Modulation of cardiovascular response to exercise by yoga training

This study reports the effects of yoga training on cardiovascular response to exercise and the time course of recovery after the exercise. Cardiovascular response to exercise was determined by Harvard step test using a platform of 45 cm height. The subjects were asked to step up and down the platform at a rate of 30/min for a total duration of 5 min or until fatigue, whichever was earlier. Heart rate (HR) and blood pressure response to exercise were measured in supine position before exercise and at 1, 2, 3, 4, 5, 7 and 10 minutes after the exercise. Rate-pressure product [RPP = (HR x SP)/100] and double product (Do P = HR x MP), which are indices of work done by the heart were also calculated. Exercise produced a significant increase in HR, systolic pressure, RPP & DoP and a significant decrease in diastolic pressure. After two months of yoga training, exercise-induced changes in these parameters were significantly reduced. It is concluded that after yoga training a given level of exercise leads to a milder cardiovascular response, suggesting better exercise tolerance.     

Effect of head-up tilt on cardiovascular responses in normal young volunteers

Since the cardiovascular effects of tilting are influenced by degree as well as duration of the tilt, we planned to study the time course of blood pressure and heart rate (HR) responses during 30 degrees, 60 degrees, 80 degrees head up tilt (HUT). The study was conducted on 20 volunteers aged 18-20 y who were tilted on a tilting table. Blood pressure was determined by sphygmomanometer and HR was calculated from R-R interval of ECG. 30 degrees HUT produced an insignificant decrease in systolic pressure (SP) and pulse pressure (PP) while diastolic pressure (DP), mean pressure (MP) and rate-pressure-product (RPP) registered an insignificant rise. The changes produced by 60 degrees and 80 degrees HUT were more marked than those produced by 30 degrees HUT. While SP and PP decreased significantly, HR and RPP increased significantly. In conclusion, 30 degrees HUT produces insignificant changes while 60 degrees and 80 degrees HUT produce significant changes in SP, PP and RPP.     

Correlation between body mass index and blood pressure indices, handgrip strength and handgrip endurance in underweight, normal weight and overweight adolescents

In the present study, we investigated the correlation between body mass index (BMI), blood pressure (BP) indices and indices of physical fitness in apparently healthy subjects aged 14-18 years. We obtained data from 145 (105 males and 40 females) and assessed the correlation between BMI, and heart rate, systolic pressure (SP), diastolic pressure (DP), pulse pressure (PP), mean arterial pressure (MP), rate-pressure product, endurance in the 40 mm Hg test, handgrip strength (HGS), and handgrip endurance. Subjects with BMI <18.5 kg/m2, 18.5-25 kg/m2 and >25 kg/m2 were classed as underweight (65 males and 9 females), normal weight (27 males and 20 females), and overweight (13 males and 11 females) respectively. In view of gender differences in autonomic regulation, data of male and female subjects were analyzed separately. We used analysis of variance to compare differences between the three groups. Correlation between BMI and other indices was tested using Pearson's correlation coefficient. A P value <0.05 was considered statistically significant Both SP and DP were highest in overweight and least in underweight male subjects (P<0.05 for both), whereas in females, differences in DP alone were statistically significant (P<0.05). In underweight male subjects, there was a positive correlation between BMI and SP, DP, PP, MP and HGS (P<0.05 for all). There was a positive correlation between BMI and SP in overweight male subjects (r = 0.5 P = 0.07, n = 13). A positive correlation was observed between BMI and rate-pressure product (r = 0.5, P = 0.45, n = 11) and BMI and HGS (r = 0.6, P = 0.05, n = 11) in overweight females. Our observations indicate that there are gender differences in the correlation between BMI and BP indices especially in underweight and overweight subjects. The observed differences between the three groups and gender differences in correlation between BMI and BP indices may be due to differences in autonomic function and or energy metabolism.     

Effect of yoga training on handgrip, respiratory pressures and pulmonary function

Although there are a number of reports on the effect of yoga training on pulmonary functions, very few studies have been undertaken on the effect of yoga training on respiratory pressures and handgrip endurance. Hence the present work was planned to study the effect of yoga training on hand grip strength (HGS), hand grip endurance (HGE), maximum expiratory pressure (MEP), maximum inspiratory pressure (MIP), forced expiratory volume (FEV), forced expiratory volume in first second (FEV1) and peak expiratory flow rate (PEFR). 20 school children in the age group of 12 to 15 years were given yoga training (asans and pranayams) for 6 months. 20 age and gender-matched students formed the control group. Yoga training produced statistically significant (P < 0.05) increase in HGS and HGE. MEP, MIP, FEV, FEV1 and PEFR also increased significantly (P < 0.001) after the yoga training. In contrast, the increase in these parameters in the control group was statistically insignificant. Our study shows that yoga training for 6 months improves lung function, strength of inspiratory and expiratory muscles as well as skeletal muscle strength and endurance. It is suggested that yoga be introduced at school level in order to improve physiological functions, overall health and performance of students.     

VOLUNTARY BLOOD PRESSURE CONTROL BY BIOFEEDBACK: RELATIONSHIP TO PSYCHOLOGICAL CHARACTERISTICS

1. Psychological characteristics were studied in 25 hypertensives (mean and standard deviation of blood pressure 150/95 +/- 12/5 mmHg), who received blood pressure (BP) biofeedback (BFB). Personality factors and success in BFB-BP modifying ability were correlated and the predictive value of psychological factors was estimated. 2. Questionnaires consisted of a Locus of Control of Behaviour (LCB) scale, the Spielberger state trait anxiety inventory and the Framingham Type A personality inventory. 3. BP was monitored continuously from the finger by volume clamp plethysmography during eight BFB sessions, each with three trials of raising, ignoring and lowering systolic blood pressure (SP). 4. SP was raised/lowered by 12 +/- 11/6 +/- 9 mmHg and heart rate (HR) increased by 10 +/- 3.9/+ 1 +/- 6.1. Ten subjects were able to lower SP by greater than or equal to 5 mmHg (15 +/- 7.5) and raise it by 17 +/- 11. The others achieved no decrease in SP and were also less successful at raising (8 mmHg, P = 0.04). 5. Changes in LCB and trait anxiety correlated with DP rise, whereas type A and pre-study state anxiety correlated with rising HR. Lowering of SP correlated weakly with change in LCB (r = 0.47, P = 0.06). 6. Combinations of psychological factors had independent predictive value for BP and HR change: trait anxiety (P = 0.03) and change in LCB (P = 0.009) with rise in diastolic blood pressure (DP); type A (P = 0.009), pre-study LCB (P = 0.02) and pre-study state anxiety (P = 0.01) with HR rise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correlation between short-term heart rate variability indices and heart rate, blood pressure indices, pressor reactivity to isometric handgrip in healthy young male subjects

The purpose of the present study was to determine whether readily measured blood pressure (BP) indices and, responses to autonomic reflex tests could be used as surrogates of short-term heart rate variability (HRV), which is an established marker of autonomic regulation of SA node. Therefore, we examined the correlation between short-term HRV and heart rate (HR), BP indices viz. systolic pressure, diastolic pressure, pulse pressure (PP), and rate-pressure product (RPP), during supine rest and head-up tilt in 17 young healthy normotensive subjects, aged 19.8 +/- 1 yr (mean +/- SD). Three classic autonomic indices viz. Valsalva ratio, HR response to deep breathing and pressor response to isometric handgrip were also determined. We noted two interesting and statistically significant (P < 0.05 in both cases) correlations viz. i) a positive correlation (r = 0.6) between change in RPP during tilt and change in low frequency (LF) RR spectral power expressed in normalized units (LF nu) during tilt, and ii) a negative correlation (r = -0.6) between change in PP during isometric handgrip and LF nu during tilt. The possible physiologic significance of these and other correlations is discussed in this paper. In conclusion, the presence of a statistically significant correlation between RPP, PP and spectral measures of short-term HRV supports a simplistic approach to autonomic assessment, in that, easily measurable BP indices could be used as surrogates of HRV when it is not feasible to determine HRV indices directly. However, the same have to be tested in healthy subjects belonging to various age groups and in patients with conditions known to be associated with autonomic dysregulation.     

线粒体融合素2在糖尿病大鼠心肌损伤中的变化

目的:探讨线粒体融合素2(mitofusin 2,Mfn2)在糖尿病大鼠心肌损伤中的变化。方法:腹腔注射55mg/kg链脲佐菌素复制糖尿病大鼠模型,分为正常组、糖尿病4周组和糖尿病8周组。测定血流动力学指标、大鼠心系数;自动生化分析仪测定血浆肌酸激酶同工酶(creatine kinaseisozyme,CK-MB)水平。RT-PCR检测左室心尖部组织Mfn2的表达。结果:与正常大鼠相比,糖尿病4周、8周大鼠左室发展压、左室最大上升和下降速率、心率、左室做功均明显下降(P<0.05,P<0.01),心室舒张末压上升(P<0.01),心系数(HW/BW)明显增加(P<0.01),血浆CK-MB水平升高(P<0.05,P<0.01),Mfn2mRNA的表达降低(P<0.01);与糖尿病4周相比,糖尿病8周大鼠左室发展压、左室最大上升速率和下降速率、心率及左室做功进一步下降(P<0.05,P<0.01),心室舒张末压升高(P<0.01),HW/BW、CK-MB水平持续性升高(P<0.01),Mfn2mRNA的表达进一步降低(P<0.01)。结论:随着糖尿病病程的延长,糖尿病大鼠心室功能进一步下降,其机制可能与Mfn2的表达降低有关。     

多柔比星对兔心脏的损伤和牛磺酸的保护作用

为了研究多柔比星 (Dox)心脏损伤机理和牛磺酸 (Tau)的保护作用 ,将实验兔随机分成Dox组 ,对照组 (即生理盐水组 ,NS组 )和Dox +Tau组 .兔均于第12周 ,测量心输出量 (CO) ,颈动脉收缩压 (SP)和舒张压 (DP) ,颈动脉平均压 (MAP) ,左心室收缩压(LVSP)和左心室舒张末压 (LVEDP) .取左心室心肌细胞检测细胞内游离钙离子浓度 ([Ca2 +]i) ;用血清检测一氧化氮 (NO)的含量 .结果表明 ,Dox组CO ,SP ,DP ,MAP ,LVSP均明显低于NS组 ,LVEDP显著高于NS组 ,Dox +Tau组SP ,DP ,MAP ,LVSP均显著低于NS组 ,LVEDP明显低于Dox组 ,但明显高于NS组 .Dox组和Dox +Tau组血清NO含量均明显高于NS组 .Dox组左心室心肌细胞 [Ca2 +]i 明显高于NS组 ,Dox +Tau组心肌细胞 [Ca2 +]i 明显低于Dox组 .本文提示 ,Tau对Dox损伤心脏具有一定的保护作用     

Influence of alternate nostril breathing on cardiorespiratory and autonomic functions in healthy young adults

Alternate nostril breathing (ANB) may modulate cardio-respiratory and autonomic functions. However, the studies are scarce and results highly conflicting. The present study was conducted in healthy young volunteers comprising of males (n=20) and females (n=20) in range of 17-22 years. In both groups respiratory rate (RR/min), heart rate (HR/ min), systolic blood pressure (SBP; mm Hg), diastolic blood pressure (DBP; mm Hg), peak expiratory flow rate (PEFR; L/min) and galvanic skin resistance (GSR; microV) were recorded thrice; once as control and then after 15 min (acute exposure) and following 8 wks of training in ANB (15 min daily). In males the control RR was 16.60 +/- 2.01, HR 75.75 +/- 11.07, SBP-115.9 +/- 7.33, DBP 70.4 +/- 6.28 and PEFR 550.00 +/- 51.50. After 15 min of ANB-RR (14.75 +/- 1.41, P<0.001), HR (68.45 +/- 12.41, P<0.01) and SBP (113.6 +/- 6.04, P<0.05) fell significantly. After 8 wks of ANB training RR (12.35 +/- 1.35, P<0.0001), HR (63.20 +/- 11.11, P<0.001), SBP (109.5 +/- 5.61, P<0.001), declined to much greater extent and PEFR (571.50 +/- 46.26, P<0.01) rose significantly. In females the control RR was 17.25 +/- 1.89, HR-74.90 +/- 12.85, SBP-106.70 +/- 6.91, DBP-68.70 +/- 5.52 and PEFR-394.50 +/- 44.89. After 15 min of ANB RR (15.05 +/- 1.54, P<0.001) and HR (64.75 +/- 9.80, P<0.001) showed significant decline with concomitant rise in PEFR (407.00 +/- 2.31, P<0.05). Following 8 wks training the decrement in RR (12.60 +/-1.50, P<0.0001) and HR (63.30 +/- 8.65, P<0.001) was maintained. SBP (103.10 +/- 4.92, P<0.001) and DBP (65.8 +/- 5.54, P<0.001) decreased further and PEFR (421.00 +/- 38.51 P<0.001) rose, GSR was unaffected by ANB in both males and females. These results suggest that in general there is a tilt towards parasympathetic dominance by alternate nostril breathing. This breathing may be a useful adjuvant to medical therapy of hypertension and COPD.     

Effect of yoga training on reaction time, respiratory endurance and muscle strength.

There is evidence that the practice of yoga improves physical and mental performance. The present investigation was undertaken to study the effect of yoga training on visual and auditory reaction times (RTs), maximum expiratory pressure (MEP), maximum inspiratory pressure (MIP), 40 mmHg test, breath holding time after expiration (BHTexp), breath holding time after inspiration (BHTinsp), and hand grip strength (HGS). Twenty seven student volunteers were given yoga training for 12 weeks. There was a significant (P < 0.001) decrease in visual RT (from 270.0 +/- 6.20 (SE) to 224.81 +/- 5.76 ms) as well as auditory RT (from 194.18 +/- 6.00 to 157.33 +/- 4.85 ms). MEP increased from 92.61 +/- 9.04 to 126.46 +/- 10.75 mmHg, while MIP increased from 72.23 +/- 6.45 to 90.92 +/- 6.03 mmHg, both these changes being statistically significant (P < 0.05). 40 mmHg test and HGS increased significantly (P < 0.001) from 36.57 +/- 2.04 to 53.36 +/- 3.95 s and 13.78 +/- 0.58 to 16.67 +/- 0.49 kg respectively. BHTexp increased from 32.15 +/- 1.41 to 44.53 +/- 3.78s (P < 0.01) and BHTinsp increased from 63.69 +/- 5.38 to 89.07 +/- 9.61 s (P < 0.05). Our results show that yoga practice for 12 weeks results in significant reduction in visual and auditory RTs and significant increase in respiratory pressures, breath holding times and HGS.     

Isometric exercise before and after nadolol treatment in uncomplicated essential hypertension

Systolic, diastolic and mean arterial pressure (SAP, DAP, MAP), heart rate (HR) and tension time index (TTI) were evaluated in 20 uncomplicated hypertensives and in 20 normotensives at rest and during isometric exercise, performed by handgrip (HG). In the hypertensive population the same parameters were evaluated also after two and six weeks of treatment with a beta-blocking agent, nadolol, given in a single daily dose. In all cases isometric exercise induced a significant increase of SAP, DAP, MAP, HR and TTI and this increase was more relevant in hypertensives than in controls. In the hypertensive population, nadolol was effective in lowering arterial pressure at rest, and significantly reduced the levels of SAP, DAP, MAP, HR and TTI reached at the end of the HG test. Moreover, the increments of the investigated parameters induced by isometric exercise were significantly reduced after nadolol. The results suggest that nadolol, unlike other beta-blocking agents, exerts a "protective" action against the hazardous increments of blood pressure which may occur in the daily life of hypertensive subjects during involuntary isometric exercises, and which could trigger dangerous cardiovascular complications.     

AUTONOMIC BLOCKADE AMPLIFIES CORTISOL-INDUCED HYPERTENSION IN MAN

1. We investigated the role of the autonomic nervous system (ANS) in Cortisol induced hypertension using the technique of total autonomic blockade (AB). 2. Four healthy young males were given 50 mg Cortisol 6 hourly for 6 days. On the day prior to, and the last day of, Cortisol treatment, AB was produced using oral prazosin 1 mg, intravenous clonidine 300 μg, propranolol 0.2 mg/kg and atropine 2 mg. The adequacy of blockade was assessed using the haemodynamic response to Valsalva manoeuvre. 3. Cortisol produced a significant rise in systolic blood pressure (130 ± 2 vs 110 ± 1 mmHg, pre vs post Cortisol; P<0.01). On the final treatment day, AB augmented the increase in diastolic blood pressure (ΔDBP), mean arterial pressure (ΔMAP) and heart rate (ΔHR) compared to the pre-treatment day, ΔDBP: 43 ± 6 vs 17 ± 4 mmHg, post vs pre Cortisol, P<0.005, ΔMAP: 39 ± 4 vs 14 ± 4 mmHg, P<0.001, ΔHR: 45 ± 5 vs 26 ± 4 b.p.m., P<0.05. The change in systolic blood pressure (ΔSBP) was not statistically significant (32 ± 4 vs7 ± 3 mmHg, P= 0.065). 4. These results suggest that the ANS exerts a modulating influence on the hypertensive effect of Cortisol.     

Blood pressure responses to whole-body cold exposure: effect of carvedilol

OBJECTIVE: The aim of this study was to test the effects of carvedilol on blood pressure (BP) and heart rate (HR) during whole-body cold exposure in hypertensive and normotensive subjects. METHODS: Ten hypertensive and twelve normotensive subjects were exposed to cold (-15 degrees C, wind 3.5 m/s) three times for 15 min with a 1-week interval between the exposures. The study design was made according to a randomised double-blind, crossover method. Before the cold exposures the subjects ingested carvedilol or placebo once a day (carvedilol 12.5 mg/day for 2 days and then 25 mg/day for 5 days) for 1 week. The systolic (SBP) and diastolic (DBP) blood pressure and HR were measured every 3 min during the test procedures using an indirect ambulatory blood pressure monitor device (ABPM-02, Meditech Co.). RESULTS: In the hypertensive group, the cold exposure increased SBP/DBP from 119/75 mmHg to 143/96 mmHg during carvedilol treatment (P<0.001) and from 132/85 mmHg to 159/106 mmHg during placebo (P<0.001). In the normotensive group the cold exposure increased SBP/DBP from 112/72 mmHg to 142/93 mmHg during carvedilol treatment (P<0.001) and from 121/75 mmHg to 147/98 mmHg during placebo (P<0.001). In the hypertensive group, the levels of SBP, DBP and MAP (mean arterial pressure) were significantly lower with carvedilol than with placebo during the cold exposure although carvedilol did not affect the cold-induced rise of the BP. The BPs were lower also with carvedilol in the normotensive group than the placebo during the cold exposure, but the differences were smaller than in the hypertensive group. Carvedilol decreased the BP more the higher the initial mean SBP/DBP was with placebo during the cold exposure. CONCLUSION: Carvedilol reduced the BP during the cold exposure, especially in the hypertensive subjects but also in normotensive ones, without effect on the cold-induced rise of the BP.     

The effects of right and left nostril breathing on cardiorespiratory and autonomic parameters

The responses of right nostril breathing (RNB) and left nostril breathing (LNB) on cardio-respiratory and autonomic functions were investigated in healthy student volunteers of both sexes. The RNB and LNB groups comprised of 10 males and 10 females in each in age range of 17-22 years. Initially, in both groups control values of respiratory rate (RR), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBF), peak expiratory flow rate (PEFR) and galvanic skin resistance (GSR) were recorded. The same parameters were recorded after 15 min (acute exposure) and 8 wks of training in RNB and LNB. In males RR (P<0.0001), SBP (P<0.05) and DBF (P<.05) fell significantly after 15 min of RNB. After 8 wks training in RNB, HR (P<0.01) decreased, SBP (P<0.001) declined more profoundly and RR (P<0.0001) and DBP (P<0.05) decrement was maintained. After 15 min of LNB, RR (P<0.01), HR (P<0.01), SBP (P<0.001) and DBP (P<0.01) declined significantly, on 8 wks training, RR (P<0.0001) and HR (P<0.001) decreased further, the decrement in SBP (P<0.001) and DBP (P<0.01) was the same. In females, RR alone fell significantly (P<0.05) after 15 min RNB. After 8 wks RR decrement was more profound (P<0.0001) and DBP also declined significantly (P<0.01). Similarly, 15 min LNB resulted in significant reduction in RR (P<0.001) and HR (P<0.05) only. Following 8 wks, of training in LNB, in addition to RR (P<0.0001) and HR (P<0.05) decrement, SBP (P<0.01) and DBP (P<0.05) also fell significantly. Both in males and females, GSR did not change significantly (P>0.05) either after RNB or LNB (15 min/8 wks). PEFR rose significantly (P<0.05) only in females after 8 wks of LNB. The results suggest that there are no sharp distinctions between effects of RNB and LNB either acute exposure (15 min) or after training (8 wks). However, there is a general parasympathetic dominance evoked by both these breathing patterns.     

Effect of calcium antagonists on stress-induced rise in blood pressure and heart rate: a double-blind, placebo-controlled study

OBJECTIVE: The current study was designed to evaluate the effect of treatment with calcium antagonists on stress-induced increases in blood pressure and heart rate. SUBIECTS, MATERIAL AND METHODS: Two models of stress were chosen, cold stress and isometric handgrip exercise. Six healthy volunteers were randomized to receive amlodipine (5 mg), lacidipine (4 mg) for a two-day period in a double-blind, crossover design. Thirty hypertensive patients received the same treatment for a period of one week in a double-blind, parallel design. The effects of stress on blood pressure and heart rate were taken at baseline and after drug treatment. RESULTS: Cold stress and handgrip exercise significantly increased the systolic and diastolic blood pressure as well as the heart rate. In normotensive volunteers, the resting heart rate and blood pressure were not altered by the drugs. The increase in systolic and diastolic blood pressure produced by cold stress and isometric exercise were unchanged by amlodipine and lacidipine. In hypertensive patients, both drugs reduced the resting blood pressure (p < 0.05). As in normotensive individuals, the pressor response to stress was not altered by the drugs. CONCLUSION: Cold stress and handgrip exercise produced a significant rise in blood pressure and heart rate in normotensive volunteers and patients with hypertension. Cardiovascular reactivity to cold stress and handgrip exercise is not altered by the administration ofamlodipine and lacidipine.     

Effect of yoga on cardiovascular system in subjects above 40 years

This study was conducted to examine the effect of yoga on cardiovascular function in subjects above 40 yrs of age. Pulse rate, systolic and diastolic blood pressure and Valsalva ratio were studied in 50 control subjects (not doing any type of physical exercise) and 50 study subjects who had been practicing yoga for 5 years. From the study it was observed that significant reduction in the pulse rate occurs in subjects practicing yoga (P<0.001). The difference in the mean values of systolic and diastolic blood pressure between study group and control group was also statistically significant (P<0.01 and P<0.001 respectively). The systolic and diastolic blood pressure showed significant positive correlation with age in the study group (r1 systolic= 0.631 and r1 diastolic = 0.610) as well as in the control group (r2 systolic = 0.981 and r2 diastolic = 0.864). The significance of difference between correlation coefficient of both the groups was also tested with the use of Z transformation and the difference was significant (Z systolic= 4.041 and Z diastolic= 2.901). Valsalva ratio was also found to be significantly higher in yoga practitioners than in controls (P<0.001). Our results indicate that yoga reduces the age related deterioration in cardiovascular functions.     

Effect of nifedipine on plasma renin,aldosterone and catecholamines in arterial hypertension

Summary Acute sublingual administration of nifedipine 10–20 mg to 13 hypertensive patients caused a rapid decrease in blood pressure (BP) and a concomitant increase in heart rate (HR), plasma noradrenaline (NA) and plasma renin activity (PRA); there was no significant change in plasma adrenaline (A) or aldosterone (ALDO). Basal PRA was the major determinant of the rise in PRA, as a close correlation was present between the basal value and the increase caused by nifedipine (r=0.92, p<0.001). The rise in PRA was also correlated with the plasma concentration of nifedipine after 60 min (r=0.80, p<0.01), but it was not correlated with the decrease in BP, the rise in HR or the increase in NA. Nifedipine 30–60 mg daily for 6 weeks caused a reduction in mean BP from 133 to 113 mmHg (p<0.001). Body weight and serum potassium decreased but no consistent change was noted in NA, PRA, ALDO or 24 h-excretion of catecholamines. A significant correlation was present between the change in NA and that in PRA (r=0.74, p<0.01). The alterations in the various parameters in the acute and chronic studies were not correlated. The findings indicate that different regulatory mechanisms are activated during acute and chronic administration of nifedipine. It is suggested that an initial rise in sympathetic activity gradually decreases during prolonged therapy, but it still remains a determinant of PRA.     

Exercise is good for your blood pressure: effects of endurance training and resistance training

1. Although several epidemiological studies have not observed significant independent relationships between physical activity or fitness and blood pressure, others have concluded that blood pressure is lower in individuals who are more fit or active. However, longitudinal intervention studies are more appropriate for assessing the effects of physical activity on blood pressure. 2. Previously, we have performed meta-analyses of randomized controlled trials involving dynamic aerobic endurance training or resistance training. Inclusion criteria were: random allocation to intervention and control; physical training as the sole intervention; inclusion of healthy sedentary normotensive and/or hypertensive adults; intervention duration of at least 4 weeks; availability of systolic and/or diastolic blood pressure; and publication in a peer-reviewed journal up to December 2003. 3. The meta-analysis on endurance training involved 72 trials and 105 study groups. After weighting for the number of trained participants, training induced significant net reductions of resting and day time ambulatory blood pressure of 3.0/2.4 mmHg (P < 0.001) and 3.3/3.5 mmHg (P < 0.01), respectively. The reduction of resting blood pressure was more pronounced in the 30 hypertensive study groups (-6.9/-4.9) than in the others (-1.9/-1.6; P < 0.001 for all). Systemic vascular resistance decreased by 7.1% (P < 0.05), plasma noradrenaline by 29% (P < 0.001) and plasma renin activity by 20% (P < 0.05). Bodyweight decreased by 1.2 kg (P < 0.001), waist circumference by 2.8 cm (P < 0.001), percentage body fat by 1.4% (P < 0.001) and the Homeostatic Model Assessment (HOMA) index of insulin resistance by 0.31 units (P < 0.01). High-density lipoprotein-cholesterol increased by 0.032 mmol/L (P < 0.05). 4. Resistance training has been less well studied. A meta-analysis of nine randomized controlled trials (12 study groups) on mostly dynamic resistance training revealed a weighted net reduction of diastolic blood pressure of 3.5 mmHg (P < 0.01) associated with exercise and a non-significant reduction of systolic blood pressure of 3.2 mmHg (P = 0.10). 5. In conclusion, dynamic aerobic endurance training decreases blood pressure through a reduction of systemic vascular resistance, in which the sympathetic nervous system and the renin-angiotensin system appear to be involved, and favourably affects concomitant cardiovascular risk factors. In addition, the few available data suggest that resistance training is able to reduce blood pressure.     

丙泊酚分步靶控输注对全麻诱导期血流动力学的影响

目的 观察丙泊酚分步靶控输注对腹腔镜胆囊切除术患者全身麻醉诱导插管过程血流动力学的影响.方法 选择42例ASAⅠ～Ⅱ级行择期腹腔镜胆囊切除术患者,随机分为实验组(T组)和对照组(C组),每组21例.麻醉诱导T组采用丙泊酚静脉分步靶控输注,血浆靶浓度从1.0 mg·L-1开始递增,递增梯度为0.5 mg·L-1,每靶浓度输注1 min,目标靶浓度设定为3.0 mg·L-1;C组采用人工单次静脉注射丙泊酚2 mg·kg-1,同时两组均给予芬太尼2 μg·kg-1,罗库溴铵0.9 mg·kg-1静脉推注后行气管插管.连续监测并记录患者诱导前(T1)、插管前(T2)、插管即刻(T3)和插管后5 min(T4)血压(SBP/DBP)和心率(HR)并计算RPP.结果 T组全麻诱导过程中各时点血压、心率和RPP无统计学差异(P>0.05),而对照组插管前(T2)插管即刻(T3)和插管后5 min(T4)血压、心率和RPP与诱导前(T1)和C组相比较差异均具有统计学意义(P<0.01).结论 丙泊酚分步递增靶控输注诱导有利于维持腹腔镜胆囊切除术患者全麻诱导插管期的血流动力学稳定.     

口底多间隙感染应用负压吸引对VAS的影响

目的观察口底多间隙感染应用负压吸引的疗效及对VAS的影响。方法选择笔者所在医院2005年1月～2010年1月口腔科收治的口底多间隙感染患者52例作为研究对象,根据术后引流情况随机分为两组:负压吸引组(简称A组,n=31),引流管组(简称B组,n=21),比较两组的手术疗效及对VAS的影响。结果两组治疗后未置引流时的SP、DP、HR与术前SP、DP、HR比较,差异无统计学意义(P>0.05)。引流开始3min时两组SP、DP下降,HR升高,但与治疗前及治疗后未置引流时比较差异无统计学意义(P>0.05),且上述两组间比较差异也无统计学意义(P>0.05)。引流结束后30minSP、DP、HR分别恢复至治疗前,分别与治疗前及治疗后未置引流时、引流开始3min时比较,差异无统计学意义(P>0.05)。引流结束后30min两组间SP、DP、HR比较,差异也无统计学意义(P>0.05)。与B组比较,A组患者的VAS评分低、患者疼痛程度轻、引流时间短、患者治疗后住院时间短、并发症发生率低(P<0.05)。结论口底多间隙感染应用负压吸引疗效好、患者痛苦少,缩短了住院时间,对患者的心率、血压无明显影响,其疗效优于传统引流管,值得临床推广应用。