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Explain interactions of muscle groups in maintaining posture and in locomotion of the whole body

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M3- Explain interactions of muscle groups in maintaining posture and in locomotion of the whole body Muscles can cause either locomotion of the organism itself or movement of internal organs. Cardiac and smooth muscle contraction occurs without conscious thought and is necessary for survival. Examples are the contraction of the heart and peristalsis which pushes food through the digestive system. When a person walks, the calf muscle contracts and raises the heel, it pushes the ball of the foot against the ground. The hamstring muscles then contract to pull the femur back and bend the knee. The leg is now raised. The weight of the body is now supported by the left leg since the right foot loses contact with the ground. The quadriceps will contract, pulling the femur forward and extending the leg. After the extension of the legs, the foot with the heel touching the ground first will regain contact with the ground again. The weight of the whole body is supported by the right leg. This sequence is repeated with the left leg. At the time of heel-strike, the ankle is in slight dorsiflexion and the anterior leg muscles contract in order to prevent the forefoot from slapping down. ...read more.


The position of the line of gravity, which is determined by the distribution of body weight, is important in determining the degree of muscular activity involved in maintaining all phases of posture. The line of gravity extends superiorly through the junctions of the curves of the vertebral column and inferiorly in a line posterior to the hip joints but anterior to the knee and ankle joints. When a person is in the easy standing position, the hip and knee joints are extended and are in their most stable positions. Because the line of gravity passes posterior to the hip joint and anterior to the knee joint, the weight of the body tends to hyperextend these articulations. At the hip this is resisted by the iliofemoral ligament and at the knee by the ligamentous apparatus of the knee and the action of the hamstrings. Similarly, the generally anterior carriage of the weight of the body tends to cause dorsiflexion at the ankle joint, and this is resisted by contraction of the calf muscles. These muscles, along with paraspinal muscles are the only absolutely essential muscles for maintenance of the upright posture. The brain assumes we are balanced when we sense equal stress on both sides of the body. ...read more.


If one segment or link in the kinetic chain is out of sync, there is potential for a performance error or injury. Posture is clearly an integral part of many aspects of movement. In fact, I believe that dynamic postural alignment and subsequent dynamic muscle balance are fundamental movement skills. So it should be no surprise that a training regimen for good posture is very similar to any functional strength and conditioning program. We need to train strength, flexibility, balance, and movement. We need to incorporate multi-joint and multi-plane work with high proprioceptive demand. We need to target deficiencies with remedial work whenever warranted. The four primary anti-gravity muscle groups are: the gastroc/soleus group, the quadriceps group, the glutes, and the erector spinae group. When the body is upright, as is the case in most sport activities, the anti-gravity muscle groups work in conjunction with other muscle groups to maintain upright posture. These muscles act on information from three major sensory systems in the body: the proprioceptive, vestibular, and visual systems. Therefore, movements that work these muscles must be given prime consideration in a conditioning program. Tight muscles can contribute to poor dynamic posture, so a sound program of functional flexibility that addresses the target muscles must also be part of the athlete's daily routine. ...read more.

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