Maybe we should keep this in mind while "gait retraining" and "rehabbing". You could be inducing the changes you are seeing on a cortical level.
This makes you wonder about walking and thinking about sometime else. Being mindful has its advantages, like less cortical laterality and dominance. Remember, in this study, the arm swing is les on the right, so theoretically, less cortical motor drive from the left side. No wonder your gait changes! Be careful which hand you are texting with : )...Better yet, don't walk and text....
Human arm swing looks and feels highly automated, yet it is increasingly apparent that higher centres, including the cortex, are involved in many aspects of locomotor control. The addition of a cognitive task increases arm swing asymmetry during walking, but the characteristics and mechanism of this asymmetry are unclear. We hypothesized that this effect is lateralized and a Stroop word-colour naming task-primarily involving left hemisphere structures-would reduce right arm swing only. We recorded gait in 83 healthy subjects aged 18-80 walking normally on a treadmill and while performing a congruent and incongruent Stroop task. The primary measure of arm swing asymmetry-an index based on both three-dimensional wrist trajectories in which positive values indicate proportionally smaller movements on the right-increased significantly under dual-task conditions in those aged 40-59 and further still in the over-60s, driven by reduced right arm flexion. Right arm swing attenuation appears to be the norm in humans performing a locomotor-cognitive dual-task, confirming a prominent role of the brain in locomotor behaviour. Women under 60 are surprisingly resistant to this effect, revealing unexpected gender differences atop the hierarchical chain of locomotor control.
R Soc Open Sci. 2017 Jan 25;4(1):160993. doi: 10.1098/rsos.160993. eCollection 2017 Jan.
Increasing cognitive load attenuates right arm swing in healthy human walking.
Killeen T1, Easthope CS1, Filli L2, Lőrincz L2, Schrafl-Altermatt M1, Brugger P2, Linnebank M3, Curt A1, Zörner B1, Bolliger M1.
free full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319362/