Changes in deadlift six repetition maximum, countermovement jump performance, barbell velocity, and perceived exertion over the duration of a microcycle

The primary aim of this study was to investigate the stability of the six-repetition maximum (6RM) deadlift over the length of a five-day microcycle and whether the fatigue induced by maximal effort testing detrimentally impacted preparedness. Twelve participants performed four testing sessions, comprising a one-repetition maximum test and three 6RM tests separated by 48 hours. Countermovement jumps were performed before each testing session, and barbell velocity was measured during each warm-up set to assess changes in preparedness. The 6RM deadlift was not statistically different between any of the testing sessions ( p  =  .056; ηp2  =  0.251). Similarly, there were no significant differences in jump height or other CMJ variables between sessions ( p > .05). There were small to moderate differences in mean barbell velocity between the first and second 6RM test ( g  =  0.24–0.88), while there were only small differences in mean velocity (MV) between the second and third 6RM test at some of the warm-up loads (40% 6RM: g  =  0.20; 80% 6RM: g  =  −0.47). Taken collectively, these data indicate that 6RM deadlift strength is stable over five days and does not appear to induce sufficient fatigue to impact vertical jump performance or rating of perceived exertion despite some changes in barbell velocity.