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Effect of age on functional anthropometry of older Mexican American adults: a cross-sectional study
International Journal of Industrial Ergonomics 32 (2003) 39–49
Effect of age on functional anthropometry of older Mexican American adults: a cross-sectional study Arunkumar Pennathura,*, Winifred Dowlingb b
a Mechanical and Industrial Engineering Department, University of Texas at El Paso, El Paso, TX 79968-0521, USA Aging Services Administration, Department of Community and Human Development, City of El Paso, El Paso, TX 79901, USA
Received 8 October 2002; received in revised form 4 December 2002; accepted 11 February 2003
Abstract Overall goal of the research reported in this paper was to determine if, and to what extent, age affects functional anthropometry of older Mexican American adults. Primary objectives were: (1) to determine if age affects limiting functional outer fingertip and grip reaches, for women and men separately; and (2) to determine, through a crosssectional comparison, if functional anthropometric measures of older Mexican American females and males are different from a younger group of Mexican American females and males. Determining through factor analysis, a smaller number of explanatory factors from 15 different observed functional anthropometric measures observed was a secondary objective. Older Mexican American women and men, aged 60–85, recruited from Senior Centers in El Paso, and young Mexican American adults, aged 20–29, recruited for the study from the student body at the University of Texas at El Paso, were participants in the study. Stature, several vertical fingertip and grip reaches, and several horizontal fingertip and grip reaches, among other dimensions, were measured. Linear regression models were fit for older women and men separately, with age as the independent variable and functional anthropometric dimensions as dependent variables. Two-sample t-tests were conducted to analyze cross-sectional differences between the older and young Mexican American females, and older and young Mexican American males. Regression analysis results show a significant linear relationship between age and sitting height for females (po0:05), and stature (po0:05) and sitting height (po0:05) for males. Cross-sectional two-sample t-tests show statistically that older Mexican American female stature, vertical fingertip reach, vertical reach angle, sitting height, horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal reach angle, horizontal grip reaches (lateral, and at 0 and 90 ), mean grip diameter, and finger angle, are significantly different from Mexican American young females. Stature, vertical fingertip and grip reaches, vertical reach angle, sitting height and horizontal reach angle are significantly different between older and young Mexican American males. None of the horizontal reaches were significantly different for males. Overall, functional reach differences in Mexican American women were found to be more pronounced than functional reach differences in Mexican American men. Relevance to industry Functional anthropometry affects functional performance of older persons, both in work settings, and in activities of daily living. Engineering designers, particularly, product designers and engineers in the housing industry, need to
*Corresponding author. Tel.: +1-915-747-7988; fax: +1-915-747-5019. E-mail address: [email protected] (A. Pennathur). 0169-8141/03/$ - see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0169-8141(03)00028-3
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consider functional anthropometry of older persons when designing daily living environments and products of daily use for older users. r 2003 Elsevier Science B.V. All rights reserved. Keywords: Older Mexican Americans; Functional anthropometry; Reach dimensions
1. Introduction Older Mexican American women and men report higher degrees of functional limitations in activities of daily living compared to other older adult populations, including older Whites, African Americans, and other Hispanic older adult groups (Markides et al., 1989, 1997, 2001; De Arellano, 1994; Pennathur et al., 2003). While there is clear evidence of limitations in performing daily living functions among older Mexican American women and men from self-reports, there is little documentation on older Mexican American anthropometric functional reaches. There is anthropometry data (mostly static anthropometric dimensions), on several older population groups in the world. Smith et al. (2000) contains data on older adult anthropometry from all over the world. However, anthropometric reach profiles of older Mexican Americans are non-existent. Based on a survey of functional anthropometry, this paper reports findings from a cross-sectional study of reach abilities of older Mexican Americans and compares older adult reach abilities with a younger cohort of Mexican American adults.
2. Materials and methods 2.1. Study participants Older Mexican Americans aged 60–85 were recruited from Senior Centers in the City of El Paso. The number of older women in the study varied from 42 for some dimensions to 106 for other dimensions. The number of older men in the study varied from 16 for some dimensions to 40 for other dimensions. All older persons, who participated in this study lived independently in their own homes, were of sound health, and did
not report any major medical problems. Older participants did not use walkers, wheelchairs or canes for improved mobility. A younger group of Mexican Americans aged 20–29 was recruited from the student body at the University of Texas at El Paso. The number of young females in the study varied from 4 for some dimensions to 19 for others, while the number of young males varied from 18 for some dimensions to 33 for others. All participants signed informed consent forms approved by the Institutional Review Board at the University of Texas at El Paso. All participants in the study were provided token complimentary gifts from the University of Texas at El Paso for participation. 2.2. Experimental methods 2.2.1. Equipment used Anthropometric dimensions were measured with a Swiss-made GPM anthropometer #101 and the Lafayette Instrument Company’s #J00200 goniometers. For measurement of older persons, all measuring instruments were transported to the senior centers for data collection. The younger group was measured in the research laboratory at the University of Texas at El Paso. Sitting height and all horizontal reach measurements were made with subjects in a seated position. Subjects were seated in a chair with a flat seat pan positioned 40 cm from the floor level and backrest positioned 17 cm vertically from seat pan. The backrest was 40 cm in height. No adjustments were made to chair dimensions during the study. A radial scale with different radial degree markings in increments of 10 was used as a reference scale for horizontal reach measurements. A plumb bob attached to the end of a small chain as described by Asfour et al. (1978) was used align the arm to the radial scale.
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2.2.2. Protocol for measurements Anthropometric measurements obtained from this study (illustrated in Figs. 1 and 2) are based on protocols as outlined primarily in Wright et al. (1997), and also in Pheasant (1996), Roebuck, (1995) and Smith et al. (2000). All participants were provided adequate rest (self-determined as and when needed) between measurements to minimize effect of static fatigue. Stature was measured from a level floor to the crown on the head. Participants were instructed to stand with their backs and shoulders against a wall
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and the palms of their hands facing the sides. Standing with feet slightly apart, and feet firmly planted on the ground, participants were asked to inhale while stature was measured using an anthropometer. While standing in the same position used for stature, the distance from floor to tip of the third finger of the extended arm was measured as the Vertical Fingertip Reach. Vertical Grip Reach was measured as the same distance as for vertical fingertip reach, except that the participant was now instructed to grip a pointer. While measuring
K
P C
H
E
D
G
L
O M
J B
N F
I A
Q
Fig. 1. Horizontal functional anthropometric dimensions compared between young and older Mexican American adults. Explanation of symbols: (A) Sitting height for older adults. (B)Horizontal fingertip reach at 0 for older adults. (C) Horizontal fingertip reach at 90 for older adults. (D) Horizontal lateral fingertip reach for older adults. (E) Horizontal lateral reach angle for older adults. (F) Horizontal grip reach at 0 for older adults. (G) Horizontal lateral grip reach for older adults. (H) Horizontal grip reach at 90 for older adults. (I) Sitting height for young adults. (J) Horizontal fingertip reach at 0 for young adults. (K) Horizontal fingertip reach at 90 for young adults. (L) Horizontal lateral fingertip reach for young adults. (M) Horizontal lateral reach angle for young adults. (N) Horizontal grip reach at 0 for young adults. (O) Horizontal lateral grip reach for young adults. (P) Horizontal grip reach at 90 for young adults. (Q) Sitting pan height.
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G
C
F
J A
E
B
I
H
D
Fig. 2. Vertical functional anthropometric dimensions compared between young and older Mexican American adults. Explanation of symbols: (A) Stature of older adults. (B) Vertical fingertip reach of older adults. (C) Vertical reach angle of older adults. (D) Step height of older adults. (E) Stature of young adults. (F) Vertical fingertip reach of young adults. (G) Vertical reach angle of young adults. (H) Step height of young adults. (I) Vertical grip reach of older adults. (J) Vertical grip reach of young adults.
vertical grip reach, the angle between the raised arm and the longitudinal axis of the body was measured as the Vertical Reach Angle. For all vertical reach measurements, participants were instructed to use their dominant arm, and flex their shoulders in the sagittal plane. Participants also fully extended their elbows and fingers and kept their wrists in a pronated, neutral position. Sitting Height was measured as the distance from the sitting surface to the crown of the head (Roebuck, 1995). Participants sat erect in the chair with backs and shoulders against the backrest of the chair, and looked straight ahead when sitting height was measured. Horizontal Fingertip Reach at 90 , was measured in a sitting position as the distance between the center of the radial scale and the tip of the third finger. Horizontal Fingertip Reach at 0 was measured similar to horizontal fingertip reach at 90 , except that participants were instructed to
move the arm to zero degrees. Horizontal Lateral Fingertip Reach was measured in the same manner as horizontal fingertip reach at 90 , but participants were required to move the arm as far as possible in adduction across the front of the body. Horizontal Lateral Reach Angle was measured as the angle between the position of the arm at horizontal lateral fingertip reach and 0 . Horizontal Grip Reach at 90 and 0 , and horizontal lateral grip reach, were measured similar to horizontal fingertip reaches at 90 and 0 , and horizontal lateral fingertip reach respectively, except that participants were instructed to grip a pointer (Wright et al., 1997). The circumference made when the end of the thumb touches the end of the middle finger was measured as the maximum grip diameter (Pheasant, 1996). The angle made by the index finger when it gradually bends for a period of 3 s was measured as the finger angle (Wright et al., 1997). The distance
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from a level floor to the bottom of the raised preferred foot was measured as the maximum step height when ascending. 2.2.3. Data analyses All functional anthropometry dimensions measured in this study were separated by males and females. Descriptive statistics, including means and standard deviations were calculated for every dimension for older and young males and females separately. To determine the cross-sectional effect of age on functional anthropometric dimensions for older persons measured in this study, linear regression models were fit to male and female data separately. Age was the independent variable; the dependent variables in the analysis were stature, sitting height, step height, vertical fingertip reach, vertical reach angle, horizontal grip reach at 0 and 90 , and horizontal fingertip reaches at 0 and 90 . To enable cross-sectional comparison of older persons’ dimensions with the young, a two-sample t-test (with an assumption of unequal variances, due to different sample sizes) was conducted, in addition to generation of 95% confidence intervals for differences in mean dimensions between the older persons and the young. A factor analysis
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using the principal components method (using an initial communality estimate of 1), for females and males separately was performed to extract important functional anthropometric measures from among 15 anthropometric variables collected in this study. Minitab Release 13 for Windows was used to generate all descriptive statistics and perform the regression analyses and all comparisons and the factor analysis.
3. Results Table 1 presents descriptive anthropometric statistics of older and young Mexican American women who participated in this study. Older and young male anthropometric characteristics are presented in Table 2. Results from the regression analysis for older females is presented in Table 3. Table 4 presents results from regression analysis for older males. Results from the two-sample t-test comparing older and young women, and older and young men are reported in Tables 5 and 6 respectively. Tables 7 and 8 present results of factor analyses for older females and older males respectively for 15 different anthropometric variables collected. Tables 9 and 10 present the
Table 1 Summary anthropometry statistics for older and younger Mexican American women Anthropometric dimension
Stature (cm) Vertical fingertip reach (cm) Vertical grip reach (cm) Vertical reach angle (deg) Sitting height (cm) Horizontal fingertip reach at 90 (cm) Horizontal fingertip reach at 0 (cm) Horizontal lateral fingertip reach (cm) Horizontal lateral reach angle (deg) Horizontal grip reach at 90 (cm) Horizontal grip reach at 0 (cm) Horizontal lateral grip reach (cm) Maximum grip diameter (cm) Finger angle (deg) Maximum step height ascending (cm)
Older women
Young women
Mean
Standard deviation
Mean
Standard deviation
152.57 (n ¼ 106) 180.69 (n ¼ 106) 167.41 (n ¼ 42) 142.79 (n ¼ 106) 75.66 (n ¼ 42) 64.04 (n ¼ 106) 65.74 (n ¼ 106) 64.96 (n ¼ 106) 27.93 (n ¼ 106) 53.05 (n ¼ 42) 54.03 (n ¼ 42) 54.39 (n ¼ 42) 3.972 (n ¼ 42) 77.21 (n ¼ 42) 28.15 (n ¼ 42)
9.89 15.16 20.39 21.54 3.88 3.53 7.82 4.99 16.27 4.01 4.09 3.72 5.96 12.67 8.12
161.36 (n ¼ 19) 199.52 (n ¼ 19) 170.8 (n ¼ 4) 176.87 (n ¼ 19) 127.85 (n ¼ 4) 67.87 (n ¼ 19) 68.97 (n ¼ 19) 68.60 (n ¼ 19) 40.20 (n ¼ 19) 58.74 (n ¼ 4) 58.81 (n ¼ 4) 58.56 (n ¼ 4) 42.75 (n ¼ 4) 98.8 (n ¼ 4) 33.67 (n ¼ 4)
4.52 6.01 49.1 7.5 1.83 3.20 3.23 3.56 11.0 1.26 1.43 1.13 1.71 10.5 5.15
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Table 2 Summary anthropometry statistics for older and younger Mexican American men Anthropometric dimension
Older men
Stature (cm) Vertical fingertip reach (cm) Vertical grip reach (cm) Vertical reach angle (deg) Sitting height (cm) Horizontal fingertip reach at 90 (cm) Horizontal fingertip reach at 0 (cm) Horizontal lateral fingertip reach (cm) Horizontal lateral reach angle (deg) Horizontal grip reach at 90 (cm) Horizontal grip reach at 0 (cm) Horizontal lateral grip reach (cm) Maximum grip diameter (cm) Finger angle (deg) Maximum step height ascending (cm)
Mean
Standard deviation
Mean
Standard deviation
166.43 (n ¼ 40) 193.1(n ¼ 40) 180.9 (n ¼ 16) 136.3 (n ¼ 40) 80.09 (n ¼ 16) 69.91 (n ¼ 40) 70.94 (n ¼ 40) 70.36 (n ¼ 40) 23.30 (n ¼ 40) 57.28 (n ¼ 16) 58.57 (n ¼ 16) 58.87 (n ¼ 16) 41.56 (n ¼ 16) 80.3 (n ¼ 16) 36.24 (n ¼ 16)
7.90 24.1 24.2 26.3 3.33 4.58 4.45 4.41 9.11 4.35 3.85 4.13 5.08 12.5 8.54
175.67 (n ¼ 33) 214.2 (n ¼ 33) 201.32 (n ¼ 18) 168.9 (n ¼ 33) 130.56 (n ¼ 18) 70.87 (n ¼ 33) 70.88 (n ¼ 33) 71.00 (n ¼ 33) 34.00 (n ¼ 33) 60.71 (n ¼ 18) 60.76 (n ¼ 18) 60.72 (n ¼ 18) 42.11 (n ¼ 18) 100.9 (n ¼ 18) 35.8 (n ¼ 18)
7.64 11.2 7.85 30.8 2.49 5.59 5.31 5.22 9.89 5.83 5.79 5.75 5.83 16.6 11.2
Table 3 Results from regression analysis (age as independent variable) for older Mexican American women. Dependent variable
Stature (n ¼ 106) Sitting height (n ¼ 42) Maximum step height (ascending) (n ¼ 42) Vertical fingertip reach (n ¼ 106) Vertical reach angle (n ¼ 106) Horizontal grip reach at 0 (n ¼ 42) Horizontal grip reach at 90 (n ¼ 42) Horizontal fingertip reach at 0 (n ¼ 106) Horizontal fingertip reach at 90 (n ¼ 106) Horizontal lateral fingertip reach (n ¼ 106) Horizontal reach angle (n ¼ 106) a b
Significant at the 10% level. Significant at the 5% level.
p-Value
0.052a 0.0280b 0.7948 0.423 0.486 0.8765 0.7542 0.671 0.394 0.439 0.554
Young men
Model for significant variables (age) 168–0.206 90.889–0.210
Table 4 Results from regression analysis (age as independent variable) for older Mexican American men Dependent variable
p-Value
Model for significant variables (age)
Stature (n ¼ 40) Sitting height (n ¼ 16) Maximum step height (ascending) (n ¼ 16) Vertical fingertip reach (n ¼ 40) Vertical reach angle (n ¼ 40) Horizontal grip reach at 0 (n ¼ 16) Horizontal grip reach at 90 (n ¼ 16) Horizontal fingertip reach at 0 (n ¼ 40) Horizontal fingertip reach at 90 (n ¼ 40) Horizontal lateral fingertip reach (n ¼ 40) Horizontal reach angle (n ¼ 40)
0.015a 0.0248a 0.0679b
194–0.371 99.127–0.246 77.130–0.529
a b
Significant at the 5% level. Significant at the 10% level.
0.663 0.067b 0.2021
207–0.946
0.2618 0.286 0.451 0.625 0.027a
52.7–0.392
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Table 5 Cross-sectional comparison of functional anthropometry of older and young women Anthropometric dimension
Estimate of difference in means
95% confidence interval for difference in means
p-Value
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach at 90 Horizontal fingertip reach at 0 Horizontal lateral fingertip reach Horizontal lateral reach angle Horizontal grip reach at 90 Horizontal grip reach at 0 Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
8.79 18.83 3.3 34.08 52.19 3.830 3.23 3.643 12.28 5.689 4.783 4.165 3.03 21.54 5.52
(11.62, 5.95) (22.86, 14.81) (82.0, 75.4) (39.47, 28.69) (54.87, 49.51) (5.497, 2.163) (5.35, 1.11) (5.580, 1.705) (18.35, 6.22) (7.654, 3.723) (6.939, 2.627) (5.938, 2.392) (5.77, 0.30) (39.42, 3.65) (13.47, 2.43)
0.000n 0.000n 0.901 0.000n 0.000n 0.000n 0.003* 0.001n 0.000n 0.000n 0.001n 0.000n 0.032n 0.031n 0.126
n
Significance at the 5% significance level.
Table 6 Cross-sectional comparison of functional anthropometry of older and young men Anthropometric dimension
Estimate of difference in means
95% confidence interval for difference in means
p-Value
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach at 90 Horizontal fingertip reach at 0 Horizontal lateral fingertip reach Horizontal lateral reach angle Horizontal grip reach at 90 Horizontal grip reach at 0 Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
9.24 21.14 20.41 32.65 50.46 0.96 0.07 0.64 10.71 3.42 2.18 1.86 0.55 20.58 0.45
(12.88, 5.60) (29.71, 12.57) (33.77, 7.05) (46.20, 19.09) (52.56, 48.37) (3.38, 1.47) (2.25, 2.39) (2.94, 1.65) (15.19, 6.22) (7.00, 0.15) (5.60, 1.23) (5.34, 1.62) (4.37, 3.27) (30.82, 10.33) (6.46, 7.37)
0.000n 0.000n 0.005n 0.000n 0.000n 0.433 0.953 0.576 0.000n 0.060 0.201 0.285 0.771 0.000n 0.895
n
Significance at the 5% significance level.
equations which estimate the common factors after performance of a varimax rotation for older Mexican American females and males, respectively. Regression analysis results indicate that for older women, age had a significant effect on stature (po0:10) and sitting height (po0:05). For
older men, age had a significant effect on stature (po0:05), sitting height (po0:05), maximum step height (ascending) (po0:1), and vertical and horizontal reach angles (po0:1). Results from cross-sectional comparisons of older and younger adults indicate that, for women (Table 5), stature, vertical fingertip reach, vertical
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Table 7 Factor analysis results for older females (for 42 complete cases
Table 8 Factor analysis results for older males (for 16 complete cases)
Factor
Eigenvalue Percent of variance
Factor
Eigenvalue Percent of variance
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
6.70678 2.65997
44.712 17.733
44.712 62.445
7.77697 3.01935
51.846 20.129
51.846 71.975
1.53273 1.03446 0.705155 0.550227
10.218 6.896 4.701 3.668
72.663 79.560 84.261 87.929
1.36987 0.919638 0.735635 0.424471
9.132 6.131 4.904 2.830
81.108 87.239 92.143 94.973
0.52092
3.473
91.402
0.371818
2.479
97.452
0.422376
2.816
94.217
0.13665
0.911
98.363
0.32817
2.188
96.405
0.116108
0.774
99.137
0.193276
1.289
97.694
0.0572674
0.382
99.519
0.167712
1.118
98.812
0.0405932
0.271
99.789
0.0828623
0.552
99.364
0.0192461
0.128
99.917
0.0586136
0.391
99.755
0.00757069
0.050
99.968
0.0203785 0.0163789
0.136 0.109
99.891 100.000
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.00415196 0.028 0.000660319 0.004
99.996 100.000
Cumulative percentage of variance
reach angle, sitting height, horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal lateral reach angle, horizontal grip reaches at 0 and 90 , horizontal lateral grip reach, maximum grip diameter, and finger angle, of older Mexican American women are significantly different (po0:05) from young Mexican American women. Vertical grip reach and maximum step height (ascending) are the only measures not significantly different. Results for older Mexican American men (Table 6) indicate that stature, vertical fingertip reach, vertical grip reach, vertical reach angle, sitting height, horizontal lateral reach angle, and finger angle are significantly different (po0:05) from young Mexican American men. Horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal grip reaches at 0 and 90 , horizontal lateral grip reach, maximum grip diameter, and maximum
Cumulative percentage of variance
step height (ascending) were all not significantly different between older and young adults. Factor analyses of 15 different anthropometric variables for older Mexican American females extracted 4 factors of the 15 accounting for almost 80% of the variability in the original data. For older Mexican American males, 3 extracted factors of the 15 account for almost 81% of the variability in the original data. This indicates that a few explanatory anthropometric factors (represented by the weighted equations presented in Tables 9 and 10) sufficiently explain changes in functional anthropometric variables considered in this study.
4. Discussion The objective of this cross-sectional study was to determine if age affected functional reach abilities
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Table 9 Estimated coefficients for factor loading matrix for the 4 extracted factors after Varimax rotation for older females Variable
Factor 1
Factor 2
Factor 3
Factor 4
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.815224 0.22628 0.16061 0.234899 0.806584 0.921324 0.916164 0.882966 0.0539708 0.789292 0.771213 0.821117 0.581594 0.249134 0.0227186
0.0154666 0.927983 0.888662 0.889967 0.0693527 0.124352 0.0692387 0.0974683 0.167266 0.00119475 0.0291124 0.0133408 0.21245 0.196894 0.207233
0.078879 0.0972219 0.024948 0.0407608 0.174761 0.032756 0.133888 0.250031 0.792897 0.458704 0.53467 0.445572 0.0993725 0.677575 0.0937046
0.0297349 0.0721374 0.00584728 0.11301 0.0722901 0.0146644 0.0522189 0.0809303 0.253281 0.0151266 0.109628 0.170305 0.428873 0.117883 0.906277
Table 10 Estimated equations for common factors after Varimax rotation for older males Variable
Factor 1
Factor 2
Factor 3
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.881003 0.237362 0.237445 0.0287613 0.700905 0.899204 0.932431 0.936723 0.237916 0.934236 0.950445 0.977532 0.426653 0.287306 0.590398
0.342178 0.929802 0.91917 0.929726 0.425883 0.0104974 0.17678 0.126318 0.473211 0.0180027 0.0355258 0.0130948 0.320454 0.377005 0.15451
0.181313 0.0941756 0.103881 0.21018 0.243584 0.371438 0.106897 0.024903 0.730804 0.223694 0.244406 0.14556 0.283513 0.549072 0.247777
of older Mexican Americans females and males. Two approaches were used in studying this objective—a regression analysis of age versus functional reaches for older Mexican Americans, and a cross-sectional two-sample comparison of functional anthropometry of older Mexican Americans with a group of young Mexican American adults. Regression results show that age affects stature and sitting height for both older female and male
Mexican American adults. Cross-sectional comparisons between older females and the younger female cohort show that in addition to stature and sitting height, most horizontal and vertical fingertip reaches are significantly different for females. While cross-sectional differences between younger and older Mexican American females are pronounced, regression analyses indicate that, in older women, age affects stature and sitting height the most; other horizontal and vertical fingertip
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reaches that show significant differences in the cross-sectional analyses are not significantly affected by age. When viewed in unison, this is initial indication that after a certain age, functional anthropometry, for older Mexican American females, is not influenced by their age. A similar pattern is evident for men, although age seems to significantly affect more functional dimensions than in older women—for older men, not only are stature and sitting height significantly affected by age, but, also maximum step height, and vertical and horizontal reach angles. This is a significant finding with respect to the older Mexican American adult population, and should be included in models of disablement process in older Mexican American adults. A possible explanation for this pattern could be the cultural and social factors that mediate pathways to disability in older Mexican American adults. A majority of older Mexican American women surveyed in this study still perform active household duties that require significant reaching for task initiation, completion and performance—it is, therefore, reasonable to expect that functional reaches among older Mexican American women may not show a decrease with age. Our study suggests that older Mexican American men may be at a greater risk of developing disability in the older years perhaps due their sedentary lifestyles after they retire from work, compared to older Mexican American women. Comparison of functional anthropometry of older Mexican American adults with functional anthropometry of other older adult groups can help explain differences in disability levels between older adult groups, and help understand and model pathways to disability among older adults. The present study is cross-sectional and can only detect inter-individual and cohort differences due to aging at a specific point in time. This study does not measure intra-individual decline in study variables over a period of time. In addition, cross-sectional comparisons in this study with the younger female and male cohorts is limited by the sample sizes for young females and males. Also, the present study was based on a convenience sample of older adults who visit senior recreation centers. Hence, older Mexican American adults
who do not have an opportunity to visit senior recreation centers either due to disability or due to a lack of availability of transportation, were not included in the study—their functional anthropometry decline and the consequent effect on task performance in activities of daily living can be an important aspect in the disablement model development process.
5. Conclusions Accommodating age related changes in functional reach abilities is vital for increasing functional independence of older adults. It is important for engineering designers, especially, product designers, and designers in the housing and construction industries to consider functional capabilities and limitations of older adults when designing products of daily use, and daily living environments. Self-reported performance indicators for activities of daily living show that older Mexican Americans report greater levels of difficulty in performing activities of daily living, especially in tasks that involve reaching for task initiation, performance and completion, than any other older adult group in the United States. This difficulty may be mediated not only by various physical impairments, and psychological and social factors, but, also with environmental factors including workspace design variables, and with inherent declines in functional performance abilities. A better understanding of the mechanisms underlying this decline, and quantification of this decline with age, will result in better products and design for the older adult.
Acknowledgements The authors thank all participants in this study. The authors are grateful to Elvia Martinez, and Gustavo Fierro, for assistance with data collection activities. The authors thank Dr. Julia Bader in the Statistical Consulting Laboratory at the University of Texas at El Paso for assistance with statistical analyses. The authors also thank Rohini Magham for assistance with data compilation.
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References Asfour, S., Ayoub, M.M., Mital, A., Bethea, N., 1978. Reach profiles for males and females under restrained and unrestrained conditions. In: Human Factors Society (Ed.), Proceedings of the Human Factors Society 22nd Annual Meeting. Michigan, Detroit, pp. 671–673. De Arellano, R.A.B., 1994. The elderly. In: Molina, C.W., Aguirre-Molina, M. (Eds.), Latino Health in the US: A Growing Challenge. American Public Health Association, Washington, DC, pp. 189–208. Markides, K.S., Coreil, J., Rogers, L.P., 1989. Aging and health among southwestern Hispanics. In: Markides, K.S. (Ed.), Aging and Health: Perspectives on Gender, Race, Ethnicity, and Class. Sage Publications, Newbury Park, CA, pp. 177–210. Markides, K.S., Rudkin, L., Angel, R.J., Espino, D.V., 1997. Health status of Hispanic elderly. In: Martin, L.J., Soldo, B. (Eds.), Racial and Ethnic Differences in the Health of Older Americans. National Academy Press, Washington, DC, pp. 285–300.
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Markides, K.S., Black, S.A., Ostir, G.V., Angel, R.J., Guralnik, J.M., Lichtenstein, M., 2001. Lower body function and mortality in Mexican American elderly people. Journal of Gerontology Medical Sciences. 56A, M243–M247. Pennathur, A., Sivasubramaniam, S., Contreras, L.R., 2003. Functional limitations in Mexican American elderly. International Journal of Industrial Ergonomics 31, 41–50. Pheasant, S., 1996. Bodyspace, 2nd Edition. Taylor & Francis, London, UK. Roebuck, J., 1995. Anthropometric Methods: Designing to Fit the Human Body. Human Factors and Ergonomics Society, Santa Monica, CA. Smith, S., Norris, B., Peebles, L. (Eds.), 2000. Older Adult Data: The Handbook of Measurements and Capabilities of the Older Adult. Institute for Occupational Ergonomics, University of Nottingham, Nottingham, United Kingdom. Wright, U., Govindaraju, M., Mital, A., 1997. Reach profiles of men and women 65 to 89 years of age. Experimental Aging Research. 23, 369–395.
Effect of age on functional anthropometry of older Mexican American adults: a cross-sectional study Arunkumar Pennathura,*, Winifred Dowlingb b
a Mechanical and Industrial Engineering Department, University of Texas at El Paso, El Paso, TX 79968-0521, USA Aging Services Administration, Department of Community and Human Development, City of El Paso, El Paso, TX 79901, USA
Received 8 October 2002; received in revised form 4 December 2002; accepted 11 February 2003
Abstract Overall goal of the research reported in this paper was to determine if, and to what extent, age affects functional anthropometry of older Mexican American adults. Primary objectives were: (1) to determine if age affects limiting functional outer fingertip and grip reaches, for women and men separately; and (2) to determine, through a crosssectional comparison, if functional anthropometric measures of older Mexican American females and males are different from a younger group of Mexican American females and males. Determining through factor analysis, a smaller number of explanatory factors from 15 different observed functional anthropometric measures observed was a secondary objective. Older Mexican American women and men, aged 60–85, recruited from Senior Centers in El Paso, and young Mexican American adults, aged 20–29, recruited for the study from the student body at the University of Texas at El Paso, were participants in the study. Stature, several vertical fingertip and grip reaches, and several horizontal fingertip and grip reaches, among other dimensions, were measured. Linear regression models were fit for older women and men separately, with age as the independent variable and functional anthropometric dimensions as dependent variables. Two-sample t-tests were conducted to analyze cross-sectional differences between the older and young Mexican American females, and older and young Mexican American males. Regression analysis results show a significant linear relationship between age and sitting height for females (po0:05), and stature (po0:05) and sitting height (po0:05) for males. Cross-sectional two-sample t-tests show statistically that older Mexican American female stature, vertical fingertip reach, vertical reach angle, sitting height, horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal reach angle, horizontal grip reaches (lateral, and at 0 and 90 ), mean grip diameter, and finger angle, are significantly different from Mexican American young females. Stature, vertical fingertip and grip reaches, vertical reach angle, sitting height and horizontal reach angle are significantly different between older and young Mexican American males. None of the horizontal reaches were significantly different for males. Overall, functional reach differences in Mexican American women were found to be more pronounced than functional reach differences in Mexican American men. Relevance to industry Functional anthropometry affects functional performance of older persons, both in work settings, and in activities of daily living. Engineering designers, particularly, product designers and engineers in the housing industry, need to
*Corresponding author. Tel.: +1-915-747-7988; fax: +1-915-747-5019. E-mail address: [email protected] (A. Pennathur). 0169-8141/03/$ - see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0169-8141(03)00028-3
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consider functional anthropometry of older persons when designing daily living environments and products of daily use for older users. r 2003 Elsevier Science B.V. All rights reserved. Keywords: Older Mexican Americans; Functional anthropometry; Reach dimensions
1. Introduction Older Mexican American women and men report higher degrees of functional limitations in activities of daily living compared to other older adult populations, including older Whites, African Americans, and other Hispanic older adult groups (Markides et al., 1989, 1997, 2001; De Arellano, 1994; Pennathur et al., 2003). While there is clear evidence of limitations in performing daily living functions among older Mexican American women and men from self-reports, there is little documentation on older Mexican American anthropometric functional reaches. There is anthropometry data (mostly static anthropometric dimensions), on several older population groups in the world. Smith et al. (2000) contains data on older adult anthropometry from all over the world. However, anthropometric reach profiles of older Mexican Americans are non-existent. Based on a survey of functional anthropometry, this paper reports findings from a cross-sectional study of reach abilities of older Mexican Americans and compares older adult reach abilities with a younger cohort of Mexican American adults.
2. Materials and methods 2.1. Study participants Older Mexican Americans aged 60–85 were recruited from Senior Centers in the City of El Paso. The number of older women in the study varied from 42 for some dimensions to 106 for other dimensions. The number of older men in the study varied from 16 for some dimensions to 40 for other dimensions. All older persons, who participated in this study lived independently in their own homes, were of sound health, and did
not report any major medical problems. Older participants did not use walkers, wheelchairs or canes for improved mobility. A younger group of Mexican Americans aged 20–29 was recruited from the student body at the University of Texas at El Paso. The number of young females in the study varied from 4 for some dimensions to 19 for others, while the number of young males varied from 18 for some dimensions to 33 for others. All participants signed informed consent forms approved by the Institutional Review Board at the University of Texas at El Paso. All participants in the study were provided token complimentary gifts from the University of Texas at El Paso for participation. 2.2. Experimental methods 2.2.1. Equipment used Anthropometric dimensions were measured with a Swiss-made GPM anthropometer #101 and the Lafayette Instrument Company’s #J00200 goniometers. For measurement of older persons, all measuring instruments were transported to the senior centers for data collection. The younger group was measured in the research laboratory at the University of Texas at El Paso. Sitting height and all horizontal reach measurements were made with subjects in a seated position. Subjects were seated in a chair with a flat seat pan positioned 40 cm from the floor level and backrest positioned 17 cm vertically from seat pan. The backrest was 40 cm in height. No adjustments were made to chair dimensions during the study. A radial scale with different radial degree markings in increments of 10 was used as a reference scale for horizontal reach measurements. A plumb bob attached to the end of a small chain as described by Asfour et al. (1978) was used align the arm to the radial scale.
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2.2.2. Protocol for measurements Anthropometric measurements obtained from this study (illustrated in Figs. 1 and 2) are based on protocols as outlined primarily in Wright et al. (1997), and also in Pheasant (1996), Roebuck, (1995) and Smith et al. (2000). All participants were provided adequate rest (self-determined as and when needed) between measurements to minimize effect of static fatigue. Stature was measured from a level floor to the crown on the head. Participants were instructed to stand with their backs and shoulders against a wall
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and the palms of their hands facing the sides. Standing with feet slightly apart, and feet firmly planted on the ground, participants were asked to inhale while stature was measured using an anthropometer. While standing in the same position used for stature, the distance from floor to tip of the third finger of the extended arm was measured as the Vertical Fingertip Reach. Vertical Grip Reach was measured as the same distance as for vertical fingertip reach, except that the participant was now instructed to grip a pointer. While measuring
K
P C
H
E
D
G
L
O M
J B
N F
I A
Q
Fig. 1. Horizontal functional anthropometric dimensions compared between young and older Mexican American adults. Explanation of symbols: (A) Sitting height for older adults. (B)Horizontal fingertip reach at 0 for older adults. (C) Horizontal fingertip reach at 90 for older adults. (D) Horizontal lateral fingertip reach for older adults. (E) Horizontal lateral reach angle for older adults. (F) Horizontal grip reach at 0 for older adults. (G) Horizontal lateral grip reach for older adults. (H) Horizontal grip reach at 90 for older adults. (I) Sitting height for young adults. (J) Horizontal fingertip reach at 0 for young adults. (K) Horizontal fingertip reach at 90 for young adults. (L) Horizontal lateral fingertip reach for young adults. (M) Horizontal lateral reach angle for young adults. (N) Horizontal grip reach at 0 for young adults. (O) Horizontal lateral grip reach for young adults. (P) Horizontal grip reach at 90 for young adults. (Q) Sitting pan height.
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42
G
C
F
J A
E
B
I
H
D
Fig. 2. Vertical functional anthropometric dimensions compared between young and older Mexican American adults. Explanation of symbols: (A) Stature of older adults. (B) Vertical fingertip reach of older adults. (C) Vertical reach angle of older adults. (D) Step height of older adults. (E) Stature of young adults. (F) Vertical fingertip reach of young adults. (G) Vertical reach angle of young adults. (H) Step height of young adults. (I) Vertical grip reach of older adults. (J) Vertical grip reach of young adults.
vertical grip reach, the angle between the raised arm and the longitudinal axis of the body was measured as the Vertical Reach Angle. For all vertical reach measurements, participants were instructed to use their dominant arm, and flex their shoulders in the sagittal plane. Participants also fully extended their elbows and fingers and kept their wrists in a pronated, neutral position. Sitting Height was measured as the distance from the sitting surface to the crown of the head (Roebuck, 1995). Participants sat erect in the chair with backs and shoulders against the backrest of the chair, and looked straight ahead when sitting height was measured. Horizontal Fingertip Reach at 90 , was measured in a sitting position as the distance between the center of the radial scale and the tip of the third finger. Horizontal Fingertip Reach at 0 was measured similar to horizontal fingertip reach at 90 , except that participants were instructed to
move the arm to zero degrees. Horizontal Lateral Fingertip Reach was measured in the same manner as horizontal fingertip reach at 90 , but participants were required to move the arm as far as possible in adduction across the front of the body. Horizontal Lateral Reach Angle was measured as the angle between the position of the arm at horizontal lateral fingertip reach and 0 . Horizontal Grip Reach at 90 and 0 , and horizontal lateral grip reach, were measured similar to horizontal fingertip reaches at 90 and 0 , and horizontal lateral fingertip reach respectively, except that participants were instructed to grip a pointer (Wright et al., 1997). The circumference made when the end of the thumb touches the end of the middle finger was measured as the maximum grip diameter (Pheasant, 1996). The angle made by the index finger when it gradually bends for a period of 3 s was measured as the finger angle (Wright et al., 1997). The distance
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from a level floor to the bottom of the raised preferred foot was measured as the maximum step height when ascending. 2.2.3. Data analyses All functional anthropometry dimensions measured in this study were separated by males and females. Descriptive statistics, including means and standard deviations were calculated for every dimension for older and young males and females separately. To determine the cross-sectional effect of age on functional anthropometric dimensions for older persons measured in this study, linear regression models were fit to male and female data separately. Age was the independent variable; the dependent variables in the analysis were stature, sitting height, step height, vertical fingertip reach, vertical reach angle, horizontal grip reach at 0 and 90 , and horizontal fingertip reaches at 0 and 90 . To enable cross-sectional comparison of older persons’ dimensions with the young, a two-sample t-test (with an assumption of unequal variances, due to different sample sizes) was conducted, in addition to generation of 95% confidence intervals for differences in mean dimensions between the older persons and the young. A factor analysis
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using the principal components method (using an initial communality estimate of 1), for females and males separately was performed to extract important functional anthropometric measures from among 15 anthropometric variables collected in this study. Minitab Release 13 for Windows was used to generate all descriptive statistics and perform the regression analyses and all comparisons and the factor analysis.
3. Results Table 1 presents descriptive anthropometric statistics of older and young Mexican American women who participated in this study. Older and young male anthropometric characteristics are presented in Table 2. Results from the regression analysis for older females is presented in Table 3. Table 4 presents results from regression analysis for older males. Results from the two-sample t-test comparing older and young women, and older and young men are reported in Tables 5 and 6 respectively. Tables 7 and 8 present results of factor analyses for older females and older males respectively for 15 different anthropometric variables collected. Tables 9 and 10 present the
Table 1 Summary anthropometry statistics for older and younger Mexican American women Anthropometric dimension
Stature (cm) Vertical fingertip reach (cm) Vertical grip reach (cm) Vertical reach angle (deg) Sitting height (cm) Horizontal fingertip reach at 90 (cm) Horizontal fingertip reach at 0 (cm) Horizontal lateral fingertip reach (cm) Horizontal lateral reach angle (deg) Horizontal grip reach at 90 (cm) Horizontal grip reach at 0 (cm) Horizontal lateral grip reach (cm) Maximum grip diameter (cm) Finger angle (deg) Maximum step height ascending (cm)
Older women
Young women
Mean
Standard deviation
Mean
Standard deviation
152.57 (n ¼ 106) 180.69 (n ¼ 106) 167.41 (n ¼ 42) 142.79 (n ¼ 106) 75.66 (n ¼ 42) 64.04 (n ¼ 106) 65.74 (n ¼ 106) 64.96 (n ¼ 106) 27.93 (n ¼ 106) 53.05 (n ¼ 42) 54.03 (n ¼ 42) 54.39 (n ¼ 42) 3.972 (n ¼ 42) 77.21 (n ¼ 42) 28.15 (n ¼ 42)
9.89 15.16 20.39 21.54 3.88 3.53 7.82 4.99 16.27 4.01 4.09 3.72 5.96 12.67 8.12
161.36 (n ¼ 19) 199.52 (n ¼ 19) 170.8 (n ¼ 4) 176.87 (n ¼ 19) 127.85 (n ¼ 4) 67.87 (n ¼ 19) 68.97 (n ¼ 19) 68.60 (n ¼ 19) 40.20 (n ¼ 19) 58.74 (n ¼ 4) 58.81 (n ¼ 4) 58.56 (n ¼ 4) 42.75 (n ¼ 4) 98.8 (n ¼ 4) 33.67 (n ¼ 4)
4.52 6.01 49.1 7.5 1.83 3.20 3.23 3.56 11.0 1.26 1.43 1.13 1.71 10.5 5.15
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Table 2 Summary anthropometry statistics for older and younger Mexican American men Anthropometric dimension
Older men
Stature (cm) Vertical fingertip reach (cm) Vertical grip reach (cm) Vertical reach angle (deg) Sitting height (cm) Horizontal fingertip reach at 90 (cm) Horizontal fingertip reach at 0 (cm) Horizontal lateral fingertip reach (cm) Horizontal lateral reach angle (deg) Horizontal grip reach at 90 (cm) Horizontal grip reach at 0 (cm) Horizontal lateral grip reach (cm) Maximum grip diameter (cm) Finger angle (deg) Maximum step height ascending (cm)
Mean
Standard deviation
Mean
Standard deviation
166.43 (n ¼ 40) 193.1(n ¼ 40) 180.9 (n ¼ 16) 136.3 (n ¼ 40) 80.09 (n ¼ 16) 69.91 (n ¼ 40) 70.94 (n ¼ 40) 70.36 (n ¼ 40) 23.30 (n ¼ 40) 57.28 (n ¼ 16) 58.57 (n ¼ 16) 58.87 (n ¼ 16) 41.56 (n ¼ 16) 80.3 (n ¼ 16) 36.24 (n ¼ 16)
7.90 24.1 24.2 26.3 3.33 4.58 4.45 4.41 9.11 4.35 3.85 4.13 5.08 12.5 8.54
175.67 (n ¼ 33) 214.2 (n ¼ 33) 201.32 (n ¼ 18) 168.9 (n ¼ 33) 130.56 (n ¼ 18) 70.87 (n ¼ 33) 70.88 (n ¼ 33) 71.00 (n ¼ 33) 34.00 (n ¼ 33) 60.71 (n ¼ 18) 60.76 (n ¼ 18) 60.72 (n ¼ 18) 42.11 (n ¼ 18) 100.9 (n ¼ 18) 35.8 (n ¼ 18)
7.64 11.2 7.85 30.8 2.49 5.59 5.31 5.22 9.89 5.83 5.79 5.75 5.83 16.6 11.2
Table 3 Results from regression analysis (age as independent variable) for older Mexican American women. Dependent variable
Stature (n ¼ 106) Sitting height (n ¼ 42) Maximum step height (ascending) (n ¼ 42) Vertical fingertip reach (n ¼ 106) Vertical reach angle (n ¼ 106) Horizontal grip reach at 0 (n ¼ 42) Horizontal grip reach at 90 (n ¼ 42) Horizontal fingertip reach at 0 (n ¼ 106) Horizontal fingertip reach at 90 (n ¼ 106) Horizontal lateral fingertip reach (n ¼ 106) Horizontal reach angle (n ¼ 106) a b
Significant at the 10% level. Significant at the 5% level.
p-Value
0.052a 0.0280b 0.7948 0.423 0.486 0.8765 0.7542 0.671 0.394 0.439 0.554
Young men
Model for significant variables (age) 168–0.206 90.889–0.210
Table 4 Results from regression analysis (age as independent variable) for older Mexican American men Dependent variable
p-Value
Model for significant variables (age)
Stature (n ¼ 40) Sitting height (n ¼ 16) Maximum step height (ascending) (n ¼ 16) Vertical fingertip reach (n ¼ 40) Vertical reach angle (n ¼ 40) Horizontal grip reach at 0 (n ¼ 16) Horizontal grip reach at 90 (n ¼ 16) Horizontal fingertip reach at 0 (n ¼ 40) Horizontal fingertip reach at 90 (n ¼ 40) Horizontal lateral fingertip reach (n ¼ 40) Horizontal reach angle (n ¼ 40)
0.015a 0.0248a 0.0679b
194–0.371 99.127–0.246 77.130–0.529
a b
Significant at the 5% level. Significant at the 10% level.
0.663 0.067b 0.2021
207–0.946
0.2618 0.286 0.451 0.625 0.027a
52.7–0.392
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Table 5 Cross-sectional comparison of functional anthropometry of older and young women Anthropometric dimension
Estimate of difference in means
95% confidence interval for difference in means
p-Value
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach at 90 Horizontal fingertip reach at 0 Horizontal lateral fingertip reach Horizontal lateral reach angle Horizontal grip reach at 90 Horizontal grip reach at 0 Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
8.79 18.83 3.3 34.08 52.19 3.830 3.23 3.643 12.28 5.689 4.783 4.165 3.03 21.54 5.52
(11.62, 5.95) (22.86, 14.81) (82.0, 75.4) (39.47, 28.69) (54.87, 49.51) (5.497, 2.163) (5.35, 1.11) (5.580, 1.705) (18.35, 6.22) (7.654, 3.723) (6.939, 2.627) (5.938, 2.392) (5.77, 0.30) (39.42, 3.65) (13.47, 2.43)
0.000n 0.000n 0.901 0.000n 0.000n 0.000n 0.003* 0.001n 0.000n 0.000n 0.001n 0.000n 0.032n 0.031n 0.126
n
Significance at the 5% significance level.
Table 6 Cross-sectional comparison of functional anthropometry of older and young men Anthropometric dimension
Estimate of difference in means
95% confidence interval for difference in means
p-Value
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach at 90 Horizontal fingertip reach at 0 Horizontal lateral fingertip reach Horizontal lateral reach angle Horizontal grip reach at 90 Horizontal grip reach at 0 Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
9.24 21.14 20.41 32.65 50.46 0.96 0.07 0.64 10.71 3.42 2.18 1.86 0.55 20.58 0.45
(12.88, 5.60) (29.71, 12.57) (33.77, 7.05) (46.20, 19.09) (52.56, 48.37) (3.38, 1.47) (2.25, 2.39) (2.94, 1.65) (15.19, 6.22) (7.00, 0.15) (5.60, 1.23) (5.34, 1.62) (4.37, 3.27) (30.82, 10.33) (6.46, 7.37)
0.000n 0.000n 0.005n 0.000n 0.000n 0.433 0.953 0.576 0.000n 0.060 0.201 0.285 0.771 0.000n 0.895
n
Significance at the 5% significance level.
equations which estimate the common factors after performance of a varimax rotation for older Mexican American females and males, respectively. Regression analysis results indicate that for older women, age had a significant effect on stature (po0:10) and sitting height (po0:05). For
older men, age had a significant effect on stature (po0:05), sitting height (po0:05), maximum step height (ascending) (po0:1), and vertical and horizontal reach angles (po0:1). Results from cross-sectional comparisons of older and younger adults indicate that, for women (Table 5), stature, vertical fingertip reach, vertical
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Table 7 Factor analysis results for older females (for 42 complete cases
Table 8 Factor analysis results for older males (for 16 complete cases)
Factor
Eigenvalue Percent of variance
Factor
Eigenvalue Percent of variance
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
6.70678 2.65997
44.712 17.733
44.712 62.445
7.77697 3.01935
51.846 20.129
51.846 71.975
1.53273 1.03446 0.705155 0.550227
10.218 6.896 4.701 3.668
72.663 79.560 84.261 87.929
1.36987 0.919638 0.735635 0.424471
9.132 6.131 4.904 2.830
81.108 87.239 92.143 94.973
0.52092
3.473
91.402
0.371818
2.479
97.452
0.422376
2.816
94.217
0.13665
0.911
98.363
0.32817
2.188
96.405
0.116108
0.774
99.137
0.193276
1.289
97.694
0.0572674
0.382
99.519
0.167712
1.118
98.812
0.0405932
0.271
99.789
0.0828623
0.552
99.364
0.0192461
0.128
99.917
0.0586136
0.391
99.755
0.00757069
0.050
99.968
0.0203785 0.0163789
0.136 0.109
99.891 100.000
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.00415196 0.028 0.000660319 0.004
99.996 100.000
Cumulative percentage of variance
reach angle, sitting height, horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal lateral reach angle, horizontal grip reaches at 0 and 90 , horizontal lateral grip reach, maximum grip diameter, and finger angle, of older Mexican American women are significantly different (po0:05) from young Mexican American women. Vertical grip reach and maximum step height (ascending) are the only measures not significantly different. Results for older Mexican American men (Table 6) indicate that stature, vertical fingertip reach, vertical grip reach, vertical reach angle, sitting height, horizontal lateral reach angle, and finger angle are significantly different (po0:05) from young Mexican American men. Horizontal fingertip reaches at 0 and 90 , horizontal lateral fingertip reach, horizontal grip reaches at 0 and 90 , horizontal lateral grip reach, maximum grip diameter, and maximum
Cumulative percentage of variance
step height (ascending) were all not significantly different between older and young adults. Factor analyses of 15 different anthropometric variables for older Mexican American females extracted 4 factors of the 15 accounting for almost 80% of the variability in the original data. For older Mexican American males, 3 extracted factors of the 15 account for almost 81% of the variability in the original data. This indicates that a few explanatory anthropometric factors (represented by the weighted equations presented in Tables 9 and 10) sufficiently explain changes in functional anthropometric variables considered in this study.
4. Discussion The objective of this cross-sectional study was to determine if age affected functional reach abilities
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Table 9 Estimated coefficients for factor loading matrix for the 4 extracted factors after Varimax rotation for older females Variable
Factor 1
Factor 2
Factor 3
Factor 4
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.815224 0.22628 0.16061 0.234899 0.806584 0.921324 0.916164 0.882966 0.0539708 0.789292 0.771213 0.821117 0.581594 0.249134 0.0227186
0.0154666 0.927983 0.888662 0.889967 0.0693527 0.124352 0.0692387 0.0974683 0.167266 0.00119475 0.0291124 0.0133408 0.21245 0.196894 0.207233
0.078879 0.0972219 0.024948 0.0407608 0.174761 0.032756 0.133888 0.250031 0.792897 0.458704 0.53467 0.445572 0.0993725 0.677575 0.0937046
0.0297349 0.0721374 0.00584728 0.11301 0.0722901 0.0146644 0.0522189 0.0809303 0.253281 0.0151266 0.109628 0.170305 0.428873 0.117883 0.906277
Table 10 Estimated equations for common factors after Varimax rotation for older males Variable
Factor 1
Factor 2
Factor 3
Stature Vertical fingertip reach Vertical grip reach Vertical reach angle Sitting height Horizontal fingertip reach (90 ) Horizontal fingertip reach (0 ) Horizontal lateral fingertip reach Horizontal reach angle Horizontal grip reach (90 ) Horizontal grip reach (0 ) Horizontal lateral grip reach Maximum grip diameter Finger angle Maximum step height (ascending)
0.881003 0.237362 0.237445 0.0287613 0.700905 0.899204 0.932431 0.936723 0.237916 0.934236 0.950445 0.977532 0.426653 0.287306 0.590398
0.342178 0.929802 0.91917 0.929726 0.425883 0.0104974 0.17678 0.126318 0.473211 0.0180027 0.0355258 0.0130948 0.320454 0.377005 0.15451
0.181313 0.0941756 0.103881 0.21018 0.243584 0.371438 0.106897 0.024903 0.730804 0.223694 0.244406 0.14556 0.283513 0.549072 0.247777
of older Mexican Americans females and males. Two approaches were used in studying this objective—a regression analysis of age versus functional reaches for older Mexican Americans, and a cross-sectional two-sample comparison of functional anthropometry of older Mexican Americans with a group of young Mexican American adults. Regression results show that age affects stature and sitting height for both older female and male
Mexican American adults. Cross-sectional comparisons between older females and the younger female cohort show that in addition to stature and sitting height, most horizontal and vertical fingertip reaches are significantly different for females. While cross-sectional differences between younger and older Mexican American females are pronounced, regression analyses indicate that, in older women, age affects stature and sitting height the most; other horizontal and vertical fingertip
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reaches that show significant differences in the cross-sectional analyses are not significantly affected by age. When viewed in unison, this is initial indication that after a certain age, functional anthropometry, for older Mexican American females, is not influenced by their age. A similar pattern is evident for men, although age seems to significantly affect more functional dimensions than in older women—for older men, not only are stature and sitting height significantly affected by age, but, also maximum step height, and vertical and horizontal reach angles. This is a significant finding with respect to the older Mexican American adult population, and should be included in models of disablement process in older Mexican American adults. A possible explanation for this pattern could be the cultural and social factors that mediate pathways to disability in older Mexican American adults. A majority of older Mexican American women surveyed in this study still perform active household duties that require significant reaching for task initiation, completion and performance—it is, therefore, reasonable to expect that functional reaches among older Mexican American women may not show a decrease with age. Our study suggests that older Mexican American men may be at a greater risk of developing disability in the older years perhaps due their sedentary lifestyles after they retire from work, compared to older Mexican American women. Comparison of functional anthropometry of older Mexican American adults with functional anthropometry of other older adult groups can help explain differences in disability levels between older adult groups, and help understand and model pathways to disability among older adults. The present study is cross-sectional and can only detect inter-individual and cohort differences due to aging at a specific point in time. This study does not measure intra-individual decline in study variables over a period of time. In addition, cross-sectional comparisons in this study with the younger female and male cohorts is limited by the sample sizes for young females and males. Also, the present study was based on a convenience sample of older adults who visit senior recreation centers. Hence, older Mexican American adults
who do not have an opportunity to visit senior recreation centers either due to disability or due to a lack of availability of transportation, were not included in the study—their functional anthropometry decline and the consequent effect on task performance in activities of daily living can be an important aspect in the disablement model development process.
5. Conclusions Accommodating age related changes in functional reach abilities is vital for increasing functional independence of older adults. It is important for engineering designers, especially, product designers, and designers in the housing and construction industries to consider functional capabilities and limitations of older adults when designing products of daily use, and daily living environments. Self-reported performance indicators for activities of daily living show that older Mexican Americans report greater levels of difficulty in performing activities of daily living, especially in tasks that involve reaching for task initiation, performance and completion, than any other older adult group in the United States. This difficulty may be mediated not only by various physical impairments, and psychological and social factors, but, also with environmental factors including workspace design variables, and with inherent declines in functional performance abilities. A better understanding of the mechanisms underlying this decline, and quantification of this decline with age, will result in better products and design for the older adult.
Acknowledgements The authors thank all participants in this study. The authors are grateful to Elvia Martinez, and Gustavo Fierro, for assistance with data collection activities. The authors thank Dr. Julia Bader in the Statistical Consulting Laboratory at the University of Texas at El Paso for assistance with statistical analyses. The authors also thank Rohini Magham for assistance with data compilation.
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