Validity and Reliability of the Insole3 Instrumented Shoe Insole for Ground Reaction Force Measurement during Walking and Running

Abstract

Pressure-detecting insoles such as the Insole3 have potential as a portable alternative for assessing vertical ground reaction force (vGRF) outside of specialized laboratories. This study evaluated whether the Insole3 is a valid and reliable alternative to force plates for measuring vGRF. Eleven healthy participants walked overground at slow and moderately paced speeds and ran at a moderate pace while collecting vGRF simultaneously from a force plate (3000 Hz) and Insole3 (100 Hz). Intraclass correlation coefficients (ICC) demonstrated excellent vGRF agreement between systems during both walking speeds for Peak 1, Peak 2, the valley between peaks, and the vGRF impulse (ICC > 0.941). There was excellent agreement during running for the single vGRF peak (ICC = 0.942) and impulse (ICC = 0.940). The insoles slightly underestimated vGRF peaks (−3.7% to 0.9% bias) and valleys (−2.2% to −1.8% bias), and slightly overestimated impulses (4.2% to 5.6% bias). Reliability between visits for all three activities was excellent (ICC > 0.970). The Insole3 is a valid and reliable alternative to traditional force plates for assessing vGRF during walking and running in healthy adults. The excellent ICC values during slow walking suggests that the Insole3 may be particularly suitable for older adults in clinical and home settings.

Wearables for Running Gait Analysis: A Systematic Review

“…Ankle/foot kinematics n = 19 Description of ankle or foot movement in any of the three cardinal planes: sagittal, frontal, transverse planes, without consideration for forces [19,20,33,43 A measure of the force applied for a specific time and distance [34,45,47,123,124,140,142,149] Braking…”

“…Fifty-six studies focussed on the validation of wearables for running gait assessments, with 18 also examining the reliability of devices [47,98,99,103,104,110,117,120,130,134,136,140,144,149]. Eleven studies investigated between-day reliability [34,47,98,106,117,120,122,140,142,144,149], and three studies solely examined the reliability of wearable technology [87,134,138] Overall, studies included between five [27] and 100 [95,96] participants, with the average number of participants being 22 (± 18). The mean age of participants was 26.8 (± 4.5) years.…”

“…Six validity and/or reliability studies used outdoor environments, with participants running on concrete [79,87], artificial turf [105] and track [102,105,120,152]. Of the remaining studies that used indoor environments, 31 ran on treadmills, 15 ran over-ground [45,63,78,85,94,104,110,115,121,124,127,130,141,142,150] and six ran on a track [61,99,100,129,133,136]. No studies used both indoor and outdoor testing or examined running gait over more than one surface.…”

“…Within reliability studies, ten analysed test-re-test reliability in a single day (i.e. two sessions in 1 day) [98,99,103,104,106,110,130,[134][135][136] and 11 studies performed a test-re-test analysis on different days [34,47,87,117,120,122,138,140,142,144,149]. Those studies that assessed running gait on different days separated testing by a minimum of 24 h [34,140,144], and repeated testing within 1 week [120,149], 2 weeks [47,87] or 1 month [117,142], with one study repeating testing at 1 week and 6 months [138] (Table 2 of the ESM).…”

“…Most studies did not comment on the footwear used. Thirteen studies standardised the footwear of participants [45,61,62,83,85,115,116,123,124,138,142,144,149], 17 allowed participants to wear their own running shoes [27,34,79,81,87,98,99,101,103,105,106,120,128,140,141] and one study required participants to run unshod while wearing insoles under socks [150].…”