participant is followed, keeps a very detailed diary, orfills out detailed questionnaires.
In a study by Machado-Rodrigues et al. ( 2011 ), both accelerometry and diary entries
indicated that activity energy expenditure was significantly higher in older than that in
younger boys; however, accelerometry indicated a greater degree of difference
between the age-groups (0.90 kcal min−^1 , F= 161.0) versus diary entries (0.
40 kcal min−^1 ,F= 36.1). Using the accelerometry data as the gold standard, it
appears that the three-day diary data underestimated activity energy expenditure in
older adolescents. In a different study, energy expenditure was higher when estimated
from a diary compared to a monitor (Wickel et al. 2006 ).
Can someone judge their own rate of physical exertion? Exercise scientists have
documented that people stop exercising when they do not enjoy it (Ekkekakis et al.
2011 ). Adherence is lower with higher-intensity exercise programs, and intensity of
exercise is more important than frequency of exercise for discontinuing adherence
to exercise (Perri et al. 2002 ). In order to measure how hard someone feels they are
working during a bout of exercise, investigators use perceived exertion scales, such
as the rated perceived exertion (RPE) scale from the Cleveland Clinic. The RPE
scale used by patients has a 0–10 range of intensity, with labels from“nothing at all,
just noticeable, very light”to“very, very heavy.”A cartoon man indicates various
levels of comfort with exertion (Fig.15.3; http://my.clevelandclinic.org/)..)
Researchers use a similar scale, but the range extends from 6 to 20 with 6 corre-
sponding to rest and 20 corresponding to the maximal exertion someone is not able
to maintain. Exercisers can learn to self-regulate their intensity using the RPE and
other scales (Ekkekakis et al. 2004 ).
00.51 2 3 4 5 6 7 8 910**Nothing at allJust noticeableVery lightLightModerateSomewhat heavyHeavyVery heavyVery, very heavyMaximalFig. 15.3 Rated Perceived HOW HARD IS THE ACTIVITY?
Activity Scale
318 L.L. Sievert and D.E. Brown