This work presents a wearable shirt fitted with dry electrodes to measure EMG in upper limbs during physical exercise. The hardware acquires signals from 6 channels and transmits wirelessly to a PC via Bluetooth. In the PC, EMG signals are analyzed to give feedback to the user regarding the exercise being performed. To alert for muscle fatigue, the Dimitrov index is used, with much better results that classic mean or median EMG frequency tracking. The system is able to monitor EMG activity and provide valuable information in real-time for professional and amateur athletes and their sports coach, improving their training protocols.