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M.Jovanović, M.Кapeleti, M.Ubović, N.Pažin, D.Ilić, V.Mrdaković. PROFEX - Academy of Healthy Living, Belgrade, Serbia; Faculty of Sports Management, Alpha University, Belgrade, Serbia; FSPE, University of Belgrade, Serbia. | ||
 Abstract
Deadlift is a measure of the overall strength of the whole body and it is one of the three exercises in the powerlifting competition. There are conventional and sumo variant of deadlift. The aim of this study was to determine the differences between the two lifting techniques from the aspect of kinematics, kinetics and electromyography. Nine physically active men, average age 29.1 ± 3.3 years, body height 181.0 ± 1.0 cm, body weight 82.3 ± 13.3 kg and body mass index 25.0 ± 3.8 kg/m2 were recruited for this study. Each subject lifted weight close to his own body weight with three repetitions, in three series, for each of the techniques. The speed of one lift was 3 seconds for each of the phases (concentric and eccentric). The angles and amplitudes for the following figurative points were monitored: trunk in relation to the horizontal plane (angle), center of the hip joint and center of the knee joint in the "liftoff" (LO – position in which the weight separates from the ground) and "knee passing" (KP – position in which the weight passes in front of the knee position), i.e. in the liftoff-knee passing (LO-KP), knee passing-lift completion (KP-LC; LC – final, i.e. completely upright body position) and liftoff-lift completion (LO-LC) phase. The mechanical work was monitored as a one of the kinetic variables. Electromyographic activity was monitored for the following muscles: m. vastus medialis, m. vastus lateralis, m. rectus femoris, m. gluteus maximus, m. erector spinae (L3-L4), m. semimembranosus and m. biceps femoris caput longum. The monitored electromyographic variable was the average normalized amount of muscle activation in relation to maximal voluntary contraction, for all 18 individual deadlift repetitions (3 series × 3 repetitions × 2 techniques). One-way analysis of variance with repeated measurements (for the amount of muscle activation and performed mechanical work) and two-way analysis of variance with repeated measurements (for angles and amplitudes) were used for statistical data processing. Significant differences were found between techniques in the initial angular positions in all monitored joints (p<0.05), except for the angle in the knee joint where the trend was observed (p=0.0996), as well as in the transit position for the trunk angle relative to the horizontal plane and angle at the hip joint (p<0.05). There was a statistically significant difference between techniques in amplitudes in the hip joint during KP-LC phase (p<0.05) and total amplitude (p<0.05), as well as in the knee joint during LO-KP phase (p<0.05) and total amplitude in the form of a trend (p=0.0996). The performed mechanical work is significantly higher when lifting the load with the conventional deadlift technique (DLcon) (p<0.05). Activation of medial and lateral heads of m. quadriceps femoris is significantly higher (p<0.05) when lifting with sumo deadlift technique (DLsu). It was noticed that activation of postural muscle groups (m. erector spinae, m. gluteus maximum, m. semitendinosus and m. biceps femoris caput longum) is higher when lifting the load with DLcon, but not significantly (p>0.05).
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MUSCLE ACTIVATION / MECHANICAL WORK / JOINT ANGLES / STRENGTH TRAINING | |
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