title: Reliability and validity of the Mywellness Key physical activity monitor.
abstract: BACKGROUND
  This study evaluated the reliability and criterion validity of the Mywellness Key accelerometer (MWK) using treadmill protocols and indirect calorimetry.
  
  
  METHODS
  Twenty-five participants completed two four-stage 20-minute treadmill protocols while wearing two MWK accelerometers. Reliability was assessed using raw counts. Validity was assessed by comparing the estimated VO(2) calculated from the MWK with values from respiratory gas exchange.
  
  
  RESULTS
  Good overall and point estimates of reliability were found for the MWK (all intraclass correlations > 0.93). Generalizability theory coefficients showed lower values for running speed (0.70) versus walking speed (all > 0.84), with the majority of the overall percentage of variability derived from the participant (68%-88% of the total 100%). Acceptable validity was found overall (Pearson's r = 0.895-0.902, P < 0.0001), with an overall mean absolute error of 16.22% and a coefficient of variance of 16.92%. Bland-Altman plots showed an overestimation of energy expenditure during the running speed, but total kilocalories were underestimated during the protocol by approximately 10%.
  
  
  CONCLUSIONS
  Good validity was found during light and moderate walking, while running was slightly overestimated. The MWK may be useful for clinicians and researchers interested in promotion or assessment of physical activity.
authors: Medical University of South Carolina, College of Nursing, Charleston, SC.
authors: John C
authors: JC
authors: Sieverdes
authors: Eric E
authors: EE
authors: Wickel
authors: Gregory A
authors: GA
authors: Hand
authors: Marco
authors: M
authors: Bergamin
authors: Robert R
authors: RR
authors: Moran
authors: Steven N
authors: SN
authors: Blair
keywords: accelerometer; health monitor; physical activity
references: Res Q Exerc Sport. 2000 Mar;71(1):36-43
references: 10763519
references: Med Sci Sports Exerc. 1999 Jun;31(6):908-12
references: 10378921
references: Med Sci Sports Exerc. 2005 Jul;37(7):1216-23
references: 16015141
references: Br J Sports Med. 2011 Feb;45(2):109-13
references: 19736173
references: Med Sci Sports Exerc. 1993 Jan;25(1):71-80
references: 8292105
references: J Phys Act Health. 2011 Sep;8 Suppl 2:S161-70
references: 21918229
references: Med Sci Sports Exerc. 1992 Oct;24(10):1167-72
references: 1435166
references: Am J Prev Med. 2010 Jun;38(6):682-3
references: 20494248
references: Sports Med. 1998 Oct;26(4):217-38
references: 9820922
references: J Sports Sci Med. 2012 Mar 01;11(1):57-63
references: 24149122
references: Int J Behav Nutr Phys Act. 2010 Aug 03;7:60
references: 20682057
references: Pediatr Exerc Sci. 2007 Aug;19(3):310-8
references: 18019589
references: Lancet. 1986 Feb 8;1(8476):307-10
references: 2868172
references: Support Care Cancer. 2007 Feb;15(2):203-11
references: 17001492
references: AANA J. 1996 Jun;64(3):261-8
references: 9095698
references: Med Sci Sports Exerc. 2010 Aug;42(8):1528-34
references: 20139788
references: Med Sci Sports Exerc. 2004 Sep;36(9):1637-45
references: 15354049
references: Psychometrika. 1965 Dec;30(4):395-418
references: 5217607
references: Psychooncology. 2013 Jan;22(1):54-64
references: 21905158
references: Appl Physiol Nutr Metab. 2008 Dec;33(6):1155-64
references: 19088773
references: Med Sci Sports Exerc. 2003 Aug;35(8):1447-54
references: 12900703
references: Med Sci Sports Exerc. 1990 Dec;22(6):858-62
references: 2287266