Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD).The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available.Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.
BackgroundIt is important to include large sample sizes and different factors that
influence the six-minute walking distance (6MWD) in order to propose
reference equations for the six-minute walking test (6MWT). ObjectiveTo evaluate the influence of anthropometric, demographic, and physiologic
variables on the 6MWD of healthy subjects from different regions of Brazil
to establish a reference equation for the Brazilian population. MethodIn a multicenter study, 617 healthy subjects performed two 6MWTs and had
their weight, height, and body mass index (BMI) measured, as well as their
physiologic responses to the test. Delta heart rate (∆HR), perceived effort,
and peripheral oxygen saturation were calculated by the difference between
the respective values at the end of the test minus the baseline value. ResultsWalking distance averaged 586±106m, 54m greater in male compared to
female subjects (p<0.001). No differences were observed among the 6MWD
from different regions. The quadratic regression analysis considering only
anthropometric and demographic data explained 46% of the variability in the
6MWT (p<0.001) and derived the equation:
6MWDpred=890.46-(6.11×age)+(0.0345×age2)+(48.87×gender)-(4.87×BMI).
A second model of stepwise multiple regression including ∆HR explained 62%
of the variability (p<0.0001) and derived the equation:
6MWDpred=356.658-(2.303×age)+(36.648×gender)+(1.704×height)+(1.365×∆HR).
ConclusionThe equations proposed in this study, especially the second one, seem
adequate to accurately predict the 6MWD for Brazilians.
In conclusion, the variability of the ISWT is explained largely by gender, age and BMI. The reference values for the ISWT can be adequately predicted using the equation proposed in this study.
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