PURPOSE: Previous studies reported muscular strength may protect against cognitive decline in aging adults. However, the specific aspects of cognitive function that may be sensitive to muscular strength are unclear. Thus, this study sought to explore the cross-sectional relationship between muscular strength, cathepsin B (CTSB), and the N2 and P3 event related potentials (ERPs), neurophysiological markers of inhibition and attention. METHODS: Adults (N = 37; 45-64 yrs) underwent strength testing measured via isokinetic knee extensions at 60, 120, and 180 deg·s-1. Inhibitory control and attentional resource allocation was assessed through neuroelectrical indices of the N2 and P3 during the Eriksen Flanker task. Lean body mass was measured through dual X-ray absorptiometry. CTSB was measured in plasma samples after an overnight fast and analyzed via enzyme-linked immunosorbent assay (ELISA). RESULTS: Isokinetic strength was determined by summing the respective z-scores of the peak torque at each velocity. Upon adjusting for covariates, isokinetic strength was inversely associated with congruent (β = -0.664, P = 0.005) and incongruent (β = -0.655, P = 0.005) reaction time, but not accuracy. Similarly, isokinetic strength was inversely associated with congruent (β = -0.619, P = 0.014) and incongruent (β = -0.532, P = 0 .026) mean amplitude, as well as incongruent fractional peak latency (β = -0.736, P = 0.003) of the N2. However, isokinetic strength was not associated with the P3. Similar to isokinetic strength, CTSB was inversely associated with congruent (β = -0.479, P = 0.002) and incongruent (β = -0.437, P = 0.004) reaction time, but not accuracy. However, CTSB was not associated with the N2. Finally, CTSB was inversely associated with incongruent fractional peak latency of the P3 (β = -0.356, P = 0.042). CONCLUSION: These findings suggest that greater muscular strength and CTSB may support cognitive control through different neuroelectrical pathways, particularly when upregulation of cognitive control is required. Specifically, individuals with greater isokinetic strength exhibit greater ability to allocate resources to inhibitory control while exhibiting faster information processing speed, and individuals with greater CTSB exhibit faster stimulus processing. This work was funded by The Beef Checkoff.