Lifting velocity predicts the maximum number of repetitions to failure with comparable accuracy during the Smith machine and free-weight prone bench pull exercises.

This study compared the accuracy of the fastest mean velocity from set (MV) to predict the maximum number of repetitions to failure (RTF) between 2 variants of prone bench pull (PBP) exercise (Smith machine and free-weight) and 3 methods (generalized, individualized multiple-point, and individualized 2-point). Twenty-three resistance-trained males randomly performed 2 sessions during Smith machine PBP and 2 sessions during free-weight PBP in different weeks. The first weekly session determined the RTF-MV relationships and subjects completed single sets of repetitions to failure against 60-70-80-90%1RM. The second weekly session explored the accuracy of RTFs prediction under fatigue conditions and subjects completed 2 sets of 65%1RM and 2 sets of 85%1RM with 2 min of rest. The MV associated with RTFs from 1 to 15 were greater for Smith machine compared to free-weight PBP ( ≥ 42.9;  < 0.001) and for multiple-point compared to 2-point method ( ≥ 4.6;  ≤ 0.043). The errors when predicting RTFs did not differ between methods and PBP variants, whereas all RTF-MV relationships overestimated the RTF under fatigue conditions. These results suggest that RTF-MV relationships present similar accuracy during Smith machine and free-weight PBP exercises and it should be constructed under similar training conditions.