For total EE , correlation coefficients were statistically significantly lower in uniaxial compared to multisensor devices .
For active EE , correlations were slightly but not significantly lower in uniaxial compared to triaxial and multisensor devices .
The high level of heterogeneity in the validation studies is only partly explained by the type of activity monitor and the activity monitor outcome .
Triaxial and multisensor devices tend to be more valid monitors .
The assessment of physical activity in healthy population s and in those with chronic diseases is challenging .
The aim of this systematic review was to identify whether available activity monitors ( AM ) have been appropriately vali date d for use in assessing physical activity in these groups .
Assessment of physical activity in older individuals: a doubly labeled water study.
We compared the accuracy of two physical activity recall question naires and a motion detector in 45- to 84-yr-old women ( n = 35 ) and men ( n = 32 ) , using doubly labeled water ( DLW ) in conjunction with indirect calorimetry as the criterion measure . Subjects were administered the  Yale Physical Activity Survey ( YPAS ) and  Minnesota Leisure Time Physical Activity Question naire ( LTA ) .  Physical activity energy expenditure was determined over a 10-day period by using a Caltrac uniaxial accelerometer and DLW in conjunction with indirect calorimetry . In older women , Minnesota LTA ( 386 + /- 228 kcal/day ) and Caltrac ( 379 + /- 162 kcal/day ) underestimated physical activity by approximately 55 % compared with DLW ( 873 + /- 244 kcal/day ) . No difference was observed between daily physical activity measured by the YPAS ( 863 + /- 447 kcal/day ) and DLW in older women . In older men , Minnesota LTA ( 459 + /- 288 kcal/day ) and Caltrac ( 554 + /- 242 kcal/day ) underestimated daily physical activity by approximately 50 - 60 % compared with DLW ( 1,211 + /- 429 kcal/day ) . No difference was found between physical activity measured by the YPAS ( 1,107 + /- 612 kcal/day ) and DLW in older men . Despite no difference in mean physical activity levels between YPAS and DLW in women and men , Bl and and Altman ( Lancet 1 : 307 - 310 , 1986 ) analyses demonstrated poor concordance between DLW and YPAS ( i.e. , limits of agreement = -1,310 - 1,518 kcal/day ) . Our data suggest that the Minnesota LTA recall and Caltrac uniaxial accelerometer may significantly underestimate free-living daily physical activity energy expenditure in older women and men . Although the YPAS compares favorably with DLW on a group basis , its use as a proxy measure of individual daily physical activity energy expenditure may be limited in older women and men
For total EE , correlation coefficients were statistically significantly lower in uniaxial compared to multisensor devices .
For active EE , correlations were slightly but not significantly lower in uniaxial compared to triaxial and multisensor devices .
The high level of heterogeneity in the validation studies is only partly explained by the type of activity monitor and the activity monitor outcome .
Triaxial and multisensor devices tend to be more valid monitors .
The assessment of physical activity in healthy population s and in those with chronic diseases is challenging .
The aim of this systematic review was to identify whether available activity monitors ( AM ) have been appropriately vali date d for use in assessing physical activity in these groups .