Antioxidant and redox status after maximal aerobic exercise at high altitude in acclimatized lowlanders and native highlanders.

Exercise-induced increase in oxygen consumption leads to oxidative stress. On the contrary, hypoxia triggers oxidative stress despite decreased oxygen flux. Therefore, exercise under hypoxia may aggravate oxidative damage. Highlanders are expected to have better antioxidant capacity than lowlanders as a result of adaptation to hypoxia. The present study was undertaken to investigate the effect of exercise on antioxidant system in lowlanders and highlanders at high altitudes (HA). This study was conducted on active male volunteers, randomly selected and categorized into three groups, i.e., lowlanders tested at sea level (LL-SL, n = 35), lowlanders tested at altitude of 4560 m (LL-HA, n = 35) and native highlanders tested (HAN, n = 20) at the same height. Volunteers performed maximal exercise until exhaustion. Blood samples were collected before and after exercise. Both LL-SL and HAN had shown similar VO2max, which was significantly higher than LL-HA. GSH/GSSG ratio significantly increased in LL-SL and decreased in HAN after exercise. With exercise there were a decrease in superoxide dismutase and increase in glutathione peroxidase and catalase activities in HAN. Therefore, the results have suggested that HAN are more susceptible to oxidative stress when subjected to high-intensity exercise than lowlanders. The cumulative effect of higher VO2max and longer duration of exercise in hypoxia may be the reason of higher level of oxidative insult among HAN. Comparatively better management of antioxidant system observed in lowlanders at HA may be explained by the lower VO2max and shorter duration of exercise in hypoxia.

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.

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.

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.

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.

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.

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.