Cover Image
close this bookResearch Methods in Nutritional Anthropology (UNU, 1989, 201 pages)
close this folder3. Methodological procedures for analysing energy expenditure
View the document(introductory text...)
View the documentIntroduction
View the documentSurvey of habitual activities
View the documentDetermination of critical activities
View the documentDetermination of key participants
View the documentMeasuring energy expenditure rates
View the documentTime-motion analysis
View the documentEstimation of energy expenditure rates from time-allocation data
View the documentAssessment of endurance capacity
View the documentSummary
View the documentReferences

Determination of critical activities

With data on habitual activity patterns, it is possible to define activities that demand more precise methods for determining energy expenditure ("critical activities"), as opposed to those for which less precision is required ("non-critical activities"). The distinction between critical and non-critical activities is important because it is virtually impossible to measure accurately the energy costs of all activities performed by members of a population. Furthermore, greater precision in estimating energy expenditure tends to be more costly in terms of required time and personnel.

Determinations of critical versus non-critical activities naturally depend on the specific research goals of a project. Nevertheless, some general criteria can be suggested for identifying those of relevance: (a) the importance of an activity to a population's or family's subsistence; (b) the extent to which an activity is relied upon; and (c) the performance effort necessary to accomplish a task or activity. In reference to the latter, it is often desirable to include activities representing a broad range of energy expenditure levels. Combining these parameters, critical activities can be delimited with respect to frequency of occurrence, economic importance, and required effort. Under research conditions involving severe time and personnel constraints, priority for actual measurement of energy expenditure should be given to tasks determined to have both high economic importance and high energy demands, as it is these activities that are likely to present potential stress points in the pattern of overall population adaptation.

Table 3 presents a list of activities for which measurements were obtained in the Nuñoa study cited above. Decisions as to which activities to measure were made primarily on the basis of responses to the questionnaire outlined in table 2. The activities selected ranged from those with a high frequency of occurrence and low work-intensity (e.g. sleeping and herding) to those with low or seasonal occurrence and high work-intensity (e.g. planting potatoes and foot ploughing). Such activities also included economically important production-related tasks such as planting, picking, threshing, and grinding of most major crops. Taken together with generalized activities such as sitting, standing, lying, and walking, these comprise a large portion of the average daily energy expenditure of population members. The measurement of generalized activities is also particularly valuable in providing a basis for extrapolation of expenditure rates for many tasks and activities not directly measured. Spinning, for example, is a low work-level task for which sitting or standing measures can be used with reasonable accuracy.

Table 3. Energy-expenditure rates and percentage of maximal values for measured activities as performed by Nuñoa men and womena

 

Men

Women

Activity

Expenditure rate (kcal/min)

% max.

Expenditure rate (kcal/min)

% max.

Sleepingb

1.0

9.4

-

-

Basal (BMR)b

1.1

10.4

-

-

Lying (RMR)

1.2

11.3

1.1

14.7

Sitting

1.3

12.3

1.2

16.0

Standing

1.5

14.2

1.2

16.0

Herding

1.9

17.9

-

-

Picking canihua

1.9

17.9

1.7

22.7

Picking quiñoa

2.2

20.8

2.1

28.0

Grinding

-

-

2.3

30.7

Walking (3 kph)

3.3

31.1

3.0

40.0

Foot ploughing (female)

-

-

3.1

41.3

Potato planting (female)

-

-

3.3

44.0

Slaughtering and dressing

4.0

37.7

   
Threshing quiñoa

4.0

37.7

3.4

45.3

Picking potatoes

4.2

39.6

   
Threshing canihua

4.4

41.5

4.0

53.3

Spreading dung

-

-

4.4

58.7

Walking (5 kph)

4.6

43.4

-

-

Planting quiñoa (raking)

5.2

49.0

-

-

Planting potatoes (male)

6.0

56.6

-

-

Foot ploughing (male)

6.4

60.4

-

-

Foot ploughing without rows (male)

8.2

77.4

-

-

Maximal work capacitya

10.6

100.0

7.5

100.0

a. Conversion factors of 4.85 and 5 kcal/litre of oxygen consumed has been used for computing submaximal and maximal values. Based on anthropometric data (Frisancho, 1979), a typical man and woman of 20 years and above weigh 54 and 52 kgs respectively.
b. From Mazess et al., 1969.
Source Thomas 1973a, p. 75.