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4.3. Energy costs in relation to age and sex

A summary of the energy costs of the ten categories of activities described in Table 10 is shown in Tables 11 and 12, expressed as X BMR or cal/kg/min, respectively. They are the mean values, weighted for the number of children in each study and rounded to one decimal place, from combined data of developing and industrialized countries. When the number of children was not given in a study, the mean value was weighted for the number of studies in that category of activities. Based on the preceding comments about the studies of Taylor and collaborators, the weighted means were calculated excluding or including (in brackets) data from those studies. For purposes of comparison, the energy costs of similar activities for adults are also shown (FAO/WHO, 1973; FAO/WHO/UNU, 1985).

The gaps in knowledge are evident in Tables 11 and 12. For some ages the existing data derive from only one or two studies, and some investigations only included 5 or less children (Table 10).

With those limitations in mind, the data in Table 11 suggest the following when energy costs are calculated in relation to BMR:

(a) Sedentary activities that do not involve body displacement have similar energy costs from preschool to adult age.

(b) The energy cost of walking and moving around increases with age from preschool years to mid-adolescence.

(c) The energy costs of the activities that have been assessed in adolescents beyond 15 years of age, are similar to those of adults.

(d) The few activities assessed in girls and boys had similar energy costs in all age groups.

The data in Table 12 indicate that:

(a) The energy cost per unit of body weight of activities performed by adults should not be used to calculate the cost of children's activities, as discussed in a previous publication (TORUN, 1983). The errors will be greater the younger the children are.

(b) The energy costs of the activities assessed in 17- to 19-year-old boys and girls are similar to those of adults.

(c) In the few activities assessed in over-6-year-old girls and boys, girls seem to spend about 10% less energy than boys per unit of body weight.

TABLE 10: ENERGY COST OF ACTIVITIES-GROUPED BY CATEGORIES

Type of activity

Country a

No. of studies (children)

Weight (kg) b

Energy cost of activities c

kcal/min

cal/kg/min

X BMR

PRESCHOOL AGE (1.5 - 6 y) - COMBINED SEXES

Lying down, resting or playing

D

4 (17, 20, 20, 23) d

10-11

0.52 (0.49-0.56)

46 (44-50)

1.11 (1.06-1.17)

Sitting quietly

D

1 (11)

11

0.53

47

1.24

Walking, free, velocity, level ground

D

1 (8)

11

0.88

78

2.05

Walking, constant pace, uphill

D

1 (23)

11

1.12

98

2.58

Ascending and descending ramps

D

1 (7)

11

0.98

87

2.29

Riding tricycle slowly, climbing staircase slowly

D

2 (1, 6)

11

1.03 (0.82-1.06)

91 (73-94)

2.39 (1.92-2.47)

SCHOOL-AGE (7-12 y) - BOYS

Lying down

D

1 (14)

21

0.74

35

1.08

Sitting quietly, reading, writing, playing, etc.

D

5 (14, 14, 19, 23, 26)

19-32

0.88 (0.80-1.02)

37 (31-42)

1.17 (1.16-1.19)

I

6 (6, 6, 6, 10, 12, 22)

22-37

1.24 (1.12-1.37)

40 (34-52)

1.49 (1.40-1.62) e

Standing quietly, little movement

I

2 (7, 8)

35-37

1.66 (1.45-1.87)

46 (39-53)

1.91 (1.58-2.24) e

D

1 (14)

21

1.47

69

2.15

Standing and moving

I

1 (7)

35

2.51

72

3.02 e

D

1 (14)

21

1.84

88

2.70

Walking, free velocity, level ground

I

2 (33, 34)

30-36 f

2.52 (2.26-2.79)

76 (76-T7)

2.93 (2.79-3.07) f

Walking fast, uphill or carrying a load

D

3 (14,14,14) d

21

2.36 (2.27-2.54)

110 (105-118)

3.45 (3.31-3.71)

Leisure time, moderate play

D

2 (19, 25)

24-26

1.60 (1.47-1.74)

64 (61-68)

2.31 (2.30-2.32)

I

3 (?,?, 54)

28-32 g

3.13(2.41-3.97)

103(76-126)

3.78 (2.87-4.73) g

At school (classroom)

D

1 (19)

26

1.41

55

1.88

I

1 (54)

28 f

2.40

84

3.00 f

EARLY ADOLESCENCE (13-14 y) BOYS

Lying down

D

3 (14, 14, 16)

30-53

0.94 (0.88-1.08)

26 (20-29)

1.03 (0.99-1.06)

Sitting quietly, reading, writing

D

3 (14, 14, 16)

30-53

0.95 (0.87-1.07)

26 (20-30)

1.04 (0.98-1.10)

I

2 (?, 10)

41-45 f

1.34(1.25-1.44)

32(28-35)

1.43 (1.25-1.61) e f

Standing quietly, little movement

D

2 (14, 16)

31-53

1.16 (1.03-1.29)

27 (24-30)

1.21 (1.18-1.24)

I

1 (?)

45 f

1.40

31

1.40 f

Standing and moving

D

1 (14)

30

1.77

58

2.13

I

2 (?, 5)

41-45 f

1.97 (1.80-2.14)

46 (44-48)

2.06 (1.98-2.14) f

Walking, free velocity, level ground

D

3 (14, 14, 16)

30-53

2.39 (2.10-2.70)

64 (51-79)

2.63 (2.48-2.89)

I

1 (?)

45 f

3.14

70

3.14 f

Walking fast, uphill or carrying a load

D

3 (14) d

30

3.09 (2.92-3.38)

103 (97-112)

3.76 (3.55-4.11)

Leisure time, moderate play

I

2 (?, 11)

41-45 f

2.75 (2.50-3.00)

65 (56-75)

2.90 (2.50-3.30) f

Running, exercise, sports

D

3 (14, 14, 16)

31-53

4.37 (3.48-5.07)

110 (96-132)

4.78 (4.19-5.49)

I

3 (?) d

45 g

4.47 (3.06-5.60)

99 (68-124)

4.47 (3.06-5.60) g

MID-ADOLESCENCE (15-16 y) - BOYS

Lying down

D

1 (14)

49

1.18

25

1.13

I

1 (5)

57

1.16

20

1.08

Sitting quietly, reading, writing

D

4 (12, 14, 15, 17)

45 (35-49)

1.24 (1.10-1.37)

28 (26-32)

1.21 (1.17-1.32)

Standing quietly, little movement

D

1 (12)

48

1.60

33

1.54

Standing and moving

D

1 (14)

49

2.53

52

2.40

Walking, free velocity, level ground

D

2 (12, 14)

48-49

3.21 (3.06-3.36)

66 (64-69)

3.06 (2.94-3.19)

I

2 (5, 25)

57- 64 f

3.98 (3.88-4.08)

66 (64-68)

3.48 (3.32-3.63) f

Walking, uphill or carrying a load

D

3 (14, 14) d

49

4.58 (4.53-4.63)

94 (93-94)

4.36 (4.32-4.41)

Leisure time, rate play

D

1 (25)

34

1.82

54

2.46

Running, exercise, sports

1

1 (5)

57

3.84

67

3.59

LATE ADOLESCENCE (17-19 y) - BOYS

Lying down

D

1 (9)

56

1.21

22

1.24

I

1 (95)

68

1.33

20

1.05

Sitting quietly, reading, writing

D

3 (3, 9, 15)

56-66

1.53 (1.27-2.02)

26 (20-36)

1.39 (1.04-1.84) h

Standing quietly, little movement

D

4 (3, 9, 9, 15) d

56-66

1.58 (1.38-1.94)

27 (21-35)

1.48 (1.10-1.76) h

Walking, free velocity, level ground

D

4 (1, 3, 9, 15)

56-66

3.13 (2.73-3.69)

53 (45-66)

3.09 (2.38-3.80) h

Sedentary and light work

D

1 (9)

56

1.64

30

1.68

Running, exercise, sports

D

5 (1, 2, 9, 9, 9) d

56-66

4.91 (3.97-6.50)

82 (72-99)

4.57 (3.93-5.37)

SCHOOL-AGE (7-12 y) - GIRLS

Sitting quietly, drawing, singing

I

5 (9, 10, 15, 17, 21)

31-34

1.07 (0.98-1.22)

32 (30-34)

1.28 (1.20-1.41) e

Standing quietly, little movement

I

2 (9, 12)

34

1.36 (1.26-1.47)

40 (36-44)

1.61(1.46-1.76) e

Standing and moving

I

1 (12)

34

2.26

67

2.72 e

Walking, free velocity, level ground

I

3 (12, 27, 27)

30-36

2.30 (2.11-2.57)

68 (65-70)

2.72 (2.56-2.95)

EARLY AND KID-ADOLESCENCE (13-15 y) - GIRLS

Sitting quietly

D

1 (13)

47

1.25

27

1.36

Standing quietly

D

1 (13)

47

1.32

28

1.43

Walking

D

1 (13)

47

2.55

54

2.77

I

1 (28) f

56

3.43

61 f

3.43 f

LATE ADOLESCENCE (16-19 y)-GIRLS

Lying down

D

2 (9, 24)

48-48

0.82 (0.81-0.82)

18 (17-18)

1.10 (1.08-1.13)

I

1 (2)

63

1.10

18

1.07

Sitting quietly, reading, writing

D

4 (4, 8, 9, 24)

44-56

0.98 (0.88-1.16)

21 (19-27)

1.24(1.18-1.39)

Standing quietly, little movement

D

4 (4, 9, 9, 24)

44-56

1.08 (0.90-1.57)

24 (20-33)

1.37 (1.24-1.71)

Walking, free velocity, level ground

D

4 (4, 8, 9, 24)

44-56

2.90 (2.09-3.40)

56 (46-60)

3.42 (2.62-3.58)

I

1 (2)

63

4.20

70

4.08

At school or light work (class-room, laboratory)

D

3 (2, 9, 24)

44-50

1.26 (1.22-1.46)

27 (26-29)

1.68 (1.65-1.82)

I

1 (10)

60

1.89

31

1.83

Light and moderate household work

D

2 (9, 24)

44-48

2.40 (2.21-2.60)

49 (46-58)

3.11 (2.94-3.57)

Leisure time, moderate play

D

1 (9)

44

2.24

50

3.08

I

2 (10, 10) d

60

2.24 (1.92-2.57)

37 (32-43)

2.18 (1.86-2.49)

Running, exercise, sports

D

4 (1, 9, 9, 24) d

44-70

3.32 (3.02-7.10)

71 (62-100)

4.44 (4.02-5.92)

I

1 (2)

63

4.00

67

3.88

a: D = developing; I = industrialized

b: Range of mean weights of the various studies

c: Mean (range) of study means; weighted by the number of children or number of studies; X BMR = multiples of BMR

d: Different activities measured within the same category m the same children

e: Host or all studies by Taylor et al. (1948a, b, 1949, 1951)

f: Using estimates of weight for cal/kg/min and X BMR in one study

g: Using estimates of might for cal/kg/min and X BMR in all studies

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