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Original Study
Is Trunk Posture in Walking a Better Marker than Gait Speed
in Predicting Decline in Function and Subsequen...
With the aging of the population and the rising costs of health care,
many countries are refocusing health care policy on ...
right heel strikes. The mean of the 4 values was then considered as the
participant’s shoulder offset value for purposes o...
may be because none of the participants, all living and functioning in
the community, were so frail as to have significant ...
results of this study show a more stage-wise transition from a mean
9.03-mm shoulder offset in the healthy elderly (compar...
References
1. Fried LP, Walston J. Frailty and failure to thrive. In: Hazzard WR, Blass JP,
Ettinger Jr WH, editors. Princ...
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Is Trunk Posture in Walking a Better Marker than Gait Speed in Predicting Decline in Function and Subsequent Frailty - Gautam Singh

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Is Trunk Posture in Walking a Better Marker than Gait Speed in Predicting Decline in Function and Subsequent Frailty - Gautam Singh

  1. 1. Original Study Is Trunk Posture in Walking a Better Marker than Gait Speed in Predicting Decline in Function and Subsequent Frailty? Reshma A. Merchant MBBS, MRCP a,b , Subhasis Banerji PhD c , Gautam Singh MSc c , Effie Chew MBBS, MRCP a,b , Chueh L. Poh PhD d , Sarah C. Tapawan MRCPCH c , Yan R. Guo BSc c , Yu W. Pang Dip c , Mridula Sharma PhD e , Ravi Kambadur PhD f , Stacey Tay MBBS, MMed (Paeds), FRCPCH c,g, * a Department of Medicine, National University Health System, Singapore b Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore c Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore d Division of Molecular Genetics and Cell Biology, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore e Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore f Division of Molecular Genetics and Cell Biology, School of Biological Sciences, Nanyang Technological University, Singapore g Department of Paediatrics, KTP-National University Children’s Medical Institute, National University Health System, Singapore Keywords: Sarcopenia frailty gait speed walking speed posture adaptation gait analysis falls a b s t r a c t Background: Many recent guidelines and consensus on sarcopenia have incorporated gait speed and grip strength as diagnostic criteria without addressing early posture changes adopted to maintain gait speed before weakness is clinically evident. Objectives: Older adults are known to compensate well for declining physiological reserve through environmental modification and posture adaptation. This study aimed to analyze and identify significant posture adaptation in older adults that is required to maintain gait speed in the face of increasing vulnerability. This would be a useful guide for early posture correction exercise interventions to prevent further decline, in addition to traditional gait, balance, and strength training. Design: A community-based cross-sectional study. Setting and Participants: The participants comprised 90 healthy community-dwelling Chinese men between the ages of 60 and 80 years and 20 Chinese adults between the ages of 21 and 50 years within the normal BMI range as a comparison group. Measurements: All the participants underwent handgrip strength testing, 6-minute walk, timed up-and- go (TUG), and motion analysis for gait characteristics. Low function was characterized by slow walking speed (<1.0 m/s) and/or slow TUG (>10 seconds), whereas low strength was determined by hand grip dynamometer testing (<26 kg). The degree of frailty was classified using the Canadian Study for Health and Ageing Clinical Frailty Scale (CSHA-CFS) to differentiate between healthy and vulnerable older adults. Results: As expected, the vulnerable older adults had lower functional performance and strength compared with the healthy older adults group. However, a significant number demonstrated posture adaptations in walking in all 3 groups, including those who maintained a good walking speed (>1.0 m/s). The extent of such adaptation was larger in the vulnerable group as compared with the healthy group. Conclusion: Although gait speed is a robust parameter for screening older adults for sarcopenia and frailty, our data suggest that identifying trunk posture adaptation before the onset of decline in gait speed will help in planning interventions in the at-risk community-dwelling older adults even before gait speed declines. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine. The authors declare no conflicts of interest. This work was supported by a grant (NRF 2008 NRF-CRP 001e30) from the Competitive Research Program of the National Research Foundation, Singapore. * Address correspondence to A/Prof Stacey Tay, Department of Paediatrics, Na- tional University Health System, 1E Kent Ridge Road, NUHS Tower Block, Level 12, Singapore 119228. E-mail address: stacey_tay@nuhs.edu.sg (S. Tay). JAMDA journal homepage: www.jamda.com http://dx.doi.org/10.1016/j.jamda.2015.08.008 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine. JAMDA xxx (2015) 1e6
  2. 2. With the aging of the population and the rising costs of health care, many countries are refocusing health care policy on health promotion and disability prevention among older people. It has been argued that efforts aimed at identifying at-risk groups of older people so as to provide early intervention and/or multidisciplinary case management should be done at the level of general practice via adoption of a clinical paradigm based on the concept of frailty, which fits well with the biopsychosocial model of primary care. However, this ideal has exposed the lack of frailty metrics that are appropriate for primary care. Indeed, family physicians and community practitioners are still in need of easy instruments for identifying and estimating frailty early. Fried and Walston1 had hypothesized a “cycle of frailty” that was consistent with clinical signs and symptoms. This hypothesis indi- cated reduced levels of nutrition and activity, age-related musculo- skeletal changes, and disease as being the possible precursors to loss of muscle mass as seen in the onset of sarcopenia, which then pro- gressed to decreased walking speed, strength, and power along with respiratory and metabolic changes. In keeping with this hypothesis, various researchers have tried to develop simplified protocols to reliably identify frailty and associated sarcopenia, with the result that a strong consensus has emerged around the use of walking or gait speed as the most reliable and easy to administer marker.2e4 Gait speed is now considered a strong predictor of a wide range of out- comes in older adults, including falls and fractures, hospitalization, cognitive decline, and mortality.5,6 Hence, many recent guidelines and consensus definitions of sarcopenia have been based on gait speed, but without addressing posture adaptation to maintain gait speed in the face of weakness or joint stiffness. With aging, older adults compensate for general decline through environmental modification and posture adaptation. Lord et al7 demonstrated that to be dwelling in the community, one must maintain a walking speed close to 1.14 m/s. Kang and Dingwell8 also showed that the young and elderly both reported the same preferred walking speed. Because the individuals in this study were all com- munity dwelling, the obvious question was whether they were adapting posture and gait to maintain a reasonable gait speed. It is possible that those who developed early adaptations in posture were more prone to early functional deficits and, hence, at a greater risk of rapid progression to sarcopenia and frailty. These would represent, more accurately, the “transition to frailty and sarcopenia” group in the otherwise healthy, community-dwelling group of Chinese men. Such an adaptation-mediated compensation for declining gait speed is not very well addressed in the literature at the moment. The objective of this prospective, cross-sectional community study was, therefore, to identify early adaptations in posture during walking that may precede actual decline in gait speed among healthy community-dwelling Chinese men. A progression pathway from posture adaptation to gait adaptation leading to decline in functional measures such as gait speed and timed up-and-go (TUG) measures was also hypothesized after data analysis. Methods The study team recruited 90 community-dwelling older Chinese adults between the ages of 60 and 80 years with body mass index (BMI) in the normal range (18.5e23.5 according to Asian standards). An additional 20 adults were recruited in the 21 to 50 years age group to act as a reference comparison. Their function was evaluated using handgrip strength testing, 6-minute walk, TUG, and 6-camera motion analysis for gait characteristics. Parameter cutoffs were initially benchmarked using data from published literature by the Asian Working Group on Sarcopenia for Chinese subjects9 and modified based on data obtained from this study. Low function was character- ized by slow walking speed (<1.0 m/s) and/or slow TUG (>10 seconds), whereas low strength was determined by handgrip dynamometer testing (<26 kg). The degree of frailty was classified using the Canadian Study for Health and Ageing Clinical Frailty Scale (CSHA-CFS)10 to differentiate between healthy and vulnerable elderly. Rockwood et al10 proposed the CSHA-CFS, a global clinical measure of fitness and frailty in elderly people (CSHA 1: Very fit; CSHA 2: Without active disease but less fit than CSHA 1; CSHA 3: Well, with treated and well-controlled comorbid disease; CSHA 4: Apparently vulnerable, not dependent but complain of being “slowed up” and have disease symptoms). The CSHA-CFS was derived from a 5-year prospective cohort study. This 7-point scale was then further trans- lated by Chan et al11 as the Chinese-Canadian physician version and used to validate a telephone version. We used the CSHA-CFS physician version algorithm to categorize our participants into 3 groups. Group 1 was healthy older adults (CSHA 1 and 2, n ¼ 41), group 2 was intermediate-risk older adults (CSHA 3, n ¼ 33), and group 3 consisted of the vulnerable older adults (CSHA 4, n ¼ 16). This was appropriate because all the participants were community dwelling with no evi- dence of significant functional impairment or dependence, which may have placed them in the frailer categories of CSHA 5 to 7. None of the recruited individuals remembered having a fall in the past 12 months. Those with chronic obstructive pulmonary disease and cardiac pace- makers were screened out, as were those on steroid medication and growth hormones. Further, blood samples were drawn to record free testosterone, growth hormone levels, and insulin-like growth factor (IGF-1). This was done to further qualify the frailty classification, as all 3 blood markers are associated with frailty in published literature.12e14 To analyze joint and limb segment kinematics, each participant was fitted with 31 reflective anatomical (25-mm diameter) markers, positioned according to the standard Plug-in Gait Marker Set, along with 5 additional markers to track the head and 1 marker on the chin. Participants were asked to walk along a walkway 6 meters in length with 2 force plates, recording at least 3 trials per participant. Six infrared cameras (Vicon MX system; Oxford Metrics, Oxford UK) placed around the walkway recorded the coordinates of these reflective markers at 200 Hz in 3 dimensions. The kinematics data were smoothed using a Woltring filter with a mean squared error of 20. The software for data collection was the Vicon Workstation 5.1 and the data analysis was performed with Vicon Polygon 3.1. Ethics approval was obtained from Domain-Specific Review Board of National Healthcare Group, Singapore. All participants provided signed consent. Data Analysis At first, the strength and function data were used to verify that the clinical frailty classification using the CSHA-CFS was accurate and was reflected in the strength and function measures. We analyzed the walking speed as measured in both 6-minute walk and camera-based motion analysis study separately. The latter was performed in a lab- oratory and involved only a few footfalls. It has been reported to be a good measure for assessing frailty. However, the community-dwelling participants in this study tended not to walk at their normal pace in the gait laboratory and appeared to walk more normally (and faster) while doing a 6-minute walk in the gym. Both the measures were analyzed, as we did not know the extent of gait difficulties that might be present in the individuals recruited from the community. The joint and limb kinematics of each participant were analyzed using the motion analysis data. For trunk posture, markers placed at C7 on spinous process on the back, shoulders (acromion process), sternum, anterior superior iliac spine (ASIS), and posterior superior iliac spine were studied to identify posture variations in pitch and roll during walking. The Plug-in Gait kinematic model from the Vicon Polygon software was used to measure shoulder offset in the X-di- rection (direction of walking) during 2 consecutive sets of left and R.A. Merchant et al. / JAMDA xxx (2015) 1e62
  3. 3. right heel strikes. The mean of the 4 values was then considered as the participant’s shoulder offset value for purposes of analysis and clas- sification. Sway was similarly measured in the X-direction (ante- roposterior movement) and Y-direction (mediolateral movement), whereas hip elevation was measured using Z-direction (vertical movement component) displacement of the ASIS markers. Ankle dorsiflexion, ankle plantar flexion, knee and hip flexion angles were similarly generated using the kinematic limb segment model. Statistical analysis using Minitab (Minitab Inc., State College, PA) software tools was carried out for the healthy, intermediate, and vulnerable groups to study general distribution, trends, and statistical significance of differences in posture and gait adaptation measures between groups. Results Validating CSHA Groups Using Strength and Function Data The strength, function, and temporal gait data were first evaluated to validate the categorization of individuals based on frailty scale. Grip strength, walking speed, and TUG measures were compiled, which showed that the performance of some participants in the older adults age group were comparable with the younger age group on one hand, whereas others were significantly lower, as expected. Although the testosterone and growth hormone values did not show any clear trend, IGF-1 in the vulnerable group was lower than the other groups. Table 1 gives the demographics, strength, function, and IGF-1 profiles of the groups. Cutoffs of strength and function were calculated as 2 SDs below the mean of the control age group of 21 to 30 years. These cutoffs were comparable to those reported by the Asian Working Group on Sarcopenia. Walking speed (<1.0 m/s), grip strength (<26 kg), and TUG (>10 seconds) were identified as benchmarks to further classify those in the healthy older adults (CSHA 1 and 2) and intermediate-risk older adults (CSHA 3) groups. Overall, the vulnerable olderadult group (CSHA 4) performed worse in the function tests as compared with the healthy group (Table 1). Grip strength mean values were, however, comparable. All 3 older adult groups had various degrees of mix between those who performed poorly on strength and function and those who performed well. Study of Overall Posture and Gait Kinematics The vulnerable older adult group had significantly altered posture when compared with the healthy older adult group while walking. This difference was less between the intermediate-risk group and the healthy older adults and significant to a lesser extent. The postural parameters tracked during the gait cycle included trunk rotation, hip flexion, and hip rotation. The parameters in the swing phase of gait included knee flexion, dorsi- and plantar flexion, and anteroposterior and mediolateral sway of the hip. The individual analyses are as follows. Stage-wise increasing trunk rotation with increased vulnerability The posture was deemed to be significantly altered in groups 1 and 2 if the shoulder offset (representing trunk rotation) was equal to or more than the mean value for group 3 (24.30 mm), as group 3 was the clinically vulnerable group and had a large majority of subjects who showed maximum posture adaptation. The degree of trunk rotation, as seen in the shoulder offset, increased with increasing vulnerability (Figure 1). The trunk was rotated toward the left side, which was the preferred stabilizing lower limb in 70.7% of group 1, 87.9% of group 2, and 94.0% of group 3 participants (Table 2). There was a progressively decreasing number of participants who maintained gait speed greater than 1.0 m/s from group 1 to group 3. However, an increasing number of such “healthy walkers” displayed significant trunk rotation from group 1 to group 3 (Table 2). An example of such progressive adap- tation is shown in Figure 2. Trunk posture adaptation correlated with deficits of strength, function, and walking speed in each of the groups. The data show that it may be difficult to separate those who are clinically healthy and those who may be transitioning to frailty based on gait speed alone, especially in community-dwelling older adults. The trunk rotation measures provide a clearer picture of progressive deterioration, allowing earlier detection. Although there is increased hip flexion in Figure 2 (B and C), the actual angle at the hip during walking was not significantly different between the groups. The greater difference was in the trunk rotation, and all those with trunk rotation displayed the bent-forward posture. The pitch and roll of the upper body as measured by movement of the C7 marker with respect to center of mass was also found to have no significant difference. This Table 1 Demographic Data of Individuals With Strength, Function, Gait, and Blood Parameters Data Particulars Young Adults, 21e50 y n ¼ 20 Mean (SD) Older Adults, 60e80 y Group 1, CSHA 1 and 2 n ¼ 41 Mean (SD) Group 2, CSHA 3 n ¼ 33 Mean (SD) Group 3, CSHA 4 n ¼ 16 Mean (SD) No. of individuals Age, y 33.85 (10.49) 66 (4.97) 66.33 (3.96) 70.56 (4.55) BMI, kg/m2 21.47 (2.49) 22.98 (1.89) 23.45 (1.74) 23.03 (3.45) Grip strength, kg 35 (7.27) 28.9 (5.93) 29.88 (5.11) 29.62 (4.85) Gait speed: motion analysis, m/s 1.21 (0.14) 1.13 (0.17) 1.14 (0.17) 1.03 (0.25) Gait speed: 6-min walk, m/s 1.70 (0.29) 1.42 (0.25) 1.43 (0.23) 1.27 (0.33) TUG, s 7.84 (1.15) 8.57 (1.96) 8.89 (1.44) 10.03 (3.03) Toe-off as percentage of stance phase of gait cycle, % 58.61 (2.35) 59.85 (2.15) 60.18 (1.98) 60.45 (2.45) Stride length, m 1.27 (0.18) 1.24 (0.11) 1.25 (0.10) 1.18 (0.14) IGF-1, ng/mL 181.95 (47.85) 132.07 (46.87) 130.24 (46.93) 129.19 (42.73) Fig. 1. The trunk rotation adaptation within groups 1, 2, and 3 increased progressively from the healthy (group 1) to the vulnerable (group 3). Differences in the shoulder offset were particularly significant between groups 1 and 4. R.A. Merchant et al. / JAMDA xxx (2015) 1e6 3
  4. 4. may be because none of the participants, all living and functioning in the community, were so frail as to have significant hip flexion, hip hitching, or increased upper body mediolateral movement during walking. Adaptations in gait kinematics associated with trunk adaptation Although the hip and knee flexion in the older adult age group overall during the swing phase of gait was less than the young age groups, they did not differ significantly between healthy and vulner- able older adults. Individuals with significant trunk rotation toward the left side among the vulnerable older adult group demonstrated reduced hip elevation and hip rotation during the swing phase of gait on the left side as compared with healthy older adults, as also increased dorsi- flexion in swing phase and reduced plantar flexion at toe-off stage of gait as seen in the motion analysis (Table 3). Although the healthy older adults showed a difference in hip elevation between left and right side of approximately 2 mm, in the vulnerable, the left elevation was on an average approximately 7 mm less than the right. In the vulnerable group, hip rotation measured primarily negative values (backward rotation) and the hip never rotated past the zero-angle mark, whereas the healthy group rotated the hip on both sides (positive and negative) of the zero mark. The maximum plantar flexion on the left side during toe-off was reduced overall in the vulnerable group (although not significant), with a corresponding increase in dorsiflexion during swing (as a possible compensation for the reduced hip elevation). The sway in group 3 was reduced in the anteroposterior direction, but with a greater percent- age increase in backward sway. The mediolateral sway in this group was reduced as well, in particular the sway toward the left side. On revisiting the gait analysis data, it was found that the vulnerable group also had increased toe-off percentage in stance phase and decreased stride length (Table 1). Discussion To our knowledge, this is the first study that has explicitly shown that posture adaptation precedes decline in gait speed. Most of the literature on sarcopenia and frailty focuses around gait speed, as it is well known that slow gait speed leads to falls and fractures, hospi- talization, cognitive decline, and subsequent mortality. Most in- terventions for frailty and sarcopenia have focused mainly on resistance, endurance, and balance training without specific attention to correcting posture. The findings from our study support the need for posture correction rehabilitation for all older adults who display posture adaptation, even though they may have good gait speed at the time of evaluation. Such intervention may then affect the occurrence of falls, as well as reduce the increased backward sway shown by the vulnerable group. A posture adaptation study with elderly in quiet standing was published by Kirby et al.15 Kirby et al15 found that the elderly in- dividuals placed the left foot approximately 30 to 40 mm behind the right foot so as to stabilize in quiet standing. Such an adaptation resulted in minimizing anteroposterior and mediolateral sway. The Table 2 Trunk Rotation (Shoulder Offset) Values and Percentage Distribution Between Groups Group Mean Shoulder Offset, mm Mean (SD) Overall % Individuals With Trunk Rotation % of Individuals With Gait Speed >1 m/s % of Individuals With Gait Speed >1 m/s AND Significant Trunk Rotation 1 (CSHA 1, 2) 9.03 (10.07) 70.7 95.12 24.39 2 (CSHA 3) 15.11 (15.74) 87.9 93.93 39.39 3 (CSHA 4) 24.30 (8.31) 94.0 62.50 67.00 Fig. 2. (A, B) Individuals who have walking speed >1.0 m/s. (A) Individual from group 1 and shows no posture adaptation. (B) Individual from group 2 who showed posture adaptation while maintaining a good walking speed. (C) Participant from group 3 with a walking speed <1.0 m/s and an altered posture. R.A. Merchant et al. / JAMDA xxx (2015) 1e64
  5. 5. results of this study show a more stage-wise transition from a mean 9.03-mm shoulder offset in the healthy elderly (comparable with that in younger individuals) during walking to 15.11 mm in the interme- diate group to 24.30 mm in the vulnerable elderly group (Table 1). The range of offset in group 2 was the largest, arguably characterizing a group that is in transition. The percentages of individuals adapting in each group was also progressively higher, from 70.7% in the healthy group up to 94.0% in the vulnerable group. Although grip strength in the dominant hand, walking speed, and TUG trended toward lower values in the vulnerable group, each group had a mix of those who performed as well as the healthy group. In particular, more than half of the vulnerable group maintained a gait speed faster than 1 m/s, of whom 67% had adapted posture. All of the slow walkers in the 3 groups showed posture adaptation, with most stabilizing on the left side. This seems to suggest that posture adaptation during walking precedes decline in gait speed and is a better marker to identify early those at risk of functional decline and frailty. This adaptation could be due to a hip strategy that might facilitate step initiation with the dominant right leg.16 Change in the walking posture was also associ- ated with standing posture with individuals displaying a distinct retropulsion stance when not walking.17 An example of such a case from the intermediate-risk group is shown in Figure 3. Diseases causing backward disequilibrium in older adults (such as Parkinson disease, multiple systems atrophy, strokes, and normal-pressure hy- drocephalus) are known to be associated with higher risk of falls, highlighting the importance of retropulsion in both normal aging as well as in disease states.18 The decline in hip rotation, hip elevation, and plantar flexion at the ankle with increased dorsiflexion during swing phase on the left side suggests a progression to adaptation in traditional gait characteristics. Although the reduced hip movement may ultimately manifest as or exacerbate existing hip stiffness and weakness, the reduced ankle plantar flexion is known to affect the swing phase and stride length in gait. It is likely that the deficits in hip movement and stride length would then combine to affect traditional measures of frailty, such as gait speed and TUG. Based on this information, one may hypothesize that posture and gait adaptations precede actual decline in walking speed, as the older adults adjust to increasing weakness and joint stiffness until the scope of such adaptation is exhausted. The progression may be represented by the following stages: Increasing tendency to stabilize due to age and weakness Adaptation with trunk rotation toward one side (most stabilize on the left side) Reduced hip rotation angle and reduced hip elevation on sta- bilizing side Resultant adaptation with a reduced plantar flexion at toe-off and increased ankle dorsiflexion during swing of left leg to compensate for poor hip elevation Progressive reduction in stride length due to a shorter swing phase and higher toe-off percentage in stance phase Reduced gait speed and poor TUG due to reduced stride length and increased hip stiffness combined A future longitudinal study may be used to investigate such a progression hypothesis. Although gait speed is measured often as part of screening for frailty, there are varied opinions on exercise in- terventions to improve failing gait ability.19e21 This data analysis suggests that specific exercises addressing biomechanical alignment, improved range of motion of the hip, strengthening of the gluteus medius, and strengthening of the muscles to improve plantar flexion and posture correction exercises to reduce trunk rotation and retro- pulsion, among others, would benefit those older adults in the com- munity to delay the decline in gait speed and help them remain active and healthy much longer. Conclusion Decline in gait speed is widely used as a reliable marker for onset of frailty and associated sarcopenia. This study indicates that trunk posture adaptation precedes decline in gait speed. A significant number of Chinese male older adults who maintained good gait speed demonstrated posture adaptations in walking, whereas all slow walkers had posture adaptation. It is useful to track trunk posture adaptation during walking to identify the at-risk older adults earlier, even before gait speed declines. Early exercise interventions concentrated around posture correc- tion, hip and ankle range of motion, and strengthening of specific muscles on the stabilizing side may then help delay such vulnerable community-dwelling elders from progressing to frailty, keeping them independent longer. Further prospective studies are needed to see if healthy older adults with trunk posture adaptation and normal gait speed develop impaired gait speed earlier than those without such adaptation and if this can be prevented with posture correction and range of motion exercises. Fig. 3. Example of a participant from group 2, considered intermediate risk, who had healthy gait speed (1.33 m/s) but displayed posture adaptation in walking (A) and retropulsion while standing (B) with increased sway asymmetry as shown in Table 2. Table 3 Hip and Ankle Movement and Sway Characteristics on Stabilizing Left Side for the Older Adults Indicating Adaptation in Gait in Group 3 as Compared With Group 1 Group Hip Rotation, Degrees Hip Elevation Difference, mm Dorsiflexion in Swing Phase, Degrees Plantarflexion in Toe-off Phase, Degrees Sway, mm Left (Right) À (Left) Left Left Left Back Group 1 2 2.2 6 11 16.3 9.5 Group 3 À3 7.1 9 6 10.1 13 R.A. Merchant et al. / JAMDA xxx (2015) 1e6 5
  6. 6. References 1. Fried LP, Walston J. Frailty and failure to thrive. In: Hazzard WR, Blass JP, Ettinger Jr WH, editors. Principles of Geriatric Medicine and Gerontology. 4th ed. New York: McGraw Hill; 1998. p. 1387e1402. 2. Syddall HE, Westbury LD, Cooper C, Sayer AA. Self-reported walking speed: A useful marker of physical performance among community-dwelling older people? J Am Med Dir Assoc 2015;16:323e328. 3. Guedes RC, Dias RC, Pereira LSM, et al. Influence of dual task and frailty on gait parameters of older community dwelling individuals. Braz J Phys Ther 2014;18: 445e452. 4. Parentoni AN, Mendonça VA, Dos Santos KD, et al. Gait speed as a predictor of respiratory muscle function, strength and frailty syndrome in community dwelling elderly people. J Frailty Aging 2015;4:64e68. 5. Afilalo J, Eisenberg MJ, Morin JF, et al. Gait speed as an incremental predictor of mortality and major morbidity in elderly patients undergoing cardiac surgery. J Am Coll Cardiol 2010;56:1668e1676. 6. Quach L, Galica AM, Jones RN, et al. The non-linear relationship between gait speed and falls: The maintenance of balance, independent living, intellect and zest in the elderly Boston study. J Am Geriatr Soc 2011;59: 1069e1073. 7. Lord SE, McPherson K, McNaughton HK, et al. Community ambulation after stroke: How important and obtainable is it and what measures appear pre- dictive? Arch Phys Med Rehabil 2004;85:234e239. 8. Kang HG, Dingwell JB. Effects of walking speed, strength and range of motion on gait stability in healthy older adults. J Biomech 2008;41: 2899e2905. 9. Chen LK, Liu LK, Woo J, et al. Sarcopenia in Asia: Consensus report of the Asian Working Group for Sarcopenia. J Am Med Dir Assoc 2014;15:95e101. 10. Rockwood K, Song X, McKnight C, et al. A global clinical measure of fitness and frailty in elderly people. CMAJ 2005;173:489e495. 11. Chan DC, Tsou HH, Chen CY, Chen CY. Validation of the Chinese-Canadian study of health and ageing clinical frailty scale (CSHA-CFS) telephone version. Arch Gerontol Geriatr 2010;50:e74ee80. 12. Yang CW, Li TC, Li CI, et al. Insulin-like growth factor-1 and its binding protein- 3 polymorphisms predict circulating igf-1 level and appendicular skeletal muscle mass in Chinese elderly. J Am Med Dir Assoc 2015;16:365e370. 13. Hyde Z, Flicker L, Almeida OP, et al. Low free testosterone predicts frailty in older men: The health in men study. J Clin Endocrinol Metab 2010;95: 3165e3172. 14. Hennessey JV, Chromiak JA, DellaVentura S, et al. Growth hormone adminis- tration and exercise effects on muscle fiber type and diameter in moderately frail older people. J Am Geriatr Soc 2001;49:852e858. 15. Kirby RL, Price NA, MacLeod DA. The influence of foot position on standing balance. J Biomech 1987;20:423e427. 16. Berger L, Chuzel M, Buisson G, Rougier P. Undisturbed upright stance control in the elderly: Part 1. Age-related changes in undisturbed upright stance control. J Mot Behav 2005;37:348e358. 17. Morley JE, Rolland Y, Tolson D, Vellas B. Increasing awareness of the factors producing falls: The Mini Falls Assessment. J Am Med Dir Assoc 2012;13: 87e90. 18. Manckoundia P, Mourey F, Perennou D, Pfitzenmeyer P. Backward disequilib- rium in elderly subjects. Clin Interv Aging 2008;3:667e672. 19. Van Swearingen JM, Perera S, Brach JS, et al. Impact of exercise to improve gait efficiency on activity and participation in older adults with mobility limitations: A randomized controlled trial. Phys Ther 2011;91: 1740e1751. 20. Valenzuela T. Efficacy of progressive resistance training interventions in older adults in nursing homes: A systematic review. J Am Med Dir Assoc 2012;13: 418e428. 21. Cadore EL, Rodriguez-Manas L, Sinclair A, Izquierdo M. Effects of different exercise interventions on risk of falls, gait ability and balance in physically frail older adults: A systematic review. Rejuvenation Res 2013;16:105e114. R.A. Merchant et al. / JAMDA xxx (2015) 1e66

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