Journal of Personalized Medicine

Article Withings Body Cardio Versus Gold Standards of -Wave Velocity and Body Composition

Scott R. Collier 1,*, Conner McCraw 1, Megan Campany 1, Austin Lubkemann 1, Price StClair 1, Hong Ji 2, Kathryn Sandberg 2, Joseph W. Morgan 1 and Caroline J. Smith 1

1 Department of Health and Exercise Science, Appalachian State University, Boone, NC 28608, USA; [email protected] (C.M.); [email protected] (M.C.); [email protected] (A.L.); [email protected] (P.S.); [email protected] (J.W.M.); [email protected] (C.J.S.) 2 Department of Medicine, Georgetown University, Washington, DC 20008, USA; [email protected] (H.J.); [email protected] (K.S.) * Correspondence: [email protected]; Tel.: +828-262-7145

 Received: 11 February 2020; Accepted: 6 March 2020; Published: 11 March 2020 

Abstract: Home monitors are widely used by consumers yet cardiovascular health may be better defined by pulse-wave velocity (PWV). So far, the Withings Body Cardio scale is the only consumer device that has been designed to measure PWV and body composition, including fat mass (FM) and fat-free mass (FFM), in the home setting. While one study has demonstrated that this device meets the acceptable accuracy standards of the Society, no study has accounted for the gravitational effect of standing on a scale on aortic-leg PWV. Purpose: The purpose of this study was to assess the accuracy of PWV and body composition as determined by the Body Cardio scale. Methods: Measurements of PWV and body composition in healthy, young males and females (n = 20) using the Body Cardio device were compared to PWV assessed by applanation tonometry (SphygmoCor) and body composition analysis determined by air displacement plethysmography (Bod Pod). Bland–Altman analysis and mean absolute percent error (MAPE) were used to assess accuracy. Results: Data are reported as the mean bias (95% confidence interval). The Body Cardio overestimated PWV by 0.68 m/s ( 0.16, 1.51) and FM by 2.91 kg ( 2.91, 8.73). Body Cardio PWV and − − FM estimations had a MAPE of 9.7% and 25.8%, respectively. The Body Cardio underestimated body mass (BM) and FFM by 0.11 kg ( 0.41, 0.18) and 2.87 kg ( 9.04, 3.30), respectively. Body Cardio BM − − and FFM estimations had a MAPE of 0.15% and 5.6%, respectively. Conclusions: The Body Cardio scale provides accurate measures of BM and PWV; however, it should be used cautiously for measures of FM and FFM.

Keywords: arterial health; pulse transit time; body composition comparison; mobile health

1. Introduction There is a growing interest from consumers, healthcare providers and researchers in using consumer devices to monitor cardiovascular health outside the healthcare provider’s office. The number of monitors sold exceeded 235 million in 2018 in the United States alone. Pulse wave velocity (PWV) is another valuable measure of vascular health because this measure is an indicator of arterial stiffness. Arterial stiffness relates to the mechanical properties of that subsequently affect cardiovascular health. In a healthy or young population, arteries are more distensible when compared to an unhealthy or older population [1]. Arterial distensibility is critical for health because it helps attenuate pulsatile flow and aligns the timing of pressure waves returning to the heart for optimal

J. Pers. Med. 2020, 10, 17; doi:10.3390/jpm10010017 www.mdpi.com/journal/jpm J. Pers. Med. 2020, 10, 17 2 of 16 coronary perfusion. Arterial stiffness is considered a major risk factor of and has been shown to be a predictor of cardiovascular and coronary heart events. Another key factor in cardiovascular health is body composition. According to data from the National Health and Nutrition Examination Survey (NHANES) more than two out of three U.S. adults are considered to be overweight or obese (defined by a body mass index 25 kg m 2)[2]. It is estimated ≥ · − that if the current rate of prevalence continues, then 86.3% of adults in the United States will be overweight or obese by the year 2030 [3]. Overweight and obesity are body weight categories defined as abnormally high or excessive fat accumulation that may impair health (Overweight & Obesity. (2018, September 17). Retrieved from https://www.cdc.gov/obesity/index.html). Excessive visceral adipose tissue is an independent risk factor for diabetes, , and all-cause mortality [4–7]. The purpose of this study was to assess the accuracy of a consumer device, the Withings Body Cardio scale (Withings, Issy-les Moulineux, France), that measures PWV and body composition including body mass (BM), fat mass (FM) and fat-free mass (FFM), as valuable measures of vascular health. Body Cardio measures of PWV and body composition were compared to laboratory gold standard measurements using the SphygmoCor Xcel (XCEL; AtCor Medical, Inc., Itasca, IL, USA) and Bod Pod (Gold, Rome, Italy).

2. Methods

2.1. Participants Following approval of the study from the Institutional Review Board (IRB), prospective participants were contacted via face to face conversation or through an IRB approved email advertisement. All participants were required to have a personal (iOS or Android) smartphone and a service plan that they were able to use for this study. Additional inclusion criteria included being 18 years or older, healthy, and normotensive with no known cardiovascular metabolic or renal disease. Exclusion criteria included having and/or taking medication for a chronic disease (e.g., hypertension, peripheral arterial disease, effort angina, heart failure, and rheumatologic disorders). In addition, subjects were excluded if they had a health condition that limited their physical activity and/or ability to conduct the laboratory measurements. One hundred percent of the subjects interested in participating in the study met the inclusion criteria.

2.2. Materials and Methods Subjects were instructed to report to the Vascular Biology and Autonomic Studies Laboratory at the Appalachian State University and be well-rested, fasted for 12 h, and without ingesting any stimulants twelve hours prior to testing. The investigator and subject reviewed an informed consent form, which resulted in the subject’s signature if they agreed to the terms and procedures of the study. Demographic data (i.e., sex, date-of-birth, race by self-report) were collected via a medical history. Next, subjects rested while seated for fifteen minutes before brachial systolic and diastolic blood were manually and automatically recorded by a medical grade stethoscope and SphygmoCor, respectively. The sphygmacor uses an arm cuff and embedded microphone to determine systolic and diastolic pressures. Manual auscultation was performed to confirm the SphygmoCor measurements. No discrepancies were observed between the stethoscope and SphygmoCor measurements. Before all laboratory measurements, the subject was required to remove all jewelry, shoes and socks, and any excess clothing. In addition, the subject was required to wear compression clothing (e.g., spandex, compression shorts, sports bra) per standard Bod Pod procedures to eliminate negative volume displacement caused by the compressibility of air close to skin, hair, and clothing. A stadiometer and calibrated scale (Health-o-meter Professional) were used to record height and body weight. The order of instrument readings was randomly assigned. Half of the participants were measured in the Bod Pod first followed by the SphygmoCor and Body Cardio, while the reverse order was used in the other half. J. Pers. Med. 2020, 10, 17 3 of 16

2.2.1. Body Cardio Assessment The Body Cardio is a 12.9 12.9 0.8-inch, Wi-Fi-enabled consumer scale that costs USD 179.95. × × The scale utilizes multi-frequency bioelectric impedance analysis (BIA) technology to measure BM, FFM, and FM. Using both high and low frequencies allows for the measurement of both extracellular and intracellular fluid conductance from which an estimation of total body water (TBW) is determined. FFM can then be predicted from TWB because FM only consists of about 7% water. The Body Cardio uses ballistocardiography (BCG) and impedance plethysmography (IPG) to determine an aortic-leg pulse wave velocity (al-PWV). The BCG measures slight weight variations due to left-ventricle ejection of blood and corresponds well to the opening of the aortic valve. IPG measures blood volume changes at the measurement site and is used to determine the arrival time of the pulse wave to the feet from the aortic valve. Subtracting the arrival time from the left ventricle ejection of blood and the pulse wave’s arrival time at the feet results in al-PWV. Participants were instructed to stand barefoot on the Body Cardio scale until all measures were recorded. The instrument reports measures in the following order: BM (kg), % body fat, muscle mass (kg), BM index, and PWV (m/s). The subject was instructed to stand on the Body Cardio until PWV measures were garnered. Body fat mass was calculated by multiplying the body weight by the % body fat. The Body Cardio was cleaned between subjects using 70% ethanol.

2.2.2. SphygmoCor Assessment Before all SphygmoCor (XCEL; AtCor Medical, Inc., Itasca, IL, USA) assessments, the subject was instructed to stand up next to the SphygmoCor with the Withings Body Cardio in proximal distance. The researcher measured standing brachial blood pressure after the subject had rested in the standing position for three minutes. The SphymoCor measures brachial systolic and diastolic blood pressure by inflating a cuff with a built-in pressure sensor that can measure the brachial pulsatile waveform. This brachial waveform is processed algorithmically by the SphygmoCor to determine central blood pressure, which were not used in the present study. Next, the femoral cuff was placed on the subject and carotid to femoral artery distance was measured using the fabric tape measuring device provided by SphygmoCor. Next, the researcher began assessment of PWV by placing a Doppler pen via applanation tonometry on the subject’s carotid artery. PWV was measured three times and in between measurements, body composition and PWV were determined on the Body Cardio. All subjects were within the normative hydration range in accordance with the Withings scale readout.

2.2.3. Bod Pod Assessment The Bod Pod by Cosmed is a body composition analysis system that uses air displacement plethysmography and whole-body densitometry to determine body composition (FM and FFM). Before measuring body composition with the Bod Pod, subjects were outfitted with a swim cap and instructed to breathe normally and sit still while in the Bod Pod. Thoracic gas volumes were predicted using the Bod Pod software (software version 5.4.3) for body volume corrections. Two measurements were completed over 30 min using the Bod Pod and unless the two were significantly different, i.e., more than one standard deviation, then no third measurement was made.

3. Statistical Analyses An a priori power calculation was performed based on means and standard deviations from laboratory pilot data with the mean and standard deviations from the PMV (transit times in aged-matched population) and body composition data (fat and fat free mass in aged-matched populations). It was determined that 20 subjects were required to reach statistical significance with an alpha level set at 0.05 with a power of 0.93. Data was collected from each device’s particular software and the Withings’ “Healthmate” website, and compiled into a secure database. The average of three measurements were used for SphygmoCor and Body Cardio analyses. Two measurements were used J. Pers. Med. 2020, 10, 17 4 of 16 J. Pers. Med. 2020, 10, x FOR PEER REVIEW 4 of 16 violin,for Bod Bland–Altman Pod analyses. or The regression data are graphs. expressed Violin as plots the mean illustratestandard the measurement error of the mean mean and and the plotted upper ± andas violin, lower Bland–Altmanquartiles. Additionally, or regression a two-way graphs. ANOVA Violin plotswas conducted illustrate theto analyze measurement variance mean attributable and the toupper sex and devices. lower quartiles. A one-sample Additionally, t-test was a two-way performed ANOVA to acquire was conductedthe mean difference to analyze and variance 95% confidenceattributable intervals to sex and for devices. the Bland–Altman A one-sample plots.t-test Fu wasrthermore, performed regression to acquire analysis the mean was diperformedfference and to assess95% confidence proportional intervals bias forand the to Bland–Altman determine the plots. Pearson Furthermore, correlation regression coefficient. analysis The mean was performed absolute percentto assess error proportional (MAPE), biasi.e., the and error to determine as a percentage the Pearson of the correlationoverall mean, coe wasfficient. calculated The mean to assess absolute the degreepercent of error error. (MAPE), Criterion-related i.e., the error validity as a was percentage assessed of by the correlating overall mean, PWV wasdetermined calculated on the to assessBody Cardiothe degree with of measures error. Criterion-related of systolic blood validity pressure was (SBP), assessed heart by rate correlating (HR), BM, PWV FM determined and FFM on on the SphygmoCorBody Cardio and with comparing measures ofPearson’s systolic r bloodwith these pressure same (SBP), correlations heart rate determined (HR), BM, using FM PWV and FFM on the on SphygmoCor.the SphygmoCor and comparing Pearson’s r with these same correlations determined using PWV on the SphygmoCor. 4. Results 4. Results 4.1. Participants 4.1. Participants Ten male and ten female healthy adults, 18–25 years of age were included in this study. All participantsTen male were and students ten female from the healthy University adults, community 18–25 years and Caucasian. of age were All includedparticipants in completed this study. 100%All participants of the study. were There students were no from sex differences the University in the communityage of the participants and Caucasian. ((years): All Men, participants 21.1 ± 2.0; Women,completed 21.5 100% ± 1.9) of or theSBP study. measured There by werethe SphygmoCor no sex differences ((mm Hg): in the Men, age 112 of ± the 2.5;participants Women, 107 ((years):± 2.0) or Men, 21.1 2.0; Women, 21.5 1.9) or SBP measured by the SphygmoCor ((mm Hg): Men, 112 2.5; by manual ±auscultation ((mm Hg):± Men, 114 ± 2.2; Women 109 ± 2.6). The men were 10 cm taller than± the Women, 107 2.0) or by manual auscultation ((mm Hg): Men, 114 2.2; Women 109 2.6). The men women (Height± (cm): Men, 178 ± 1.6 vs. Women, 168 ± 1.9; p < 0.01). ± ± were 10 cm taller than the women (Height (cm): Men, 178 1.6 vs. Women, 168 1.9; p < 0.01). ± ± 4.2. Comparison of Body Cardio PWV Measurements with SphygmoCor Determinations 4.2. Comparison of Body Cardio PWV Measurements with SphygmoCor Determinations Analysis of variance revealed a significant effect of device on PWV measurements, though no effectAnalysis of sex (Figure of variance 1A). PWV revealed measured a significant on the Body effect Cardio of device was on 0.7 PWV m/s measurements,lower than that thoughmeasured no oneff ectthe ofSphygmoCor. sex (Figure1A). PWV measured on the Body Cardio was 0.7 m /s lower than that measured on the SphygmoCor.

10 A B 2.0 1.5 8 * * 1.0 0.5 6 0.0 Men 4 Women -0.5 Pulse Wave Velocity (m/s) Velocity Pulse Wave PWV (Sphyg - BodyC, m/s) Sphyg BodyC 5678 PWV ((Sphyg + BodyC)/2, m/s)

Figure 1. Comparison of pulse-wave velocity (PWV) measured by the Body Cardio compared with FigureSphygmoCor 1. Comparison determinations. of pulse-wave (A) Violin velocity plot of PWV(PWV) measured measured by by the the SphygmoCor Body Cardio (Sphyg) compared and Bodywith SphygmoCorCardio (BodyC) determinations. in men and women; (A) Violinp < 0.01,plot Sphygof PWV vs. measured BodyC by by two-way the SphygmoCor ANOVA; n(Sphyg)= 10/group. and Body(B) Q-Q Cardio plot of(BodyC) PWV determined in men and by women; the Sphyg p

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J. Pers. Med. 2020, 10, x FOR PEER REVIEW 5 of 16 The 95% confidence interval (CI) was 0.16 to 1.5 m/s for all participants, which was similar to the − CI in men and women only populationsTable 1. (Table Altman1). statistical analyses.

Parameter CohortTable 1. Altman Bias statistical± SD analyses. 95% Limits of Agreement Men + Women 0.68 ± 0.43 −0.16 to 1.50 Parameter Cohort Bias SD 95% Limits of Agreement PWV Men only 0.71 ± ±0.44 −0.17 to 1.58 WomenMen + onlyWomen 0.65 0.68 ± 0.430.43 0.16−0.19 to 1.50to 1.50 ± − PWV Men only 0.71 0.44 0.17 to 1.58 Men + Women 0.18 ±± 1.97 − −3.68 to 4.05 Women only 0.65 0.43 0.19 to 1.50 HR Men only −0.05 ±± 2.37 − −4.70 to 4.60 Men + Women 0.18 1.97 3.68 to 4.05 Women only 0.42 ±± 1.57 − −2.65 to 3.49 HR Men only 0.05 2.37 4.70 to 4.60 Men + Women −0.11− ±± 0.15 − −0.41 to 0.18 Women only 0.42 1.57 2.65 to 3.49 BM Men only −0.18 ±± 0.12 − −0.42 to 0.05 Men + Women 0.11 0.15 0.41 to 0.18 Women only −1.04− ±± 0.15 − −0.34 to 0.25 BM Men only 0.18 0.12 0.42 to 0.05 − ± − MenWomen + Women only 2.911.04 ± 2.970.15 0.34−2.91 to 0.25to 8.73 − ± − FM MenMen only+ Women 3.28 2.91 ± 2.392.97 2.91−1.41 to 8.73to 7.97 ± − FM WomenMen only only 2.543.28 ± 3.552.39 1.41−4.42 to 7.97to 9.50 ± − MenWomen + Women only −2.87 2.54 ± 3.153.55 4.42−9.05 to 9.50to 3.31 ± − FFM MenMen only+ Women −3.262.87 ± 2.553.15 9.05−8.25 to 3.31to 1.74 − ± − FFM WomenMen only only −2.483.26 ± 3.762.55 8.25−9.86 to 1.74to 4.89 − ± − Women only 2.48 3.76 9.86 to 4.89 − ± − The Pearson correlation coefficient (r) was 0.49 with evidence of proportional bias (p < 0.05). The MAPEThe was Pearson 9.7%. correlation coefficient (r) was 0.49 with evidence of proportional bias (p < 0.05). The MAPE was 9.7%. 4.3. Comparison of Body Cardio HR Measurements with SphygmoCor Determinations 4.3. Comparison of Body Cardio HR Measurements with SphygmoCor Determinations Analysis of variance showed no effect of device on HR measurements; however, both the SphygmoCorAnalysis and of variancethe Body Cardio showed revealed no effect an ofeffect device of sex on on HR HR; measurements; women had 3.8 however,and 8.6 b/m both higher the HRs,SphygmoCor respectively, and thethan Body the men Cardio (Figure revealed 2A). anThe eff Blectand–Altman of sex on HR; plot women (Figure had 2B) 3.8 shows and 8.6that b /them higher Body CardioHRs, respectively, HR measurements than the follow men (Figure a similar2A). distribution The Bland–Altman to the SphygmoCor plot (Figure HR2B) determinations. shows that the Body Cardio HR measurements follow a similar distribution to the SphygmoCor HR determinations.

100 A # B # 4

80 2

0 60 -2

Heart Rate (b/m) Men 40 Women -4 HR (Sphyg - BodyC, b/m) Sphyg BodyC 50 60 70 80 90 100 HR ((Sphyg+ BodyC)/2, b/m)

Figure 2. Comparison of heart rate (HR measured by the Body Cardio with SphygmoCor determinations. Figure(A) Violin 2. plotComparison of HR measured of heart by therate Sphyg (HR andmeasured BodyC inby men the and Body women; Cardiop < 0.01,with maleSphygmoCor vs. female determinations.by two-way ANOVA; (A) Violinn = 10 plot/group. of HR (B) measured Q-Q plot of by HR the determined Sphyg and by BodyC the Sphyg in men and BodyC.and women; Each datap < 0.01,point male represents vs. female duplicate by two-way or triplicate ANOVA; measures n = 10/group. in onestudy (B) Q-Q participant. plot of HR HR, determined heart rate. by the Sphyg and BodyC. Each data point represents duplicate or triplicate measures in one study participant. HR, The 95% CI was 3.68 to 4.1 b/m for all participants; however, the CI was greater in the men heart rate. − compared to the women (Table1). The 95% CI was −3.68 to 4.1 b/m for all participants; however, the CI was greater in the men compared to the women (Table 1).

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4.4. Comparison of Body Cardio BM Measurements with Bod Pod Determinations 4.4. Comparison of Body Cardio BM Measurements with Bod Pod Determinations Analysis of variance showed no effect of device on BM measurements; however, both the Bod Pod andAnalysis the Body of variance Cardio revealed showed an no effect effect of of sex device on BM; on BMmen measurements; weighed 18 kg however,more than both the women. the Bod (FigurePod and 3A). the The Body Bland–Altman Cardio revealed plot an (Figure effect of3B) sex sh onows BM; the men Body weighed Cardio 18BM kg measurements more than the follow women. a similar(Figure distribution3A). The Bland–Altman to the Bod Pod plot determinations. (Figure3B) shows the Body Cardio BM measurements follow a similar distribution to the Bod Pod determinations.

100 A B 0.2

0.0 80 # # -0.2 60

Body Mass (kg) Body Mass -0.4 Men 40 Women BM (BodPod - BodyC, kg) BodPod BodyC 50 60 70 80 90 100 BM ((BodPod + BodyC)/2, kg)

Figure 3. Comparison of body mass (BM) measured by the Body Cardio with Bod Pod determinations. Figure(A) Violin 3. Comparison plot of BM of measured body mass by (BM) the Bodmeasured Pod and by the BodyC Body in Cardio men and with women; Bod Podp determinations.< 0.01, male vs. (femaleA) Violin by two-way plot of BM ANOVA; measuredn = 10 by/group. the Bod (B )Pod Q-Q and plot BodyC of BM in determined men and bywomen; the Bod p < Pod 0.01, and male BodyC. vs. femaleEach data by pointtwo-way represents ANOVA; duplicate n = 10/group. or triplicate (B) measuresQ-Q plot inof oneBM studydetermined participant. by the BM, Bod body Pod mass. and BodyC. Each data point represents duplicate or triplicate measures in one study participant. BM, body The 95% CI was 0.41 to 0.18 kg for all participants; however, the CI was greater in the women mass. − compared to the men (Table1). The r value was 0.47 with evidence of proportional bias ( p < 0.05). The MAPEThe 95% was CI 0.15%.was −0.41 to 0.18 kg for all participants; however, the CI was greater in the women compared to the men (Table 1). The r value was 0.47 with evidence of proportional bias (p < 0.05). The 4.5. Comparison of Body Cardio FM Measurements with Bod Pod Determinations MAPE was 0.15%. Analysis of variance showed no effect of device or sex on FM measurements (Figure4A). 4.5.The Comparison Bland–Altman of Body plot Cardio (Figure FM4 B)Measurements shows that thewith Body Bod Pod Cardio Determinations FM measurements follow a similar distribution to the Bod Pod determinations. Analysis of variance showed no effect of device or sex on FM measurements (Figure 4A). The The 95% CI was 2.9 to 8.7 kg for all participants; however, the CI was greater in the women than Bland–Altman plot (Figure− 4B) shows that the Body Cardio FM measurements follow a similar the men (Table1). The r value was 0.16 with no evidence of proportional bias. The MAPE was 25.8%. distribution to the Bod Pod determinations.

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30 A B 10 J.J. Pers. Pers. Med. Med. 20202020, ,1010, ,x 17 FOR PEER REVIEW 77 of of 16 16 20 5

30 A B 10 10 0 Fat Mass (kg) 20 Men 5 0 Women -5 FM (BodPod - BodyC, kg) FM (BodPod 10 BodPod BodyC 0 5 10 15 20 25 0

Fat Mass (kg) FM ((BodPod + BodyC)/2, kg) Men 0 Women -5

Figure 4. Comparison of fat mass (FM) measured by the Body Cardio with Bod Pod determinations. - BodyC, kg) FM (BodPod (A) Violin plotBodPod of FM measured BodyC by the Bod Pod0 and BodyC 5 in 10men and 15 women; 20n = 10/group. 25 (B) Q- Q plot of FM determined by the Bod Pod and BodyC. Each data point represents duplicate or triplicate FM ((BodPod + BodyC)/2, kg) measures in one study participant. FM, fat mass.

Figure 4. Comparison of fat mass (FM) measured by the Body Cardio with Bod Pod determinations. FigureThe(A) Violin 95% 4. ComparisonCI plot was of − FM2.9 measured toof fat8.7 masskg byfor (FM) the all Bod participants;measured Pod and by BodyC thehoweve Body in men r,Cardio the and CI with women; was Bod greatern Pod= 10 determinations. /ingroup. the women (B) Q-Q than the men(plotA) Violin (Table of FM plot determined1). ofThe FM r valuemeasured by the was Bod by 0.16 Podthe with Bod and Podno BodyC. ev andidence EachBodyC dataof in proportional men point and represents women; bias. duplicate nThe = 10/group. MAPE or triplicate was (B) Q- 25.8%. Qmeasures plot of FM in determined one study participant. by the Bod FM,Pod fatand mass. BodyC. Each data point represents duplicate or triplicate 4.6. Comparisonmeasures in ofone Body study Cardio participant. FFM Measurements FM, fat mass. with Bod Pod Determinations 4.6. Comparison of Body Cardio FFM Measurements with Bod Pod Determinations Analysis of variance showed no effect of device on FFM measurements, though both the Bod Pod The 95% CI was −2.9 to 8.7 kg for all participants; however, the CI was greater in the women than and theAnalysis Body ofCardio variance revealed showed an noeffect effect of ofsex device on FFM; on FFM men measurements,had 20 kg more though FFM than both the Bodwomen. Pod the men (Table 1). The r value was 0.16 with no evidence of proportional bias. The MAPE was 25.8%. (Figureand the 5A). Body The Cardio Bland–Altman revealed an plot effect (Figure of sex 5B) on shows FFM; men that hadthe 20Body kg moreCardio FFM FFM than measurements the women. follow(Figure a5 A).similar The Bland–Altmandistribution to plotthe Bod (Figure Pod5 B)determinations. shows that the Body Cardio FFM measurements follow 4.6.a similar Comparison distribution of Body to Cardio the Bod FFM Pod Measurements determinations. with Bod Pod Determinations Analysis of variance showed no effect of device on FFM measurements, though both the Bod Pod and the Body Cardio revealed an effect of sex on FFM; men had 20 kg more FFM than the women. (Figure90 5A). AThe Bland–Altman plot (FigureB 5B) shows that the Body Cardio FFM measurements5 follow a similar distribution to the Bod Pod determinations.

70 0 # 90 A # B 5 50 -5

70 Men 0 Fat Free Mass (kg) 30 Women -10 # # FFM (BodPod - BodyC, kg) 50 BodPod BodyC 40 50 60 70 80 90 -5 FFM ((BodPod + BodyC)/2, kg) Men Fat Free Mass (kg) Figure30 5. ComparisonWomen of fat free mass. (FFM) measured by the Body Cardio with Bod Pod determinations.-10 Figure(A) Violin 5. plotComparison of FFM measuredof fat free by mass. the Bod (FFM) Pod andmeasured BodyC by in menthe andBody women. Cardiop with< 0.01 Bod, male Pod vs. FFM (BodPod - BodyC, kg) determinations.female by two-wayBodPod (A) ANOVA; Violin plot BodyCn = of10 FFM/group. measured40 (B) Q-Q by plot 50 the of Bod FFM 60Pod determined and 70BodyC by in the 80 men Bod and Pod 90 women. and BodyC. p < 0.01,Each male data pointvs. female represents by two-way duplicate ANOVA; or triplicate n = 10/group. measures ( inB) oneQ-Q study plot of participant. FFM determined FFM, fat by free the mass. Bod Pod and BodyC. Each data point represents duplicatFFM ((BodPode or triplicate measures+ BodyC)/2, in one study kg) participant. FFM,The 95% fat free CI wasmass. 9.0 to 3.3 kg for all participants; however, the CI was greater in the women than − the menFigure (Table 5. Comparison1). The r value of fat was free 0.06 mass. with (FFM) no evidence measured of proportional by the Body bias. Cardio The with MAPE Bod was Pod 5.6%. determinations. (A) Violin plot of FFM measured by the Bod Pod and BodyC in men and women. p < 4.7. Relationship0.01, male vs. offemale SBP Measuredby two-way on ANOVA; the SphygmoCor n = 10/group. with ( PWVB) Q-Q as plot a Function of FFM determined of Device by the Bod PodThere and was BodyC. a weak Each data correlation point represents between duplicat PWVe andor triplicate SBP measured measures onin one the study SphygmoCor participant. in all participantsFFM, fat (rfree< 0.34)mass. (Figure6A). There was a stronger correlation between PWV and SBP (r = 0.50) in

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The 95% CI was −9.0 to 3.3 kg for all participants; however, the CI was greater in the women than the men (Table 1). The r value was 0.06 with no evidence of proportional bias. The MAPE was 5.6%.

4.7. Relationship of SBP Measured on the SphygmoCor with PWV as a Function of Device There was a weak correlation between PWV and SBP measured on the SphygmoCor in all J. Pers. Med. 2020, 10, 17 8 of 16 participants (r < 0.34) (Figure 6A). There was a stronger correlation between PWV and SBP (r = 0.50) in the female only population (Figure 6C), while little correlation was observed in men (r < 0.2) (Figure 6E).the femaleSimilarly, only when population PWV was (Figure me6asuredC), while on littlethe Body correlation Cardio, was there observed was a inweak men correlation (r < 0.2) (Figure between6E). PWVSimilarly, and whenSBP in PWV all participants was measured and on in thethe Bodywomen Cardio, (r = 0.29) there (Figure was a weak6D), which correlation was not between present PWV in theand men SBP (r in < all 0.2) participants (Figure 6F). and in the women (r = 0.29) (Figure6D), which was not present in the men (r < 0.2) (Figure6F).

9 A: all participants B: all participants 8 8 7 7 6 6 Pulse Wave Velocity r2=0.1181 r2=0.1079 5 p=0.1380 p=0.1574 5 90 100 110 120 130 90 100 110 120 130

9 C: male D: male 8

8 7 (Body Cardio, m/s) 7 6 6 r2=0.0137 r2=0.0.0002 p=0.7474 p=0.9689 5 90 100 110 120 130 90 100 110 120 130

8 E: female

Pulse Wave Velocity (SphygmoCor, m/s) (SphygmoCor, Velocity Wave Pulse F: female 8

7 7

6 6

r2=0.2478 r2=0.2928 5 p=0.1432 p=0.1063 5

90 100 110 120 130 90 100 110 120 130 Systolic Blood Pressure (SphygmoCor, mm Hg)

Figure 6. Relationship of systolic blood pressure (SBP) measured on the SphygmoCor with PWV as Figurea function 6. Relationship of device. Comparisonof systolic blood of SBP pressure with PWV(SBP) measuredmeasured on the SphygmoCor SphygmoCor with (A,C PWV,E) or as the a functionBody Cardio of device. (B,D, FComparison) in all participants of SBP with (diamond PWV )(measuredA,B) or specificallyon the SphygmoCor in the male (A (,Csquare,E) or )(theC ,BodyD) or Cardiofemale (Bcircle,D,F)() inE ,allF) participants population. ( Eachdiamond data) point(A,B) or represents specifically duplicate in the male or triplicate (square) measures (C,D) or female in one (studycircle) participant. (E,F) population. The confidence Each data interval point wasrepresents greater dupl in theicate women or triplicate compared measures to the men in one (Table study1). participant. The confidence interval was greater in the women compared to the men (Table 1). 4.8. Relationship of HR Measured on the SphygmoCor with PWV as a Function of Device

There was a small relationship between PWV and HR measured on the SphygmoCor in all participants (r < 0.2) or specifically in the male (r < 0.2) or female (r < 0.2) population. Similarly, there was a slight to weak relationship between HR measured on the SphygmoCor with PWV measured on the Body Cardio in all participants (r < 0.2) or in the male (r = 0.25) and female (r = 0.31) only populations. J. Pers. Med. 2020, 10, x FOR PEER REVIEW 9 of 16

4.8. Relationship of HR Measured on the SphygmoCor with PWV as a Function of Device There was a small relationship between PWV and HR measured on the SphygmoCor in all participants (r < 0.2) or specifically in the male (r < 0.2) or female (r < 0.2) population. Similarly, there was a slight to weak relationship between HR measured on the SphygmoCor with PWV measured on the Body Cardio in all participants (r < 0.2) or in the male (r = 0.25) and female (r = 0.31) only populations.J. Pers. Med. 2020 , 10, 17 9 of 16

4.9. Relationship of BM Measured on the Bod Pod with PWV as a Function of Device 4.9. Relationship of BM Measured on the Bod Pod with PWV as a Function of Device There was a moderate correlation between PWV measured on the SphygmoCor with BM determinedThere wasby the a moderateBod Pod in correlation all participants between (r = PWV0.49) (Figure measured 7A). on This the correlation SphygmoCor was withstrong BM in mendetermined (r = 0.61) by (Figure the Bod 7C) Pod and in allweak participants in women (r (r= <0.49) 0.2) (Figure(Figure7 A).7E). This These correlation correlations was between strong in PWV men and(r = BM0.61) were (Figure similar7C) andwhen weak measured in women on the (r < Body0.2) (FigureCardio7 inE). all These participants correlations (r = 0.39) between (Figure PWV 7B) and or inBM the were male similar (r = 0.53) when (Figure measured 7D) and onthe female Body (r Cardio < 0.2) (Figure in all participants 7F) only populations. (r = 0.39) (Figure 7B) or in the male (r = 0.53) (Figure7D) and female (r < 0.2) (Figure7F) only populations.

9 A: all participants B: all participants 8

8 7 7 6 6 2 2

r =0.2416 r =0.1545 Pulse Wave Velocity m/s) Cardio, (Body 5 p=0.0277 p=0.0864 5

50 60 70 80 90 100 50 60 70 80 90 100

9 C: male D: male 8

8 7 7 6 6 r2=0.3740 r2=0.2779 5 p=0.0603 p=0.1200 5

50 60 70 80 90 100 50 60 70 80 90 100

9 8 Pulse Wave Velocity (SphygmoCor, m/s) (SphygmoCor, Velocity Pulse Wave E: female F: female

8 7 7 6 6 r2=0.1245 r2=0.0002 5 p=0.3173 p=0.9697 5

50 60 70 80 90 100 50 60 70 80 90 100 Body Mass (BodPod, kg)

Figure 7. RelationshipRelationship of of BM BM measured measured on the Bod Pod wi withth PWV as a function function of device. Comparison Comparison of BM with PWV measured on the SphygmoCor ( A,C,E) or the Body Body Cardio Cardio ( B,,D,,F) in in all all participants participants diamond A B square C D circle E F (diamond)() (A,,B)) oror specifically specifically in in the the male male ( (square)( ) ,(C),D or) femaleor female ( (circle)( ,) )(E population.,F) population. Each Each data point represents duplicate or triplicate measures in one study participant. data point represents duplicate or triplicate measures in one study participant. 4.10. Relationship of FM Measured on the Bod Pod with PWV as a Function of Device There was little relationship between PWV measured on the SphygmoCor with FM determined on the Bod Pod in all participants (r < 0.2) (Figure8A); however, in the male only population, there was a moderate correlation between PWV and FM (r = 0.52) (Figure8C), which was absent in women r < 0.2) (Figure8E). Similarly, when PWV was measured by the Body Cardio, there was a weak correlation with J. Pers. Med. 2020, 10, x FOR PEER REVIEW 10 of 16

4.10. Relationship of FM Measured on the Bod Pod with PWV as a Function of Device There was little relationship between PWV measured on the SphygmoCor with FM determined on the Bod Pod in all participants (r < 0.2) (Figure 8A); however, in the male only population, there was a moderate correlation between PWV and FM (r = 0.52) (Figure 8C), which was absent in women r < 0.2) (Figure 8E). Similarly, when PWV was measured by the Body Cardio, there was a weak J. Pers. Med. 2020, 10, 17 10 of 16 correlation with FM in the male only population (r = 0.30) (Figure 8D) whereas there was little relationship observed in all participants (r < 0.2) (Figure 8B) or in the female only population (r < 0.2) FM(Figure in the 8F). male only population (r = 0.30) (Figure8D) whereas there was little relationship observed in all participants (r < 0.2) (Figure8B) or in the female only population (r < 0.2) (Figure8F).

9 A: all participants B: all participants 8

8 7 7 6 6 2 2

r =0.2416 r =0.1545 WavePulse VelocityCardio, m/s) (Body 5 p=0.0277 p=0.0864 5

50 60 70 80 90 100 50 60 70 80 90 100

9 C: male D: male 8

8 7 7 6 6 r2=0.3740 r2=0.2779 5 p=0.0603 p=0.1200 5

50 60 70 80 90 100 50 60 70 80 90 100

9 8 Pulse Wave Velocity (SphygmoCor, m/s) (SphygmoCor, Velocity Pulse Wave E: female F: female

8 7 7 6 6 r2=0.1245 r2=0.0002 5 p=0.3173 p=0.9697 5

50 60 70 80 90 100 50 60 70 80 90 100 Body Mass (BodPod, kg)

Figure 8. Relationship of FM measured on the Bod Pod with PWV as a function of device. Comparison ofFigure FM with 8. Relationship PWV measured of FM on measured the SphygmoCor on the Bod (A Pod,C,E wi) orth the PWV Body as a Cardio function (B, ofD, device.F) in all Comparison participants (ofdiamond FM with)( PWVA,B) measured or specifically on the in SphygmoCor the male (square (A,C)(,EC) ,orD) the or femaleBody Cardio (circle ()(B,ED,,FF)) population.in all participants Each data(diamond point) represents(A,B) or specifically duplicate orin triplicatethe male measures(square) in(C, oneD) or study female participant. (circle) (E,F) population. Each data point represents duplicate or triplicate measures in one study participant. 4.11. Relationship of FFM Measured on the Bod Pod with PWV as a Function of Device 4.11. Relationship of FFM Measured on the Bod Pod with PWV as a Function of Device There was a moderate correlation between PWV measured on the SphygmoCor with FFM determinedThere was on the a Bodmoderate Pod in correlation all participants between (r = 0.42) PWV (Figure measured9A) and on in thethe maleSphygmoCor (r = 0.46) (Figurewith FFM9C) anddetermined female (ron= the0.49) Bod (Figure Pod in9E) all only participants populations. (r = 0.42) Similar (Figure associations 9A) and in were the observedmale (r = 0.46) when (Figure PWV was9C) and measured female by (r = the 0.49) Body (Figure Cardio 9E) in only all participantspopulations. (r Similar= 0.40) associations (Figure9B) and were in observed the male populationwhen PWV (rwas= 0.48)measured (Figure by9 D)the but Body not Cardio in the in female all participants only group (r (r = 0.40)< 0.2) (Figure (Figure 9B)9F). and in the male population (r = 0.48) (Figure 9D) but not in the female only group (r < 0.2) (Figure 9F).

J.J. Pers. Pers. Med. Med. 20202020, ,1010, ,x 17 FOR PEER REVIEW 11 of11 16 of 16

9 A: all participants B: all participants 8

8 7 7

6 Pulse Wave Velocity 6 r2=0.1790 r2=0.1627 5 p=0.0631 p=0.0779 5

40 50 60 70 80 90 40 50 60 70 80 90

9 C: male D: male 8

8 7 (Body Cardio, m/s) (Body Cardio,

7 6

r2=0.2086 r2=0.2267 6 p=0.1846 p=0.1642 5 40 50 60 70 80 90 40 50 60 70 80 90

8 E: all participants F: female 8

Pulse Wave Velocity (SphygmoCor, m/s) (SphygmoCor, Velocity Pulse Wave 7 7

6 6 2 r =0.2363 r2=0.0293 5 p=0.1543 p=0.6364 5

40 50 60 70 80 90 40 50 60 70 80 90 Fat Free Mass (BodPod, kg)

Figure 9. Relationship of FFM measured on the Bod Pod with PWV as a function of device. Comparison Figure 9. Relationship of FFM measured on the Bod Pod with PWV as a function of device. of FFM with PWV measured on the SphygmoCor (A,C,E) or the Body Cardio (B,D,F) in all participants Comparison of FFM with PWV measured on the SphygmoCor (A,C,E) or the Body Cardio (B,D,F) in (diamond)(A,B) or specifically in the male (square)(C,D) or female (circle)(E,F) population. Each data all participants (diamond) (A,B) or specifically in the male (square) (C,D) or female (circle) (E,F) point represents duplicate or triplicate measures in one study participant. population. Each data point represents duplicate or triplicate measures in one study participant. 5. Discussion 5. Discussion The major finding of this study is that the Withings Body Cardio scale accurately assesses PWV. TheThe mean major diff erencefinding betweenof this study Body is that Cardio the Withings and SphygmoCor Body Cardio PWV scale accurately determinations assesses was PWV. less The than mean difference between Body Cardio and SphygmoCor PWV determinations was less than 0.2 with a SD 0.2 with a SD of 0.57 (m/s). This difference in PWV measures between devices is well within the of 0.57 (m/s). This difference in PWV measures between devices is well within the accuracy standards accuracy standards deemed acceptable by the ARTERY Society, that is, less than 1.0 m/s and less than deemed acceptable by the ARTERY Society, that is, less than 1.0 m/s and less than 1.5 m/s SD [8]. 1.5 m/s SD [8]. These findings extend a previous report, where Butlin et al. [9] found similar agreement of PWV These findings extend a previous report, where Butlin et al. [9] found similar agreement of measures between the Body Cardio with the SphygmoCor but relied on self-reported height and did PWV measures between the Body Cardio with the SphygmoCor but relied on self-reported height not account for the gravitational effects of standing upright on PWV [9]. We determined height by a and did not account for the gravitational effects of standing upright on PWV [9]. We determined stadiometer and measured PWV using both devices while standing. Gravity is known to affect PWV, height by a stadiometer and measured PWV using both devices while standing. Gravity is known to however, there are few studies that elucidate this phenomenon. Schroeder et al. (2017) demonstrated affect PWV, however, there are few studies that elucidate this phenomenon. Schroeder et al. (2017) that the more upright position one’s body is, the greater the within that physiological demonstrated that the more upright position one’s body is, the greater the arterial stiffness within that system [10]. Further, they found that the change in position is independent of blood pressure. This

J. Pers. Med. 2020, 10, 17 12 of 16 physiological system [10]. Further, they found that the change in position is independent of blood pressure. This was demonstrated when one went from a supine to a seated position. The increases shown in arterial stiffness were only found to be dependent on arterial pressure and not related to any other physiological influences. The arterial tree is heterogeneous. Elastic properties diminish from the central to peripheral arteries, thereby creating an increase in amplitude of the pressure wave, known as pressure amplification. Frank, Bramwell, and Hill derived this propagative model of the in the early 20th century. They concluded that pressure amplification and the PWV is inversely related to the distensibility. This principal led to a theoretical model that is the basis of current technology used in PWV measurements [11]. These seminal studies subsequently led an expert consensus group to establish the carotid-to-femoral PWV (cf-PWV) as the gold standard for non-invasive measurement of arterial stiffness [11–13]. Multiple meta-analyses have revealed that cf-PWV measures improve the prediction of cardiovascular events and mortality, independently of standard risk factors like hypertension, dyslipidemia, or high blood glucose [14–16]. The SphygmoCor XCEL uses applanation tonometry for high-frequency arterial wave form acquisition and volumetric displacement within a cuff for femoral pulse. The cf-PWV is calculated by measuring the transit time between carotid and femoral pulse and dividing it by the pulse wave’s travel distance. This travel distance is estimated by measurement of several surface points along the body to most accurately determine carotid-femoral length [14]. The SphygmoCor devices by AtCor Medical are considered a gold standard of reference for determining PWV. They have been validated against the ARTERY Society’s PWV guidelines [1,17] and their use is cited over 1000 times in peer-reviewed research articles. The Body Cardio uses ballistocardiography and impedance plethysmography to determine al-PWV [18]. Ballistocardiography measures slight weight variations due to left-ventricle ejection of blood and corresponds well to the opening of the aortic valve [18]. Impedance plethysmography measures blood volume changes at the measurement site and is used in the consumer scale to determine the arrival time of the pulse wave to the feet from the aortic valve. Subtracting the arrival time from the left ventricle ejection of blood and the pulse wave’s arrival time at the feet enable determination of al-PWV. Measurement of PWV is typically made when the body is supine. In a standing position, gravity causes an increase in blood volume in the capacitance vessels of the legs, which results in a fall of central blood volume and preload. Consequently, this leads to a decrease in mean arterial pressure. A baroreflex-mediated compensatory increase in peripheral resistance and heart rate then stabilizes the mean arterial pressure in healthy individuals within three minutes. Measuring PWV while standing may be limited by the contractions of stabilization muscles in the legs causing increased venous return by the skeletal muscle pump. Contrarily, subjects with orthostatic hypotension, hypertension, or other cohorts could change the results of the present study and this warrants further research. The Body Cardio scale is a more convenient and a less expensive alternative to devices like the SphygmoCor for measuring arterial stiffness. Furthermore, it can be used repeatedly outside the healthcare provider’s office. An affordable, portable, and accurate scale for measurement of PWV that can be monitored over time has implications for consumers, healthcare providers and researchers [19]. There has been an explosion in the interest of consumers in using PWV to follow their health. Thus, the Body Cardio has the potential to motivate consumers to make healthy lifestyle choices. The ability to repeatedly assess PWV at home is of interest to healthcare providers because this measure of arterial stiffness provides additional information that is complimentary to other assessments of a patient’s overall cardiovascular health and it improves prediction of cardiovascular disease events and mortality independently of lifestyle and standard risk factors. Furthermore, measuring PWV at home minimizes false readings at the healthcare provider’s site due to patient anxiety. The ability to record multiple measures of PWV over time in a non-clinical setting for a fraction of the cost of conducting the same measures using the SphygmoCor promotes longitudinal and large cohort studies of PWV by researchers. The second major finding of this study is that the none of the Body Cardio measures of body composition other than BM meet guidelines of acceptability. These include guidelines proposed J. Pers. Med. 2020, 10, 17 13 of 16 in a study that compared body composition measurements made by dual-energy X-ray absorptiometry to the Bod Pod [20]. FM and FFM measures were deemed acceptable if the percent error was less than 1.5%. The Body Cardio utilizes multi-frequency BIA technology to measure BM, FM, and FFM. The scale also wirelessly connects to a smart phone application where changes in body composition and weight can be tracked over time. While regular self-weighing and the use of smartphone health applications may lead to improved health outcomes, the Body Cardio has not been compared to gold standard measurement methods of body composition nor validated by an independent laboratory [21,22]. Bioimpedance technology has progressed over the last decade. However, recent study showed that when it was compared to dual-energy X-ray absorptiometry, the percent error between methods was nearly 9% [23]. A principle the BIA uses is that of a cylinder’s volume where volume equals length multiplied by the cross-sectional area and impedance is inversely proportional to its cross-sectional area. This principle also assumes that the cylinder’s material is homogeneously conductive. The human body, however, is not cylindrical, and tissues vary in conductivity [24,25]. To address this issue, engineers developed a multi-frequency BIA. Using both high and low frequencies allows the electrical current to penetrate the cell membrane and consequentially, account for both the extracellular fluid and intracellular fluid conductance from which an estimation of total body water is determined. FFM is predicted from total body water because only about 7% of FM consists of water [24,25]. Adipocytes vary in number and size. Thus, the amount of water within FM varies, which leads to inherent error in any extrapolations based on this assumption. Furthermore, the deposition of insulated tissues within the body including adipose tissue impacts the impedance of surrounding conductive tissues according to the mixing theory [26]. We compared body composition analysis using the Body Cardio with determinations made by the Bod Pod, which is a device that utilizes air displacement plethysmography. This system uses a measuring chamber of a known pressure and volume to calculate the volume of the subject. Poisson’s Law, the pressure-volume relationship at a constant temperature and humidity, and adjustments for thoracic lung volume, are used to measure the volumetric displacement the subject imposes on the chamber [27]. Body density is then derived using other demographic measures like height and BM in addition to body volume. Like hydro-densitometry, body density is then used to estimate a two-compartment body composition model consisting of FM and FFM. The Bod Pod has been validated when compared to DXA and for test-retest reliability [28,29]. Despite its validity in the measurement of body composition, the Bod Pod is not commonly available for consumers because the procedure is often costly and takes time to complete. We expected to detect sex differences in the relationship between PWV and body composition because sexual dimorphism exists in fat distribution, which affects cardio-metabolic disease risk. Males typically have an android phenotype characterized by a greater accumulation of visceral fat [30]. Females generally have a gynoid phenotype with greater subcutaneous adipose tissue accrual around the gluteo-femoral region than visceral/abdominal adipose deposition. Increased lipoprotein lipase activity in the visceral region and its suppression by testosterone in the femoral region of men likely contribute to these sex differences in fat deposition [31,32]. Growth of fat mass can occur either by growth in volume of pre-existing adipocytes (i.e., hypertrophy) or through recruitment of new preadipocytes (i.e., hyperplasia) [33]. Studies in rodents suggest that the subcutaneous depot increases by adipocyte hyperplasia while visceral fat accumulates by adipocyte hypertrophy [34]. These sex differences in adipose tissue expansion and adipocyte deposition could lead to sex differences in body composition analysis based on bioelectrical impedance. The limitations of this study include the small sample size, which could have obscured sex differences in PWV measures by the Body Cardio device. Other study limitations include the young age of the cohort, they were all Caucasian and their healthy status. Thus, the accuracy of PWV measures and the relationships observed between PWV, blood pressure and body mass may be specific to this study population and may not represent individuals at higher risk for developing cardiovascular disease such as older individuals and those with hypertension [35]. However, this age category is one J. Pers. Med. 2020, 10, 17 14 of 16 of the largest consumers of this technology. Limitations associated with using GWP like the Body Cardio scale for research purposes include changes in company ownership or software updates in the midst of a study, which can jeopardize the ability to compare measures within the study. Companies could promote the use of these devices for healthcare and research by improving the dialogue between consumers and device manufactures regarding device accuracy. In conclusion, the Withings’ Body Cardio scale has the potential to improve the arterial health of consumers by providing accurate assessment of PWV in the home. This information can serve to motivate individuals to make healthy life style choices as well as offer health care providers the ability to monitor their patient’s health. Furthermore, this feature offers researchers an inexpensive method for studying PWV longitudinally in an ecological setting. In contrast, the use of the Body Cardio to assess percent of body fat must be used with caution as the MAPE is greater than 25%.

Author Contributions: Conceptualization, S.R.C., C.M., J.W.M. and C.J.S.; Methodology, K.S., S.R.C., C.J.S.; Formal Analysis, S.R.C., H.J., K.S.; Investigation, S.R.C., A.L., C.M., P.S. and M.C.; Resources, S.R.C., K.S.; Data Curation, C.M., A.L., M.C., and P.S.; Writing—Original Draft Preparation, C.M., M.C., A.L., P.S. and S.R.C.; Writing—Review & Editing, S.R.C., C.J.S. and K.S.; Visualization, H.J.; Project Administration, S.R.C.; Funding Acquisition, K.S. and S.R.C. All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by grants from the National Institutes of Health: UL1-TR001409 (K.S. & S.R.C.). Conflicts of Interest: No conflicts of interest declared.

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