System, for assisting a weightlifting workout, having a plurality of weight plates arranged along an axis of movement, the system comprising: • a memory; • a controller; • at least three sensors each comprising an emitter/receiver pair (102, 103) managed by the controller whereas there is present a spacing, between neighboring sensors, which is a multiple of a height of a weight plate; • wherein each weight plate comprises a reflective marker (111, 121) configured to reflect a signal of the emitter and reflect it towards the receiver; • wherein the three sensors are arranged with respect to an engaging movement vector, selectively applied to the weight plates, as follows: ∘ a middle sensor being the first sensor to detect, due to their relative positioning, a front weight plate, in the initial state in which the number of weight plates reported by the middle sensor is zero, when considering the direction of said engaging movement whereas said front weight plate is the first of said plurality of weight plates to reach said middle sensor; ∘ a top sensor being the sensor following the middle sensor when considering the direction of said engaging movement; ∘ a bottom sensor being the sensor preceding the middle sensor when considering the direction of said engaging movement; the system being characterized in that: • each reflective marker (111, 121) comprises two distinct elements (111A-B, 121A-B): reflector A (111A, 121A) and reflector B (111B, 121B), having different reflective properties; • reflectors A (111A, 121A) reflect more light while reflectors B (111B, 121B) reflect less light whereas both reflectors A and B reflect light to such an extent that it is possible to differentiate between said reflectors and the weight plate as well as an empty space, between weight plates, is present in front of a receiver; • each sensor comprises an emitter as well as two receivers (202, 204) positioned such that there is a shift between them along the expected axis of movement of said markers positioned on the weight plates. • a memory; • a controller; • at least three sensors each comprising an emitter/receiver pair (102, 103) managed by the controller whereas there is present a spacing, between neighboring sensors, which is a multiple of a height of a weight plate; • wherein each weight plate comprises a reflective marker (111, 121) configured to reflect a signal of the emitter and reflect it towards the receiver; • wherein the three sensors are arranged with respect to an engaging movement vector, selectively applied to the weight plates, as follows: ∘ a middle sensor being the first sensor to detect, due to their relative positioning, a front weight plate, in the initial state in which the number of weight plates reported by the middle sensor is zero, when considering the direction of said engaging movement whereas said front weight plate is the first of said plurality of weight plates to reach said middle sensor; ∘ a top sensor being the sensor following the middle sensor when considering the direction of said engaging movement; ∘ a bottom sensor being the sensor preceding the middle sensor when considering the direction of said engaging movement; the system being characterized in that: ∘ a middle sensor being the first sensor to detect, due to their relative positioning, a front weight plate, in the initial state in which the number of weight plates reported by the middle sensor is zero, when considering the direction of said engaging movement whereas said front weight plate is the first of said plurality of weight plates to reach said middle sensor; ∘ a top sensor being the sensor following the middle sensor when considering the direction of said engaging movement; ∘ a bottom sensor being the sensor preceding the middle sensor when considering the direction of said engaging movement; • each reflective marker (111, 121) comprises two distinct elements (111A-B, 121A-B): reflector A (111A, 121A) and reflector B (111B, 121B), having different reflective properties; • reflectors A (111A, 121A) reflect more light while reflectors B (111B, 121B) reflect less light whereas both reflectors A and B reflect light to such an extent that it is possible to differentiate between said reflectors and the weight plate as well as an empty space, between weight plates, is present in front of a receiver; • each sensor comprises an emitter as well as two receivers (202, 204) positioned such that there is a shift between them along the expected axis of movement of said markers positioned on the weight plates.