J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Original Article

Volume 17, Number 4, April 2025, pages 200-207

Evaluating Postural Sway in the Elderly Using Inertial Measurement Units: A Study on Center of Mass Measurements via Accelerometers and Gyroscopes

Figure 2. Bar graph depicting COM postural sway in accelerometer (RMS, RANGE, SA, and SD) ranging from a variety of increasingly challenging conditions of base of support in (a) AP and (b) ML planes. COM: center of mass; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

Figure 3. Bar graph depicted COM postural sway in gyroscope (RMS, RANGE, SA, and SD) ranging from a variety of increasingly challenging conditions of base of support in (a) AP and (b) ML planes. COM: center of mass; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

**Table 1.** Demographic and Clinical Data
Characteristic	Mean ± SD	Min - Max
BMI: body mass index; SD: standard deviation.
Male/female, N (%)	58 (50.90%)/56 (49.10%)
Age (years)	65.90 ± 6.60	60.00 - 84.00
Weight (kg)	57.40 ± 9.40	38.00 - 90.00
Height (cm)	158.80 ± 7.70	145.00 - 175.00
BMI (kg/m²)	22.80 ± 3.80	15.80 - 40.00

Table 1. Demographic and Clinical Data

Characteristic

Mean ± SD

Min - Max

BMI: body mass index; SD: standard deviation.

Male/female, N (%)

58 (50.90%)/56 (49.10%)

Age (years)

65.90 ± 6.60

60.00 - 84.00

Weight (kg)

57.40 ± 9.40

38.00 - 90.00

Height (cm)

158.80 ± 7.70

145.00 - 175.00

BMI (kg/m²)

22.80 ± 3.80

15.80 - 40.00

**Table 2.** AP and ML Planes of Accelerometer-Derived Sway Metrics for Each Test Condition
Sensor variable-plane	SO	STO	TO	SL
SO: standing in a double stance; STO: semi-tandem stance; TO: tandem stance; SL: single-leg stance; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.
RMS-AP	6.79 ± 1.56 (4.14 - 14.73)	7.59 ± 2.39 (4.79 - 25.31)	8.31 ± 2.32 (4.49 - 17.50)	16.43 ± 8.44 (6.99 - 43.68)
RANGE-AP	47.49 ± 22.84 (27.30 - 217.04)	54.61 ± 36.99 (30.23 - 340.39)	56.41 ± 18.85 (27.64 - 126.31)	132.22 ± 88.60 (43.84 - 513.53)
SD-AP	1,827.48 ± 442.49 (155.36 - 4,125.70)	2,051.46 ± 539.91 (1,247.46 - 5,208.08)	2,265.73 ± 675.61 (128.78 - 4,718.57)	3,664.93 ± 1,697.59 (263.45 - 10,243.82)
SA-AP	105.44 ± 23.84 (9.64 - 216.12)	117.38 ± 29.28 (75.57 - 287.88)	129.16 ± 37.58 (7.45 - 270.44)	203.91 ± 95.40 (16.64 - 562.37)
RMS-ML	6.42 ± 1.26 (3.98 - 11.74)	7.15 ± 2.32 (3.98 - 26.42)	8.13 ± 2.24 (4.61 - 21.80)	16.92 ± 9.16 (6.79 - 50.78)
RANGE-ML	44.34 ± 18.19 (23.00 - 162.58)	51.20 ± 36.15 (23.00 - 368.64)	55.70 ± 20.72 (27.48 - 164.75)	138.77 ± 95.19 (41.48 - 463.85)
SD-ML	1,715.77 ± 371.94 (172.02 - 3,150.02)	1,920.74 ± 476.83 (1,041.54 - 5,113.17)	2,220.84 ± 638.73 (151.54 - 6,118.31)	3,715.43 ± 1,062.16 (224.74 - 10,440.58)
SA-ML	99.93 ± 20.21 (10.87 - 183.46)	110.64 ± 26.26 (63.68 - 285.77)	126.48 ± 35.79 (8.49 - 344.33)	205.56 ± 88.28 (14.72 - 575.24)

Table 2. AP and ML Planes of Accelerometer-Derived Sway Metrics for Each Test Condition

Sensor variable-plane

STO

Mean ± SD (min - max)

SO: standing in a double stance; STO: semi-tandem stance; TO: tandem stance; SL: single-leg stance; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

RMS-AP

6.79 ± 1.56 (4.14 - 14.73)

7.59 ± 2.39 (4.79 - 25.31)

8.31 ± 2.32 (4.49 - 17.50)

16.43 ± 8.44 (6.99 - 43.68)

RANGE-AP

47.49 ± 22.84 (27.30 - 217.04)

54.61 ± 36.99 (30.23 - 340.39)

56.41 ± 18.85 (27.64 - 126.31)

132.22 ± 88.60 (43.84 - 513.53)

SD-AP

1,827.48 ± 442.49 (155.36 - 4,125.70)

2,051.46 ± 539.91 (1,247.46 - 5,208.08)

2,265.73 ± 675.61 (128.78 - 4,718.57)

3,664.93 ± 1,697.59 (263.45 - 10,243.82)

SA-AP

105.44 ± 23.84 (9.64 - 216.12)

117.38 ± 29.28 (75.57 - 287.88)

129.16 ± 37.58 (7.45 - 270.44)

203.91 ± 95.40 (16.64 - 562.37)

RMS-ML

6.42 ± 1.26 (3.98 - 11.74)

7.15 ± 2.32 (3.98 - 26.42)

8.13 ± 2.24 (4.61 - 21.80)

16.92 ± 9.16 (6.79 - 50.78)

RANGE-ML

44.34 ± 18.19 (23.00 - 162.58)

51.20 ± 36.15 (23.00 - 368.64)

55.70 ± 20.72 (27.48 - 164.75)

138.77 ± 95.19 (41.48 - 463.85)

SD-ML

1,715.77 ± 371.94 (172.02 - 3,150.02)

1,920.74 ± 476.83 (1,041.54 - 5,113.17)

2,220.84 ± 638.73 (151.54 - 6,118.31)

3,715.43 ± 1,062.16 (224.74 - 10,440.58)

SA-ML

99.93 ± 20.21 (10.87 - 183.46)

110.64 ± 26.26 (63.68 - 285.77)

126.48 ± 35.79 (8.49 - 344.33)

205.56 ± 88.28 (14.72 - 575.24)

**Table 3.** AP and ML Planes of Gyroscope-Derived Sway Metrics for Each Test Condition
Sensor variable-plane	SO	STO	TO	SL
ST: standing in a double stance; STO: semi-tandem stance; TO: tandem stance; SL: single-leg stance; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.
RMS-AP	13.76 ± 6.60 (6.60 - 37.87)	15.89 ± 7.80 (6.60 - 57.53)	18.08 ± 7.53 (7.38 - 49.57)	48.52 ± 38.48 (13.33 - 221.85)
RANGE-AP	100.68 ± 77.87 (35.78 - 428.28)	123.64 ± 106.13 (35.78 - 809.96)	131.41 ± 79.71 (404.35 - 479.31)	368.33 ± 314.66 (91.81 - 2,030.45)
SD-AP	3,927.88 ± 1,702.50 (278.63 - 10,457.95)	4,480.53 ± 1,812.35 (1,965.70 - 11,185.88)	5,176.23 ± 2,027.73 (309.03 - 14,579.99)	10,358.00 ± 5,467.50 (1,805.89 - 29,778.82)
SA-AP	209.19 ± 91.48 (15.20 - 549.83)	237.03 ± 96.96 (108.02 - 604.03)	274.22 ± 109.74 (16.39 - 755.50)	542.40 ± 288.58 (98.16 - 1,608.70)
RMS-ML	12.31 ± 6.84 (5.91 - 52.28)	18.07 ± 14.11 (5.91 - 116.08)	25.48 ± 13.57 (7.41 - 88.73)	64.98 ± 39.69 (16.49 - 193.58)
RANGE-ML	94.32 ± 90.73 (33.13 - 665.48)	141.74 ± 166.90 (36.20 - 1,265.98)	182.92 ± 115.91 (43.99 - 720.27)	467.52 ± 324.89 (124.74 - 1,944.65)
SD-ML	3,452.58 ± 1,618.41 (212.47 - 13,451.28)	4,989.07 ± 2,760.91 (1,712.87 - 19,905.53)	7,346.36 ± 3,819.67 (566.10 - 25,711.87)	15,186.71 ± 7,620.50 (1,418.84 - 42,005.72)
SA-ML	180.95 ± 81.34 (11.95 - 681.07)	258.82 ± 140.16 (93.46 - 1,024.37)	378.90 ± 195.82 (29.87 - 1,339.51)	778.13 ± 391.17 (76.09 - 2,170.28)

Table 3. AP and ML Planes of Gyroscope-Derived Sway Metrics for Each Test Condition

Sensor variable-plane

STO

Mean ± SD (min - max)

ST: standing in a double stance; STO: semi-tandem stance; TO: tandem stance; SL: single-leg stance; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

RMS-AP

13.76 ± 6.60 (6.60 - 37.87)

15.89 ± 7.80 (6.60 - 57.53)

18.08 ± 7.53 (7.38 - 49.57)

48.52 ± 38.48 (13.33 - 221.85)

RANGE-AP

100.68 ± 77.87 (35.78 - 428.28)

123.64 ± 106.13 (35.78 - 809.96)

131.41 ± 79.71 (404.35 - 479.31)

368.33 ± 314.66 (91.81 - 2,030.45)

SD-AP

3,927.88 ± 1,702.50 (278.63 - 10,457.95)

4,480.53 ± 1,812.35 (1,965.70 - 11,185.88)

5,176.23 ± 2,027.73 (309.03 - 14,579.99)

10,358.00 ± 5,467.50 (1,805.89 - 29,778.82)

SA-AP

209.19 ± 91.48 (15.20 - 549.83)

237.03 ± 96.96 (108.02 - 604.03)

274.22 ± 109.74 (16.39 - 755.50)

542.40 ± 288.58 (98.16 - 1,608.70)

RMS-ML

12.31 ± 6.84 (5.91 - 52.28)

18.07 ± 14.11 (5.91 - 116.08)

25.48 ± 13.57 (7.41 - 88.73)

64.98 ± 39.69 (16.49 - 193.58)

RANGE-ML

94.32 ± 90.73 (33.13 - 665.48)

141.74 ± 166.90 (36.20 - 1,265.98)

182.92 ± 115.91 (43.99 - 720.27)

467.52 ± 324.89 (124.74 - 1,944.65)

SD-ML

3,452.58 ± 1,618.41 (212.47 - 13,451.28)

4,989.07 ± 2,760.91 (1,712.87 - 19,905.53)

7,346.36 ± 3,819.67 (566.10 - 25,711.87)

15,186.71 ± 7,620.50 (1,418.84 - 42,005.72)

SA-ML

180.95 ± 81.34 (11.95 - 681.07)

258.82 ± 140.16 (93.46 - 1,024.37)

378.90 ± 195.82 (29.87 - 1,339.51)

778.13 ± 391.17 (76.09 - 2,170.28)

**Table 4.** Spearmen’s Rho Correlation Coefficient of Accelerometer Compared With Gyroscope Derived From Inertial Measurement Unit
Sensor variable	Correlation coefficient
RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.
RMS-AP	0.81	< 0.001
RMS-ML	0.86	< 0.001
RANGE-AP	0.82	< 0.001
RANGE-ML	0.84	< 0.001
SD-AP	0.79	< 0.001
SD-ML	0.85	< 0.001
SA-AP	0.79	< 0.001
SA-ML	0.85	< 0.001

Table 4. Spearmen’s Rho Correlation Coefficient of Accelerometer Compared With Gyroscope Derived From Inertial Measurement Unit

Sensor variable

Correlation coefficient

P-value

RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

RMS-AP

0.81

< 0.001

RMS-ML

0.86

< 0.001

RANGE-AP

0.82

< 0.001

RANGE-ML

0.84

< 0.001

SD-AP

0.79

< 0.001

SD-ML

0.85

< 0.001

SA-AP

0.79

< 0.001

SA-ML

0.85

< 0.001

**Table 5.** ICC of Accelerometer Compared With Gyroscope Derived From Inertial Measurement Unit
Sensor variable	ICC
ICC: intraclass correlation coefficient; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.
RMS-AP	0.58	0.55	0.65	< 0.001
RMS-ML	0.54	0.45	0.62	< 0.001
RANGE-AP	0.64	0.56	0.70	< 0.001
RANGE-ML	0.60	0.52	0.67	< 0.001
SD-AP	0.63	0.56	0.70	< 0.001
SD-ML	0.50	0.39	0.59	< 0.001
SA-AP	0.65	0.58	0.71	< 0.001
SA-ML	0.52	0.42	0.60	< 0.001

Table 5. ICC of Accelerometer Compared With Gyroscope Derived From Inertial Measurement Unit

Sensor variable

ICC

ICC_(2,1)

Lower 95%

Upper 95%

P-value

ICC: intraclass correlation coefficient; RMS: root mean square of magnitude; RANGE: summation of the range of signals; SA: sway area; SD: summation of distance; AP: anteroposterior; ML: mediolateral.

RMS-AP

0.58

0.55

0.65

< 0.001

RMS-ML

0.54

0.45

0.62

< 0.001

RANGE-AP

0.64

0.56

0.70

< 0.001

RANGE-ML

0.60

0.52

0.67

< 0.001

SD-AP

0.63

0.56

0.70

< 0.001

SD-ML

0.50

0.39

0.59

< 0.001

SA-AP

0.65

0.58

0.71

< 0.001

SA-ML

0.52

0.42

0.60

< 0.001