[Objective] The purpose of this study was to investigate the effects of acupuncture on exercise-induced prolongation of information processing and decrease in attentional resource allocation, excluding the placebo effect.[Design] Crossover, double-blind randomized controlled trial[Settings] Tokyo Ariake University[Subjects] Fifteen healthy men aged 21.1 ± 0.9 years[Methods] We used a handgrip exercise for exercise loading. The handgrip was maintained for six seconds at an intensity of 40% of the maximal voluntary contraction (MVC), followed by rest for four seconds. This was alternately repeated and continued until the subject was incapable of exerting a grip strength of 40% of the MVC. To induce P300, an auditory oddball paradigm was used, and P300 was measured before and after the handgrip exercise. In the same subjects, thumbtack needle (TN) intervention (TN group) and placebo thumbtack needle (PTN) intervention (PTN group) were performed in random order. TN or PTN was applied to ST36, HT7, and GV14 before the handgrip exercise. After the experiment, we asked the subjects and practitioner about the intervention (TN or PTN). The allocation was conducted by a third party who did not participate in the experiment, and the subjects, practitioner, and measurer completed a series of all the experiment procedures and were blinded to the results.[Outcomes] The indicators for measuring the main outcomes were P300 latency and amplitude. reaction time, and masking were indicators for secondary outcomes. [Results and Conclusion] In the PTN group, P300 latency was increased significantly and P300 amplitude was decreased significantly after the handgrip exercise. In the TN group, no significant changes were observed in P300 latency and amplitude after the handgrip exercise. In both groups, reaction time was considerably slower after the handgrip exercise. The k value indicating the degree of agreement between the actual (genuine or placebo) and guessed intervention assignment was k = -0.06 for the practitioner and k = 0.66 for the subjects. No adverse events were found in this study.[Conclusions] The index changes in the TN and PTN in this study were the same as in our previous studies, and acceptable reproducibility was observed. However, the k values indicated that subject masking was inadequate. In the future, the reliability and validity of PTN must be investigated further.