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 .
Activity-monitor accuracy in measuring step number and cadence in community-dwelling older adults.
The primary purpose of this study was to investigate the accuracy of the activPAL physical activity monitor in measuring step number and cadence in older adults .  Two pedometers ( New-Lifestyles Digi-Walker SW-200 and New-Lifestyles NL2000 ) used in clinical practice to count steps were simultaneously evaluated . Observation was the criterion measure . Twenty-one participants ( 65 - 87 yr old ) recruited from community-based exercise classes walked on a treadmill at 5 speeds ( 0.67 , 0.90 , 1.12 , 1.33 , and 1.56 m/s ) and outdoors at 3 self-selected speeds ( slow , normal , and fast ) . The absolute percentage error of the activPAL was < 1 % for all treadmill and outdoor conditions for measuring steps and cadence . With the exception of the slowest treadmill speed , the NL-2000 error was < 2 % . The SW-200 was the least accurate device , particularly at slower walking speeds . The activPAL monitor accurately recorded step number and cadence . Combined with its ability to identify primary postures , the activPAL might be a useful and versatile device for measuring activity in older adults
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 .