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 slow and fast pranayams on reaction time and cardiorespiratory variables.

We planned to undertake a comparative study of the effect of short term (three weeks) training in savitri (slow breathing) and bhastrika (fast breathing) pranayams on respiratory pressures and endurance, reaction time, blood pressure, heart rate, rate-pressure product and double product. Thirty student volunteers were divided into two groups of fifteen each. Group I was given training in savitri pranayam that involves slow, rhythmic, and deep breathing. Group II was given training in bhastrika pranayam, which is bellows-type rapid and deep breathing. Parameters were measured before and after three week training period. Savitri pranayam produced a significant increase in respiratory pressures and respiratory endurance. In both the groups, there was an appreciable but statistically insignificant shortening of reaction time. Heart rate, rate-pressure product and double product decreased in savitri pranayam group but increased significantly in bhastrika group. It is concluded that different types of pranayams produce different physiological responses in normal young volunteers.

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.

Tilt table testing in the diagnostic evaluation of presyncope and syncope: a case-series report.

Tilt table testing has long been used as a standard tool in the diagnostic evaluation of syncope. However, differences of opinion exist with regard to its utility in the evaluation of patients with only presyncopal attacks. We present the results of drug-free, 70-degree head-up tilt table tests (maximum duration of 45 minutes), conducted between May 2002 and May 2003 in the Department of Physiology at JIPMER. This series consisted of both male and female patients (age 6-79 yr) with presyncope (n = 43), unexplained syncope (n = 43) and asymptomatic healthy volunteers without a history of syncope (n = 14). 28 out of 43 patients with unexplained syncope had a history of recurrent syncope while the remaining 15 had only 1 episode. 2 out of 43 patients (4.6%) with a history of only presyncopal attacks had a positive test (induction of intense presyncope and/or syncope accompanied by hypotension and/or a relative bradycardia). 21 out of 43 patients (49%) with a history of syncope had a positive test. 7 had vasodepressor syncope due to hypotension, 6 had cardioinhibitory syncope characterized by asystole and 10 had a mixed form of the vasovagal syndrome characterized by hypotension as well as bradycardia. 18 out of 28 patients (64%) with recurrent unexplained syncope had a positive test. All fourteen healthy volunteers had a negative test. We conclude that tilt table testing is useful in the diagnostic evaluation of patients with unexplained syncope, especially those with recurrent syncope, but not in the evaluation of patients with presyncope alone.

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.

Acute effect of Mukh bhastrika (a yogic bellows type breathing) on reaction time.

Reaction time (RT) is an index of the processing ability of central nervous system and a simple means of determining sensory-motor performance. It has been reported that yoga training improves human performance including central neural processing. Earlier studies from our laboratories have shown that yoga training produces a significant decrease in visual reaction time (VRT) and auditory reaction time (ART). The present work was planned to determine if mukh bhastrika (a yogic technique in which breath is actively blasted out in 'whooshes' following a deep inspiration) has any effect on central neural processing by studying its effect on RT. 22 healthy schoolboys who were practising yoga for the past three months were recruited for the present study. VRT and ART were recorded before and after nine rounds of mukh bhastrika. Mukh bhastrika produced a significant (P < 0.01) decrease in VRT as well as ART. A decrease in RT indicates an improved sensory-motor performance and enhanced processing ability of central nervous system. This may be due to greater arousal, faster rate of information processing, improved concentration and/ or an ability to ignore extraneous stimuli. This is of applied value in situations requiring faster reactivity such as sports, machine operation, race driving and specialised surgery. It may also be of value to train mentally retarded children and older sports persons who have prolonged RT.

Effect of pranayam training on cardiac function in normal young volunteers.

Systolic time intervals (STI) are non-invasive and sensitive tests for measuring the ventricular performance. It has been reported that practice of pranayam modulates cardiac autonomic status and improves cardio-respiratory functions. Keeping this in view, the present study was designed to determine whether pranayam training has any effect on ventricular performance as measured by STI and cardiac autonomic function tests (AFT). Twenty four school children were randomly divided into two groups of twelve each. Group I (pranayam group) subjects were given training in nadishuddhi, mukh-bhastrika, pranav and savitri pranayams and practiced the same for 20 minutes daily for a duration of 3 months. Group II (control group) subjects were not given any pranayam training. STI (QS2, LVET and PEP) and AFT (RRIV and QT/QS2) were measured in both the groups at the beginning and again at the end of three months study period. Pranayam training produced an increase in RRIV and a decrease in QT/QS2, suggesting an enhanced parasympathetic and blunted sympathetic activity respectively. QS2, PEP and PEP/LVET increased significantly, whereas LVET was reduced significantly in pranayam group. In contrast, the changes in STI and AFT were much less marked in the control group. Our study shows that three months of pranayam training modulates ventricular performance by increasing parasympathetic activity and decreasing sympathetic activity. Further studies on a larger sample size may illustrate the underlying mechanism(s) involved in this alteration.

Modulation of cold pressor-induced stress by shavasan in normal adult volunteers.

Shavasan is known to enhance one's ability to combat stressful situations. The present study was planned to determine if shavasan could modulate the physiological response to stress induced by cold pressor test (CPT) and the possible mechanisms involved. Ten normal adults were taught shavasan and practiced the same for a total duration of seven days. RR interval variation (RRIV), deep breathing difference (DBD), and heart rate, blood pressure & rate-pressure-product (RPP) response to CPT were measured before and immediately after shavasan. Shavasan produced a significant increase in DBD and an appreciable but statistically insignificant increase in RRIV suggesting an enhanced parasympathetic activity. Significant blunting of cold pressor-induced increase in heart rate, blood pressure and RPP by shavasan was seen during and even five minutes after CPT suggesting that shavasan reduces the load on the heart by blunting the sympathetic response. It is concluded that shavasan can enhance one's ability to withstand stress induced by CPT and this ability can be achieved even with seven days of shavasan training.