Improvement in muscular strength, body flexibility and balance by yoɡasana and with reduced detraining effects by yoɡa breathing maneuvers: A non-randomized controlled study

BACKGROUND

Yoɡa was reported to have the potential to improve physical fitness. Its applications are being used by common persons for wellness, but literature on the training and detraining effects of components of yoga is scarce.

OBJECTIVES

To explore the potential of different proportions of yoga postures (Yogasana) and yoga breathing maneuvers (YBM), consisting of Pranayama and kriya, on muscular strength, flexibility, and balance in training and detraining management.

METHODS

ː 32 physically active male students, aged 20.5 ± 1.3 yrs, were divided into control (CG) and yoga group (YG). YG practiced yogasana, YBM, and dhyana for 45 min in each session for 6 days per week for 12 weeks. From 1st week to 6th week, they practiced yogasana in greater proportion. 7th week onwards YBM was inducted by increasing its duration and varieties. CG did not practice yoga. Back-leg strength (BLS), Hand Grip Strength (HGS), flexibility, and balance were recorded before, the 6th week and 12th weekend of training.

RESULTS

ː.In YG, the pre-training value of BLS was 110.8 ± 12.6 kg. It increased (2.3 %) to 113.3 ± 11.4 kg (p < 0.001) on the 6th weekend. On the 12th weekend, it further increased in lesser magnitude (0.4 %) to 113.7 ± 11 kg (p < 0.05) and the pattern of improvement was the same in other parameters, but in flexibility and balance its magnitude was greater (p < 0.001). CG did not show such changes.

CONCLUSIONS

ː Yogasana helps in the improvement of muscular strength, flexibility, and balance and YBM counteracts detraining effects in the absence of yogasana. Judiciously selected components of yoga/YBM may have applications in sports, occpational health and recuperative patients.

Training and detraining management of performance measures by Yoga among middle-aged blue-collar men

To observe the effect of yogasanas and yoga breathing maneuvers (YBM) on body flexibility, balance, muscular strength and reaction time on middle aged blue-collar individuals, 8 healthy blue collar, males (age 37±6.2 years) were trained in yoga for 12 weeks. First 6 weeks, they practiced mostly yogasanas. From 7th week, progressively the YBM practice increased up to 12th week. Their body flexibility, balance, maximal hand grip strength (HGS) and HGS endurance  at 50 % maximal strength for both hands, back -leg strength (BLS), reaction times for both visual (VRT) and auditory (ART) mode, were measured before and at the end of 6th and 12th weeks yoga training. Data was analysed by ANOVA. With more yogasanas practice, their body flexibility improved from base line 14.1±4.5 cm to 18.3±4.3 cm (P<0.001, magnitude 29.8%) after 6 weeks of yoga training.  With proportionately greater YBM practice, still it increased in lower magnitude (9.3%) to 20±4.6 cm (p<0.001) after 12 weeks of training. Balance showed similar pattern of changes like flexibility. In VRT, baseline value of 281.4±16.4ms reduced to 271.14±16.1 ms and 251.7±15.4 ms after 6 weeks and 12 weeks respectively, indicating greater reaction time improvement by YBM. ART also showed similar pattern of changes. Left and Right HGS endurance have improved by 19% and 23.1% respectively, after 6 weeks. BLS and HGS improved in small magnitude. Detraining and age related deterioration of body flexibility, balance, reaction time and strength endurance could be controlled by yogasanas. YBM have greater positive role in reaction time.

Improvement in Visual and Auditory Reaction Time with Reduced Detraining Effects of Yogic Breathing ManoeuversA Non Randomised Controlled Study

Introduction: Earlier, different components of yoga i.e., asanas (static physical postures), Yoga Breathing Manoeuvers (YBM) and meditation were reported to have different magnitude of effects on reaction time. YBM showed greater magnitude of effects on Visual Reaction Time (VRT) and Auditory Reaction Time (ART), than that of asanas in different groups of subjects. So, to observe the effect of different proportions of asanas and YBM in a yoga program on reaction time, with its possible applications in training and in detraining management, the study was undertaken. Aim: To study the effects of asanas and YBM in different proportions on VRT and ART among the same subjects to explore the magnitude of its effects for applications in training and detraining management. Materials and Methods: This interventional non randomised controlled study was conducted in the Department of Sports Science and Yoga, Ramakrishna Mission Vivekananda Educational and Research Institute, Belur Math, West Bengal, India, from July 2019 to September 2019 on 32 healthy, male, undergraduate student volunteers in the age group of 19 to 21 years. Subjects were divided into two groups i.e., Yoga Group (YG) and Control Group (CG). CG did not practice yoga. YG practiced yoga for 45 minutes daily, six days per week for 12 weeks. Total time of practicing YBM gradually increased every week. For the first two weeks it was a session of 45 minutes and from 3rd week YBM was increased by 1-2 minutes every week up to 6th week. Then, at 7th week it increased by 8 minutes. From 8th week to 10th week it increased by 1-2 minutes in every week. On 11th and 12th week it increased 10-12 minutes on average. Up to 6th week they practiced mostly all asanas. From the 7th week to 12th week mostly YBM were practiced. Thus, at the end of 6th and 12th week, effect of greater duration of mostly all asanas and YBM, respectively were available. Measurements of VRT and ART were taken by ‘Audio- VRTr’, at baseline, 6th week and 12th week end of training on both groups. Study design helped to observe separately the effect of greater duration of asana and YBM practice on same group of subjects. Intragroup and intergroup comparisons were done by repeated measures of Analysis of Variance (ANOVA) and unpaired t-test, respectively. Results: Both YG and CG had similar age, body weight and body fat percentage and activity pattern. So, groups were homogeneous in nature. VRT and ART were improved significantly (p-value<0.001) by greater practice of asanas for 6 weeks. Similarly greater YBM practice on subsequent six weeks showed further improvement (p-value<0.001) in both parameters, which even masked the natural detraining effects of these parameters due to withdrawal of asana practice, which was reflected in the magnitude of improvement (as obtained from the % calculation from difference of mean values between two time points like baseline to 6th week end) at the 6th week end (VRT: 7.4%, ART: 7.8%) as compared to that of 6th to 12th week end (VRT: 10.4%, ART: 11.6% ). YG showed significantly (p-value<0.001) faster VRT and ART than those of CG at the 6th and 12th week end. Conclusion: Judicious selection of the proportion of asanas, YBM and meditation in a yoga program, optimise Central Nervous System (CNS) arousal with better VRT and ART. YBM helped to reduce detraining effects of reaction time due to the curtailment of asana practice. This might have application in any training and also to counteract detraining effects in sports and among recuperative patients.

Genetic diversity for drought and low-phosphorus tolerance in rice (Oryza sativa L.) varieties and donors adapted to rainfed drought-prone ecologies

Drought and phosphate availability are two major abiotic factors limiting productivity of rice in rainfed upland areas. There has been a constant need for new improved donor with tolerance to multiple abiotic stress conditions for rainfed rice breeding. In the present study, a set of 32 popular rice varieties and landraces were evaluated for drought and low-phosphorus (P) tolerance, and also characterized using grain yield under reproductive drought QTLs (DTY QTLs) and Pup1 linked/specific molecular markers. Twenty-seven genotypes were identified as tolerant to moderately tolerant to drought. The SSR markers linked to ten DTY QTLs classified the genotypes into two groups corresponding to aus and indica. The tolerant genotypes were distributed under both groups. Based on the core markers of Pup1 locus, complete tolerant haplotype was recorded in nine genotypes other than the tolerant check Dular. Nine more genotypes showed the incomplete tolerant haplotypes. The rice genotypes showed significantly high genetic variability for low-P tolerance in hydroponic study. A few genotypes revealed non-Pup1 type tolerance which needs further confirmation.

Hatha yoga practices: energy expenditure, respiratory changes and intensity of exercise

The aim of this study was to critically observe the energy expenditure, exercise intensity and respiratory changes during a full yoga practice session. Oxygen consumption ([Formula: see text]), carbon dioxide output ([Formula: see text]), pulmonary ventilation ([Formula: see text]E), respiratory rate (Fr) and tidal volume (VT), were measured in 16 physical posture (asanas), five yoga breathing maneuvers (BM) and two types of meditation. Twenty male (age 27.3 ± 3.5 years, height 166.6 ± 5.4 cm and body weight 58.8 ± 9.6 kg) yoga instructors were studied. Their maximal oxygen consumption ([Formula: see text]) was recorded. The exercise intensity in asanas was expressed in percentage [Formula: see text] . In asanas, exercise intensity varied from 9.9 to 26.5% of [Formula: see text] . Highest energy cost was 3.02 kcal min(-1). In BM highest [Formula: see text]E was 53.7 ± 15.5 l min(-1). VT was 0.97 ± 0.59, 1.41 ± 1.27 and 1.28 ± l/breath with corresponding Fr of 14.0 ± 5.3, 10.0 ± 6.35, 10.0 ± 5.8 breaths/min. Average energy expenditure in asanas, BM and meditation were 2.29, 1.91 and 1.37 kcal min(-1), respectively. Metabolic rate was generally in the range of 1-2 metabolic equivalents (MET) except in three asanas where it was >2 MET. [Formula: see text] was 0.27 ± 0.05 and 0.24 ± 0.04 l min(-1) in meditation and Shavasana, respectively. Although yogic practices are low intensity exercises within lactate threshold, physical performance improvement is possible owing to both better economy of breathing by BM and also by improvement in cardiovascular reserve. Other factors such as psycho-physiological and better relaxation may contribute to it.

Different adaptation patterns of antioxidant system in natives and sojourners at high altitude

Comparative studies on the adaptation pattern of antioxidant status among high altitude natives and acclimatized sojourners are very scanty. The aim of the present study was to compare the differences in antioxidant profile between two groups of active male volunteers, i.e. native highlanders (HAN, n=66) in their natural hypoxic environment with that of sojourners (SOJ, n=81) from sea level (SL) after 4 weeks of stay at an altitude of 4560m. Blood samples of SOJ were collected at SL and HA. Same was collected from HAN once at HA. HAN had significantly higher SOD activity and significantly lower catalase, GPX and GR activities than SOJ at HA. Ratio of GSH/GSSG was also significantly higher in HAN than SOJ at HA. In SOJ, antioxidant profile showed an upregulation after HA stay but it was not effective to reduce the levels of oxidative stress markers. Therefore, it can be stated that lifelong exposure to hypoxia has beneficial adaptive effects on antioxidant system in HAN. Similarly, acclimatization to HA also has beneficial preconditioning effects on antioxidant system in SOJ, but, may not be sufficient to ameliorate oxidative stress completely. Transient increase in metabolic rate due to hypoxia may be a causative factor for excess free radical generation among sojourners at HA.

Improvement of glutathione and total antioxidant status with yoga

OBJECTIVE

Several studies suggest that yoga can decrease oxidative stress. However reports are scanty regarding whether yoga training can improve the glutathione level of individual. This study is designed to appraise the role of yoga in maintaining glutathione (reduced and oxidized) levels and antioxidant status.

STUDY DESIGN

This study was conducted on healthy male volunteers from the Indian Navy, who were divided into two groups--a yoga (n = 30) group and a control (n = 21) group. The yoga group was trained in yoga for 6 months. The yoga schedule consisted of prayers, asana, pranayama, and meditation. The control group practiced routine physical training exercise for 6 months. Blood samples were collected when the volunteers were in fasting condition before and after completion of 6-month training period. Reduced and oxidized glutathione, glutathione reductase activity and total antioxidant status (TAS) were estimated.

RESULTS

Reduced glutathione level increased significantly (p < 0.05) in the yoga group after completion of training. Glutathione reductase activity increased significantly in the control group (p < 0.05). TAS increased significantly (p < 0.001) in the yoga group and decreased significantly (p < 0.001) in the control group.

CONCLUSIONS

Regular practice of yoga can maintain or improve antioxidant level of the body. The clinical relevance is that yoga practice can be used to maintain the antioxidant defense system under stressful conditions of training as observed in the case of soldiers and athletes.

Energy cost and cardiorespiratory changes during the practice of Surya Namaskar

Surya Namaskar (SN), a group of Yogic exercise consists of a set of twelve postures which is practiced by some of the yoga practitioners. The present study was undertaken to observe critically the energy cost and different cardiorespiratory changes during the practice of SN. Twenty-one male volunteers from the Indian Army practiced selected Yogic exercises for six days in a week for three months duration. The Yogic practice schedule consisted of Hatha Yogic Asanas (28 min), Pranayama (10.5 min) and Meditation (5 min). In the Yogic practice schedule 1st they practiced Kapal Bhathi (breathing maneuvers) for 2 min then Yogamudra (yogic postural exercise) for 2 min, after that they took rest until oxygen consumption and heart rate (HR) came to resting value. Subsequently subjects performed SN for 3 min 40 seconds on an average. After three months of training at the beginning of the fourth month subjects performed entire Yogic practice schedule in the laboratory as they practiced during their training session and experiments were carried out. Their pulmonary ventilation, carbondioxide output, Oxygen consumption, HR and other cardiorespiratory parameters were measured during the actual practice of SN. Oxygen consumption was highest in the eighth posture (1.22+/-0.073 1 min(-1)) and lowest in the first posture (0.35+/-0.02 1 min(-1)). Total energy cost throughout the practice of SN was 13.91 kcal and at an average of 3.79 kcal/min. During its practice highest HR was 101+/-13.5 b.p.m. As an aerobic exercise SN seemed to be ideal as it involves both static stretching and slow dynamic component of exercise with optimal stress on the cardiorespiratory system.

Aerobic capacity & perceived exertion after practice of Hatha yogic exercises

BACKGROUND & OBJECTIVES

Reports on the effect of yogic exercises on aerobic capacity are few. There is also no literature available on the effect of yogic exercise on perceived exertion (PE) after maximal exercise. In this study the effect of training in Hatha yogic exercises on aerobic capacity and PE after maximal exercise was observed.

METHODS

Forty men from the Indian army (aged 19-23 yr) were administered maximal exercise on a bicycle ergometer in a graded work load protocol. The oxygen consumption, carbon dioxide output, pulmonary ventilation, respiratory rate, heart rate (HR) etc., at maximal exercise and PE score immediately thereafter were recorded. The subjects were divided into two equal groups. Twelve subjects dropped out during the course of study. One group (yoga, n = 17) practiced Hatha yogic exercises for 1 h every morning (6 days in a week) for six months. The other group (PT, n = 11) underwent conventional physical exercise training during the same period. Both groups participated daily in different games for 1 h in the afternoon. In the 7th month, tests for maximal oxygen consumption (VO2Max) and PE were repeated on both groups of subjects.

RESULTS

Absolute value of VO2Max increased significantly (P < 0.05) in the yoga group after 6 months of training. The PE score after maximal exercise decreased significantly (P < 0.001) in the yoga group after 6 months but the PT group showed no change.

INTERPRETATION & CONCLUSION

The practice of Hatha yogic exercises along with games helps to improve aerobic capacity like the practice of conventional exercises (PT) along with games. The yoga group performed better than the PT group in terms of lower PE after exhaustive exercise.

Effect of yogic exercises on physical and mental health of young fellowship course trainees

A study was undertaken to observe any beneficial effect of yogic practices during training period on the young trainees. 54 trainees of 20-25 years age group were divided randomly in two groups i.e. yoga and control group. Yoga group (23 males and 5 females) was administered yogic practices for the first five months of the course while control group (21 males and 5 females) did not perform yogic exercises during this period. From the 6th to 10th month of training both the groups performed the yogic practices. Physiological parameters like heart rate, blood pressure, oral temperature, skin temperature in resting condition, responses to maximal and submaximal exercise, body flexibility were recorded. Psychological parameters like personality, learning, arithmetic and psychomotor ability, mental well being were also recorded. Various parameters were taken before and during the 5th and 10th month of training period. Initially there was relatively higher sympathetic activity in both the groups due to the new work/training environment but gradually it subsided. Later on at the 5th and 10th month, yoga group had relatively lower sympathetic activity than the control group. There was improvement in performance at submaximal level of exercise and in anaerobic threshold in the yoga group. Shoulder, hip, trunk and neck flexibility improved in the yoga group. There was improvement in various psychological parameters like reduction in anxiety and depression and a better mental function after yogic practices.

A new physiological approach to control essential hypertension

This study was conducted on 20 male patients of Essential Hypertension (EH) in order to explore the possible role of baroreflex mechanism in the etiology of EH and also to find out whether by restoration of baroreflex sensitivity to normal level either by postural tilt stimulus on a tilt table or by the equivalent yogic postural exercise (Yogic asanas), the EH could be cured or controlled. Patients on therapeutic regime were gradually withdrawn from drug therapy, and later divided into two groups of 10 each. Group-I (age 34 +/- 1.7 years) was subjected to a 3 week course of 70 degrees head-up tilt for 30 min daily, while in group-II (age 50 +/- 3.3 years), specific yogic exercises equivalent to head-up or head-down tilt were administered for the same duration. The progressive autonomic readjustments were assessed by a battery of tests including cardiovascular responses to head up tilt, cold pressor response at 4 degrees C water (CPR), alpha index of EEG (AI), level of blood catecholamines (CA) and plasma renin activity (PRA). At the end of 3 weeks, there was a significant reduction (P < 0.001) in blood pressure in both the groups. Progressive changes in BP and HR response to tilt during 3 weeks course of tilt and yogic exercise clearly indicated gradual improvement in baroreflex sensitivity. Likewise, changes in other indices like CPR, AI, CA and PRA indicated progressive attenuation of sypatho-adrenal and renin-angiotensin activity. All these changes together with the reduction in BP strongly suggest a close link between the etiology of EH and baroreflexes on the one hand and controlling influence of the latter on sympatho-adrenal and renin-angiotensin systems on the other. It also throws light on the physiological mechanism underlying the effects of selected yogic exercises in the treatment of EH.

Body composition in air and road inductees at high altitude during the initial days of acclimatization

This study assesses body composition changes and their time course during the initial days of acclimatization to high altitude (HA). Comparisons were made between gradual and acute induction to HA using 60 male lowlander volunteers (24-28 years of age) divided into two equal groups for inducting them to HA. Thirty subjects were air-lifted from sea level (SL) to 3500 m HA in 1 h. These subjects were air inductees (AI). The other 30 subjects were transported in 4 days by road to the same location at 3500 m. These were road inductees (RI). After remaining for 15 days at 3500 m both groups were inducted to 4200 m by road. All the subjects could not reach the various altitudes at the same time due to logistical problems. Ultimately, data for each altitude (SL, 3500 m and 4200 m) were available for only 26 RI subjects and 10 AI subjects. Skinfold thickness (SKF) measurements for the subscapular, thigh, triceps, biceps, juxtanipple, umbilicus, suprailiac and calf regions were taken in order to calculate fat percentages. Measurements were taken at SL and on days 1 and 9 at both 3500 m and 4200 m. On day 1 at 3500 m, RI showed a significant fall in body weight (BW) with respect to SL but AI maintained it. On subsequent days at HA both groups showed a significant fall in BW and lean body mass but not in percentage fat. SKF in the biceps and triceps regions decreased significantly but in the umbilicus and suprailiac regions it significantly increased at HA in both groups. Body composition, along with other parameters, is discussed determining the acclimatization schedule for sojourners at HA. Possibly, translocation of body fat takes place from the periphery to deep body fat depots in the core/main trunk due to the cold at HA.

Physiological, biochemical and histological changes due to physostigmine in monkeys

Physostigmine (Phy), a short-acting reversible anticholinesterase agent is considered to be a potent prophylactic antidote for the highly toxic organophosphorous (OP) compounds. The toxic effects, if any, of the probable prophylactic doses of Phy have been evaluated by studying its physiological, biochemical and histological effects in monkeys. Phy only at 100 micrograms/kg resulted in certain cholinergic signs such as salivation, lacrymation and muscular faciculations; physiological changes such as mild tachycardia, tachypnea, higher amplitude in electrical activity of the brain, clinico-chemical effects like fall in PO2, PCO2 and alkalosis and histologically an inflammatory reaction in the lungs. On the other hand, the lower dose, i.e. 50 micrograms/kg appeared to be devoid of cholinergic signs and symptoms. However, we observed a significant inhibition of both plasma and erythrocyte ChE and increase in the rectal temperature in both the Phy treated groups. From this study, Phy at a dose of 50 micrograms/kg could be inferred as a safe, sign free intramuscular dose and may probably be used in pretreatment regimen against nerve agents.

Acclimatization at high altitude in gradual and acute induction

The study assessed physiological responses to induction to high altitude first to 3,500 m and then to 4,200 m and compared the time course of altitude acclimatization in two groups of male volunteers. The acutely inducted group was transported by aircraft (AI) to 3,500 m in 1 h, whereas the gradually inducted group was transported by road (RI) in 4 days. Baseline recordings of basal cardiovascular, respiratory, and blood gas variables were monitored at sea level as well as at 3,500 m on days 1, 3, 5, and 7. Blood gases were measured on day 10 also. After 15 days at 3,500 m, the subjects were inducted to 4,200 m by road, and measurements were repeated on days 1, 3, and 5, except blood gas variables, which were done on day 10 only. Acute mountain sickness symptoms were recorded throughout. The responses of RI were stable by day 3 of induction at 3,500 m, whereas it took 5 days for AI. Four days in transit for RI appear equivalent to 2 days at 3,500 m for AI. Acclimatization schedules of 3 and 5 days, respectively, for RI and AI are essential to avoid malacclimatization and/or high-altitude illness. Both groups took 3 days at 4,200 m to attain stability for achieving acclimatization.

Auditory evoked responses in tropical men during sojourn over the arctic region

The influence of an arctic environment on auditory evoked responses, both brainstem and cognitive, were evaluated in 10 Indian soldiers. They were first tested in Delhi and then flown to an arctic region where they were tested in the first week and again in the eighth week of their stay. Two migrants from Moscow, their usual place of residence, and six natives, born and brought up in the arctic, were also tested for comparison. The Indians, on their return to India, were tested again. The auditory evoked responses were recorded using the Nicolet (USA) Compact 4 Instrument. The Indians showed a delay in all the waves of the auditory brainstem response (ABR) during their induction in the arctic and these persisted even on their return to India whereas the migrants and the natives had relatively higher ABR latency values.

Personality traits and performance of military parachutist trainees

Fifty-two Indian military parachutist trainees were studied throughout the training period to investigate effects of stress in parachutist training on performance efficiency. Stress attributable to fear, anxiety, and apprehension about the inherent risk of paratrooping was studied along with physiological and biochemical changes. An attempt is made to correlate personality traits with performance efficiency. In cognitive and psychomotor tests, maximum deterioration was seen before the tower jump and aircraft jump. The deterioration was correlated with the level of anxiety and urinary catecholamine levels. Inter-correlations between anxiety, catecholamine, and blood pressure were positive, and the level of anxiety was seen to be affecting the quality of performance adversely.

Responses of Arctic and tropical men to a standard cold test and peripheral vascular responses to local cold stress in the Arctic

Thermoregulatory, metabolic and peripheral vascular responses to cold were studied in two groups (six each) of healthy men during exposure to the natural cold environment of the Arctic. Group A comprised of two arctic natives and four temporary residents who had migrated from the temperature zone of Russia. Group B consisted of six soldiers from a tropical region (India). Group B was airlifted to the arctic (70 degrees N, 38 degrees E). Both groups stayed in a field camp. The experiments were conducted during the 7th week of the stay. The volunteers were subjected to a standard cold test at 10 degrees C for 2 h wearing only shorts. Their heart rate, blood pressure, ventilation, oxygen consumption, oral temperature, mean skin and extremity temperatures were recorded initially and at 30 min intervals during standard cold test. The cold-induced vasodilatation response in both groups was also studied separately. The tropical natives (Group B) were flown back to Delhi and retested after 6 weeks. The physiological responses to general cold exposure as well as peripheral vascular response to local arctic cold stress were similar in both groups. The observation suggested that cold acclimatization in tropical men is similar to that of the people of Russian origin from a temperature zone.

Role of xanthinol nicotinate in the revival of monkeys subjected to acute haemorrhagic shock

The therapeutic potential of xanthinol nicotinate in the revival of anaesthetised monkeys subjected to acute blood loss was investigated. The arterial pressure was lowered to 40 +/- 5 mmHg by rapid arterial bleeding and was maintained at this level for 2 h. Shed blood was then returned through infusion, to the animals. Animals alive at the end of 72 h observation period were considered as survivors. The test drug was infused 1/2 h prior to and 1/2 h, 1 h, 1 1/2 h and 2 h after the onset of oligaemic hypotension. The animals which received normal saline instead of test drug were treated as control. The physiological and biochemical parameters recorded prior to and after the onset of oligaemic hypotension were heart rate, pulse pressure, electrocardiogram, electroencephalogram (EEG), lactic acid, creatine phosphokinase, urea and glucose. The results showed tachycardia, narrowing of pulse pressure, depression of ST segment with occasional T inversion, slowing of EEG with increase in amplitude, rise in blood lactic acid, creatine phosphokinase, urea and glucose. The magnitude of these responses were proportional to the duration and severity of shock. These changes were markedly attenuated in the drug treated group. Enhancement of survival was observed in drug treated groups as compared to control. It was 10 per cent in control as against 60, 86, 71, 57 and 50 per cent in the groups which received the test drug 1/2 h prior to and 1/2 h, 1 h, 1 1/2 h and 2 h after the onset of oligaemic hypotension. It is concluded that the beneficial effect of the drug in the revival of monkeys subjected to acute haemorrhagic shock may be due to better maintenance of tissue perfusion.

Acute toxicity of methyl isocyanate, administered subcutaneously in rabbits: changes in physiological, clinico-chemical and histological parameters

Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LD50 and 1 LD50 doses in female rabbits resulted in significant changes in physiological, clinico-chemical and histological parameters. There was a fall in arterial blood pressure and cardioacceleration in both the 0.5 LD50 and 1 LD50 groups, while the respiration showed a differential response in these groups with the former showing hyperpnoea and the latter showing respiratory inhibition. A significant increase in the arterial blood lactic acid, lactate/pyruvate ratio and 2,3-diphosphoglycerate levels, and the significant changes in acid-base status of both arterial and venous blood indicated tissue hypoxia of a stagnant type. Histopathological observations revealed a mild to moderate degree of congestion, focal lymphocytic infiltrations and necrosis in all visceral organs examined. These findings suggest that acute toxicity of MIC in vivo may be mediated by its effects on vascular beds.

Optimal rate of work for mountaineers

The physiological responses of seven young male highlanders were recorded at high altitude while they were carrying loads (0, 25, 35, 45, and 55 kg) on snow at different speeds, supporting the loads on their backs by circular straps around the forehead. The rates of work calculated from the gross weight (body weight plus actual load in kg) multiplied by the speed of walking, m.min-1, ranged from 4,460 to 8,440 kg.m.min-1. The relationship between the rate of work and energy expenditure was rectilinear within the present range of values. The oxygen consumption (51.6 and 59.7 ml.min-1.kg-1 BW) for 55-kg load (at 4.09 and 4.64 km.h-1) possibly reached maximal aerobic capacity. At higher energy output at high altitude the subjects were exhausted after a short period of work. The proportion of increase of oxygen consumption per kg gross weight carried or per kg.m was almost constant up to a 55-kg experimental load. It is suggested that for day-to-day operations work should not be undertaken at more than 30-40% of maximal work capacity; a rate of work around 4,000 kg.m.min-1 (25-30 kg actual load at 3.0 to 3.5 km.h-1) may be considered as optimal for highlanders and porters at high altitude.