Background
Methods
Protocol and registration
Literature review
Inclusion criteria
Exclusion criteria
Study selection
Assessment of Methodologic quality
Data extraction
Quantitative synthesis
Identification of the optimal threshold levels of step width variability
Results
Study selection
Study subjects
Author / Year | Sample size | Exposure | Preferred walking speed protocol | Step width calculation | Step width variability / analyzed steps (avg.) |
---|---|---|---|---|---|
Almarwani et al. (2016a) [39] | OA, n = 111 (82 f), age = 77.25 ± 6.0 yr., ht. = 163.4 ± 9.5 cm, wt. = 77.4 ± 15.7 kg; YA, n = 40 (30 f), age = 26.60 ± 6.0 yr., ht. = 168.4 ± 8.3 cm, wt. = 66.4 ± 12.4 kg | Walking on a 4 m walkway in 3-speed conditions | Participants were instructed to walk at a pace that represented their usual walking speed. OA, PWS = 1.07 ± 0.26 m/s; YA, PWS = 1.29 ± 0.19 m/s. | The distance between the outermost borders of two consecutive footprints (GaitMat II). | OA: 3.70 ± 1.80 cm; YA: 2.40 ± 0.60 cm. OA: 23 steps YA: 38 steps |
Almarwani et al. (2016b) [40] | OA, n = 46 (35 f), age = 78.09 ± 6.2 yr., ht. = nr cm, mass = nr kg; YA, n = 40 (30 f), age = 26.6 ± 6.0 yr., ht. = nr cm, mass = nr kg; | Walking on an 8 m walkway at preferred speed | Authors did not describe how the preferred walking speed was determined. OA, PWS = 0.95 ± 0.28 m/s; YA, PWS = 1.29 ± 0.19 m/s. | The distance between the outermost borders of two consecutive footprints (GaitMat II). | OA: 3.00 ± 1.41 cm; YA: 2.50 ± 1.41 cm OA: 23 steps YA: 38 steps |
Decker et al. (2016) [41] | OA, n = 19 (9 f), age = 69.26 ± 1.11 yr., ht. = 171 ± 2 cm, mass = 77.45 ± 2.78 kg; YA, n = 20 (12 f), age = 24.45 ± 0.87 yr., ht. = 173 ± 2 cm, mass = 70.41 ± 2.63 kg | Three-minutes treadmill walking at 4 attentional demands conditions at a preferred speed | Participants started walking at a slow speed while the treadmill was slowly accelerated by 0.1 km/h until the participants reported their PWS. Then the speed was increased by 1.5 km/h and was slowly decreased by 0.1 km/h until the participants reported their PWS. This procedure was repeated until a less than 0.4 km/h difference was achieved. OA, PWS = 0.77 ± 0.04 m/s; YA, PWS = 1.06 ± 0.03 m/s. | Mediolateral distance between foot midpoints calculated over the consecutive instants when the left (or right) swing limb’s knee passed in front of the right (or left) stance limb’s knee | OA: 1.70 ± 0.17 cm; YA: 1.92 ± 0.08 cm OA: ≥ 256 steps YA: ≥ 256 steps |
Ihlen et al. (2012) [42] | OA, n = 10 (4 f), age = 75.4 ± 4.6 yr., ht. = 170.9 ± 11.8 cm, mass = 76 ± 13.1 kg; YA, n = 10 (4 f), age = 25.7 ± 4.7 yr., ht. = 177.6 ± 8.3 cm, mass = 74.5 ± 9.5 kg | Ten-minutes treadmill walking in 3-speed conditions | Authors did not describe how the preferred walking speed was determined. OA, PWS = 1.17 ± 0.10 m/s; YA, PWS = 1.11 ± 0.15 m/s. | Step width was defined as the mediolateral distance between heel markers at the time of heel strike | OA: 2.55 ± 0.35 cm; YA: 1.91 ± 0.30 cm OA: nr steps YA: nr steps |
Kang et al. (2008) [43] | OA, n = 18 (6 f), age = 72.1 ± 6.0 yr., ht. =170 ± 10.4 cm, mass = 73.2 ± 12.3 kg; YA, n = 17 (5 f), age = 23.6 ± 2.6 yr., ht. = 173 ± 9.4 cm, mass = 71.1 ± 9.86 kg | Five-minutes treadmill walking in 5-speed conditions | Participants reported the limits of their preferred speed while the treadmill was slowly accelerated, then decelerated three times. These upper and lower limits were averaged to determine their preferred walking speed. OA, PWS = 1.29 ± 0.15 m/s; YA, PWS = 1.30 ± 0.10 m/s. | Step width was defined as the distance between the heel and the contralateral heel at each heel contact in the mediolateral direction | OA: 2.14 ± 0.54 cm; YA: 2.01 ± 0.56 cm OA: nr steps YA: nr steps |
Lovden et al. (2008) [38] | OA, n = 32 (16 f), age = 73.6 ± 2.9 yr., ht. = 169.4 ± 10 cm, mass = 74.3 ± 11.5 kg; YA, n = 32 (16 f), age = 25.0 ± 2.9 yr., ht. = 177.6 ± 9.8 cm, mass = 71.6 ± 13.1 kg | Twenty-secs treadmill walking in 4 conditions of working memory load at a preferred speed | Participants gradually increased speed to determine preferred walking speed. After walking at their self-selected speed for 3 min were asked again if they felt comfortable with their choice. OA, PWS = 0.87 ± 0.13 m/s; YA, PWS = 1.04 ± 0.11 m/s. | The step width was measured as the perpendicular distance between the line of progression and the heel location of the contralateral foot. | OA: 2.19 ± 0.11 cm; YA: 1.97 ± 0.12 cm OA: 18 steps YA: 18 steps |
Marigold et al. (2008) [44] | OA, n = 10 (5 f), age = 74.1 ± 7.2 yr., ht. = nr cm, mass = nr kg; YA, n = 10 (5 f), age = 26.1 ± 5.2 yr., ht. = nr cm, mass = nr kg | walking on a multi-surface terrain in 4 different terrain configurations for YA and in 3 different conditions for OA, respectively, at a preferred speed | Authors did not describe how the preferred walking speed was determined. OA, PWS = 1.20 ± 0.12 m/s; YA, PWS = 1.32 ± 0.16 m/s. | The mediolateral distance between ankle markers | OA: 4.09 ± 0.70 cm; YA: 2.96 ± 1.29 cm OA: nr steps YA: nr steps |
Owings et al. (2004a) [45] | OA, n = 12 (nr), age = 73.4 ± 2.3 yr., ht. = 172 ± 13 cm, mass = 76.3 ± 15.5 kg; YA, n = 18 (nr), age = 27.7 ± 3.3 yr., ht. = 168 ± 11 cm, mass = 35.9 ± 10.2 kg | Ten-minutes treadmill walking for OA and 15-min for YA at a preferred speed | Authors did not describe how the preferred walking speed was determined. OA, PWS = 0.97 ± 0.17 m/s; YA, PWS = 1.06 ± 0.28 m/s. | Step width was determined as the mediolateral distance between the sequential left and right heel-strikes | OA: 2.50 ± 0.70 cm; YA: 2.10 ± 0.50 cm OA: nr steps YA: nr steps |
Paterson et al. (2009) [46] | OA, n = 32 (32 f), age = 67.4 ± 6.3 yr., ht. = 162 ± 7 cm, mass = 65.1 ± 13.2 kg; YA, n = 22 (22 f), age = 21.2 ± 2.5 yr., ht. = 166 ± 8 cm, mass = 62.6 ± 9.8 kg | 10 m continuous laps of a walking circuit at a preferred speed | Authors did not describe how the preferred walking speed was determined. OA, PWS = nr; YA, PWS = nr. | The midline midpoint of the current footprint to the midline midpoint of the previous footprint on the opposite foot (GaitRite). | OA: 2.50 ± 0.83 cm; YA: 1.90 ± 0.83 cm OA: nr steps YA: nr steps |
Thies et al. (2005) [47] | OA, n = 12 (12 f), age = 70.2 ± 4.1 yr., ht. = nr cm, mass = nr kg; YA, n = 12 (12 f), age = 22.2 ± 3.0 yr., ht. = nr cm, mass = nr kg, | Walking on a 10 m walkway in 4 task conditions at a preferred speed | Subjects were asked throughout the experiment to walk at a comfortable speed as if they were going to mail a letter. OA, PWS = 1.15 ± 0.06 m/s; YA, PWS = 1.08 ± 0.06 m/s. | Mediolateral distance between the left and right foot ankle (tibiotalar joint) markers during double support | OA: 2.99 ± 0.20 cm; YA: 2.50 ± 0.17 cm OA: 55 steps YA: 63 steps |
Woledge et al. (2005) [48] | OA, n = 21 (8 f), age = 72.7 ± 1.21 yr., ht. = 166 ± 2 cm, mass = 68.3 ± 2.6 kg; YA, n = 17 (11 f), age = 27.3 ± 1.5 yr., ht. = 171 ± 2 cm, mass = 64.3 ± 2.9 kg | Walking on 8 m walkway at a preferred speed | Authors did not describe how the preferred walking speed was determined. OA, PWS = 1.12 ± 0.06 m/s; YA, PWS = 1.19 ± 0.03 m/s. | The lateral difference between successive footfall positions (medial malleoli) | OA: 2.32 ± 0.28 cm; YA: 1.73 ± 0.37 cm OA: 34 steps YA: 34 steps |
Instrumentation used for measuring step width
ITEM | STUDY | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Almarwani et al. (2016a) [39] | Almarwani et al. (2016b) [40] | Decker et al. (2016) [41] | Ihlen et al. (2012) [42] | Kang et al. (2008) [43] | Lovden et al. (2008) [38] | Marigold et al. (2008) [44] | Owings et al. (2004a) [45] | Paterson et al. (2009) [46] | Thies et al. (2005) [47] | Woledge et al. (2005) [48] | |
1. Is the hypothesis/aim/objective of the study clearly described? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
2. Are the main outcomes to be measured clearly described in the Introduction or Methods section? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
3. Are the characteristics of the participants included in the study clearly described? | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 |
5. Are the distributions of the principal confounders in each group of subjects to be compared clearly described? | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
6. Are the main findings of the study clearly described? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
7. Does the study provide estimates of the random variability in the data for the main outcomes? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
10. Have actual probability values been reported (e.g. 0.035 rather than < 0.05) for the main outcomes except where the probability value is less than 0.001? | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 |
11. Were the subjects asked to participate in the study representative of the entire population from which they were recruited? | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 |
12. Were those subjects who were prepared to participate representative of the entire population from which they were recruited? | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
13. Were the staff, place and facilities where the study was set representative of a laboratory environment? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
16. If any of the results of the study were based on “data dredging”, was this made clear? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
20. Were the main outcome measures used accurate (valid and reliable)? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
21. Were the subjects recruited from the same population? | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 |
22. Were study subjects recruited over a defined period of time? | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
25. Was there adequate adjustment for confounding in the analysis from which the main findings were drawn? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
27. Did the study have a power analysis? | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
TOTAL | 14 | 14 | 12 | 10 | 13 | 13 | 14 | 11 | 11 | 14 | 13 |
Assessment of publication Bias and heterogeneity sensitivity analysis
Step width variability in younger adults vs older adults
Discrimination of step width variability for predicting age group
Classified | Actual | |
---|---|---|
Younger adults | Older adults | |
Younger adults (SWV < Lo) | 3 | 0 |
Uncertain Interval (Lo ≤ SWV ≤ Hi) | 6 | 5 |
Older adults (SWV > Hi) | 1 | 5 |