Cardiorespiratory fitness and sex assigned at birth contribute to brake reaction time in older adults

Introduction: Age-related increases in reaction time (RT) are pervasive. Driver RT is a crucial component of roadway safety. Superior cardiorespiratory fitness (CRF) is associated with faster RTs on a variety of behavioral tasks. Driver RT, as with any RT measure, is comprised of constituent components that contribute to a total response time (TT). Simple RT (sRT) is comprised of the requisite sensory and central processing of TT. Movement time (MT) is comprised of the requisite movement of a particular behavioral response (e.g., moving your foot from the accelerator to the brake pedal). This study aimed to determine the strongest predictor of constituent components of driver RT on a brake onset test. Methods: Cross-sectional analysis. Predictor variables included CRF, age and sex. Participants were 50 community-dwelling older adults between the ages of 60 and 77 (mean age = 66.5 years, SD = 4.1). Maximal graded exercise tests were used to assess CRF. A driving simulator was used to assess constituent components of driving-related RT. Results: Findings indicated that CRF was the largest contributor to sRT variance (beta = −0.35, p = 0.03). Sex was the largest contributor to MT (beta = −0.44, p = 0.003) and TT (beta = −0.28, 0.05) variance. CRF also demonstrated a marginal contribution to TT variance (beta = −0.25, p = 0.08). Age did not significantly contribute to sRT, MT or TT. Conclusions: Age-related increases in RT can jeopardize roadway safety. Findings from this study demonstrate that a modifiable lifestyle variable may have the ability to reduce roadway risk by improving constituent components of driver RT.