# Inclined treadmill walking kinetics of the non-paretic leg in early post-stroke survivors: an observational case-control study

## TL;DR

This study examines how early post-stroke survivors use their non-paretic leg during incline treadmill walking, revealing compensatory strategies and reduced force generation compared to healthy individuals.

## Contribution

The study provides new insights into non-paretic leg mechanics during incline walking in early post-stroke survivors, highlighting the need for targeted rehabilitation.

## Key findings

- Stroke survivors showed lower vertical ground reaction force peaks and impulses in the non-paretic leg compared to controls during incline walking.
- Inclined walking increased F1 and decreased F2 for both groups, but stroke survivors showed reduced F3, indicating impaired push-off mechanics.
- The study suggests rehabilitation should focus on motor control and force steadiness in both legs to improve walking efficiency.

## Abstract

Stroke remains the primary source of prolonged disability worldwide since it often results in gait asymmetry. Research shows compensatory mechanisms in chronic stroke patients’ non-paretic legs but lacks knowledge about these adaptations during the early post-stroke period when walking on inclines which mimic real-world mobility challenges.

This study sought to clarify the compensatory strategies in the non-paretic leg of early post-stroke survivors by analyzing the changes in vertical ground reaction force (GRF) profiles and respective variabilities during level (0%) and inclined (6%) treadmill walking, relative to healthy, matched controls.

The study included fourteen early post-stroke survivors who were three months post-event or less along with fourteen matched controls. Participants walked at their preferred speeds on treadmill at 0% and 6% grade incline settings. Researchers determined key vertical GRF profiles, including peak amplitudes (F1, F2, F3), impulses (J1–J4), timing to each peak, loading/unloading rates, and their respectively variabilities. Mixed two-way repeated measures Analysis of covariance (ANCOVA) were used and preferred walking speed was used as a covariate.

Stroke survivors demonstrated significantly slower walking speeds compared to control participants (0.6 km/hr vs. 2.15 km/hr) while both groups shared similar demographic characteristics. It is worth mentioning that this study specifically focused on the non-paretic side; therefore, only GRF components corresponding to the non-paretic leg of the stroke survivors were investigated. During weight acceptance (F1) and push-off (F3) phases, stroke survivors showed lower vertical ground reaction force (VGRF) peak amplitudes (F1- control (C): 1.11 vs. patients (P): 1.04, F3 - C: 1.09 vs. P: 1.03) and impulse magnitudes (J1- C: 25.46 vs. P: 18.74, J2 - C: 21.37 vs. P: 13.46, J3- C: 22.38 vs. P: 15.71, J4 - C: 22.16 vs. P: 18.19) in their non-paretic leg compared to control subjects regardless of inclines. Stroke survivors presented higher F2 (mid-stance, F2 - C: 0.92 vs. P: 0.98) values which might indicate a flatter vertical ground reaction force profile due to compensatory or pathological gait mechanisms. Inclined walking produced increased F1 (Grade 0%: 1.06 vs. Grade 6%: 1.10) and decreased F2 (Grade 0%: 0.97 vs. Grade 6%: 0.93) for both participant groups, but controls exhibited increased F3 (Grade 0%: 1.06 vs. Grade 6%: 1.12) while stroke survivors showed reductions in F3 (Grade 0%: 1.05 vs. Grade 6%: 1.01) which indicated impaired push-off mechanics.

The study demonstrates that treating the non-paretic leg as a healthy limb is inadequate and shows the necessity for rehabilitation approaches that target both legs individually. Focusing on motor control and force steadiness instead of simply strength can more effectively reduce maladaptive variability and enhance safe and efficient walking patterns.