is the 1 repetition maximum estimation reliable using the load-velocity relationship? comparison of different methods

The study aimed to determine the relationship and differences between estimation methods which are the minimal velocity threshold 1rm (1rmmvt) and load at zero velocity 1rm (1rmld0). the load-velocity relationship was obtained through the 1 repetition maximum (1-rm) with the exercises of free weight and smith machine barbell bench press. the study consisted of fifteen male who were interested in recreationally bodybuilding with at least five years of resistance training experience. the study was completed in four sessions. free weight and smith machine barbell bench press 1rm and the velocity measurements were determined in the 1st and 2nd sessions. the load-velocity profile was generated in the 3rd and 4th sessions with the barbell bench press exercise by using the loads between 30-85% of 1rm determined in the 1st and 2nd sessions. mvt and ld0 methods were used to estimate 1 rm with the load-velocity relationship. pearson correlation analysis was used to determine the relationship between direct measured 1rm and estimation methods and the repeated measures anova was used to determine the differences between the three methods. there were strong positive correlations (between r=0.918-0.949 for the smith machine, between r=0.923-0.937 for free weight) between directly measured 1rm, 1rmmvt, 1rmld0 in both free weight and smith machine barbell bench press. however, no statistical difference was found between all 1rm methods (p>0,05). it was found that the estimation methods of 1rmmvt and 1rmld0 are valid and reliable to estimate 1rm. practitioners can estimate the 1rm from the load-velocity profile with both the free weight and smith machine for barbell bench press exercise by using two alternative methods.