Marginal malnutrition in school-aged Colombian boys: metabolic rate and estimated daily energy expenditure.

Total daily energy expenditure (TDEE) and energy expenditure in activity (EAc) were estimated in 114 free-ranging, nutritionally normal, and undernourished boys 6-16 yr of age by measuring basal and resting metabolic rates, average daily heart rate while awake, and oxygen consumption and heart rate during exercise on a treadmill. Mean daily heart rates were in the range of exercising heart rates and gave reasonable estimates of TDEE and EAc. TDEE increased with age (p less than 0.001) and was reduced in undernourished boys (p = 0.011). Results indicate that nutritional group differences in TDEE were due to differences in body size. EAc increased with age but did not show significant differences between nutritional groups, indicating that in the marginal malnutrition of school-aged children, reduced growth and associated economy of energy expenditure in locomotion is sufficient physiological adaptation. Peer pressure in school and play activities may interfere with the protective mechanism of reduced activity.

Basal metabolic rate of Colombian children 2-16 y of age: ethnicity and nutritional status.

Measurements of basal metabolic rate (BMR) were made in 528 children 2-16 y of age living in underprivileged areas of the city of Cali, Colombia (153 control and 186 undernourished boys, 93 control and 96 undernourished girls). The data are related to BMR calculated from the equations of Schofield and to estimates of the lean body mass (LBM). The ethnic composition of the subjects was 80% mestizo (mixed European and South Amerindian ancestry), 15% black, and 5% white. The data do not show any variations due to race in these subjects. The Schofield equations overestimate the BMR of boys by approximately 6% whereas the estimation of BMR in girls is not significantly different from measured values. More than 65% of the variation in BMR of both nutritionally normal and undernourished boys and girls is explained by variation in body size as estimated by the LBM.

Energy expenditure of urban Colombian women: a comparison of patterns and total daily expenditure by the heart rate and factorial methods.

The heart rate and factorial methods of measuring both total daily energy expenditure (TDEE) and the daily pattern of energy expenditure (EE) were compared in nonpregnant, nonlactating women aged 19-43 y living in urban conditions of economic deprivation. The methods were applied on each of 2 successive days. There were no significant differences between the 2 d by either method. Women who worked at their household chores at home (n = 29) and those who also worked for remuneration (at work) in various kinds of employment (n = 23) were compared. The factorial method gave values for TDEE and for the pattern of EE that were significantly lower than those obtained by the heart rate method. This was related to lower values for EE for certain activities obtained from the literature than for values measured in these subjects. Women at work had significantly higher values for both TDEE and for the pattern of EE than did those at home. The TDEE at home by the heart rate method was 8.83 +/- 1.94 MJ/d and at work was 9.99 +/- 1.91 MJ/d (P = 0.036); this difference disappeared when adjusted for body weight or fat-free mass. Physical activity levels were 1.83 +/- 0.43 for women at home and 1.90 +/- 0.46 for women at work, which indicate moderate to heavy work. The factorial method should be used with measured EE values in the present subject population. The heart rate method can detect differences in TDEE and in the pattern of EE between women engaged in different activities and may offer an experimental approach to the study of the effects of daily variations in EE on nutritional energy intake.

Productivity and maximal oxygen consumption in sugar cane cutters.

Vo2max and daily productivity (metric tons/day) have been measured in 46 sugar cane cutters 18 to 34 years of age. A multiple regression analysis demonstrated that productivity was simultaneously related to VO2max, height and body fat (r=0.685;P less than 0.001). The multiple regression equation was: productivity (tons/day)=0.81 VO2max-0.14 percent fat +0.03 height -1.96. The data indicate that productivity is affected indirectly by nutritional status through the influence of the latter on height, fat content and VO2max. The decrease in VO2max that occurs with age was similar to that reported in the literature. Evidence is presented that, as the worker ages, a higher percent VO2max has to be utilized to maintain productivity.

Energy expenditure, productivity, and physical work capacity of sugarcane loaders.

VO2, E and heart rates (fH) were measured in 28 Colombian sugarcane loaders while loading cane and in the laboratory during a VO2max test. Productivity (metric tons-day-1) of the workers was also obtained. During work, VO2 was 1.251-min-1, VE 38.81 min-1, and fH 120 beats-min-1. The subjects worked at 42% of VO2max (6.3 +/- 1.0 kcal-min-1) during the field measurement periods. Energy expenditure was estimated to average 3,281 kcal-24 hr-1. Productivity was higher in men with lower fat content, resting fH and fH at VO2 = 1.25 1-min-1, indicating a positive relationship between productivity and physical fitness. Productivity was not related to age but, since VO2max decreased with age, the relative effort required to maintain productivity increased in the older workers. Efficiency (kg cane loaded-1 VO2-1) and estimated sustained effort (percent VO2max) were not significantly correlated with productivity in this type of discontinuous, moderate work.

Marginal malnutrition in school-aged Colombian boys: anthropometry and maturation.

Colombian reference data for weight and height were used to classify 1108 boys 6 to 16 yr old as nutritionally normal, low weight for age, and low weight for height. The normal group in upper socioeconomic urban and normal, low weight for age, low weight for height groups in lower socioeconomic urban and rural populations were studied. The achieved growth, growth velocities, skinfolds, mid-arm and head circumferences, and sexual maturation were all depressed in the nutritionally deprived groups indicating marginal malnutrition. Since normal boys exist in low socioeconomic and rural populations, normative data for economically advantaged children (national standards), on the average, may serve as desirable goals for low socioeconomic and rural populations. Different cutoff points for achieved growth might be established for marginal malnutrition using national or international reference populations. These ought to be age-related because of accumulated effect of slowed growth with age. Head circumference of school-aged children may proved a useful anthropometric tool in deciding early nutritional history.

PIP: Colombian reference data for weight and height were used to classify 1108 boys 6 to 16 years old as nutritionally normal, low weight for age, and low weight for height. The normal group in upper socioeconomic urban and normal, low weight for age, low weight for height groups in lower socioeconomic urban and rural populations were studied. The achieved growth, growth velocities, skinfolds, midarm and head circumferences, and sexual maturation were all depressed in the nutritionally deprived groups indicating marginal malnutrition. Since normal boys exist in low socioeconomic and rural populations, normative data for economically advantaged children (national standards), on the average, may serve as desirable goals for low socioeconomic and rural populations. Different cutoff points for achieved growth might be established for marginal malnutrition using national or international reference populations. These ought to be age related because of accumulated effect of slowed growth with age. Head circumference of school aged children may provide a useful anthropometric tool in deciding early nutritional history.

Comparisons of body fat estimated from total body water and skinfold thicknesses of undernourished men.

In 49 chronically undernourished adult males, classified as having mild, intermediate, or severe nutritional compromise, comparisons were made of body fat calculated from total body water with values obtained from triceps and scapular skinfolds. These same comparisons were followed in 19 of the severely undernourished subjects during a 2 1/2-month period of dietary repletion. Results indicate that the correlations between fat estimates obtained from body water and skinfolds are good (r greater than 0.8) in mildly undernourished subjects, but that they are progressively reduced as the nutritional compromise becomes more severe until statistical significance disappears. Dietary repletion of 2 1/2-month duration did not restore a statistically significant relationship between fat and triceps and scapular skinfolds. These data imply that the triceps and scapular skinfolds do not adequately represent body fat in chronically undernourished adult males and that new empirical equations are required which take into account nutritional status and possible shifts in fat deposit sites in chronic undernutrition.

Development of standards for rapid assessment of nutritional status: Colombian children.

A method is described for deriving polynomial equations which describe weight and height for age and weight and height for children between 6 and 16 yr of age. Data for Colombian boys and girls have been utilized to illustrate the procedure.

Functional assessment of nutritional status: heart rate response to submaximal work.

The heart rate response to submaximal treadmill work been calculated using the heart rates and oxygen intakes obtained from normally nourished and undernourished adult male subjects during a maximal oxygen consumption test. Increased severity of malnutrition was associated with an increased heart rate response to the same submaximal work loads. The response was observed to decrease during a period of high protein dietary repletion of the most severely malnourished subjects. The data suggest the possibility of developing a submaximal work test for use in the field to provide physiological data to supplement anthropometric and biochemical information used to assess the nutritional status of populations.

Body composition in chronic undernutrition.

Anthropometric (height, weight, and skinfolds), biochemical (serum proteins, albumin, and cholesterol), metabolic (nitrogen balance and creatinine excretion), hematological (plasma volume, hemoglobin, hematocrit, bone marrow hemosiderin, percent transferrin saturation, vitamin B12, and folic acid) variables and body water compartments (total and extracellular) have been measured in 49 adult male subjects who exhibited a wide range of nutritional states from normal to severely undernourished. Changes in body composition associated with moderate degrees of nutritional compromise were related principally to decreases in body cell mass (-15%). Body fat was normal. With severe nutritional involvement, both fat depots (-29%) and body cell mass (-29%) were significantly diminished. Muscle cell mass was more affected than other cells in the body (-41%). These data could indicate that in the group with moderate compromise, energy reserves (and hence energy balance) were maintained but dietary protein deficiencies were not compensated for. Both calorie and protein deficiencies were evident in the subjects with severe undernutrition. Multiple regression equations (r greater than 0.8) were developed that allow prediction of muscle cell mass, fat-free weight, and body cell mass from simple anthropometry and serum albumin levels. Decreases in serum albumin concentration were best related to deficits in muscle mass (r = 0.77).

Marginal malnutrition in school-aged Colombian boys: efficiency of treadmill walking in submaximal exercise.

Measurements of oxygen consumption (VO2) were made during submaximal treadmill exercise (3.5 mph) in 658 boys 6 to 16 yr of age classified as nutritionally normal, low weight for age, and low weight for height. Gross efficiency (at 15% grade) increased with age and was significantly lower in low weight for age and height boys than in normal children but delta efficiency showed no statistically significant differences between nutritional groups. It is concluded that marginal malnutrition has no effect on the efficiency of submaximal work during treadmill walking.

Marginal malnutrition in school-aged Colombian boys: body composition and maximal O2 consumption.

Do changes in body composition account for the changes in O2 consumption during maximal exercise (VO2max) in nutritionally deprived boys? School age urban and rural boys with no deficits (N) or with significant deficits (W-H) in weight for age and for height were studied. Percentage lean body mass was higher in W-H than in N boys. By contrast percentage intracellular water, the creatinine excretion coefficient and percentage arm muscle mass were not higher in W-H boys. Thus nutritional compromise decreased more the cellular than the support tissues of the body. VO2max per unit body weight was higher in W-H than in N boys. In the rural group, this was accounted for by the higher percentage lean body mass in W-H boys. In the urban group, VO2max/lean body mass was also higher in most W-H boys. Thus W-H urban boys had higher levels of aerobic training than N urban boys, reflecting perhaps a relative increase in daily physical activity as the same tasks have to be performed with less muscle by W-H boys.

Body composition of Colombian women.

Measurements of anthropometry and total body water (TBW) were made in 99 women 19-44 y of age living in socioeconomically deprived circumstances in Cali, Colombia. TBW was measured by dilution of deuterium oxide. An empirical equation for estimating lean body mass (LBM) was derived and applied satisfactorily to an independent study group. Comparisons were also made with body-composition values obtained by the Durnin and Womersley equations and an equation derived from rural women living in Guatemala. Neither set of equations was suitable for use with the Colombian subjects because both significantly overestimated LBM and therefore underestimated body fat. Lower values of standing height in older women suggest that they may have been subjected to more severe undernutrition during their growth than the younger subjects. When compared with a group of US women, Colombian subjects were less physically fit and had greater subcutaneous-fat deposits, which were distributed over the trunk and limbs, whereas body mass indexes and waist-hip ratios were not significantly different.

Marginal malnutrition in school-aged Colombian boys: functional consequences in maximum exercise.

The maximum treadmill oxygen consumption was measured in 1013 boys, 6 to 16 yr of age classified as nutritionally normal, low weight for age and low weight for height in upper socioeconomic urban and lower socioeconomic urban and rural groups. The marginally malnourished children (low weight for age and height) in both lower socioeconomic urban and rural groups had significantly depressed maximum treadmill oxygen consumption (85%) compared to normal boys, associated with smaller body weights. It is suggested that the reduced body size and maximum treadmill oxygen consumption resulting from marginal malnutrition during growth will have a detrimental effect on work capacity and productivity of these children when they become engaged in heavy physical work as adults. There was no statistically significant correlation between blood Hb concentration (approximately 10 to 15 g x dl-1) and aerobic capacity.

Aerobic work capacity and endurance during nutritional repletion of severely undernourished men.

Oxygen consumption in maximal exercise (VO2max) was found to increase during nutritional rehabilitation of severely undernourished, sedentary adult males only when dietary protein was increased from 27 to 100 g/day. Adequate caloric intake, maintained for 45 days before the increase in protein content of the diet, had no effect on VO2max. The VO2max values were found to correlate best with the creatinine excretion rates (an index of the muscle cell mass) at the different stages of repletion. The average increment in VO2max/muscle cell mass ratio, although significant, was of a small magnitude (+15%). The VO2max/muscle cell mass ratio correlated only with the blood and plasma volumes at the different stages of repletion. After 2.5 months of protein repletion the VO2max values were still lower than those in mildly undernourished or normal Colombian adult males. Maximal endurance time at 80% aerobic load decreased significantly from an average of 113 min at the beginning of hospitalization to 42 min at the end of the period of protein repletion. This could be the result of replacing carbohydrate calories with protein in the diet, producing depletion of muscle glycogen stores, and/or to "detraining" effects associated with sedentary hospital life.

Body composition during nutritional repletion of severely undernourished men.

Body composition was studied in severely undernourished adult male inhabitants of a rural area of Colombia to evaluate the extent and the time course of the changes occurring upon nutritional repletion. During a 45-day basal period on a low (26g/day) protein diet containing adequate calories, body fat depots increased significantly (mean +/- SD = +3.02 +/- 2.9 kg), and there was a significant decrease in cell hydration from 81.8 to 76.4% (-5.4 +/- 9.1%). Upon protein repletion (100 g/day), cell hydration decreased significantly to 71.4%, while body cell mass increased markedly (9.0 +/- 1.1 kg). During protein repletion, muscle cell mass increased significantly (+5.5 +/- 0.6 kg) and rapidly, while the increase in nonmuscle cells (+3.5 +/- 3.8 kg) and specifically in red cell mass lagged behind. With repletion, the changes in the absolute values for plasma volume (+0.4 +/- 0.13 liters) were significant, but those in extracellular fluid volume (-0.7 +/- 1.9 liters) were not. Thus, the major compositional changes observed occurred in the body fat and the body cell mass components; these occurred independently of each other.

Energy expenditure from minute-by-minute heart-rate recording: comparison with indirect calorimetry.

Total daily energy expenditure (TDEE) and energy expended in activity (EAC) were estimated by the minute-by-minute heart-rate method in 22 (16 men, 6 women) individually calibrated subjects and compared with values obtained by whole-body indirect calorimetry. Subjects followed four activity protocols during the 22 h in the calorimeter; no exercise (n = 6) and 2 (n = 5), 4 (n = 4), and 6 (n = 6) 30-min bouts of exercise on a bicycle ergometer at varying intensities. There were no statistically significant differences between the two methods in TDEE or EAC in any of the sex or protocol groupings. The regression of TDEE by heart rate on TDEE in the calorimeter was y = 0.92x + 1.0 MJ; (r = 0.87, SEE = 0.91 MJ). The heart-rate method also follows the varying activity patterns of individuals and can be used to closely estimate the TDEE and EAC of even small (n = 4-6) groups of subjects. In the present measurements, it gave a maximum error of TDEE for individuals of +20% and -15%.

Variation of the basal metabolic rate and dietary energy intake of Colombian women during 1 y.

Anthropometry, basal and resting metabolic rates (BMR and RMR), and dietary energy intake were measured on five occasions approximately 3 mo apart for 1 y in 21 nonpregnant, non-lactating women 20-42 y of age living under deprived economic conditions in Cali, Colombia. There was a significant increase in body weight (1-1.5 kg) because of increased body fat during the last two rounds of measurement. BMR was elevated in the first round but fell to stable values that did not vary significantly from 3 to 12 mo. The intraindividual CV of BMR was 8.3% whereas the intraindividual CV of dietary energy intake was 17%. Measured BMR was closely related to the BMR estimates provided by the empirical equations of Schofield, but significantly higher than estimates from the equations of Henry and Rees. RMR-BMR ratios were very close to those published by FAO/WHO/UNU. Autocorrelation analysis of BMR showed weak ability to predict subsequent variation of BMR over time and is consistent with random variation of the data.

Treadmill vs. floor walking: kinematics, electromyogram, and heart rate.

To identify the degree of difference between treadmill and floor walking, kinematic, electromyographic (EMG), and heart rate measurements were recorded in seven normal female subjects during walking at three speeds on the treadmill and on the floor. During treadmill walking, subjects tended to use a faster cadence and shorter stride length than during floor walking. In addition the displacements of the head, hip, and ankle in the sagittal plane showed statistically significant differences between floor and treadmill walking. Average EMG activity was usually greater on the treadmill than on the floor; however, this difference was only significant for the quadriceps. Heart rate was significantly higher during fast treadmill walking than floor walking. In general, treadmill walking was not found to differ markedly from floor walking in kinematic measurements or EMG patterns.

Daily pattern of %VO2max and heart rates in normal and undernourished school children.

The pattern of usage of the VO2max, expressed as %VO2max during ordinary school days, with minute-by-minute heart rate recording, was studied in 106 boys and 83 girls, 6-16 yr of age divided into three age groups (6-8, 10-12, and 14-16 yr), living under economically deprived conditions in Colombia and classified as nutritionally normal or marginally malnourished. In a 12-h period, the 12 groups of children spent, on the average, 7-10 h at less than 30% VO2max, 1.5-4 h at 30-50% VO2max, and an accumulated time of 20-60 min above 50% VO2max. The latter occurred in short bursts rather than during sustained periods. There was a statistically significant but small decrease (approximately -3%) in the average 12 h %VO2max with age but no effects of sex or nutritional status. The overall average was about 25% VO2max in all groups. The data may suggest the existence of the regulation of physical activity to some level easily sustainable for long periods. Expressing the data as 30 min averages during 5 h of school and 5 h of free-time activity allows for the possibility of seeing group differences during shorter periods of time. This may prove useful in exercise training programs and studies of effort in the workplace.