A device mountable on a shaft of exercise equipment is provided. The device comprises: a housing with a hole therethrough to receive an end of the shaft; a load sensor configured to generate an indication of weight of a load attached to the shaft; a motion sensor configured to generate an indication of motion of the load over time; and an interface configured to transmit, to an external device, (i) the indication of weight of the load and (ii) a time series descriptive of a trajectory of the load over a period of time. The external device is configured to apply a set of one or more processing rules to the indication of the weight and to the time series to generate a metric of forces applied to move the load along the trajectory and provide the metric via a user interface of a client device.