Preparatory Phase
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During the preparatory phase of the clean and jerk, there is an interesting relationship between the muscles of the glenohumeral joint and the shoulder girdle. Here, the muscles of these two joints mainly work to perform a combination of eccentric and concentric contractions. Movements include: depression (frontal plane, sagittal axis), anterior tilt (sagittal plane, frontal axis), and extension (sagittal plane, frontal axis). The muscles involved in these movements are the pectoralis minor, lower trapezius, latissimus dorsi, teres major, and the posterior deltoid.
Upon the gripping of the bar, the forearms are pronated by way of the radioulnar joint. Additionally, as the lifter gets ready to lift the bar there are additional relationships between the hip joint and knee joint. As the lifter bends at the knee and maintains a straight back to reach for the bar (sagittal plane, frontal axis), and gives into gravity, the quadriceps eccentrically contract, where as the hamstring muscles concentrically contract. Helping to maintain this pose are the gluteus maximus, medius, and minimus. |