Daily energy expenditure and cardiovascular risk in Masai, rural and urban Bantu Tanzanians.

BACKGROUND: Several studies have revealed that the Masai, pastoralists in Tanzania, have low rates of coronary heart disease despite a diet high in saturated fat. It has also been suggested that they may be genetically protected. Recent studies detailing other potential protective factors, however, are lacking. METHODS: A cross-sectional investigation of 985 Tanzanian men and women (130 Masai, 371 rural Bantu and 484 urban Bantu) with mean age of 46 (9.3) years. Anthropometric measures, blood pressure, serum lipids, and the reported dietary pattern and physical activity level were assessed. RESULTS: 82% of Masai subjects reported a high fat/low carbohydrate intake, whereas 77% of the rural Bantu subjects reported a low fat/high carbohydrate intake, while a high fat/high carbohydrate intake was the main dietary pattern of the urban Bantu group as, reported by 55%. The most conspicuous finding for the Masai was the extremely high energy expenditure, corresponding to 2565 kcal/day over basal requirements, compared with 1500 kcal/day in the rural and 891 kcal/day for the urban Bantu. Mean body mass index among the Masai was lower than the rural and urban Bantu. Mean systolic blood pressure of the Masai was also lower compared with their rural and urban Bantu counterparts. The Masai revealed a favourable lipid profile. CONCLUSION: The potentially atherogenic diet among the Masai was not reflected in serum lipids and was offset probably by very high energy expenditure levels and low body weight.

Forebrain temperature activates behavioral thermoregulatory response in arctic sculpins.

Arctic sculpins of the genus Myoxocephalus adapted to water at 5 degrees C escaped from warm water at 20 degrees , 16 degrees , and 12 degrees C when their deep-body temperatures increased from an initial 5 degrees C to about 8 degrees C. Heating parts of the forebrain with water at 25 degrees C circulating through a pair of thermodes astraddle rostral parts of the forebrain shortened the time spent in the warm water and lessened the incease in deep-body temperature before exit from the warm water. Cooling the forebrain to about -1 degrees C caused a large increase in the body temperature and sometimes suppressed the escape from the warm water.

Physical activity and blood lipids in rural and urban Tanzanians.

BACKGROUND: Physical inactivity and raised blood lipids are two powerful risk factors for coronary heart disease (CHD). Incidence and mortality from CHD are expected to increase in developing countries. However, studies on the prevalence of cardiovascular risk factors in Africa are rare. In this study we examined the level of physical activity and serum lipids in rural and urban Tanzanians. METHODS: Rural and urban inhabitants, n=985, mean age 43.8 years [SD, +/-8.9] were investigated. Physical activity level (PAL) was assessed by an interview-administered questionnaire and blood samples were collected and analysed for serum lipids. RESULTS: The rural population (n=501) reported a substantially higher PAL than the urban population (n=484). They also had significantly lower mean weight, body mass index (BMI), T-cholesterol, LDL-cholesterol, and HDL-cholesterol, T-cholesterol/HDL-cholesterol ratio, triglycerides and Apolipoprotein A-1. CONCLUSION: This study demonstrates that the urban Tanzanians have a considerably lower physical activity level and a more unfavourable lipid pattern than rural Tanzanians. These findings underline the importance of undertaking preventive measures to counter the increasing incidence of CHD in urban African populations.

Cardiorespiratory fitness in relation to self-reported physical function in cancer patients after chemotherapy.

AIM: The aim of this study was to estimate the association between objective cardiorespiratory fitness (CRF) and subjective self-reported physical function, taking into account the influence of mental distress. We hypothesized an association between these parameters, since they might be thought to measure parts of the same phenomenon. METHODS: Approximately 1 month after discontinuation of all primary treatment, 90 cancer patients aged 18-50 years treated with chemotherapy were surveyed. CRF was determined by the Astrand-Ryhming indirect cycle ergometer test, which indicate peak VO2 in mL x kg(-1) x min(-1) (predicted VO2max). Self-reported physical function was assessed by The European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30). The relation between VO2max and self-reported physical function was estimated by multiple linear regression. Mental distress (assessed by The Hospital Anxiety and Depression scale), age, gender, body mass index (BMI), time from treatment to physical test and diagnoses were included as potential confounders. RESULTS: There was no association between predicted VO2max and self-reported physical function. Mental distress was negatively associated with self-reported physical function (P<0.001), but is not associated with predicted VO2max. CONCLUSIONS: The results suggest that predicted VO2max does not reflect self-reported physical function and vice versa in cancer patients after chemotherapy. If information about cardiac and/or pulmonary status is required, direct or indirect measures of VO2max should be used.

Comparison of oxygen uptake and heart rate during exercises on land and in water.

Oxygen comsumption and heart rate response during identical calisthenic-type exercises performed on land and in the water were compared in eight subjects. Both the heart rate and the oxygen uptake were greater during exercises in water. Although gravity is the primary resistance to movement on land, viscosity friction and turbulence are dominant resistive factors in the water. The results of this study indicate that the latter two factors provide a greater load during exercise than the resistance of gravity in land exercises. At a moderate rhythm of leg exercises, oxygen consumption increased about ten times over resting values in the water for men subjects and about seven times for women. Arm exercise performed in the water require less energy than leg exercises in water, but arm exercises require significantly more oxygen when performed in water than the same exercises performed on land.

Comparison of diving bradycardia and maximal aerobic power.

It has previously been suggested that diving bradycardia might be more pronounced in physically trained subjects than in unconditioned ones. Therefore, the cardiac responses to apneic face immersion in water of 25 +/- 1 degree C during rest and exercise in 24 males and females, ranging in age from 21-37 years, were compared to the subjects' levels of physical fitness, as estimated by maximal aerobic power. These values ranged from 46-74 ml.kg-1.min-1. The diving bradycardia was greatly intensified when the face immersion was superimposed on a state of apneic exercise. However, a correlation of the individuals' maximal aerobic power and the mean degree of bradycardia displayed during various maneuvers of apneic face immersion did not approach statistical significance. It is concluded that there exists no relationship between bradycardia and physical fitness, as judged from maximal aerobic power.

Indirect evidence for arterial chemoreceptor reflex facilitation by face immersion in man.

It has been demonstrated that the usual diving bradycardia can be greatly intensified when face immersion is superimposed on a state of apneic exercise. This intensification is neither due to chemoreceptor stimulation, or to face immersion per se. It is concluded that the intensification is caused by chemoreceptor reflex facilitation, due to stimulation of trigeminal receptors in the face.

[Physical activity, overweight and obesity]. / Fysisk aktivitet, overvekt og fedme.

Regular physical activity has profound effects on body composition and the utilisation of nutrients and help to maintain and increase skeletal muscle mass, with increased resting metabolic rate and enhanced capacity for lipid oxidation during rest and exercise. Regular exercise may also prevent or limit the loss of lean tissue (fat-free mass, FFM) during slimming regimens. Increased physical activity induces a number of favourable changes in the metabolism of lipoproteins: serum triglycerides are lowered by the increased lipolytic activity, the HDL concentration increases and the concentration of small dense LDL decreases. In addition, the enhanced metabolic capacity of skeletal muscle (metabolic fitness) will favorably influence risk factors such as insulin resistance and hypertension. Because regular physical activity has favorable effects on several of the comorbid conditions of obesity, particularly cardiovascular disease and type 2 diabetes, it is not surprising that the mortality rates seem to be lower in the overweight and moderately obese individuals who are physically fit compared with the unfit. The treatment of overweight and obese persons should perhaps be more focused on the level of regular physical activity than on body weight per se. For most of those who wish to reduce their body weight, it is recommended that they combine regular physical activity with a somewhat reduced energy intake, in particular of food rich in fat. Emphasis should be on promoting relatively low-intensity, long-duration physical activity which can be conveniently incorporated into daily life.

[High altitude training]. / Høydetrening.

The physiological rationale for altitude training is discussed in the article. Acclimatisation to high altitude is accompanied by increases in haematocrit and haemoglobin concentrations, primarily due to a reduction in plasma volume but also to increased erythropoiesis as a result of enhanced erythropoietin release. Owing to the reduction of training load during acclimatisation, maximal aerobic capacity is not necessarily enhanced after high altitude training. However, the increase in the blood lactate concentration during standardised submaximal work has been shown to be significantly reduced--reflecting improved ability to exercise at higher submaximal workloads, as compared with previous ability at lower altitudes. An increase in buffer capacity may be responsible. The importance of a reduced training load and individualised control of training intensity during the acclimatisation period is emphasised. This control takes the form of regular heart rate monitoring and comparison of the blood lactate concentration during training sessions with the individual's pre-established 'lactate profile'. The Norwegian Altitude training project, including the various routines, procedures and problems involved in three successive sojourns at moderate altitudes, is briefly discussed. Finally, a practical approach to altitude training is presented--dealing with training control, iron demand, nutritional advice, fluid intake and recovery. Only top athletes should be selected for training at high altitudes.

Effects of active, passive or no warm-up on the physiological response to heavy exercise.

Six endurance-trained young men were subjected to a 4 min maximal aerobic treadmill run (100% of VO2 max), after active or passive warm-up or rest on separate days. The increase in body temperature during the active and passive warm-up was controlled, so that the temperature reached the same level, before the subject was exposed to the maximal exercise. On average the rectal temperature rose to 38.3 degrees C (range 38.1-38.6 degrees C). The standard work resulted in a significant higher oxygen uptake, lower lactate concentration and higher blood pH when the work was preceded by active warm-up as compared with passive or no warm-up. The difference in total oxygen uptake during the run between the active and passive warm-up procedure was 0.8 1. No significant difference in minute volume of expired air or respiratory quotient was found. It is concluded that the physiological effects of a thorough active warm-up may be of substantial benefit to athletic performance.

Serum thyroxine, triiodothyronine and thyroid stimulating hormone after prolonged heavy exercise.

Serum thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) was measured before, immediately after and on the following days after a 70 km cross-country ski race in two groups of ten well-trained men, one aged 21--29 years, taking 5.01--7.03 h, and one aged 51--57 years, taking 6.07--7.38 h. T4 was definitely increased immediately after the race, but fell to below the initial level on the following day and was not restored to the pre-race level until 4 days after the race. T3 showed essentially the same pattern, though less pronounced, a major part of the changes being possibly due to plasma volume variations. TSH showed a tendency to rise immediately after the race, but rose further to 175% of the initial level on the following day and was not restored to the initial level 4 days after the race. The pattern of changes were independent of age. It is suggested that the prolonged rise in TSH is probably due to an exercise-induced increased peripheral need for thyroid hormone.

Pulmonary blood volume and interventricular circulation time in physically trained and untrained subjects.

Resting pulmonary plasma and blood volumes (PPV and PBV), interventricular circulation time (IVCT), cardiac and stroke index (CI and SI), heart rate (HR), total plasma and blood volumes (PV and BV) were determined in athletes (two male groups representing different types of sport activities, and one female group) and compared with those of non-athletes (one male and one female group). In addition to high maximal aerobic power, the athletes were characterized by greater SI, BV and PV and lower resting HR than non-athletes, PPV and PBV were significantly larger and IVCT significantly longer in the trained than in the untrained groups, probably reflecting an improved capacity of the pulmonary circulation. PPV as per cent of PV was almost equal in all the groups, indicating the same distribution of plasma between the pulmonary and systemic circulation. The data also indicate that total blood volume is an important determinant of the magnitude of the pulmonary vascular bed. The increased volume of flowing blood and increased stroke volume in athletes probably allows for a reduction in flow velocity and thereby a reduction in kinetic energy.

Relationship between urine flow, glomerular filtration, and urine solute concentrations during prolonged heavy exercise.

Serum and urine electrolytes, creatinine, and urea were determined in 21 well-trained men, aged 21-56 years, in connection with a 70-km cross-country ski race, lasting 4.39-6.52 h, leading to slight dehydration. Although the race urine flow was low, averaging 0.41 (0.1-0.9) ml/min, the average urine concentrations of urea, Na, Ca, Mg, Cl and P were markedly lower than during the preceding night, while the concentrations of K and creatinine were higher, the total of measured solutes being 621 nmol/l, compared with 911 nmol/l during the preceding night. Decreasing urine flow and endogenous creatinine clearance were accompanied by a falling urine solute concentration, particularly when the race creatinine clearance decreased to below 70 ml/min, mainly due to a fall in the urea, Na, and Cl concentrations. Thus, a decrease in the glomerular filtration rate was accompanied by a progressive decline in the urine concentrating ability.

Renal osmol clearance during prolonged heavy exercise.

Serum and urine osmolality and creatinine were measured in fifty-eight well-trained men, aged 21-57 years, in connection with three 70 km cross-country ski races taking place under essentially the same external circumstances, leading to slight dehydration. Although the race urine flow was low, 0.51 (0.05-1.10) ml/min, the urine osmolality and the urine to serum osmolality ratio were relatively low, averaging 860 (399-1220) mosm/kg H2O and 2.84 (1.32-4.10), respectively. Decreasing urine flow and endogenou- creatinine clearance were associated with decreasing urine to serum osmolality ratio, indicating declining urine concentrating ability. Thus, the data confirm the author's recent suggestion, based on the measurement of a limited number of urine solutes, that during prolonged heavy exercise a decrease in urine flow and glomerular filtration rate is accompanied by a decline in the urine concentrating ability.

[Physical activity and health--recommendations]. / Fysisk aktivitet og helse--anbefalinger.

BACKGROUND: The health consequences of physical inactivity and the health gains of regular physical activity are briefly summarized. We present physical activity recommendations based on a review of the literature for the general adult population. METHODS: This report employs recognised international standards for establishing causal relationships between physical activity and disease, distinguishing between four different levels: Convincing, probable, possible and insufficient evidence. Convincing or probable evidence have provided the basis for the recommendations given. RESULTS: The total amount of physical activity (a combination of intensity, duration and frequency) is related to a number of health variables in a dose-response relationship. The preventive effect (the health gain) increases with increasing activity level, but the relationship is not linear. The greatest health gains are attained by those who are least physically fit. This applies even in old age. The health gain seems primarily to be dependent on the total energy expenditure, and less on the intensity. The dose-response relationship between physical activity levels and health gains is a continuum that does not seem to have a lower limit. Thus, any activity can be said to be better than none. INTERPRETATION: We conclude that a minimum "target dose" that will yield substantial health gains for those who have been physically inactive for a long time, is activity of moderate intensity which corresponds to an energy expenditure of approximately 150 kcal (630 kJ) per day (or slightly more than 1,000 kcal (4.2 MJ) per week). This is equivalent to a daily walk of about 30 minutes. The activity can be divided into shorter intervals of physical activity during the course of the day, for instance intervals lasting 5-10 minutes. An increase in activity beyond this level will yield further health gains. The effect of exercise is just as good for older people as for younger people, and the same recommendations apply as to other adults.

Active recovery counteracts the post-exercise rise in plasma-free fatty acids.

The present study investigated the effect of active recovery (AR) as compared to rest recovery (RR) upon FFA concentrations following moderate- (MI) or high-intensity (HI) running. Fourteen well-trained males (23.7 +/- 6 years, VáO2max = 69.5 +/- 1.8ml á min-1 kg-1) were randomly assigned into two trials (HI = 30 min at 82% of VáO2max; MI = 60 min at 75% of VáO2max). Within each group, the subject completed two sets of experiments of running followed by either AR (15 min running at 50% of VáO2max) or RR (complete rest in the supine position). Plasma volume changes after the exercise did not deviate between the AR or RR trials. In both the HI and MI trials, AR resulted in lower FFA peaks and lower overall FFA concentrations while performing AR (p <.05). However, upon discontinuing AR, there was a rise in the FFA concentration. At 120-min post-exercise, the FFA concentrations after AR and RR were not significantly different. The changes in the FFA/albumin ratio were similar to the FFA responses. It is concluded that AR may counteract the rise in FFA 5-15 minutes after exercise.

L-tryptophan supplementation does not improve running performance.

In 1988 Segura and Ventura (14) reported that 1.2 g of L-Tryptophan (L-TRY) supplementation increased total exercise time by 49.4% when the subjects were running at 80% of maximal oxygen uptake (VO2max). In human performance research, acute improvements of that category are rather uncommon. Both for this reason and because ingestion of purified L-TRY may have adverse effects, it seemed pertinent to repeat the investigation of Segura and Ventura. Forty-nine well-trained male runners, aged 18-44, with an average maximal aerobic power of 66 (57-78) ml.kg-1.min-1, participated in a randomized double blind placebo (P) study. Each subject underwent four trials on the treadmill. The first two served as learning experience, including measurement of VO2max and anaerobic threshold. During the last two trials the subjects ran until exhaustion at a speed corresponding to 100% of their VO2max-first an initial trial and then after receiving a total of 1.2 g L-TRY or P over a 24 hour period prior to the run. No significant difference between the improvements in the L-TRY and P group could be demonstrated. It is concluded that oral L-TRY supplementation does not enhance running performance.

High density lipoprotein cholesterol, total cholesterol and triglycerides in serum after a single exposure to prolonged heavy exercise.

Serum high density lipoprotein (HDL) cholesterol, total serum cholesterol and triglycerides were determined in twenty men before, immediately after, and 1, 2 and 4 days after a 70 km cross-country ski race. HDL cholesterol increased by 12% of the pre-race level immediately after the race, rose further to 17% above the initial level on the following day, and was still elevated 4 days after the race. LDL + VLDL cholesterol, however, showed a tendency to decrease immediately after the race and was reduced by 17% and 11% of the pre-race level on the following 2 days. Triglycerides were reduced by 30% of the initial level immediately after the race, were still low on the following day, but were restored to normal 2 days after the race. It is concluded that a single exposure to prolonged heavy exercise induces changes in the HDL metabolism, showing that the physical exercise per se plays an important role for the increased HDL level seen in well-trained athletes.