A subgroup analysis reported significant differences in the promotion of physical activity based on baseline physical activity levels and the type of instrument used to assess levels of physical activity .
Validity of Six Activity Monitors in Chronic Obstructive Pulmonary Disease: A Comparison with Indirect Calorimetry
Reduced physical activity is an important feature of Chronic Obstructive Pulmonary Disease ( COPD ) . Various activity monitors are available but their validity is poorly established . The aim was to evaluate the validity of six monitors in patients with COPD . We hypothesized triaxial monitors to be more valid compared to uniaxial monitors . Thirty-nine patients ( age 68±7years , FEV1 54±18%predicted ) performed a one-hour st and ardized activity protocol . Patients wore 6 monitors ( Kenz Lifecorder ( Kenz ) , Actiwatch , RT3 , Actigraph GT3X ( Actigraph ) , Dynaport MiniMod ( MiniMod ) , and SenseWear Armb and ( SenseWear ) ) as well as a portable metabolic system ( Oxycon Mobile ) . Validity was evaluated by correlation analysis between indirect calorimetry ( VO2 ) and the monitor outputs : Metabolic Equivalent of Task [ METs ] ( SenseWear , MiniMod ) , activity counts ( Actiwatch ) , vector magnitude units ( Actigraph , RT3 ) and arbitrary units ( Kenz ) over the whole protocol and slow versus fast walking . Minute-by-minute correlations were highest for the MiniMod ( r = 0.82 ) , Actigraph ( r = 0.79 ) , SenseWear ( r = 0.73 ) and RT3 ( r = 0.73 ) . Over the whole protocol , the mean correlations were best for the SenseWear ( r = 0.76 ) , Kenz ( r = 0.52 ) , Actigraph ( r = 0.49 ) and MiniMod ( r = 0.45 ) . The MiniMod ( r = 0.94 ) and Actigraph ( r = 0.88 ) performed better in detecting different walking speeds . The Dynaport MiniMod , Actigraph GT3X and SenseWear Armb and ( all triaxial monitors ) are the most valid monitors during st and ardized physical activities . The Dynaport MiniMod and Actigraph GT3X discriminate best between different walking speeds
A subgroup analysis reported significant differences in the promotion of physical activity based on baseline physical activity levels and the type of instrument used to assess levels of physical activity .