Author(s): ENYEDI, K., BARABÁS, C., SZENCZI, J., SZIRMAI, D., KAMONDI, A., HORVÁTH, A.A., NÉGYESI, J., Institution: HUNGARIAN UNIVERSITY OF SPORTS SCIENCE, Country: HUNGARY, Abstract-ID: 1158

INTRODUCTION:
Healthy individuals perform motor sequencing tasks more effectively with their right hand. However, aging and task complexity appear to influence this behaviour through various, sometimes conflicting, neurological mechanisms. The primary objective of the study is to investigate how hemispheric lateralization of neural activity changes with aging and task complexity.
METHODS:
Fifteen younger (age = 22.8 ± 2.5 years, 7 females) and fifteen older (age = 59.5 ± 4.0 years, 6 females) participants performed finger key presses on a numeric keypad with each hand across four levels of sequence complexity, in a randomized order. Accuracy, reaction time (RT), motor execution time (MT), and subjective workload, as measured by NASA-TLX, were evaluated.
RESULTS:
Statistical analysis revealed that older participants were less accurate than younger participants only on the most complex task (p < 0.001, d = 5.31). In addition, older participants reacted significantly more slowly than younger participants only on the most complex tasks (level 4: p < 0.001, d = -1.57), and their MT was slower at level 3 (p = 0.001, d = -4.13) and level 4 (p < 0.001, d = -8.56). Lastly, the subjective workload associated with RT and MT was observed only among older participants at levels 2 and 4, suggesting that most participants’ subjective ratings of task difficulty did not align with the intentionally designed sequence complexity.
CONCLUSION:
Our findings indicate consistent right-hand superiority in motor sequencing, supporting the theory of left-hemisphere specialization across age groups and task difficulty. However, this lateralization does not reduce age-related declines, which are disproportionately evident during high-complexity tasks. The strong association between subjective workload and performance, observed only in older adults, suggests that aging necessitates a shift toward more cognitively demanding, conscious monitoring strategies to maintain motor output. Our ongoing study aims to determine the underlying neuronal mechanisms of these age- and complexity-dependent processes.