A device (1) for measuring muscular capacity. The device includes removable fastening device (12) for fastening the device to the athlete or to the moved weight (3 2). An autonomous electrical power supply means (15), and a display (11) are provided. A three-axis accelerometer (14) delivers a sequence of accelerations (a(t)) along the axis of movement of the weight. The sequence includes at least 100 measurements per second over a duration between 1 and 10 seconds. A data processing device (16) determines, at the end of the test, on the basis of the sequence of accelerations, at least one quantity representative of the muscular capacity of the athlete and displays this quantity on the display (11).
