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Pedometer accuracy and reliability at slow walking speeds in healthy older adults Harriman, Matthew; Krč, Katarina; Lee, Jennifer; Martin, Jessica; Mitchell, Emily; Wierzchowski, Julia 2011-08

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Matthew Harriman, Katarina Kr?, Jennifer Lee, Jessica Martin, Emily Mitchell, Julia Wierzchowski  CO-SUPERVISORS: Dr. Janice Eng and Dr. Jeremy Noble ? Literature background ? Study rationale ?Hypotheses  ?Methods ?Results/Discussion ?Question Period  ?Aging Canadian population (Statistics Canada, 2009)  ?Benefits of regular physical activity   (Marsh et al., 2007) ?Need for a reliable outcome measure   (Bassett et al., 2000) ?Walking ? preferred method of exercise for older adults (Yusuf et al., 1996; Cyarto et al., 2004; Marsh et al., 2007)  ? Pedometers can be inexpensive, and have been shown to increase physical activity (Holbrook et al., 2009)  ? Have the potential to be used in a variety of settings  ? Hospitals ? Nursing Homes ? Community ? Vary in accuracy depending on (Schneider et al., 2003): ? Internal mechanism ? Walking speeds ? Few studies have been conducted which look at slow walking speeds (< 0.9 m/s) (Bassett et al., 2000) ?Reliability ?Whether a pedometer consistently records the same number of steps over multiple trials  ?Accuracy ? How closely the pedometer recorded steps correspond to the actual number of steps measured by a gold standard  ?Gold Standard ?Manual hand count, video capture, ActiCal Accelerometer have been used  ? Coil spring (Yamax DW 200)/ Lever Arm (SportLine 330)   ?Magnetic Reed Proximity Switch (Omron HJ 105)   ? Piezoelectric   (NewLifestyles 2000, ActiCal) ?Device: Yamax Digiwalker 200 (Spring lever)  ?Population: Nursing home and community dwelling seniors  ? Speeds: 0.35 - 0.48m/s, 0.87 - 1.02m/s  ?Results: 74% error at slowest speeds in nursing home residents and 25% in community dwelling  ?Devices: 10 pedometer models of differing mechanisms  ?Population: Healthy adults (mean age 34)  ? Speeds: Self selected speeds (1.29 - 1.9m/s) and pre-selected treadmill (0.9 - 1.78m/s)             ?Devices: Walk-4-Life, Step-Keeper (spring lever), Omron HF 100 (piezoelectric) ?Population: Healthy adults ages 19-85 ? Speeds: 0.4 - 1.15m/s on a treadmill ?Device: ActiCal (accelerometer)  ?Population: Healthy adults  (mean age 34.3)  ? Speed: 0.83 - 1.38m/s walk on treadmill  ?Results: 7.4% error at slow speed, 0.01% at faster speeds ?Piezoelectric pedometers and the Yamax DW 200 are accurate in healthy adults at speeds >0.9m/s (Cyarto et al., 2004; Schneider et al., 2003; Melanson et al., 2004)  ?ActiCal is most accurate at speeds >1.38m/s   (Esliger et al., 2007)  ?To determine whether any of 5 commercially available pedometers with differing mechanisms are accurate at recording steps taken by healthy older adults at speeds <0.9m/s ? Slower walking speed associated with populations at risk of health problems related to decreased physical activity  ?To identify a reliable outcome measure for monitoring walking activity in older adults ?No significant difference between pedometers in terms of accuracy at pre-set gait speeds <0.9 m/s in healthy older adults  ?Accuracy and reliability of all pedometers tested will decrease as speed decreases regardless of brand or internal mechanism   ?Obtained from the Office of Research Ethics, University of British Columbia ?All participants provided written informed consent prior to commencement of the trial ?Recruited from local seniors centers and community centers ? Further snowball sampling  Table 1: Subject Demographics ? Mean (sd) ?Yamax Digiwalker 200 (spring lever) - $20 ?Omron HJ 105 (magnetic switch) - $12 ? Sportline 330 (coil spring lever) - $20 ?New Lifestyles 2000 (piezoelectric) - $75 ?ActiCal accelerometer (piezoelectric) - $ >500 ?1 unit of each model was randomly selected ?2 models were worn at a time, 1 on each hip ?ActiCal was worn for every trial on the left hip  ? Subjects completed a series of 80m walking trials on an oval, 40m track at selected cadences ?Cadences, dictated by a metronome,  corresponded to walking speeds of: ? Slow ? 80bpm (0.71-0.9m/s)  ? Very slow ? 66bpm (0.51-0.7 m/s)  ? Slowest  - 50bpm (0.3-0.5m/s) ? Self-selected speed (1.2-1.4m/s) ? Speed order was randomized for each subject ?Practice trial at slowest speed ? For each trial, 2 researchers followed the subject and manually counted steps (gold standard) ?Time to complete a 3m portion of track was recorded and gait velocity calculated ? Steps were recorded from all devices between trials ?The 4 trials were repeated with the remaining 2 models of pedometers ? SPSS Version 11.0 (IBM, Armonk NY)  ?Repeated-measures ANOVA between speed conditions ?Percentage error and mean percentage error for each pedometer at each speed ?Bland-Altman plot for graphical representation of deviation from gold standard ?Two-way mixed intraclass correlation coefficients (ICC (3,2)) for within brand reliability ?Repeated-measures ANOVA to ensure 3 pre-selected cadences and self-selected speed gave velocities that were significantly different from each other (F (3,51) = 157.38; p <0.0001)  Table 1: Walking speeds ?Pedometer trials that failed to register any steps were eliminated from analysis (Melanson et al., 2004) ? Removed so as not to skew % error scores  ?May be due to: ? Lack of sensitivity at slow speeds  ? Subject?s gait pattern   Table 2: Number of trials that failed to register steps ?Unable to calculate ANOVA due to drastically unequal group sizes (44% of trials removed for Omron at 50bpm) ?Percent error scores calculated for each model at each speed Table 3: Percent error mean with zeros removed ?Mean percentage error Figure 1: Mean % error of each pedometer across all speeds Mean % Error Across Devices at All Speeds0102030405060708050 66 80 Self-selectedCadence (bpm)% Error Compared to Gold Standard (%) OmronNewLifestylesSportLineYamaxActical?Mean percentage error average   Figure 2: Average mean % error across devices, stratified by speed ?Bland-Altman plots to show agreement between pedometers counts and hand counted steps  (Schneider et al., 2003) -180-160-140-120-100-80-60-40-200204060800 50 100 150 200Difference Between Pedometer Count and Gold Standard Average of Pedometer Count and Gold Standard Bland-Altman Plot - NewLifestyle NL 50bpmNL 66bpmNL 80bpmNL Normal SpeedBiasPositive LimitNegative LimitFigure 3: Bland Altman Plot for NL 2000 ? Piezoelectric/ accelerometer pedometers thought to be more accurate in measuring step count as compared to pedometers with mechanical internal mechanisms (Schneider et al., 2003 & Crouter et al., 2003) ? ICC to demonstrate within brand reliability (only calculated for self-selected speed) ? Note wide 95% confidence intervals Table 4: ICC between pedometer and hand counted steps at self selected speed ? Comparing to Ryan et al., 2006 ? Note the high ICC for ActiPal (Piezoelectric), and low ICC  for Omron (mechanical) Ryan et al., 2006Values: based on 500 outdoor track of ?slow?self-selected speedsOmron HJ 109Yamax Digiwalker 200 ActiPalICC Value 0.01 0.48 0.99Cyarto et al., 2004, March et al., 2007, Grant et al., 2008, Furlanetto et al., 2009, Basset et al., 2010 Table 5: Comparison of percent error at different speeds for piezoelectric vs. mechanical devices Table 5: Comparison of percent error at different speeds for piezoelectric vs. mechanical devices Cyarto et al., 2004, March et al., 2007, Grant et al., 2008, Furlanetto et al., 2009, Basset et al., 2010 ?Current study: New Lifestyles 2000 (piezoelectric) had one of the highest % errors at the two slowest speeds ? 69 % at 0.46m/s ? 44 % at 0.66m/s.   ?No significant difference in accuracy from one mechanism to the next at slow speeds ? Bassett et al. (2010) - Conflicting evidence on intra-device reliability of ActiCal  ? Welk et al. (2004): ActiCal had lowest intra-device reliability of all accelerometers tested  ? Esliger et al. (2006): ActiCal had best intra-device reliability.  ? Current study ? ActiCal no more accurate than any other devices even at the fastest, self-selected speeds.   ?What might contribute to the variability in results? ? Short track (80m) and short time (2 min) ? Accelerometers designed to record activity over longer period of time (Welk et al., 2004) ?All pedometers were less accurate at slower speeds and there was no significant difference between mechanisms.    ? Few units per brand ? Length of track (inflation of percent error) ?Preferentially recruiting healthy older adults who normally walk at a faster pace and do not have any gait impairments  ?Pre-set cadence may affect gait pattern ? Sample of convenience ?Examines gait speeds that are representative of older adults speeds ? Lower than speeds used in some previous research ?Walking over ground instead of treadmill ? Treadmills alter normal gait patterns (Ryan et al., 2006) ? Treadmill walking is not the preferred mode of exercise in older adults ?Want to examine normal, everyday walking activity ?Mean age (63.6 years)  ? Closer to target population ? older adults ?Comparison of multiple units of differing mechanisms ?Examines use of ActiCal accelerometer as a gold standard ?Measure in more realistic environment  ? Ankle vs. Hip mounted pedometers at slower speeds ? Validate the mathematical correction factor for missing steps proposed by Ichinoseki-Sekine (2006) ? Alternative outcome measure for recording physical activity in slow walking older adults ? Investigate pedometer accuracy and reliability in adults with slow self-selected walking speed and gait impairments ?Dr. Janice Eng ?Dr. Jeremy Noble ?Chihya Hung, Lab manager ?Everyone at the Rehab Research Lab ?Participants  ? American College of Sports Medicine. (2009). ACSM's guideline for exercise testing and prescription. (8th ed., ). Indianapolis: Lippincott Williams & Wilkins.  ? Bassett, D. R., Ainsworth, B. E., Leggett, S. R., Mathien, C. A., Main, J. A., Hunter, D. C., et al. (1996). Accuracy of five electronic pedometers for measuring distance walked. / evaluation de la precision de cinq podometres electroniques servant a mesurer la distance parcourue en marchant. Medicine & Science in Sports & Exercise, 28(8), 1071-1077.  ? Bassett D, J., John D. Use of pedometers and accelerometers in clinical populations: validity and reliability issues. PHYS THER REV 2010 06;15(3):135-142. ? Bohannon, R. W. Reference values for the timed up and go test: A descriptive meta-analysis.  ? Crouter, S. E., Schneider, P. L., Karabulut, M., & Bassett, D. R.,Jr. (2003). Validity of 10 electronic pedometers for measuring steps, distance, and energy cost. Medicine and Science in Sports and Exercise, 35(8), 1455-1460.  ? Cyarto, E. V., Myers, A. M., & Tudor-Locke, C. (2004). Pedometer accuracy in nursing home and community-dwelling older adults. Medicine & Science in Sports & Exercise, 36(2), 205-209.  ? Esliger, D. W., Probert, A., Gorber, S. C., Bryan, S., Laviolette, M., & Tremblay, M. S. (2007). Validity of the actical accelerometer step-count function. Medicine & Science in Sports & Exercise, 39(7), 1200-1204.  ? Grant, P. M., Dall, P. M., Mitchell, S. L., & Granat, M. H. (2008). Activity-monitor accuracy in measuring step number and cadence in community-dwelling older adults. Journal of Aging & Physical Activity, 16(2), 201-214.  ? Hasson, R. E., Haller, J., Pober, D. M., Staudenmayer, J., & Freedson, P. S. (2009). Validity of the omron HJ-112 pedometer during treadmill walking. Medicine & Science in Sports & Exercise, 41(4), 805-809.  ? Holbrook, E. A., Barreira, T. V., & Kang, M. (2009). Validity and reliability of omron pedometers for prescribed and self-paced walking. Medicine & Science in Sports & Exercise, 41(3), 669-673.  ? Ichinoseki-Sekine, N., Kuwae, Y., Higashi, Y., Fujimoto, T., Sekine, M., & Tamura, T. (2006). Improving the accuracy of pedometer used by the elderly with the FFT algorithm. Medicine and Science in Sports and Exercise, 38(9), 1674-1681.  ? Jehn, M. L., Schmidt-Trucksass, A., & Halle, M. (2009). Validity and reliability of omron pedometers at slow walking speeds. Medicine and Science in Sports and Exercise, 41(9), 1826.  ? Karabulut, M., Crouter, S. E., Bassett, J., & D.R. (2005). Comparison of two waist-mounted and two ankle-mounted electronic pedometers. European Journal of Applied Physiology, 95(4), 335-343.  ? Marsh, A. P., Vance, R. M., Frederick, T. L., Hesselmann, S. A., & Rejeski, W. J. (2007). Objective assessment of activity in older adults at risk for mobility disability. Medicine & Science in Sports & Exercise, 39(6), 1020-1026.  ? Melanson, E. L., Knoll, J. R., Bell, M. L., Donahoo, W. T., Hill, J. O., Nysse, L. J., et al. (2004). Commercially available pedometers: Considerations for accurate step counting. Preventive Medicine, 39(2), 361-368.  ? Ryan, C. G., Grant, P. M., Tigbe, W. W., & Granat, M. H. (2006). The validity and reliability of a novel activity monitor as a measure of walking. British Journal of Sports Medicine, 40(9), 779-784.  ? Schneider, P. L., Crouter, S. E., Lukajic, O., Bassett, J., & D.R. (2003). Accuracy and reliability of 10 pedometers for measuring steps over a 400-m walk. Medicine and Science in Sports and Exercise, 35(10), 1779-1784.  ? Statistics Canada. (2009). Canada?s population estimates: Age and sex. Retrieved July/22, 2010, from  ? Welk, G. J., Schaben, J. A., & Morrow, J., J. (2004). Reliability of accelerometry-based activity monitors: A generalizability study. Medicine & Science in Sports & Exercise, 36(9), 1637-1645.  ? Yusuf, H. R., Croft, J. B., Giles, W. H., Anda, R. F., Casper, M. L., Caspersen, C. J., et al. (1996). Leisure-time physical activity among older adults: United states, 1990. Archives of Internal Medicine, 156(12), 1321-1326.    ?Thank you  ?Any questions? 


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