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Energy expenditure, duration of activities, and physical work capacities of Burmese women weavers

Tin-May-Than

This study assesses the daily energy expenditure of Burmese women weavers and concludes that, although the total energy cost of their work is considerable because of the many hours involved, it is nor sufficiently intense either for substantial muscular development or for cardiovascular fitness. The weavers would not be able to tolerate work demanding high energy expenditure.

Introduction

Women in most developing countries play an important role in economic activities, including the production of food. Their health status may affect the nutritional status of their children, particularly during pregnancy and lactation. Despite the major contributions of women to household food supplies and their responsibility for family health, their time usage patterns are insufficiently documented.

To better understand women's role in food-related activities and their contribution to household food supplies, this study assesses the daily rate of energy expenditure of Burmese female weavers by recording the time they spend at home and at work and by measuring their dietary intake and their physical work capacity.

Subjects and methods

Twenty-two women weavers between the ages of 19 and 43, all employed in home industry, were studied. They worked from seven o'clock in the morning until very late in the evening and were paid according to the length of the material they produced.

Anthropometric measurement

Body weight: The anthropometric measurements were all made by a single investigator. The subjects were weighed in their normal clothes on a Detecto bathroom scale, which was calibrated frequently with standard weights.

Skinfold thickness and percentage body fat: The Harpenden skin-fold calliper was used by a single investigator to measure the skin folds at biceps, triceps, subscapular, and supra-iliac sites on the left side of the body. Body density was calculated using Durnin's and Rahman's regression equation for women [1]. Siri's formula was used to assess the percentage of body fat [2].

Measurement of energy expenditure

Each woman was followed throughout the waking day by an observer, who kept a diary registering the period of time spent in every activity and describing each task.

The energy cost of resting and of most typical activities was determined by indirect calorimetry using a Douglas bag. The volume of expired air was measured with a Parkinson-Cowan gas meter after samples were taken with a rubber bladder. The samples were immediately analysed by a Lloyd gas analyser for oxygen and carbon dioxide.

Total daily energy expenditure was obtained from the sum of the amount of time spent in each activity multiplied by its energy cost. The metabolic cost for sleeping was calculated using the basal metabolic rate (BMR) established for the Burmese population [3]. Measurements of energy expenditure were taken on the same three days on which dietary intake measurements were made.

Measurement of food intake

Food intake was measured by the weighted individual inventory technique for three consecutive days. Details of the method are given in reference 4.

Measurement of physical work capacity

Physical work capacity was measured by a progressive test on a bicycle ergometer (Monark). Maximum oxygen consumption was obtained by extrapolation of the subject's heart rate to 184.

Results and discussion

The women involved in this study were 19 to 43 years old. Table 1 shows their physical characteristics. The mean weight of 45.94 kg for height (1.50 m) was 90%-94% of the standard [5]. Body fat was 26% of body weight. The body fat ratio for these Burmese subjects exceeded those for American women [6] and British women [7]. For European women, the mean percentage of body fat is 20% 25% of body weight [8]; in this respect, the Burmese weavers' measurements were comparable to those for European subjects. The thickness of skin folds over the triceps was 80% of the standard given by Jelliffe for well nourished women [5].

Energy cost of activities

The findings on the energy costs of the women's daily activities are shown in table 2-expressed both in litres of oxygen consumed per minute and in kilocalories per minute. The mean body weights of the subjects are also given for comparative purposes. The energy value of weaving is 2.59 kcal' which accounted for about 32% of their maximum oxygen consumption, so that weaving cannot be considered physically strenuous work. All the measured activities of the weavers could be classified as light according to Pass more and Durnin [9]. Other activities included washing clothes and preparing Burmese make-up. For the latter, the bark of trees is ground on a circular stone disc, which is rotated around, involving an arm movement with a metabolic cost of 2.35 kcal per minute.

TABLE 1. Physical characteristics of the study subjects-22 Burmese women weavers 19-43 years old

a. Or fat-free body mass.

Activities

For the purposes of this study, sedentary activities include eating, chatting, listening to the radio, and reading. Miscellaneous activities include personal care, sweeping the floor, cooking (i.e., putting rice in a pot and waiting for it to cook), washing clothes, and preparing Burmese make-up, which usually occupied 20 to 30 minutes every day. The women spent 40% of their time and about 60% of their total energy expenditure on weaving.

The weavers' mean energy intake was 2,342 kcal (9.8 MJ), and their mean energy output was 2,475 kcal (10.4 MJ). The difference is not statistically significant at the .05 Ievel. [Although this reports an energy output slightly higher than the dietary energy intake, the difference is not significant-and could not be when body fat is so well maintained.-EDITOR]

A simple functional test of physical exercise capacity or physical work capacity is a useful adjunct to ether, more static measurements of nutritional status' such as anthropometric assessment of muscle mass or fatness. Table 3 shows the physiological response of the weavers to the maximal work load. The results give the predicted values of maximum aerobic power obtained by extrapolating oxygen consumption at lower heart rates to a heart rate of 184 to obtain maximum volume (V_O2,_max ).

TABLE 2. Energy costs of daily activities (means ± SD)

TABLE 3. Physiological response of subjects to submaximal and maximal work loads

The measurements were taken in a room air conditioned at 20 °C.

V_E = volume of air exhaled. in litres per minute.
kpm = kilopond metres ( 1 kpm = the force exerted by a mass of 1 kg; i.e.9.81 newtons).
V_O2 = volume of oxygen consumed, in litres per minute.
V_O2,_max = volume of oxygen consumed during maximal exercise.
a. Heart rate per measure of cardiac output in litres per minute.

The finding of 29 ml/kg/min (observed) and 32 ml/ kg/min (predicted) compares well with measurements made for women in North America, whose V_O2 max was 1.78 litres per minute or 29.8 ml/kg/min [11], and for women in Great Britain, whose value was 28.3 ml/ kg/min [12, 13].

Burmese women weavers can be considered sedentary since they do not engage in any recreational or work activity involving other than light muscular activity. However, their total 24-hour energy expenditure is classified between moderate and heavy according to the classification of FAO/WHO/UNU [14]. The total energy cost of weaving is a considerable increment on an average daily energy expenditure because of the many hours involved in the activity. Nevertheless, it is not sufficiently intense either for substantial muscular development or for cardiovascular fitness. The weavers would not be able to tolerate work demanding high energy expenditure at present. The intensity of work in which the weaver is engaged does not demand any higher oxygen consumption or greater energy expenditure. A lower V_O2 max is not a significant constraint on the work activity of these women because it does not require a higher oxygen expenditure rate (table 4) [15]. The low values of V_O2 max found for the weavers in this study appeared to be attributable to their sedentary life and not to energy deficiency.

TABLE 4. Subjects' habitual daily activities

a. Includes sweeping floors, cooking, washing clothes, grooming, smoking.

References

1. Durnin JVGA. Rahaman MM. The assessment of the amount of fat in the human body from measurements of skinfold thickness. Br J Nutr 1967;21:6B1.

2. Siri NE. In: Lawrence JH, Tobias CA, eds. Advances in biological and medical physics. London and New York: Academic Press, 1956.

3. Tin-May-Than, Mya-Tu M. The basal metabolic rate of the Burmese. Burma J Life Sci 1969;2:373-82.

4. Tin-May-Than, Ba-Aye. Energy intake and energy output of Burmese farmers at different seasons. Hum Nutr: Clin Nutr 1985;39:7-15.

5. Jelliffe DB. The assessment of the nutritional status of the community. Geneva: WHO, 1966.

6. Montoyle HJ, Epstein FH, Kyelsbeig MO. The measurement of body fatness. Am J Clin Nutr 1965; 16:417-27.

7. Durnin JVGA, Womersly J. A comparison of skinfold method with extent of overweight and various weight-height relationships in the assessment of obesity. Br J Nutr 1977;38:271.

8. Trimoliens J. Duration of activities and energy expenditure of female farmers in dry and rainy seasons in Upper Volta. Br J Nutr 1973;43:7. Cited by Bleigberg FM, 1980.

9. Passmore R, Durnin JVGA. Energy, work and leisure. New York: Heinemann Educational Books, 1967.

10. Astrand I. Aerobic work capacity in men and women with special reference to age. Acta Physiol Scand 1960;49(suppl 169):1-92.

11. Michael ED, Hutton KE, Horvalh SM. Cardiorespiratory responses during prolonged exercise. J Appl Physiol 1961;16:997-1000.

12. Cotes JB, Allsopp D, Sardi F. Human cardiopulmonary responses to exercise: comparison

between progressive and steady state exercise, between arm and leg exercise and between subjects differing in body weights. Q J Exp Physiol 1969;54:211-26.

13. Ducan MT, Chan DY. Aerobic work capacity in young untrained Asian women. Q J Exp Physiol 1974;59:18190.

14. FAD/WHO. Energy and protein requirements. WHO technical report series, no. 522. Geneva: WHO.

15. Spurr GB. Nutritional status and physical work capacity. Yearbook of physical anthropology 1983;26:1-35.

Mothers' nutrition knowledge and child nutritional status in India

Rita Abbi, Parul Christian, Sunder Gujaral, and Tara Gopaldas

This article analyses the effects on children's nutritional status of their mothers' knowledge of nutrition while controlling for the effects of the socio-economic characteristics of the family. In almost every test of the effects of various aspects of nutritional knowledge on weight for age and height for age, per capita monthly income was a significant intervening factor; the exception was the knowledge of ORS preparation. In the case of weight for height, house construction type was a significant intervening factor. The authors conclude that, unless mothers' economic status improves simultaneously with nutrition knowledge, they may not be able to practice what they know, but that it is nevertheless essential to increase their nutrition knowledge.

Introduction

Mothers are the foremost providers of primary care for their children. Their understanding of basic nutrition and health measures strongly influences the care they provide [1]. Household socio-economic characteristics also determine to a large extent the nutritional status of children [2], and a positive relationship between socio-economic status and the ability of mothers to provide adequate food and primary care has been observed [3]. In the present study, an attempt is made to determine the effects on children's nutritional status of their mothers' knowledge of nutrition while controlling for the effects of the socioeconomic characteristics of the family.

Methods

The data for the present study were collected as part of an impact-evaluation survey conducted under the USAID-assisted Integrated Child Development Services (ICDS) project. The study was carried out in ten rural and tribal blocks of Panchmahals District of Gujarat State, India.

Household socio-economic information was collected by interviewing the head of the family or another senior member in his or her absence. The socio-economic variables used in the study were:

• family housing: no house, hut, kicha house, semipukka or pukka house;
• land holding: no land, less than 2.5 acres (approximately 1 ha), 2.5-5 acres (1-2ha), 5-10 acres (2-4 ha), more than 10 acres.
• occupational field: agriculture, agricultural labour, non-agricultural labour, artisanry, business, service, technical work, professional work, other;
• per capita monthly income.

The nutrition knowledge of 2,618 mothers from families having children 0-72 months of age was evaluated. Each mother was asked a set of nine questions about nutrition. The aspects of nutrition knowledge studied were (1) age for introducing solid foods into a child's diet and the type of solid foods to introduce, (2) frequency of child feeding, (3) diet during diarrhoea, (4) management of diarrhoea, (5) awareness of oral rehydration therapy (ORT), (6) preparation of oral rehydration solution (ORS), (7) causes and treatment of protein-energy malnutrition (PEM), (8) growth-chart interpretation, and (9) the mother's perceptions of her own child's nutritional status. A score of 1 was given for each valid answer. A mother's overall knowledge of nutrition was rated on a scale of 0 to 9 by calculating the total of all the valid responses she made.

A mother's responses were considered valid if she provided the following information: Soft and semisolid foods should be introduced to children at the age of six months or less. Children should be fed more than three times a day. A child should be given as much or more food during diarrhoeal episodes as when the child is not ill. Diarrhoea should be managed by giving ORS or fluids to the affected child. ORS should be made with three standard tablespoons of sugar and one-half standard teaspoon of salt per litre of water. "Lack of food" and "give more food" were the valid responses for the cause and treatment, respectively, of protein-energy malnutrition.

Three growth charts were shown to the mothers. One chart showed weight gain every month (normal growth); the second showed no weight gain for six months (growth faltering); and the third showed continuous loss of weight (grade IV malnutrition). A mother's response was considered valid if she could interpret two of the three charts correctly. Whether the mother was able to perceive her own child's growth or not was determined by comparing her response concerning the child's nutritional status with its weight for age as measured by the investigators on the day of the survey. Height and weight measurements were made of all children in the age group from 0 to 72 months [4]. If a mother had more than one child in this age group, questions concerning her nutrition knowledge were asked with reference to the youngest child. The National Center for Health Statistics standards [5] were used to assess the children's nutritional status. The children's ages were determined by carefully questioning the mothers with the aid of a local events calendar to assist them in their recall.

Data processing

The data were analysed on a microcomputer using Base III Plus programming language. Software from the Centers for Disease Control (CAS Anthropometric Software Package Version 3.0) was used to exclude a few children whose z scores for weight for age and height for age were less than -6.0 or greater than 6.0, or whose z scores for weight for height were less than -4.0 or greater than 6.0. The Statistical Package for the Social Sciences (SPSS/PC+) was used for the analysis. Analysis of covariance (ANCOVA) was used to determine the effects of the mothers' nutritional knowledge on their children's nutritional status as expressed in z scores of weight for age, height for age, and weight for height. In each model, the knowledge factor was included as a main effect and the household socio-economic factors were included as covariates. A Student's t test was used to assess the mothers' valid and invalid responses correlated with the anthropometic measurements.

Results and discussion

The z-score distributions of weight for age and height for age were found to be normal, with means of -2.38 and 2.24 and standard deviations of 1.05 and 1.61 respectively. Neither kurtosis nor skewness greater than ± 1 was exhibited. Forty per cent of the children were considered malnourished according to the criterion of a weight for age below 70% of the standard, as suggested by the Indian Academy of Pediatrics classification [6]. Forty-one per cent of the children were determined to be malnourished as indicated by a height for age below 90% of the standard according to Waterlow's classification [7].

Table 1 gives the ANCOVA used to determine the effect of the mothers' nutrition knowledge on their children's nutritional status. In almost every test of the effects of the various aspects of nutrition knowledge on weight for age and height for age, per capita monthly income was a significant intervening factor. The exceptions were the analyses of covariance of the knowledge of ORS preparation with weight for age and height for age; for this aspect of nutrition knowledge, house construction type was a significant intervening factor for weight for age but not for height for age. In the case of weight for height, the type of house construction was a significant intervening factor for each of the components of nutrition knowledge.

TABLE 1. Analysis of covariance of mothers' nutrition knowledge and their children's nutritional status as assessed by F values (z scores) of weight for age, height for age. and weight for height (N = 2,618)

* Significant at 5% level

TABLE 2. Anthropometric assessment of 2,618 children (mean percentages of NCHS medians) correlated with valid and invalid responses of their mothers to nutrition-knowledge questions

* Significantly different with p < 05.
** Significantly different with p < .001.

The mothers' knowledge regarding the age for introducing solid foods and the type of solids to be given was significantly related to their children's weight for age and weight for height (table 2). Only 10% of the mothers knew the correct age and types of solid foods to introduce into the diets of their children, and most mothers incorrectly suggested delayed introduction of soft and semi-solid foods. According to a t test, the weight for age and weight for height of the children of mothers who answered correctly was significantly better than those of children whose mothers did not.

Although 50% of the mothers were of the opinion that children should eat more than three times a day, this knowledge factor had no significant bearing on their children's nutritional status. This finding can be explained in that income was an intervening factor affecting the children's nutritional status. It is likely that, although the mother had the knowledge she needed, she was unable to put it into practice because of economic or time constraints.

There was a significant positive relationship between knowledge of the correct preparation of ORS and the weight for age and weight for height of the children. Knowledge regarding diet during diarrhoea and management of diarrhoea failed to show a significant association with the weight and height for age of the children.

Knowledge regarding the cause and treatment of PEM showed no significant association with the children's nutritional status. However, as shown in table 2, 15% of the mothers could correctly state the cause, and 10% the treatment. of PEM. The fact that this knowledge failed to affect the children's growth may have been due to the low economic status of the mothers, who were probably unable to provide more food for their children.

The mothers' knowledge regarding growth charts had a significant positive relationship with their children's nutritional status as assessed by weight for age, height for age, and weight for height. All three anthropometric measurements of children whose mothers were able to interpret the growth charts correctly were higher than those of the children whose mothers could not.

The mothers' perceptions of their children's growth were strongly related to actual growth. This relationship was highly significant. A high percentage of mothers (60%) could correctly perceive their own children's growth, and the nutritional status of the children of these mothers was better than that of those who lacked this perception. This is an interesting finding in view of the fact that only 2% of the mothers could interpret growth charts correctly.

The total nutrition-knowledge score computed from all the nutrition-knowledge components showed a highly significant relationship with weight for age, height for age, and weight for height (table 1). Table 3 presents data on the weight for age of children according to the total nutrition-knowledge score of their mothers. The weight for age of the children whose mothers scored O was found to be about 65% of the median, which was lower than that of the children whose mothers made a higher score. Although the weight for age of the children whose mothers scored 1 to 3 did not vary much from that of those whose mothers scored more than 3 points, a trend for child nutritional status to improve with mothers' higher scores was observed.

TABLE 3. Mean weights for age (percentages of NCHS medians) of children in relation to the nutrition-knowledge scores of their mothers

Figures in parentheses are numbers of children.

These findings emphasize the need to increase mothers' nutrition knowledge. Unless their economic status improves simultaneously, they may not be able to put into practice all that they know. But in order to best utilize their limited resources to enhance their children's nutritional and health status, it is essential that they should have adequate nutrition knowledge.

References

1. Pinto A, Scheer P, Ebrahim GJ, Abel R, Mukherjee D5. Does health intervention ameliorate the effects of poverty related disease? The role of female literacy. J Trop Ped 1985;3:257-62.

2. Devadas RP, Rajalakshmi R, Kaveri R. Influence of family income and parents' education on the nutritional status of preschool children. Indian J Nutr Dietet 1980;17:237-44.

3. Sims LS. Demographic and attitudinal correlates of nutrition knowledge. J Nutr Educ 1976;3:122.

4. Jelliffe DB. The assessment of the nutritional status of the community. WHO monograph series, no. 53. Geneva: World Health Organization, 1966.

5. National Center for Health Statistics. NCHS growth curves for children, birth-18 years. DHEW publication no. 78. Washington, DC, 1977.

6. Ghai OP, Chaudhri SN, Kapoor S. Nutritional assessment of children of a rural community. Indian J Med Research 1970;58:162.

7. Waterlow JC. Classification and definition of protein calorie malnutrition. Br Med J 1972;iii:566-69.

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