Comparison of Foot-Response Reaction Time Between Younger and Older Adults Using the Foot Psychomotor Vigilance Test

Reaction time (RT) is a key indicator of cognitive and motor processing speed, and its age-related decline has important implications for everyday activities such as driving. However, conventional Psychomotor Vigilance Tests (PVTs) assess hand responses and do not capture lower-limb reaction characteristics relevant to pedal operations. This study aimed to compare RT characteristics between younger and older adults using the foot-response version of the PVT (Foot PVT) and to examine factors associated with RT. Sleep-related variables, physical activity level (PAL), and height were analyzed, and RT distribution characteristics were evaluated. Twenty younger adults (24 ± 3 years, range: 22–29 years) and twenty-four older adults (73 ± 5 years, range: 66–84 years) performed a 10 min Foot PVT. Mean RT was significantly slower in older adults (818 ± 105 ms) than in younger adults (700 ± 73 ms) (p < 0.001), indicating an age-related delay of approximately 120 ms. Older adults showed lower skewness and kurtosis, suggesting more homogeneous and cautious responses. In younger adults, height was negatively correlated with RT (r = −0.593, p = 0.006), and multiple regression analysis identified height as a significant predictor (adjusted R2 = 0.316). No significant predictors were found in older adults. In the combined sample, age and height jointly explained 37.2% of the variance in mean RT. These findings indicate that Foot PVT performance reflects both biomechanical characteristics and age-related declines in reaction speed, supporting its utility for assessing lower-limb reaction capabilities relevant to driving and aging.