Environmental Engineering Reference
In-Depth Information
and long-distance running have the highest energy cost
among individual sports (MET 12-18), and basketball
and soccer rank high in the group sports category (MET
8-10). Measurements of TEE during the 4000-km Tour
de France showed daily means of about 25 MJ and indi-
vidual rates up to about 32 MJ (Saris et al. 1989). Simi-
larly, studies using doubly labeled water found actual
energy expenditures during a climb of Mt. Everest at
nearly 14 MJ/day (Westerterp et al. 1992); the addition
of BMR brings the TEE of these climbers to over 20
MJ/day. These values are near the metabolic maxima
for multiday efforts.
Integrating BMR with work and leisure requirements
results in a PAL spectrum with extremes of 1.4-2.4. A
sedentary or light-activity lifestyle has a 24-h PAL range
of 1.40-1.69 (mean 1.53). The multiple rises to 1.70-
1.99 (mean 1.76) for an active or moderately active life-
style, and it goes to 2.00-2.40 (mean 2.25) for a vigor-
ous lifestyle. PAL values in excess of 2.4 cannot normally
be maintained over extended periods of time. Individual
TEEs can rise or slide along this continuum depending
on a particular day's activities. For example, a moderately
active (PAL 1.75) 40-year-old 70-kg male (BMR 7.0
MJ/day) will have a usual TEE of 12.3 MJ/day (142
W; 175 J/g), but a day-long skiing trip (PAL 2.1) can
boost it to 14.7 MJ/day (170 W; 210 J/g). Approxi-
mate daily energy requirements of adults whose work
can be classified as light (most white-collar workers,
many factory workers, and homemakers in the rich coun-
tries) correspond to PALs less than 1.75; in contrast, very
few demanding jobs in affluent countries (lumberjacks,
some miners) and traditional farmers have PALs exceed-
ing 2.0.
The United States has the longest record among
the countries that have issued their own national di-
etary recommendations. Recommended dietary allow-
ances (RDAs) were first published in 1941, and their
tenth edition came out in 1989 (FNB 1989). Recom-
mended energy intakes for adults was calculated by using
FAO (1985) end PALs of 1.6 for men and 1.55 for
women. The approach changed in 1997 with the estab-
lishment of dietary reference intakes (DRIs). These are
formulated not only in order to prevent nutrient defi-
ciencies but also to lower the risk of chronic diseases.
For food energy DRIs quantify total PAL-based daily
requirements as well as recommended intakes of carbo-
hydrates (130 g/day for adults), protein (56 g/day for
males, 46 g/day for females), and two essential fatty
acids.
DLW measurements have provided the most accurate
check of the accuracy of recommended requirements
(Black et al. 1996; FAO 2004). The highest daily PALs,
4.7 and 4.5, were found, respectively, in cyclists taking
part in Tour de France and in men pulling a sled across
the Arctic. Activity markups found by DLW studies for
individuals leading normal lifestyles corresponded very
well with expected multiples, ranging between 1.2 for
sedentary subjects to 2.5 for exceptionally active individ-
uals. PALs between 1.6 and 1.8, means for all adult sub-
jects in the analyzed studies, would tend to encompass
activity markups for most healthy, active individuals. At
the same time, there are many uncertainties. For in-
stance, the regression equations for adult BMRs (see sec-
tion 5.1) account only for variances of 36% for men and
49% for women, leaving plenty of room for substantial
individual departures from the means.
Limited databases are common. For example, the en-
ergy requirements of children and adolescents have been
based on DLW or HRM studies of only 801 boys and
808 girls 1-18 years of age (FAO 2004). Moreover,
