Pre-movement sensor-level EEG activity recorded with a portable three-channel system is associated with futsal free-kick outcomes

Brain states immediately before movement may shape skilled athletic performance, but translating electroencephalography (EEG)-based monitoring to sport has been limited by dense montages and laboratory-constrained tasks. We asked whether a portable three-channel EEG system can detect outcome-related preparatory activity during a realistic futsal free-kick task. EEG from C3, Cz, and C4 during the 2 s before each kick was used to decode successful versus unsuccessful trials with channel-wise linear support vector machines (SVMs), and the same approach was tested for transfer across recording days. To relate decoding to interpretable physiology, alpha- and beta-band power were also compared between outcomes. Successful and failed kicks were decoded significantly above label-shuffled null distributions within recording days across all channels, showing that low-density EEG can capture sensor-level information linked to subsequent performance. However, decoding did not generalize reliably across days, indicating that these neural signatures were session specific. Spectral analysis showed selectively increased C3 beta-band power before successful kicks, whereas alpha-band power showed no significant outcome-related differences. These findings support portable EEG as a practical route toward monitoring preparatory brain states in sport, while suggesting that real-world use will require short day-specific calibration or adaptive decoding.