Comparison of Lifecorder EX and ActiGraph accelerometers under free-living conditions

2007 ◽  
Vol 32 (4) ◽  
pp. 753-761 ◽  
Author(s):  
James J. McClain ◽  
Cora L. Craig ◽  
Susan B. Sisson ◽  
Catrine Tudor-Locke
Keyword(s):  
Repeated Measures ◽  
Vigorous Physical Activity ◽  
Living Conditions ◽  
Moderate Activity ◽  
Free Living ◽  
Cut Points ◽  
Model Reliability ◽  
Vigorous Intensity ◽  
Fort Walton ◽  
Free Living Conditions

The Kenz Lifecorder EX (LC; Suzuken Co. Ltd., Nagoya, Japan) offers several potentially attractive features for researchers and practitioners compared with accelerometers such as the ActiGraph (AG; ActiGraph Health Services, Fort Walton Beach, Fla.). The purposes of this study were (i) to evaluate the LC’s intra-model reliability for outputs of steps and time spent in moderate, vigorous, and combined moderate plus vigorous physical activity (MVPA) and (ii) to compare the same LC vs. AG outputs under free-living conditions. Ten participants (n = 5 males) wore two LCs and one AG accelerometer during all waking hours on one day. Steps were outputted from all monitors. Additionally, two LC and five AG intensity derivations were used to assess time in moderate activity, vigorous activity, and MVPA. Intra-class correlations (ICC) were used to assess intra-model reliability between LCs. Paired t tests and repeated-measures analyses of variance (ANOVAs) were used to assess differences between the two LCs and LC vs. AG outputs of steps and time in various intensity derivations where appropriate. No significant differences were detected between outputs from different LCs (ICCs ranged from 0.95 to 0.99). The LC detected significantly fewer steps vs. AG (mean difference = 1516 steps). All LC vs. AG vigorous-intensity derivations provided similar outputs. Additionally, comparable estimates of MVPA time were produced by one of two LC intensity derivations compared with specific AG cut points established each by Freedson, Hendelman (walking), and Matthews. LC displayed high inter-model reliability. Although the LC detected fewer steps than the AG, the LC detects time in specific PA intensity categories comparable to several existing AG cut points.

Validity of activity monitors worn at multiple nontraditional locations under controlled and free-living conditions in young adult women

2015 ◽  
Vol 40 (5) ◽  
pp. 448-456 ◽  
Author(s):  
Hideaki Kumahara ◽  
Makoto Ayabe ◽  
Misato Ichibakase ◽  
Akari Tashima ◽  
Maiko Chiwata ◽  
...  
Keyword(s):  
Young Adult ◽  
Vigorous Physical Activity ◽  
Real Life ◽  
Living Conditions ◽  
Practical Reasons ◽  
Adult Women ◽  
Young Adult Women ◽  
Free Living ◽  
Activity Monitors ◽  
Free Living Conditions

The purpose of this study was to examine the validity of counting steps and computing indices of moderate-to-vigorous physical activity (MVPA) using miniature activity monitors with 3-D technology worn at various locations under controlled (CON) and free-living conditions (FL). Kenz e-style2, Tanita Calorism Smart, and Omron Calori Scan HJA-306 activity monitors were assessed. Nine and 31 young adult women were assigned to the CON and FL studies, respectively. While walking or jogging on a treadmill at 5 different speeds, the subjects simultaneously carried the 3 different monitors in a pants pocket (PP), a chest shirt pocket, and a shoulder bag (B). Under the FL condition, the 3 monitors were placed only at the PP and B locations for practical reasons. Significant effects of monitor location and walking/jogging speed on the step count measured by the 3 monitors were evaluated under the CON condition. Monitors placed at both PP and B tended to underestimate the number of steps; however, there were no significant differences between the values obtained with the Kenz monitor and those obtained with a criterion accelerometer under the FL condition. Moreover, strong correlations were observed between steps measured by monitors placed at PP and steps measured by the criterion accelerometer. The amount of MVPA for the PP location and the non-carrying duration of the bag for the B location were considered to be important determinants of the accuracy of step counting under the FL condition. In conclusion, monitors placed at the PP location, especially the Kenz monitor, showed acceptable accuracy for young adult women in real-life settings. In contrast, MVPA indices assessed using these monitors showed limited validity.

Limitations of cadence-based walking for assessing bouts of moderate-to vigorous-intensity physical activity under free-living conditions

2013 ◽  
Vol 31 (16) ◽  
pp. 1805-1814 ◽  
Author(s):  
Makoto Ayabe ◽  
Peter H. Brubaker ◽  
Yoshiyuki Sunami ◽  
Hideaki Kumahara ◽  
Yves Schutz ◽  
...  
Keyword(s):  
Physical Activity ◽  
Living Conditions ◽  
Free Living ◽  
Intensity Physical Activity ◽  
Vigorous Intensity ◽  
Free Living Conditions

scholarly journals Fitbit Charge HR Wireless Heart Rate Monitor: Validation Study Conducted Under Free-Living Conditions (Preprint)

2017 ◽  
Author(s):  
Alexander Wilhelm Gorny ◽  
Seaw Jia Liew ◽  
Chuen Seng Tan ◽  
Falk Müller-Riemenschneider
Keyword(s):  
Heart Rate ◽  
Data Collection ◽  
Field Test ◽  
Vigorous Physical Activity ◽  
Living Conditions ◽  
Continuous Data ◽  
Free Living ◽  
Heart Rate Monitor ◽  
Predictive Values ◽  
Free Living Conditions

BACKGROUND Many modern smart watches and activity trackers feature an optical sensor that estimates the wearer’s heart rate. Recent studies have evaluated the performance of these consumer devices in the laboratory. OBJECTIVE The objective of our study was to examine the accuracy and sensitivity of a common wrist-worn tracker device in measuring heart rates and detecting 1-min bouts of moderate to vigorous physical activity (MVPA) under free-living conditions. METHODS Ten healthy volunteers were recruited from a large university in Singapore to participate in a limited field test, followed by a month of continuous data collection. During the field test, each participant would wear one Fitbit Charge HR activity tracker and one Polar H6 heart rate monitor. Fitbit measures were accessed at 1-min intervals, while Polar readings were available for 10-s intervals. We derived intraclass correlation coefficients (ICCs) for individual participants comparing heart rate estimates. We applied Centers for Disease Control and Prevention heart rate zone cut-offs to ascertain the sensitivity and specificity of Fitbit in identifying 1-min epochs falling into MVPA heart rate zone. RESULTS We collected paired heart rate data for 2509 1-min epochs in 10 individuals under free-living conditions of 3 to 6 hours. The overall ICC comparing 1-min Fitbit measures with average 10-s Polar H6 measures for the same epoch was .83 (95% CI .63-.91). On average, the Fitbit tracker underestimated heart rate measures by −5.96 bpm (standard error, SE=0.18). At the low intensity heart rate zone, the underestimate was smaller at −4.22 bpm (SE=0.15). This underestimate grew to −16.2 bpm (SE=0.74) in the MVPA heart rate zone. Fitbit devices detected 52.9% (192/363) of MVPA heart rate zone epochs correctly. Positive and negative predictive values were 86.1% (192/223) and 92.52% (2115/2286), respectively. During subsequent 1 month of continuous data collection (270 person-days), only 3.9% of 1-min epochs could be categorized as MVPA according to heart rate zones. This measure was affected by decreasing wear time and adherence over the period of follow-up. CONCLUSIONS Under free-living conditions, Fitbit trackers are affected by significant systematic errors. Improvements in tracker accuracy and sensitivity when measuring MVPA are required before they can be considered for use in the context of exercise prescription to promote better health.

Methods for Activity Monitor Validation Studies: An Example With the Fitbit Charge

2018 ◽  
Vol 1 (3) ◽  
pp. 130-135 ◽  
Author(s):  
Kathryn J. DeShaw ◽  
Laura Ellingson ◽  
Yang Bai ◽  
Jeni Lansing ◽  
Maria Perez ◽  
...  
Keyword(s):  
Vigorous Physical Activity ◽  
High Specificity ◽  
Living Conditions ◽  
Kappa Statistics ◽  
Free Living ◽  
Reference Measure ◽  
Standardized Reporting ◽  
Advance Research ◽  
Low Sensitivity ◽  
Free Living Conditions

Purpose: To advance research practices with consumer monitors, standard validation methods are needed. This study provides an example of best practices through systematically evaluating the validity of the Fitbit Charge (FBC) under free-living conditions using a strong reference measure and robust measurement agreement methods. Methods: 94 healthy participants (Mage 41.8 ±9.3 yrs) wore a FBC and two research grade accelerometers (Actigraph GT3X and activPAL) as they went about normal activities for a week. Estimated daily minutes of moderate to vigorous physical activity (MVPA) from the FBC were compared against reference estimates obtained from the Sojourns Including Posture (SIP) methodology, while daily step counts were compared against the activPAL. Results: Correlations with reference indicators were high for average daily MVPA (r = 0.8; p < .0001) and steps (r = 0.76; p < .0001), but the FBC overestimated time spent in MVPA by 56% and steps by 15%. The mean absolute percent errors of MVPA and steps estimated by FBC were 71.5% and 30.0%, respectively. Neither of the MVPA and step estimates from the FBC fell into the ±10% equivalence zone set by the criterion. The Kappa statistics of the classification agreement between the two MVPA assessment methods was 0.32 with a low sensitivity of 30.1% but a high specificity of 96.7%. Conclusion: The FBC overestimated minutes of MVPA and steps when compared to both reference assessments in free-living conditions. Standardized reporting in future studies will facilitate comparisons with other monitors and with future versions of the FBC.

Reduction in Vigorous Physical Activity during Intermittent Fasting Under Free-Living Conditions

2016 ◽  
Vol 48 ◽  
pp. 217
Author(s):  
Iain Templeman ◽  
Dylan Thompson ◽  
Javier Gonzalez ◽  
James Betts
Keyword(s):  
Physical Activity ◽  
Vigorous Physical Activity ◽  
Living Conditions ◽  
Intermittent Fasting ◽  
Free Living ◽  
Free Living Conditions

scholarly journals Interinstrument Reliability of the ActiGraph GT3X+ Ambulatory Activity Monitor During Free-Living Conditions in Adults

2015 ◽  
Vol 12 (3) ◽  
pp. 382-387 ◽  
Author(s):  
Haydn Jarrett ◽  
Liam Fitzgerald ◽  
Ash C. Routen
Keyword(s):  
Vigorous Physical Activity ◽  
Research Question ◽  
Intraclass Correlation ◽  
Activity Monitor ◽  
Living Conditions ◽  
Vigorous Activity ◽  
Ambulatory Activity ◽  
Free Living ◽  
Percent Difference ◽  
Free Living Conditions

Background:Currently, no studies have investigated interinstrument reliability of the ActiGraph (AG) GT3X+ in free-living conditions.Methods:Nineteen adults (11 males, 8 females; aged 36.8 ± 11.9 years) wore a pair of AG’s (one on each hip), during all waking hours for 1 day. Raw outputs were generated for total counts, steps, wear time and mean counts per minute. Intensity outputs were derived for time (minutes) spent in <moderate, moderate, vigorous, very vigorous and moderate-to-vigorous physical activity (MVPA). Intraclass correlation (ICC), absolute percent difference (APD), coefficient of variation (CV), Bland-Altman plots, and paired t tests were used to evaluate reliability.Results:Interinstrument reliability was high (CV < 5%) for raw count and derived intensity outputs, except vigorous and very vigorous activity. ICC, CV, and APD values for vigorous and very vigorous were .97, 12.28, 17.36% and .98, 18.15, 25.67%, respectively. Amalgamating moderate, vigorous, and very vigorous into a single MVPA category reduced the CV and APD values to 2.85 and 4.02%, and increased the ICC value to .99. No significant differences were found between contralateral units for any outputs (P > .05).Conclusion:Reliability decreases beyond moderate intensities. MVPA displays superior interinstrument reliability than individual intensity categories. Research question permitting, reporting time in MVPA may maximize reliability.

Safety and Performance of the Omnipod®Hybrid Closed-Loop System in Adolescents with Type 1 Diabetes over Five Days Under Free-Living Conditions

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 1376-P
Author(s):  
GREGORY P. FORLENZA ◽  
BRUCE BUCKINGHAM ◽  
JENNIFER SHERR ◽  
THOMAS A. PEYSER ◽  
JOON BOK LEE ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Closed Loop ◽  
Living Conditions ◽  
Loop System ◽  
Closed Loop System ◽  
Free Living ◽  
And Performance ◽  
Free Living Conditions

Safety and Performance of the Omnipod® Hybrid Closed-Loop System in Adults with Type 1 Diabetes over Five Days Under Free-Living Conditions

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 207-OR
Author(s):  
BRUCE A. BUCKINGHAM ◽  
JENNIFER SHERR ◽  
GREGORY P. FORLENZA ◽  
THOMAS A. PEYSER ◽  
JOON BOK LEE ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Closed Loop ◽  
Living Conditions ◽  
Loop System ◽  
Closed Loop System ◽  
Free Living ◽  
And Performance ◽  
Free Living Conditions

scholarly journals Data-driven modelling approach to circadian temperature rhythm profiles in free-living conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jari Lipsanen ◽  
Liisa Kuula ◽  
Marko Elovainio ◽  
Timo Partonen ◽  
Anu-Katriina Pesonen
Keyword(s):  
Skin Surface ◽  
Living Conditions ◽  
Data Driven ◽  
Physiological Data ◽  
Free Living ◽  
Physiological Level ◽  
Temperature Rhythm ◽  
Time Series Modelling ◽  
Circadian Preference ◽  
Free Living Conditions

AbstractThe individual variation in the circadian rhythms at the physiological level is not well understood. Albeit self-reported circadian preference profiles have been consolidated, their premises are grounded on human experience, not on physiology. We used data-driven, unsupervised time series modelling to characterize distinct profiles of the circadian rhythm measured from skin surface temperature in free-living conditions. We demonstrate the existence of three distinct clusters of individuals which differed in their circadian temperature profiles. The cluster with the highest temperature amplitude and the lowest midline estimating statistic of rhythm, or rhythm-adjusted mean, had the most regular and early-timed sleep–wake rhythm, and was the least probable for those with a concurrent delayed sleep phase, or eveningness chronotype. While the clusters associated with the observed sleep and circadian preference patterns, the entirely unsupervised modelling of physiological data provides a novel basis for modelling and understanding the human circadian functions in free-living conditions.

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