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.

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.

Active recovery and post-exercise white blood cell count, free fatty acids, and hormones in endurance athletes.

Strenuous endurance exercise in fasted subjects is accompanied by increased plasma levels of catecholamines, leucocytosis, low insulin, and elevated plasma free fatty acids (FFA). Immediately after such exercise, plasma FFA may rise to high and potentially harmful levels, whereas the white blood cell count (WBCC) rapidly decreases towards or below baseline values. The present work investigated how active recovery (AR) for 15 min at 50% of maximal oxygen consumption (VO2max), after 60 min of uphill running at 83% of VO2max, influenced plasma FFA, lymphocyte, neutrophil, granulocyte, and monocyte count, as well as adrenaline, noradrenaline, insulin and cortisol concentrations until 120 min post-exercise. Thirteen endurance athletes participated in the study [24.2 (3.7) years, 1.82 (0.06) m, 76.7 (7.9) kg and VO2max 69.2 (6.8) ml min-1 kg-1]. In a randomized order, the subjects completed two sets of strenuous workouts, followed by either AR or complete rest in the supine position (RR). Compared with RR, AR strongly counteracted the rapid increase in plasma FFA 5 min post-exercise. The decreases in neutrophil and monocyte counts post-exercise were nullified by AR, and the cell count stayed above resting values throughout the observation period. AR also counteracted the rapid return of hormone concentration towards baseline levels. It would appear that active recovery at low intensity after strenuous exercise can maintain sufficient adrenergic activation to counteract the post-exercise drop in WBCC. However, in spite of keeping the catecholamine concentration high and insulin levels low, AR can also maintain a low plasma FFA concentration, probably because of the continued use of FFA in muscle. It remains to be elucidated whether the observed high FFA and low WBCC values after RR have a negative effect on health. If so, AR could be a preventive measure.

[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.

[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.

Active recovery reduces the decrease in circulating white blood cells after exercise.

This study was conducted to examine the effects of different recovery regimens on white blood cell count (WBCC) and muscle enzyme activities following strenuous, submaximal, steady state workouts on a treadmill. Fourteen endurance trained, healthy, non-smoking college-aged males participated in the study. The workouts were followed by either 15-min of rest recovery (RR), or active recovery (AR). The AR consisted of running at 50% of VO2max whereas RR implied complete rest. Seven subjects completed two sets of 60-min running at 70% of VO2max (moderate intensity group, MI) followed by either RR or AR. The other seven completed two sets of 30-min running at 80% of VO2max (high intensity group, HI) followed by either RR or AR. Blood samples were drawn at rest, immediately after exercise, and at 15- and 120-min post-exercise (PE). Blood lactate concentrations increased throughout the running trials. Creatine kinase (CK), lactate dehydrogenase (LD), white blood cell count (WBCC) and thrombocyte count increased between rest and 0-min PE (p<0.05). Between 0-15-min PE, there were several significant differences between RR and AR in the HI-trial. RR was associated with a 35% reduction in WBCC, compared to only 6% decrease in AR (p<0.02). Neither during 15-120-min PE this period, nor in the 120-min sample alone, were there any significant differences in WBCC between the RR and AR experiments. In conclusion, the results show that AR as opposed to rest recovery prevents the initial 0-15-min PE fall in WBCC after strenuous endurance exercise.

Omega-3 fatty acid supplementation does not improve maximal aerobic power, anaerobic threshold and running performance in well-trained soccer players.

In a randomized, placebo-controlled study the effect of 10 weeks of supplementation with either 5.2 g of a concentrated fish oil triglyceride (Triomar) enriched in omega-3 fatty acids (1.60 g/day EPA and 1.04 g/ day DHA) or 5.2 g corn oil (serving as placebo) on maximal aerobic power, anaerobic threshold and running performance was assessed in 28 well-trained male soccer players (18-35 years). Supplements were given as 650-mg capsules. Capsule assignment was randomized to one omega-3 group (n = 15), given eight Triomar capsules per day, and one placebo group (n = 13), given eight capsules of corn oil per day. During the 10-week supplementation period the subjects maintained their usual diets and training regimes. Red blood cell (RBC) osmotic fragility, triglycerides and fatty acid composition in plasma were assessed before and after the supplementation period. The pre- and post-supplementation tests of maximal aerobic power, anaerobic power and running performance showed no significant difference between the two groups. Subjects in the omega-3 group had significantly reduced plasma triglycerides, rose EPA (175%) and DHA (40%) in the total lipid fraction of plasma after supplementation. RBC osmotic fragility did not change. In conclusion, the results do not support the hypothesis that endurance athletes can improve maximal aerobic performance by omega 3-fatty acid supplementation.

Exercise intensity. An important factor in the etiology of menstrual dysfunction?

UNLABELLED: The objective of this case control study was to compare training activity in female long distance runners with irregular (IR, n = 13) and regular (R, n = 16) menstrual function, especially with regard to exercise intensity. Serum estradiol concentration during the follicular phase was considered normal in the R subjects (31 +/- 6 pg/I). In contrast, the IR runners were clearly hypoestrogenic (11 +/- 1.6 pg/l). The two groups had similar VO2max, anaerobic threshold (AT) and maximal heart frequency (HFmax). In both groups AT was found at 88% of HFmax. The two groups had similar mean race results in half marathons during the previous year. The number of running contests was, however, twice as high in the IR group. A light portable pulse recorder was used to monitor heart rate during 1 week of regular training activity, and during a controlled high intensity work-out. During a week with normal training activity, and equal amount of training at high intensity levels (> 85% HFmax) was performed by the two groups. The amount of training at lower intensities (< 85% HFmax) was, however, more extensive in the group with irregular menstrual function. During the controlled self-administered, high intensity work-out, the amounts of training at and above AT were equal in the two groups. IN CONCLUSION: no difference in extent of high intensity training between long distance runners with regular and irregular menstrual function could be found in the present study group. The IR runners did, however, have significantly more training activity at lower intensity levels, and more frequent race participation.

[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.

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.

Comparison of changes in testosterone concentrations after strength and endurance exercise in well trained men.

Changes in the testosterone concentrations after single sessions of endurance and strength training were measured in seven well trained men, experienced in both forms of training. Both training sessions were rated as hard to very hard on the Borg scale. Blood samples for testosterone measurements were taken before, immediately after, and 2, 4 and 6 h after the training sessions as well as the next morning. The mean testosterone concentration increased 27% (P less than 0.02) and 37% (P less than 0.02) during the strength and endurance training session, respectively. Two hours after the training sessions the mean testosterone concentration had returned to the pre-training level and remained at that level for the length of the observation period. There were no significant differences in the changes in testosterone concentration after strength and endurance training but there were large differences in the testosterone response at the level of the individual. A high correlation (r = 0.98; P less than 0.001) for individuals was found between increases in testosterone concentration after strength and after endurance training. It was concluded that the changes in mean testosterone values followed the same timecourse after single sessions of strength and endurance training of the same duration and perceived exertion. The interindividual differences in testosterone response may be of importance for individual adaptation to training.

Sex differences in performance-matched marathon runners.

Six male and six female runners were chosen on the basis of age (20-30 years) and their performance over the marathon distance (mean time = 199.4, SEM 2.3 min for men and 201.8, SEM 1.8 min for women). The purpose was to find possible sex differences in maximal aerobic power (VO2max), anaerobic threshold, running economy, degree and utilization of VO2max (when running a marathon) and amount of training. The results showed that performance-matched male and female marathon runners had approximately the same VO2max (about 60 ml.kg-1.min-1). For both sexes the anaerobic threshold was reached at an exercise intensity of about 83% of VO2max, or 88%-90% of maximal heart rate. The females' running economy was poorer, i.e. their oxygen uptake during running at a standard submaximal speed was higher (P less than 0.05). The heart rate, respiratory exchange ratio and blood lactate concentration also confirmed that a given running speed resulted in higher physiological strain for the females. The percentage utilization of VO2max at the average marathon running speed was somewhat higher for the females, but the difference was not significant. For both sexes the oxygen uptake at average speed was 93%-94% of the oxygen uptake corresponding to the anaerobic threshold. Answers to a questionnaire showed that the females' training programme over the last 2 months prior to running the actual marathon comprised almost twice as many kilometers of running per week compared to the males (60 and 33 km, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of high density lipoprotein cholesterol concentration to the duration and intensity of endurance training.

Eleven healthy, male students were studied over period of 8 months. Five were sedentary subjects, and six were competitive cross-country skiers engaged in endurance training of varying amount and intensity. Serum concentration of high density lipoprotein (HDL) cholesterol increased significantly during physical endurance training of low intensity and long duration. With fewer hours of training, but of greater intensity, HDL cholesterol concentration was lower but was still significantly higher than in the control group of sedentary individuals. In conclusion the study suggests that elevated HDL cholesterol concentrations associated with high levels of physical activity are related to both amounts and intensity of the training.

Excretion of casts and uromucoid in urine after prolonged heavy exercise.

Excretion of uromucoid, albumin and casts in urine were determined in twenty well-trained men, ten aged 20-30 years, and ten aged 50-60 years, before, during and after a 70 km cross country ski race. During the race there was only a slight increase in uromucoid excretion, but a marked increase in the excretion of casts and albumin. The older subjects had a tendency to lower urine output during the race compared to the younger group. Reduction of urine output below ca. 25 ml/h was accompanied by a conspicuous increase in urine cast and albumin concentrations, with only a slight increase in uromucoid concentration, and even a reduction in uromucoid excretion. No significant relationship was found between cast excretion and uromucoid concentration. Thus the gross cylindruria observed during longstanding exercise must be ascribed to other urinary factors facilitating the formation of casts.