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 .
Step counting and energy expenditure estimation in patients with chronic obstructive pulmonary disease and healthy elderly: accuracy of 2 motion sensors.
OBJECTIVE To compare the accuracy of 2 motion sensors ( a pedometer and a multisensor ) in terms of step counting and estimation of energy expenditure ( EE ) in patients with chronic obstructive pulmonary disease ( COPD ) and in healthy elderly . DESIGN In this descriptive study , all participants wore both motion sensors while performing a treadmill walking protocol at 3 different speeds corresponding to 30 % , 60 % , and 100 % of the average speed achieved during a six-minute walk test . As criterion methods , EE was estimated by indirect calorimetry , and steps were registered by videotape . SETTING Research laboratory at a university hospital . PARTICIPANTS Patients with COPD ( n=30 ; 17 men ; mean age + /- SD , 67+/-8 y ; mean forced expiratory volume in the first second [ FEV(1 ) ] predicted + /- SD , 46%+/-17 % ; mean body mass index [ BMI ] + /- SD , 24+/-4 kg.m(2 ) ) and matched healthy elderly ( n=30 ; 15 men ; mean age + /- SD , 68+/-7 y ; mean FEV(1 ) predicted + /- SD , 104%+/-21 % ; mean BMI + /- SD , 25+/-3 kg.m(2 ) ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURE Step counting and EE estimation during a  treadmill walking protocol . RESULTS The pedometer was accurate for step counting and EE estimation in both patients with COPD and healthy elderly at the higher speed . However , it showed significant underestimation at the 2 slower speeds in both groups . The multisensor did not detect steps accurately at any speed , although it accurately estimated EE at all speeds in healthy elderly and at the intermediate and higher speeds in patients with COPD . CONCLUSIONS In both patients with COPD and healthy elderly , the multisensor showed better EE estimates during most walking speeds than the pedometer . Conversely , for step counting , accuracy is observed only with the pedometer during the higher walking speed in both groups
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 .