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Experimental Aging Research: An International Journal Devoted to the Scientific Study of the Aging Process Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uear20
Start-Up Time and Walking Speed in Older Adults Under Loaded Conditions During Simulated Road Crossing a
ab
Pui W. Kong & YaoHui K. Chua a
Click for updates
Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore b
Sport Science & Management, Nanyang Technological University, Singapore Published online: 16 Oct 2014.
To cite this article: Pui W. Kong & YaoHui K. Chua (2014) Start-Up Time and Walking Speed in Older Adults Under Loaded Conditions During Simulated Road Crossing, Experimental Aging Research: An International Journal Devoted to the Scientific Study of the Aging Process, 40:5, 589-598, DOI: 10.1080/0361073X.2014.956630 To link to this article: http://dx.doi.org/10.1080/0361073X.2014.956630
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.
Downloaded by [West Virginia University] at 11:36 17 April 2015
This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions
Experimental Aging Research, 40: 589–598, 2014 Copyright © Taylor & Francis Group, LLC ISSN: 0361-073X print/1096-4657 online DOI: 10.1080/0361073X.2014.956630
START-UP TIME AND WALKING SPEED IN OLDER ADULTS UNDER LOADED CONDITIONS DURING SIMULATED ROAD CROSSING
Downloaded by [West Virginia University] at 11:36 17 April 2015
Pui W. Kong and YaoHui K. Chua Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore; and Sport Science & Management, Nanyang Technological University, Singapore Background/Study Context: The safety of older pedestrians in road crossing has received considerable attention but previous studies measure gait characteristics only under unloaded conditions. The aim of this study was to investigate the start-up time and walking speed under loaded conditions that reflect daily activities of older adults in Singapore. Methods: Thirty-two older adults (age (SD) = 69.4 (7.0) years) and 20 young controls (age (SD) = 23.1 (2.0) years) walked under four conditions: (1) unloaded, (2) pushing a stroller loaded with 10 kg, (3) pulling a shopping cart loaded with 15 kg, and (4) carrying two shopping bags each loaded with 2 kg. Start-up time was determined from video recordings and walking speed measured using timing gates. A mixed-model analysis of variance (ANOVA; age by walking condition) with repeated measures was applied. Results: Start-up times were slower in the stroller and shopping cart conditions compared with the unloaded and shopping bags conditions. Loading reduced walking speed, with the shopping cart being the slowest, followed by the stroller and then the shopping bags. A significant interaction was found, with young controls reducing their speeds more substantially while handling the stroller/cart than older participants. Conclusion: Loading caused a compromise in start-up time and walking speed. The start-up time was slower when pushing a stroller or pulling a shopping cart but remained unaffected by carrying shopping bags. Speed was reduced under all loaded conditions, with a greater effect in young than older participants when handling a stroller or shopping cart.
Received 28 February 2013; accepted 12 October 2013. Address correspondence to Pui W. Kong, Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616. E-mail: [email protected]
Downloaded by [West Virginia University] at 11:36 17 April 2015
590
P. W. Kong and Y. K. Chua
The safety of older pedestrians in road crossing has received considerable attention in many countries, including the UK, USA, Ireland, and South Africa (Amosun, Burgess, Groeneveldt, & Hodgson, 2007; Asher, Aresu, Falaschetti, & Mindell, 2012; Bollard & Fleming, 2013; Guerrier & Jolibois, 1998; Hoxie & Rubenstein, 1994; Knoblauch, Pietrucha, & Nitzburg, 1996; Langlois et al., 1997; Romero-Ortuno, Cogan, Cunningham, & Kenny, 2010). In the calculation of signal timings required for pedestrians to safely cross the road, both start-up time and gait speed need to be considered. Start-up time refers to the time from the onset of a “green man” (signal implying “cross with care”) until the pedestrian steps onto the road. A field study observed that the start-up time of older pedestrians was slower than younger pedestrians in the United States (Knoblauch et al., 1996). Others measured the acceleration phase from standing to the first 2.5 m of road crossing (Bollard & Fleming, 2013). It is also well known that gait speed decreased with age, leading to many older pedestrians failing to complete crossing the road within the standard time allowed (Guerrier & Jolibois, 1998; Knoblauch et al., 1996; Langlois et al., 1997; Romero-Ortuno et al., 2010). These studies, however, measured gait characteristics under normal unloaded conditions only and did not assess pedestrians carrying heavy bags, pushing strollers, or grocery carts. One study has compared the gait speed in older adults between unloaded and loaded walking, but only one condition of carrying a 2-kg dumbbell was considered (Amosun et al., 2007). In Singapore, many older adults provide care for their grandchildren and shop daily at local markets for fresh food. This means that older pedestrians are likely to cross the road under loaded conditions, such as pushing a stroller, pulling a shopping cart, or carrying bags of groceries. It is, therefore, not appropriate to adopt the start-up times and gait speeds from previous studies investigating unloaded walking conditions only. In order to obtain accurate timings for future pedestrian crossing signal design, there is a need to bridge this research gap by measuring the gait characteristics of older adults under loaded conditions that reflect their daily activities. Such information may impact the road safety beyond the Singapore community owing to our diverse ethnic composition, of which 74.1% of the population are Chinese, 13.4% Malays, 9.2% Indians, and 3.3% others (Singapore Department of Statistics, 2011). Similar cultural practices such as daily grocery shopping are shared by other countries of common ethnic roots, including China, Hong Kong, Macau, Taiwan, Malaysia, Indonesia, and India. The aim of this study was, therefore, to examine the start-up time and walking speed in young and older adults under loaded conditions during simulated road crossing.
Start-up Time and Walking Speed Under Loaded Conditions
591
Downloaded by [West Virginia University] at 11:36 17 April 2015
METHODS The study was approved by the Nanyang Technological University Institutional Review Board. Thirty-one older adults and 20 young controls recruited through flyers, personal contacts, and word of mouth provided written informed consent to participate (Table 1). Participants must have fulfilled the age requirement (young: 21–35 years, old: 60 years and above) and be able to ambulate independently without any form of walking aid (e.g., walking stick). Exclusion criteria included (1) recent injury to the shoulders, arms, back, hips, or legs; (2) more than mild pain at the shoulders, arms, back, hips, or legs; (3) discomfort (e.g., back ache) when carrying heavy load; (4) a fall within the past 6 months; and (5) self-reported pregnancy. The study took place in a controlled laboratory setting. A background survey on demographic information was administered to confirm subject eligibility. The body mass and height of eligible participants were measured. After familiarization, each participant performed 20 walking trials along the 10-m walkway, 5 in each of the following conditions presented in a randomized order: (1) normal unloaded, (2) pushing a stroller loaded with 10 kg to mimic the weight of a toddler, (3) pulling a shopping cart loaded with 15 kg of groceries, and (4) carrying two (one in each hand) plastic shopping bags each loaded with 2 kg of groceries (Figure 1). The stroller model (Bonbebe BOXTER R1, Singapore) was chosen based on the median price (≈US$160) of all strollers displayed in a local hypermarket (National Trade Union Congress Fairprice Xtra, Jurong Point). The extra load of 10 kg in the stroller approximated the 50th percentile body mass of a 15-month-old boy and 18-month-old girl in Singapore (National Healthcare Group Polyclinics, 2000). The shopping cart was the most commonly used model in Singapore (≈US$10). The load of 15 kg for the
Table 1. Physical characteristics of young and older participants Characteristic Total n Males, n (%) Age range (years) Age (years) Body mass (kg) Height (m)
Young
Old
20 10 (50%) 21–29 23.1 (2.0) 61.7 (11.5) 1.69 (0.99)
32 14 (44%) 60–83 69.4 (7.0)∗ 62.5 (10.0) 1.57 (0.08)∗
Note. Data are expressed in mean (SD) unless otherwise stated. ∗ Significant difference between groups detected by independent t tests.
Downloaded by [West Virginia University] at 11:36 17 April 2015
592
P. W. Kong and Y. K. Chua
Figure 1. Three loaded conditions were used in the simulated road crossing experiment: (a) pushing a stroller loaded with 10 kg, (b) pulling a shopping cart loaded with 15 kg, and (c) carrying two shopping bags each loaded with 2 kg.
shopping cart and 2 kg per bag were estimated from pilot measurements from shoppers. Participants stood stationary behind a starting line, focusing on a television screen that displayed a pedestrian crossing signal. Upon the signal turned from red to green with an audible cue, participants commenced to walk at their comfortable pace for 10 m. Participants were given ample time to rest between trials if needed. The walking trials were recorded by a high-speed video camera (Casio EX-FH100, Tokyo, Japan) operating at 120 Hz from a sagittal view. Start-up time, defined as the instant when the pedestrian crossing signal turned green until any part of the foot touching the ground beyond a line 1 m in front of the starting line, was determined using video analysis software (Siliconcoach Pro 7; Dunedin, New Zealand). The average start-up time of five trials per walking condition was used for further analysis. Walking speed was measured by five pairs of timing gates positioned 2.5 m apart at 1, 3, 5, 7, and 9 m along the 10-m walkway (SMARTtiming Gates, Singapore). For each trial, the average speed recorded by all timing gates was calculated. The average speed of five trials per walking condition was used for further analysis. All statistical analyses were performed using SPSS 19.0 (IBM, Armonk, New York, NY, USA). Mixed-model analyses of variance (ANOVAs) were carried out to examine the effect of the between- (age group) and within(walking condition) subjects independent variables on start-up time and walking speed. Post hoc analysis with Bonferroni adjustment was applied
Start-up Time and Walking Speed Under Loaded Conditions
593
where appropriate. Since there was a wide age range in the older adult group, Pearson correlations were used to further examine the relationship between age and each of the gait variable within this group. Data are reported as mean (SD), with statistical significance set at .05 level. RESULTS
Downloaded by [West Virginia University] at 11:36 17 April 2015
Start-up Time There was a significant main effect of condition (F(3, 150) = 57.160, p < .001) and age (F(1, 50) = 19.666, p < .001) in start-up time. As can be seen in Table 2, participants started up slower in the stroller and shopping cart compared with the unloaded and shopping bags conditions. No difference in start-up time was observed between the stroller and shopping cart conditions, or between the unloaded and shopping bags conditions. Summing over all conditions, the older adults were on average 0.35 s (16%) slower than the young controls (older: 1.83 (0.26) s, young: 2.18 (0.40) s). No significant Age × Walking Condition interaction was found (F(3,150) = 1.710, p = .157). Within the older group, a significant moderate relationship was observed between age of start-up time under all conditions (r = .485–.510, all p < .05; Table 3). Walking Speed For walking speed, a significant main effect of age (F(1, 50) = 6.557, p = .014), a significant effect of walking condition (F(3, 150) = 59.305, Table 2. Start-up times and walking speeds under unloaded and loaded conditions Variable Start-up time (s)
Walking speed (m/s)
Condition
Young
Old
Unloadedb,c Strollera,d Shopping carta,d Shopping bagsb,c Unloadedb,c,d Strollera,c,d Shopping carta,b,d Shopping bagsa,b,c
1.67 (0.16) 1.99 (0.26) 1.99 (0.25) 1.68 (0.15) 1.46 (0.16) 1.30 (0.17) 1.26 (0.14) 1.43 (0.15)
2.00 (0.30) 2.27 (0.35) 2.42 (0.46) 2.04 (0.32) 1.26 (0.20) 1.24 (0.24) 1.16 (0.22) 1.24 (0.20)
Note. Data are presented in mean (SD). Post hoc significantly differed from a unloaded, cart, and d shopping bags (p < .05) with both young and old groups combined. b stroller, c shopping
594
P. W. Kong and Y. K. Chua
Table 3. Correlations (r) between age and gait variables within the older adult group (n = 32) Variable Start-up time (s)
Downloaded by [West Virginia University] at 11:36 17 April 2015
Walking speed (m/s)
Condition
r
Unloaded Stroller Shopping cart Shopping bags Unloaded Stroller Shopping cart Shopping bags
.510 .485 .502 .493 −.568 −.564 −.560 −.621
p value .003 .005 .003 .004 .001 .001 .001
Experimental Aging Research: An International Journal Devoted to the Scientific Study of the Aging Process Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uear20
Start-Up Time and Walking Speed in Older Adults Under Loaded Conditions During Simulated Road Crossing a
ab
Pui W. Kong & YaoHui K. Chua a
Click for updates
Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore b
Sport Science & Management, Nanyang Technological University, Singapore Published online: 16 Oct 2014.
To cite this article: Pui W. Kong & YaoHui K. Chua (2014) Start-Up Time and Walking Speed in Older Adults Under Loaded Conditions During Simulated Road Crossing, Experimental Aging Research: An International Journal Devoted to the Scientific Study of the Aging Process, 40:5, 589-598, DOI: 10.1080/0361073X.2014.956630 To link to this article: http://dx.doi.org/10.1080/0361073X.2014.956630
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.
Downloaded by [West Virginia University] at 11:36 17 April 2015
This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions
Experimental Aging Research, 40: 589–598, 2014 Copyright © Taylor & Francis Group, LLC ISSN: 0361-073X print/1096-4657 online DOI: 10.1080/0361073X.2014.956630
START-UP TIME AND WALKING SPEED IN OLDER ADULTS UNDER LOADED CONDITIONS DURING SIMULATED ROAD CROSSING
Downloaded by [West Virginia University] at 11:36 17 April 2015
Pui W. Kong and YaoHui K. Chua Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore; and Sport Science & Management, Nanyang Technological University, Singapore Background/Study Context: The safety of older pedestrians in road crossing has received considerable attention but previous studies measure gait characteristics only under unloaded conditions. The aim of this study was to investigate the start-up time and walking speed under loaded conditions that reflect daily activities of older adults in Singapore. Methods: Thirty-two older adults (age (SD) = 69.4 (7.0) years) and 20 young controls (age (SD) = 23.1 (2.0) years) walked under four conditions: (1) unloaded, (2) pushing a stroller loaded with 10 kg, (3) pulling a shopping cart loaded with 15 kg, and (4) carrying two shopping bags each loaded with 2 kg. Start-up time was determined from video recordings and walking speed measured using timing gates. A mixed-model analysis of variance (ANOVA; age by walking condition) with repeated measures was applied. Results: Start-up times were slower in the stroller and shopping cart conditions compared with the unloaded and shopping bags conditions. Loading reduced walking speed, with the shopping cart being the slowest, followed by the stroller and then the shopping bags. A significant interaction was found, with young controls reducing their speeds more substantially while handling the stroller/cart than older participants. Conclusion: Loading caused a compromise in start-up time and walking speed. The start-up time was slower when pushing a stroller or pulling a shopping cart but remained unaffected by carrying shopping bags. Speed was reduced under all loaded conditions, with a greater effect in young than older participants when handling a stroller or shopping cart.
Received 28 February 2013; accepted 12 October 2013. Address correspondence to Pui W. Kong, Physical Education & Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616. E-mail: [email protected]
Downloaded by [West Virginia University] at 11:36 17 April 2015
590
P. W. Kong and Y. K. Chua
The safety of older pedestrians in road crossing has received considerable attention in many countries, including the UK, USA, Ireland, and South Africa (Amosun, Burgess, Groeneveldt, & Hodgson, 2007; Asher, Aresu, Falaschetti, & Mindell, 2012; Bollard & Fleming, 2013; Guerrier & Jolibois, 1998; Hoxie & Rubenstein, 1994; Knoblauch, Pietrucha, & Nitzburg, 1996; Langlois et al., 1997; Romero-Ortuno, Cogan, Cunningham, & Kenny, 2010). In the calculation of signal timings required for pedestrians to safely cross the road, both start-up time and gait speed need to be considered. Start-up time refers to the time from the onset of a “green man” (signal implying “cross with care”) until the pedestrian steps onto the road. A field study observed that the start-up time of older pedestrians was slower than younger pedestrians in the United States (Knoblauch et al., 1996). Others measured the acceleration phase from standing to the first 2.5 m of road crossing (Bollard & Fleming, 2013). It is also well known that gait speed decreased with age, leading to many older pedestrians failing to complete crossing the road within the standard time allowed (Guerrier & Jolibois, 1998; Knoblauch et al., 1996; Langlois et al., 1997; Romero-Ortuno et al., 2010). These studies, however, measured gait characteristics under normal unloaded conditions only and did not assess pedestrians carrying heavy bags, pushing strollers, or grocery carts. One study has compared the gait speed in older adults between unloaded and loaded walking, but only one condition of carrying a 2-kg dumbbell was considered (Amosun et al., 2007). In Singapore, many older adults provide care for their grandchildren and shop daily at local markets for fresh food. This means that older pedestrians are likely to cross the road under loaded conditions, such as pushing a stroller, pulling a shopping cart, or carrying bags of groceries. It is, therefore, not appropriate to adopt the start-up times and gait speeds from previous studies investigating unloaded walking conditions only. In order to obtain accurate timings for future pedestrian crossing signal design, there is a need to bridge this research gap by measuring the gait characteristics of older adults under loaded conditions that reflect their daily activities. Such information may impact the road safety beyond the Singapore community owing to our diverse ethnic composition, of which 74.1% of the population are Chinese, 13.4% Malays, 9.2% Indians, and 3.3% others (Singapore Department of Statistics, 2011). Similar cultural practices such as daily grocery shopping are shared by other countries of common ethnic roots, including China, Hong Kong, Macau, Taiwan, Malaysia, Indonesia, and India. The aim of this study was, therefore, to examine the start-up time and walking speed in young and older adults under loaded conditions during simulated road crossing.
Start-up Time and Walking Speed Under Loaded Conditions
591
Downloaded by [West Virginia University] at 11:36 17 April 2015
METHODS The study was approved by the Nanyang Technological University Institutional Review Board. Thirty-one older adults and 20 young controls recruited through flyers, personal contacts, and word of mouth provided written informed consent to participate (Table 1). Participants must have fulfilled the age requirement (young: 21–35 years, old: 60 years and above) and be able to ambulate independently without any form of walking aid (e.g., walking stick). Exclusion criteria included (1) recent injury to the shoulders, arms, back, hips, or legs; (2) more than mild pain at the shoulders, arms, back, hips, or legs; (3) discomfort (e.g., back ache) when carrying heavy load; (4) a fall within the past 6 months; and (5) self-reported pregnancy. The study took place in a controlled laboratory setting. A background survey on demographic information was administered to confirm subject eligibility. The body mass and height of eligible participants were measured. After familiarization, each participant performed 20 walking trials along the 10-m walkway, 5 in each of the following conditions presented in a randomized order: (1) normal unloaded, (2) pushing a stroller loaded with 10 kg to mimic the weight of a toddler, (3) pulling a shopping cart loaded with 15 kg of groceries, and (4) carrying two (one in each hand) plastic shopping bags each loaded with 2 kg of groceries (Figure 1). The stroller model (Bonbebe BOXTER R1, Singapore) was chosen based on the median price (≈US$160) of all strollers displayed in a local hypermarket (National Trade Union Congress Fairprice Xtra, Jurong Point). The extra load of 10 kg in the stroller approximated the 50th percentile body mass of a 15-month-old boy and 18-month-old girl in Singapore (National Healthcare Group Polyclinics, 2000). The shopping cart was the most commonly used model in Singapore (≈US$10). The load of 15 kg for the
Table 1. Physical characteristics of young and older participants Characteristic Total n Males, n (%) Age range (years) Age (years) Body mass (kg) Height (m)
Young
Old
20 10 (50%) 21–29 23.1 (2.0) 61.7 (11.5) 1.69 (0.99)
32 14 (44%) 60–83 69.4 (7.0)∗ 62.5 (10.0) 1.57 (0.08)∗
Note. Data are expressed in mean (SD) unless otherwise stated. ∗ Significant difference between groups detected by independent t tests.
Downloaded by [West Virginia University] at 11:36 17 April 2015
592
P. W. Kong and Y. K. Chua
Figure 1. Three loaded conditions were used in the simulated road crossing experiment: (a) pushing a stroller loaded with 10 kg, (b) pulling a shopping cart loaded with 15 kg, and (c) carrying two shopping bags each loaded with 2 kg.
shopping cart and 2 kg per bag were estimated from pilot measurements from shoppers. Participants stood stationary behind a starting line, focusing on a television screen that displayed a pedestrian crossing signal. Upon the signal turned from red to green with an audible cue, participants commenced to walk at their comfortable pace for 10 m. Participants were given ample time to rest between trials if needed. The walking trials were recorded by a high-speed video camera (Casio EX-FH100, Tokyo, Japan) operating at 120 Hz from a sagittal view. Start-up time, defined as the instant when the pedestrian crossing signal turned green until any part of the foot touching the ground beyond a line 1 m in front of the starting line, was determined using video analysis software (Siliconcoach Pro 7; Dunedin, New Zealand). The average start-up time of five trials per walking condition was used for further analysis. Walking speed was measured by five pairs of timing gates positioned 2.5 m apart at 1, 3, 5, 7, and 9 m along the 10-m walkway (SMARTtiming Gates, Singapore). For each trial, the average speed recorded by all timing gates was calculated. The average speed of five trials per walking condition was used for further analysis. All statistical analyses were performed using SPSS 19.0 (IBM, Armonk, New York, NY, USA). Mixed-model analyses of variance (ANOVAs) were carried out to examine the effect of the between- (age group) and within(walking condition) subjects independent variables on start-up time and walking speed. Post hoc analysis with Bonferroni adjustment was applied
Start-up Time and Walking Speed Under Loaded Conditions
593
where appropriate. Since there was a wide age range in the older adult group, Pearson correlations were used to further examine the relationship between age and each of the gait variable within this group. Data are reported as mean (SD), with statistical significance set at .05 level. RESULTS
Downloaded by [West Virginia University] at 11:36 17 April 2015
Start-up Time There was a significant main effect of condition (F(3, 150) = 57.160, p < .001) and age (F(1, 50) = 19.666, p < .001) in start-up time. As can be seen in Table 2, participants started up slower in the stroller and shopping cart compared with the unloaded and shopping bags conditions. No difference in start-up time was observed between the stroller and shopping cart conditions, or between the unloaded and shopping bags conditions. Summing over all conditions, the older adults were on average 0.35 s (16%) slower than the young controls (older: 1.83 (0.26) s, young: 2.18 (0.40) s). No significant Age × Walking Condition interaction was found (F(3,150) = 1.710, p = .157). Within the older group, a significant moderate relationship was observed between age of start-up time under all conditions (r = .485–.510, all p < .05; Table 3). Walking Speed For walking speed, a significant main effect of age (F(1, 50) = 6.557, p = .014), a significant effect of walking condition (F(3, 150) = 59.305, Table 2. Start-up times and walking speeds under unloaded and loaded conditions Variable Start-up time (s)
Walking speed (m/s)
Condition
Young
Old
Unloadedb,c Strollera,d Shopping carta,d Shopping bagsb,c Unloadedb,c,d Strollera,c,d Shopping carta,b,d Shopping bagsa,b,c
1.67 (0.16) 1.99 (0.26) 1.99 (0.25) 1.68 (0.15) 1.46 (0.16) 1.30 (0.17) 1.26 (0.14) 1.43 (0.15)
2.00 (0.30) 2.27 (0.35) 2.42 (0.46) 2.04 (0.32) 1.26 (0.20) 1.24 (0.24) 1.16 (0.22) 1.24 (0.20)
Note. Data are presented in mean (SD). Post hoc significantly differed from a unloaded, cart, and d shopping bags (p < .05) with both young and old groups combined. b stroller, c shopping
594
P. W. Kong and Y. K. Chua
Table 3. Correlations (r) between age and gait variables within the older adult group (n = 32) Variable Start-up time (s)
Downloaded by [West Virginia University] at 11:36 17 April 2015
Walking speed (m/s)
Condition
r
Unloaded Stroller Shopping cart Shopping bags Unloaded Stroller Shopping cart Shopping bags
.510 .485 .502 .493 −.568 −.564 −.560 −.621
p value .003 .005 .003 .004 .001 .001 .001
