Relationships between TriTrac-R3D vectors, heart rate, and self-report in obese children

Abstract

The TriTrac (Professional Products, Inc., Madison, WI) triaxial accelerometer and diary self report were compared with adjusted heart rates to evaluate 3 d of leisure-time activity in 35 8- to 12-yr-old obese children. Adjusted heart rates were calculated by subtracting preexercise resting heart rates from heart rates measured in the field. TriTrac and self-reported data were converted to multiples of resting metabolic rate (METs). Correlations between accelerometer METs and adjusted heart rates (r = 0.71) were significantly higher (P < 0.001) than correlations between adjusted heart rates and self-reported METs (r = 0.36) or accelerometer and self-reported METs (r = 0.38). Self-reported METs had higher mean standard errors in estimating heart rates (13.93 +/- 6.15 beats.min-1) than did accelerometer METs (10.94 +/- 5.62 beats.min-1; P < 0.001), were significantly greater than accelerometer METs (2.50 +/- 1.48 vs 1.80 +/- 1.48; P < 0.05) and systematically overestimated accelerometer METs. The anteroposterior vector accounted for 36%, and the vector magnitude score accounted for 34% of the variance in unadjusted heart rates. The mediolateral vector and vector magnitude score accounted for 69% of the variance in self-reported METs. The vertical vector did not account for variance in either unadjusted heart rates or self-reported METs. It was concluded that the TriTrac yielded a better estimate of activity in obese children than self report. In addition, the vector magnitude composite score of the TriTrac accounted for significantly more variance in both self-reported activity and unadjusted heart rates as compared with the vertical directional vector of the TriTrac.

The Use of Uniaxial and Triaxial Accelerometers to Measure Children’s “Free-Play” Physical Activity

“…By measuring motion in more than one plane, these monitors might be better able to quantify activity than uniaxial accelerometers. Indeed, several authors have suggested that triaxial accelerometers may be more sensitive than uniaxial accelerometers to the torsional, non-vertical movements often involved in children's play (6,8,24). In this study, both accelerometers were significantly correlated with predicted METs, intensity classification, and heart rate; however, the correlations observed for the Tritrac vector sum were somewhat greater than those observed for the CSA.…”

Systematic review to identify and appraise outcome measures used to evaluate childhood obesity treatment interventions (CoOR): evidence of purpose, application, validity, reliability and sensitivity

“…Objective methods are considered optimal for quantification of PA and are advantageous over subjective methods through avoidance of reporting bias. 104 Criterion validity was assessed in 12 of the objective studies [105][106][107][108][109][110][111][112][113][114] (with correlations ranging from r = 0.47 to r = 0.82). Four out of the five studies evaluating accelerometers measured criterion validity (compared with direct observation 105,106 ); VO 2 (oxygen uptake); 107 or heart rate (HR); 108 with strong correlations observed for all (range: r = 0.71-0.86).…”

Reliability of RT3 accelerometer for measuring mobility in people with multiple sclerosis: Pilot study

“…Whereas a number of studies have examined the properties of the earlier triaxial accelerometer models in a number of population groups [1,5,[15][16][17][18][19][20][21], few studies have investigated the latest, allegedly more sensitive and expedient model, the RT3 [9][10][11][12][13][14]. Four studies have validated the RT3.…”