Table 1 Study summary for the step width variability during walking in young and older adults

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