Intermonitor Variability of GT3X Accelerometer

Abstract

The main purpose of this study was to assess the inter-monitor reliability of the tri-axial GT3X Actigraph accelerometer over a range of physical activities (PA). This device collects motion data on each of the vertical (Y), horizontal right-left (X), and horizontal front-back (Z) axes and also calculates the vector summed value √X²+Y²+Z² known as ‘vector magnitude’ (VM). 8 GT3X accelerometers were worn at the same time by the same participant. Accelerometers were placed back-to-front, all facing forward and in sets of 4 securely taped together, attached to a belt and allocating each block above either left or right hip at waist level. Inter-monitor reliability was assessed during 6 conditions: rest, walking (4 and 6 km·h^− 1), running (8 and 10 km·h^− 1) and repeated sit-to-stand (40 times·min^− 1). The intra-class correlation coefficients were high for X, Y and Z axes (i. e., all ≥0.925) and for VM (≥0.946). In conclusion, we found good inter-instrument reliability of the GT3X accelerometer across all planes, yet our results also suggest that the X and Z axes do not provide further benefits over the ‘traditional’ Y-axis to assess the movement in typical PA.

Key words

physical activity - activity assessment - accelerometry - motion sensor

• References

• 1 Atkinson G, Davison RC, Nevill AM. Performance characteristics of gas analysis systems: what we know and what we need to know. Int J Sports Med 2005; 26 (Suppl. 01) S2-S10
• 2 Bassett Jr DR. Validity and reliability issues in objective monitoring of physical activity. Res Q Exerc Sport 2000; 71: S30-S36
• 3 Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1 (8476) 307-310
• 4 Bouten CV, Sauren AA, Verduin M, Janssen JD. Effects of placement and orientation of body-fixed accelerometers on the assessment of energy expenditure during walking. Med Biol Eng Comput 1997; 35: 50-56
• 5 Brage S, Wedderkopp N, Franks PW, Andersen LB, Froberg K. Reexamination of validity and reliability of the CSA monitor in walking and running. Med Sci Sports Exerc 2003; 35: 1447-1454
• 6 Chen KY, Bassett Jr DR. The technology of accelerometry-based activity monitors: current and future. Med Sci Sports Exerc 2005; 37: S490-S500
• 7 Engineering/Marketing A . ActiLife Users Manual. Pensacola, FL: ActiGraph; 2009
• 8 Fairweather SC, Reilly JJ, Grant S, Whittaker A, Paton JY. Using the computer science and applications (CSA) activity monitor in preschool children. Pediatr Exerc Sci 1999; 11: 413-420
• 9 Garatachea N, Cavalcantil-Almeida E, De Paz JA. Methods for quantifying energy expenditure and physical activity. Archivos de Medicina del Deporte 2003; 96: 331-337
• 10 Garatachea N, Torres Luque G, Gonzalez Gallego J. Physical activity and energy expenditure measurements using accelerometers in older adults. Nutr Hosp 2010; 25: 224-230
• 11 Harriss DJ, Atkinson G. Update – ethical standards in sport and exercise science research. Int J Sports Med 2011; 32: 819-821
• 12 Holm S. A simple sequentially rejective multiple test procedure. Scand J Statist 1979; 6: 65-70
• 13 Howe CA, Staudenmayer JW, Freedson PS. Accelerometer prediction of energy expenditure: vector magnitude versus vertical axis. Med Sci Sports Exerc 2009; 41: 2199-2206
• 14 Janz KF. Physical activity in epidemiology: moving from questionnaire to objective measurement. Br J Sports Med 2006; 40: 191-192
• 15 John D, Tyo B, Bassett DR. Comparison of four ActiGraph accelerometers during walking and running. Med Sci Sports Exerc 2010; 42: 368-374
• 16 Powell SM, Jones DI, Rowlands AV. Technical variability of the RT3 accelerometer. Med Sci Sports Exerc 2003; 35: 1773-1778
• 17 Powell SM, Rowlands AV. Intermonitor variability of the RT3 accelerometer during typical physical activities. Med Sci Sports Exerc 2004; 36: 324-330
• 18 Rothney MP, Apker GA, Song Y, Chen KY. Comparing the performance of three generations of ActiGraph accelerometers. J Appl Physiol 2008; 105: 1091-1097
• 19 Trost SG, Ward DS, Moorehead SM, Watson PD, Riner W, Burke JR. Validity of the computer science and applications (CSA) activity monitor in children. Med Sci Sports Exerc 1998; 30: 629-633
• 20 Tudor-Locke CE, Myers AM. Challenges and opportunities for measuring physical activity in sedentary adults. Sports Med 2001; 31: 91-100
• 21 Ward DS, Evenson KR, Vaughn A, Rodgers AB, Troiano RP. Accelerometer use in physical activity: best practices and research recommendations. Med Sci Sports Exerc 2005; 37: S582-S588
• 22 Welk GJ. Principles of design and analyses for the calibration of accelerometry-based activity monitors. Med Sci Sports Exerc 2005; 37: S501-S511
• 23 Welk GJ, Blair SN, Wood K, Jones S, Thompson RW. A comparative evaluation of three accelerometry-based physical activity monitors. Med Sci Sports Exerc 2000; 32: S489-S497