A kinematic, kinetic and electromyographic analysis of 1-repetition maximum deadlifts

Abstract

To date, no study has explored the deadlift in terms of studying both individual body joint angles and muscle recruitment strategy on well-trained powerlifters lifting at 1-repetition maximum (1RM). The primary purpose of this study was to describe these two technical parameters and the relationship between them during 1RM deadlifts. The secondary purpose was to investigate the correlations between the relative strength parameter (1RM/BW) and lifting angle and muscle activation parameters. Ten male powerlifters with >1 year of training experience with the deadlift volunteered to participate in the study. Their mean (±SD) age, body mass, height, 1RM and 1RM normalized for body mass were 25±3 years, 86±4 kg, 183±7 cm, 220±26 kg and 2,6±0,2 1RM/body mass, respectively. The subjects were equipped with six EMG transmitters and 25 reflective markers and performed 1RM deadlifts, with each lift recorded by 16 motion analysis cameras. Main findings were considered as 1) hunching of the lower back occurred probably as a result of insufficient erector spinae (ES) activation, 2) a mean supramaximal (>100% of maximal voluntary isometric contraction (MVIC)) activation of the biceps femoris (BF) and the gluteus maximus (GM) at knee passage (KP), 3) a ”shift” in dominating knee muscle activity from the vastus medialis at lift-off (LO), to BF at KP. Furthermore, Pearson’s r correlation analyses revealed significant (p <.05), strong correlations between 1RM/body mass and 1) BW (-r=.75), 2) GM activity at LO (r=.63) and 3) hip angle (HA) at LO (r=.64). These might act as important findings, from a performance perspective as well as from a sports injury profilactic point of view.