A device for detecting significant parameters of physical activity, the device comprising: a first lever operatively engageable to a frame of a human-propelled movement system, the first lever exhibiting a free end for engaging with a first thrust element emerging transversally to a main development axis of the first lever; a second lever operatively engageable to the frame of a human-propelled movement system on an opposite side thereof with respect to the first lever, the second lever exhibiting a free end for engaging with a second thrust element emerging transversally to a main development axis of the second lever; a connecting spindle interposed between the levers (2, 6) for setting the levers (2, 6) in rotation at least about an axis, the connecting spindle developing along the axis that is transversal to the main development axis of the first and second lever (2, 6) and being predisposed to at least partially cross a frame of the human-propelled movement system; sensor means for detecting at least a significant parameter of the work performed during the rotation of at least one of the levers of the device about the axis, the sensor means are configured such as to determine the value of: at least a load selected from a group comprising: a resultant force transmitted by a user on at least one of the thrust elements, a radial component (ODX, OSX) of the resultant force, which radial component is instant by instant directed parallel to the respective lever (2, 6), a tangential component (VDX, VSX) of the resultant force, which tangential component is instant by instant directed perpendicularly to the lever (2, 6), and at least a torque with respect to a predetermined axis generated by the resultant force or by one of the tangential and radial components, characterised in that the sensor means are connected to a programmed control unit for calculating a distance (DDX, DSX) between a point of application of the resultant force on the thrust element and the development axis of the respective lever, on the basis of the measured value of the load and the measured value of the torque. a first lever operatively engageable to a frame of a human-propelled movement system, the first lever exhibiting a free end for engaging with a first thrust element emerging transversally to a main development axis of the first lever; a second lever operatively engageable to the frame of a human-propelled movement system on an opposite side thereof with respect to the first lever, the second lever exhibiting a free end for engaging with a second thrust element emerging transversally to a main development axis of the second lever; a connecting spindle interposed between the levers (2, 6) for setting the levers (2, 6) in rotation at least about an axis, the connecting spindle developing along the axis that is transversal to the main development axis of the first and second lever (2, 6) and being predisposed to at least partially cross a frame of the human-propelled movement system; at least a load selected from a group comprising: a resultant force transmitted by a user on at least one of the thrust elements, a radial component (ODX, OSX) of the resultant force, which radial component is instant by instant directed parallel to the respective lever (2, 6), a tangential component (VDX, VSX) of the resultant force, which tangential component is instant by instant directed perpendicularly to the lever (2, 6), and at least a torque with respect to a predetermined axis generated by the resultant force or by one of the tangential and radial components, characterised in that