The effect of the conventional deadlift and Romanian deadlift on muscle activation and joint angles at submaximal intensity

Abstract

For fitness professionals delivering strength and conditioning programmes and recreational athletes designing their own programmes, exercise selection and an appropriate loading stimulus over time are the cornerstones of an effective resistance training programme. The conventional deadlift (CD), a compound, closed-chain movement, is prescribed to increase the strength of the posterior chain and the quadriceps. The Romanian Deadlift (RDL) is an isolated knee variation of the CD, whereby the knee angle is stable throughout the movement (Lee et al., 2018, J Exer Sci Fit, 16, 87-93). The RDL is a key movement in weightlifting training and is a commonly used developer of posterior chain muscles (Weaver and Kerksick, 2017, Strength Cond J, 39, 85-90). Studies comparing the CD and RDL are limited. Using surface EMG 2D motion analysis of the lower limb, we aim to determine if (i) biceps femoris activation is greater than the vastus lateralis during the RDL, (ii) there is a higher activation of both vastus lateralis and biceps femoris during the CD, and (ii) whether an injury is more likely to occur during a CD or RDL using the angles and range of motion (ROM) of the hip, knee, and ankle. 15 recreationally active adults with experience with the CD and RDL were recruited. Surface EMG sensors were placed on the vastus lateralis and biceps femoris, and markers were placed for 2D motion analysis in the sagittal plane. MVC data were collected for three repetitions of both lifts at 70% RDL 1RM. Five repetitions at 50% RDL 1RM were used for analysis. Statistical analysis was conducted using a paired t-test and Wilcoxon signed-rank test. The results show greater activation of the vastus lateralis in the CD than the RDL (P < 0.05) but no difference in the biceps femoris. No differences were found in hip angles during ascent or descent at mid-thigh and knee height (P = 0.343), but there were differences at the bottom position. Knee angles during ascent and descent at the mid-thigh were different (P = 0.027) but not at knee height. No differences at the ankle joint were found at the mid-thigh (P = 0.12), but differences were found at knee height and bottom position. Finally, ROM at the hip, knee, and ankle during ascent and descent were significantly different (P = 0.002). The findings may help fitness professionals and recreational athletes make decisions such as exercise selection, load management, and injury prevention strategies based on the comparative effectiveness and risks of the CD and RDL.