The effects of cognitive-motor and motor-motor dual tasks on gait performance and dynamic stability in older adults with and without sarcopenia: a cross-sectional study.

BACKGROUND: To investigate the effects of cognitive and motor dual tasks on gait characteristics and dynamic stability in older adults with sarcopenia compared with healthy older adults, and to elucidate the mechanisms underlying their increased fall risk under dual-task conditions. METHODS: This cross-sectional study, with a limited sample size, recruited 40 older adults (mean age: 73.0 ± 4.2 years), including 20 with sarcopenia and 20 healthy controls. Gait parameters and the margin of stability (MoS)—a biomechanical measure quantifying dynamic stability as the shortest distance from the extrapolated center of mass to the boundary of the base of support—were assessed during single-task (ST), cognitive-motor dual-task (CMDT), and motor-motor dual-task (MMDT) walking. A two-way repeated-measures ANOVA was conducted to evaluate the effects of group and task on gait and stability. RESULTS: For the primary outcome, the anterior–posterior margin of stability (MoSₐₚ) was significantly reduced in older adults with sarcopenia compared to healthy controls during dual-task walking (P < 0.05). Overall, the sarcopenia group demonstrated impaired dynamic stability, also marked by reduced center of mass velocity (P < 0.05). Compared to the healthy group under the same walking conditions, the sarcopenia group exhibited significant gait alterations, including shorter step length, slower gait speed, prolonged gait cycle, and wider step width (P < 0.01). Relative to ST, dual-task conditions further decreased anterior–posterior MoS and center of mass velocity, while increasing mediolateral MoS (MoSₘₗ) as a compensatory mechanism. Additionally, step length shortened, gait speed declined, and both gait cycle and double support phase prolonged (P < 0.05). CMDT particularly impaired postural control, leading to greater reductions in gait speed, MoSₘₗ, and center of mass velocity in the sarcopenia group (P < 0.05). The correlation analysis revealed a strong positive association between gait speed and MoSₐₚ (r = 0.530, P < 0.001), as well as moderate negative correlations between MoSₘₗ and both stride length (r = -0.375, P = 0.003) and step length (r = -0.371, P < 0.004) among older adults with sarcopenia. No significant correlation was observed between MoS and step width. CONCLUSION: Older adults with sarcopenia exhibit pronounced gait and dynamic stability impairments during dual-task conditions, particularly under cognitive-motor demands. The primary gait alterations observed include reduced stride length, decreased gait speed, diminished mediolateral control of the center of mass, prolonged gait cycle, and increased double support time. These findings may inform clinical assessment by highlighting the utility of dual-task paradigms for evaluating functional deficits and tailoring interventions aimed at enhancing postural control and mitigating fall risk in this population.