Effects of arm movement on emotional state and walking outcomes during height-induced postural threat in healthy young adults

Background There is evidence that height-induced postural threat leads to detrimental effects on walking performance. However, little is known about how the additional restriction of stabilizing arm movements affects gait and emotional state outcomes. Objective The purpose was to investigate how the restriction of arm movement affects subjective and objective balance-related measures during walking at or above ground-level. Methods Twenty-two healthy young adults (11 males, 11 females; mean ± SD age; 24.4 ± 4.9 years) walked five meters at self-selected speed on ground-level (no threat) and 80 cm above ground-level (threat) with free and restricted arm movement. Emotional state outcomes were quantified by assessing self-reported balance confidence, fear of falling, perceived instability, and conscious balance processing. Walking outcomes (i.e., gait velocity, cadence, step time, normal impulse) were calculated using pressure-detecting insoles. Results Irrespective of arm movement condition, height-induced postural threat evoked a decrease in balance confidence and increases in fear of falling, perceived instability, and conscious balance processing as well as deteriorations in walking outcomes (i.e., decrease in gait speed and cadence; increase in step time and normal impulse). For balance confidence and step time, the threat-induced impairments were further amplified when arm movements were restricted. Conclusions The strengthening of the height-induced deteriorations in emotional state (balance confidence) and walking (step time) outcomes due to the restriction of the arm movements emphasizes the importance of stabilizing, free arm movements (‘upper body strategy’) for dynamic postural control.