Electromyography Of The Quadriceps And Hamstrings During The Conventional Deadlift In Two Shoe Conditions

Abstract

INTRODUCTION: The conventional deadlift is a widely used strength exercise and barefoot lifting has become a more prominent style of training. Currently there is a lack of research comparing electromyography (EMG) activity between shoe and barefoot styles of training. The purpose of the study was to compare the difference in vastus medialis and biceps femoris muscle activity during the concentric phase of the conventional deadlift. METHODS: Seven subjects with a mean weight 80.3±17.4 (kg) and height 1.8±0.1 (m) participated in the study with at least six continuous months of deadlifting experience, 1-2 days/week of strength training, no surgeries and no lower back/lower extremity injuries within the past six months. Day one consisted of 1RM testing based on NSCA guidelines. On day two subjects were fitted with two EMG sensors (biceps femoris, vastus medialis) and a maximal voluntary isometric contraction was performed. The subjects then completed two sets of five randomized repetitions (with shoes and barefoot) at 70% of their 1RM. Raw data were imported to visual 3D, EMG data were bandpass filtered (20Hz-450Hz), full-wave rectified, linear enveloped, and smoothed using a moving RMS (window size of 25 frames). A paired-samples t-test (p<0.05) was used to compare muscle activity of the biceps femoris and vastus medialis. RESULTS: The percentage of vastus medialis recruitment was significantly greater (p=0.005) in the shoe (53.5±26.9%) vs. barefoot condition (46.7±24.1%). Additionally, there was a significant difference in percentage of biceps femoris recruitment (p=0.037) between the shoe (43.8±25.0%) condition and barefoot (45.2±33.1%) condition. CONCLUSION: Using a barefoot approach in the conventional deadlift appears to have an effect on percent peak muscle activation of the biceps femoris and vastus medialis muscles. Early evidence may suggest that barefoot lifting styles increase hamstring activation while decreasing quadriceps activation.