulse curve and compared it with the value which was predicted from systolic and diastolic measures over heart rates ranging from 100 to 200 beats x min(-1). RESULTS: Predicted values were quite close to actual MAP, and the accuracy of the prediction equation changed minimally with increased exercise intensity. CONCLUSION: This method provides a valid estimation of MAP during exercise.     

Amlodipine reduces blood pressure during dynamic resistance exercise in hypertensive patients

This study investigated the effect of the dihydropyridine calcium channel antagonist, amlodipine, on blood pressure (BP) during resistance exercise performed at different intensities in hypertensives. Eleven hypertensives underwent 4 weeks of placebo and amlodipine (random double‐blinded crossover design). In each phase, they performed knee extension exercise until exhaustion following three protocols: one set at 100% of 1 RM (repetition maximum), three sets at 80% of 1 RM, and three sets at 40% of 1 RM. Intraarterial BP was measured before and during exercise. Amlodipine reduced maximal systolic/diastolic BP values achieved at all intensities (100% = 225 ± 6/141 ± 3 vs. 207 ± 6/130 ± 6 mmHg; 80% = 289 ± 8/178 ± 5 vs. 273 ± 10/169 ± 6 mmHg; 40% = 289 ± 10/176 ± 8 vs. 271 ± 11/154 ± 6 mmHg). Amlodipine blunted the increase in diastolic BP that occurred during the second and third sets of exercise at 40% of 1RM (+75 ± 6 vs. +61 ± 5 mmHg and +78 ± 7 vs. +64 ± 5 mmHg, respectively). Amlodipine was effective in reducing the absolute values of systolic and diastolic BP during resistance exercise and in preventing the progressive increase in diastolic BP that occurs over sets of low‐intensity exercise. These results suggest that systemic vascular resistance is involved in BP increase during resistance exercise, and imply that hypertensives receiving amlodipine are at lower risk of increased BP during resistance exercise than non‐medicated patients.     

Changes in blood lipids in humans during long-term ski crossing in the Extreme North]

Serum lipids were measured in the men who made two ski crosses in the Far North during polar night. The first trip, which was to train the athletes, took 17 days and the second took 38 days. In both studies, lipid mobilization and utilization increased, which led to changes in the lipid spectrum: decrease of the concentration of LDL and, in the second trip, of VLDL and HDL3, and increase of the concentration of HDL2 and cholesterol HDL. In the second trip, lipids were most intensively utilized: lipolysis enhanced and free fatty acids declined. This was also indicated by an increase of the capillary-venous difference in terms of the total fraction of LDL and VLDL as well as free fatty acids. At the end of the second trip, the positive capillary-venous difference in terms of LDL and VLDL and, accordingly, the negative capillary-venous difference in terms of HDL2 and HDL3 increased. At the end of both trips the synthesis of transport lipids grew; in the most strenuous second trip, their active utilization in the working organs was stronger.     

Protein composition of blood serum and the products of nitrogen metabolism in humans during long-term hypokinesia

Examination of 9 healthy young men exposed to antiorthostatic hypokinesia (-5 degrees) for 370 days revealed enhanced catabolic processes in the muscular tissue. This manifested as increases of creatinine in blood and urine as well as of the creatinine coefficient. The use of countermeasures prior to experimental day 170 helped to maintain the concentration of final nitrogen metabolites at the baseline level. The serum concentrations of total protein and protein fractions remained within the normal limits and varied in a phasic manner. We observed a decrease of the concentration of alpha 2-globulins, which indicates inhibition of the synthetic activity of the liver, and an increase of that of beta-globulins, which suggests an adverse effect of head-down tilt on lipid metabolism.     

Neural influence on cardiovascular and endocrine responses to static exercise in humans.

At the onset of exercise, signals from the central nervous system result in immediate vagal withdrawal and resulting increases in heart rate and arterial blood pressure. From the second heart beat peripheral nerve (reflex) influence from exercising muscle can be detected. With continued exertion, especially with large muscle groups, this influence becomes increasingly important. Sympathetic nerve signals to resting muscle can be influenced by the central nervous system, but are dominated by influence from 'metaboreceptors' in exercising muscle, while sympathetic nerve signals to skin are more influenced by the central nervous system. Cardiovascular responses to static contractions increase with the percentage of maximum contraction intensity as well as with the muscle mass involved. Plasma catecholamines rise in proportion to increases in cardiovascular variables and are influenced by a central nervous mechanism early in the contraction. Furthermore, during static contractions the increase in plasma adrenaline (epinephrine) is larger relative to that of noradrenaline than during dynamic exercise. Both catecholamine responses and the responses of pituitary hormones depend on the active muscle mass, but are small compared to those established during dynamic exercise. Experiments designed to enhance central command, resulting in increased cardiovascular and endocrine responses compared to control experiments and experiments in which an attenuation of peripheral nerve influence resulted in reduced changes in these variables during exercise, contrast with the notion that the 2 neural control mechanisms are redundant. Rather, the 2 neural influences on the autonomic nervous system work in concert in eliciting the responses manifest during static exercise.     

Carbohydrate and lipid metabolites and blood serum enzymes in humans during graded exercise test in long-term anti-orthostatic hypokinesia

Exercise tests were carried out before as well as on days 128 and 248 of a 370-day head-down tilt study. The test subjects, who took part in the study, were divided into two groups that used different regimens of countermeasures (drugs and exercise). During exercise tests the following serum parameters were measured: lactate, pyruvate, glucose, triglycerides, nonesterified fatty acids, lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase, malate dehydrogenase, creatine phosphokinase. Decrease or delayed increase in the concentration of energy substrates (nonesterified fatty acids and triglycerides) after a standard exercise test is a metabolic manifestation of deconditioning changes induced by head-down tilting. Insufficient supply of a working human body with readily utilizable lipid substrates causes inadequate activation of energy forming enzymes and excessive buildup of metabolites, i. e. lactate and pyruvate. The efficacy of corrective and prophylactic measures was verified by biochemical data.     

Effect of handlebar gripping on blood pressure during cycle ergometry

The effects on SBP, DBP and HR of gripping the cycle ergometer handlebar during dynamic cycle ergometry were evaluated in 39 healthy males. Heart rate, SBP and DBP were measured at 150 Watt power load while gripping and not gripping the handlebar of a cycle ergometer. The sequence of gripping first or second was randomized. No differences in SBP, DBP or HR were shown under the two treatments. For submaximal cycle ergometry the influence of static handgrip on the handlebar does not seem to have a significant influence on SBP, DBP or HR response to dynamic exercise.     

Effects of exercise and weight loss on blood pressure during daily life

PURPOSE: The objective of this study was to investigate the effects of exercise training and weight loss on blood pressure (BP) associated with physical activity and emotional stress during daily life. METHODS: One hundred twelve participants with unmedicated high normal or stage 1 to stage 2 hypertension were randomized to one of three conditions: a combined exercise and behavioral weight management group (WM), an exercise-only group (EX), or a wait list control group (CON). BP was assessed in the clinic and during 15 h of daytime ambulatory BP monitoring at baseline and after 6 months of treatment. RESULTS: Increased levels of physical activity and emotional distress measured during daily life were associated with increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and rate pressure product (RPP). After treatment, the WM group had significantly lower DBP, HR, and RPP responses during both high and low levels of physical activity and emotional distress compared with the CON group. The EX group had similar BP levels as the WM group, although the EX group had significantly lower BP than the CON group during low but not high levels of physical activity and emotional distress. CONCLUSION: These findings indicate that exercise, especially when combined with weight loss, reduces BP levels at rest and in situations that typically elevate BP such as intense physical activity and emotional distress.     

诊室血压与功能检查室血压的对比研究

目的：探讨诊室血压与功能检查室血压的关系及二者诊断高血压的一致性。方法入选门诊疑似高血压患者388例,年龄15～89岁,平均（54.30±14.53）岁;其中男187例,平均（50.39±15.44）岁;女201例,平均（57.95±12.66）岁。采用汞柱式标准袖带式血压计检测、记录所有患者的诊室血压并计数心率;采用欧姆龙动脉硬化检测仪（BP-203RPEⅢ）检测、记录四肢动脉血压和心率,并对上述数据进行统计学分析。结果①总体上诊室血压及心率高于功能检查室血压及心率;诊室收缩压与功能检查室收缩压差值平均值为12.36 mmHg;舒张压差值平均值为8.42 mmHg;心率差值平均值为6.17次/min。②388例疑似高血压患者中,根据诊室血压有90.72%（352/388例）被诊断为高血压;根据功能检查室血压有53.09%（206/388例）被诊断为高血压;而且诊室高血压患者中只有56.82%（200/352例）的患者通过功能检查室血压诊断为高血压。结论①诊室血压与功能检查室血压高血压诊断的一致性较差。②单纯根据诊室血压进行高血压的诊断会带来较大的误诊率和一定的漏诊率。