Acute physical exercise enhances semantic memory processing speed: evidence from a reaction-time lexical decision task

Introduction: Regular physical activity modulates neuroplasticity and protects against age-related cognitive decline. However, the acute effects of exercise on higher-order language functions remain poorly defined. This study investigated how a single moderate-intensity cycling session influences lexical-semantic processing speed in middle-aged adults.
Methods: Forty-one healthy participants (mean age 43.6 ± 1.7 years; 22 women, 19 men) were randomly assigned to an exercise group (n = 20; 15 min cycling at 65% HRmax) or control group (n = 21; passive video viewing). Cognitive performance was assessed before and after intervention using a lexical decision task involving real and pseudowords (1 s presentation). Reaction times (RTs) and accuracy were recorded. Heart rate (HR) was continuously monitored to verify exertion level. Participants were additionally divided into younger (<40 years) and older (>40 years) subgroups to assess age-related differences in cognitive response.
Results: Heart rate analysis confirmed adequate workload and recovery (p ≤ 0.001). Acute exercise significantly reduced RT for both pseudowords (d = 0.60; p ≤ 0.0001) and real words (d = 0.39; p ≤ 0.0001), whereas the control condition produced smaller but reliable improvements (pseudowords d = 0.40; p ≤ 0.001; words d = 0.27; p ≤ 0.01). Age-stratified analysis indicated more pronounced improvements in participants > 40 years (p ≤ 0.05). These behavioral changes suggest transient enhancement of cortical efficiency in semantic decision-making, possibly mediated by increased cerebral perfusion and neurotrophic signaling.
Conclusion: A brief session of moderate-intensity aerobic exercise enhances semantic processing speed, reflecting rapid neuroplastic modulation of cortical language networks. The effect was evident across both sexes and most pronounced in adults over 40, suggesting that short aerobic activity may serve as a simple, non-pharmacological intervention to preserve semantic memory and cognitive fluency during midlife and aging.