Gait analysis of running.docx
- 1. Gait analysis of running Swing phase: -Swing phase begins with toe-off and ends with the foot landing. -It is more muscular than pendular and is longer than the support phase. -The flexed leg in the swing phase brings the mass of the leg close to the hip reducing the moment of inertia. - The increase of velocity helps to drive the body’s centre of gravity forward Joint Joint action Force of movement Muscle active Kind of contration ankle dorsiflexion muscle Tibialis anterior, extensor digitorum longus, extensor hallucis longus concentric knees Flexion (fast, first 2/3) muscle Reflex action Extension (last 1/3 momentum hamstrings eccentric hip flexion muscle Iliopsoas, rectus femoris concentric Support phase: -The support phase begins with the contact of the forward foot and ends at toe-off when the body is driven into the air. -During this time, the knee and ankle “give” in flexion and then extend as the body passes over the foot and is driven into the air -The support time decreases as the speed of the run increases. Joint Joint action Force of movement Muscle active Kind of contration ankle plantarflexion muscle Gastrocnemius, soleus concentric knees Flexion (initial support) gravity quadriceps eccentric Extension (at push off) muscle quadriceps eccentric
- 2. hip flexion gravity Hamstrings, glutues maximus eccentric Aquatic locomotion : Mechanics of swimming Less force is needed to keep an object moving than to overcome its inertia. The body will move in the opposite direction to the force applied. Forward motion is produced through a combination of drag and lift forces by combination actions of the arms and legs To produce maximum force, present as broad a hand surface as possible during propulsion and exert backward pressure through as great a distance as possible. Momentum may be transferred from one body part to another body part as momentum is conserved. The body position in the water depends on buoyancy and speed through the water. The more streamlined the body, the less the resistance to progress through the water. The drag on a body in any fluid increases approximately with the square of the velocity. The sudden or quick movement of a swimmer’s body, or one of its parts, at the surface of the water tends to cause turbulence that increases drag. Sprint crawl analysis Head and trunk Body as horizontal as possible, feet below the surface, head breaking the water at the hairline Static contraction of rectus abdominis holds spine in a slightly flexed position. Lateral movements of the trunk will increase resistance to forward movement. Circular movements of the arms, legs or head cause a counter movement of the rest of the body. Turning the head to breath must be accomplished with the least possible interferenc, rotate while tucking the chin. After a quick inhalation, face is turned forward.
- 3. Breathe every stroke for distance events, and less often for sprints. By alternating actions of the left and right oblique abdominals and spinal extensors, the spine and pelvis are stabilized against the pull of the shoulder and hip muscles. Arm stoke entry and support -Entry should place the arm in the most advantageous position for exerting force. Forearm high and elbow pointing to the side. Hand passes in front of shoulder, reaches forward, and is driven forward and downward into the water directly in front of the shoulder. Elbow is slightly flexed, and extends during entry. The brief moment between entry and the beginning of the propulsive action is called the support phase. Purpose is to keep the head and shoulders high in the water. Pressure of forearm and hand is mostly downward and then backward, producing an upward and forward reactive force. Catch: propulsive action changes from downward to backward. A quick inward movement of the hand and arm that serves to bring the hand to a position in front of the axis of the body. Pull: begins with the first backward motion of the hand. Upper arm is vertical, pectoralis major and latissimus dorsi is activates for pulling downward and backward. elbow should be kept high during the first part of the pull, then by bending the elbow through the pull, the hand begins to push water backwards Elbow action assists in producing an S-curve, which creates propulsive lift. Push: transition from pull to push occurs as the arm passes under the shoulder. As forearm passes the front of the hip, the upper arm extends and the hands gives a quick push backward. Release andRecovery: Pressure is released, elbow & shoulder raised out of the water. Elbow swings forward and upward with hand trailing behind. Hand moves in front of shoulder ready for next entry. The kick Most often used is the flutter kick with the leg relatively close together as they alternate in an up and down movement, acts as stabilizer and neutralizer
- 4. Timing with arms is therefore critical. Downstroke : Begins with downward drive of the thigh. Thigh flexes only slightly, knee extends completely by the end of the stroke. Ankle and foot remain in plantar flexion. Dorsiflexors contract statically to stabilize foot against pressure of the water. Upstroke : Begins with thigh extension. Slight knee flexion develops near the end of the stroke. Foot stops just below the surface. Analysis of butterfly stroke The arm movement in butterfly stroke can be broken down into three parts: the pull, the push and the recovery. The dolphin kick is used in butterfly stroke which both legs move simultaneously, and should be pressed together to avoid a loss of water pressure. Whole body movement in a wave-like fashion-when chest rises, hips should be at their lowest position and vice versa. When arms are about to come out of the water, raise head until chin is just above the water and take a breath. Mechanical analysis of butterfly stroke The butterfly stroke is a bilateral activity, as opposed to a reciprocal, unilateral pattern in the freestyle and backstroke. The butterfly stroke typically consisting more of an S-shaped pulling pattern and the upper body pivoting up and down about the hips, instead of rotating about the central axis as in freestyle and backstroke. The hands enter the water with the arms extended forward and in front of the shoulder. The upper body presses down at the same time the arms enter the water to generate a more dynamic motion on entry and support the swimmer’s forward motion. The hands and arms should remain extended forward during the upper body press, as opposed to aiming downward.
- 5. The pulling pattern for a swimmer with a deep upper body press tends to go wide and well outside the shoulder on the early pull through. At the beginning of the late pull-through, the arms are bent and the hands are underneath the hips. The arms then extend, with the hands sweeping outward and the arms lifting upward to exit the water and transition into the recovery phase. The pulling pattern for a swimmer with a deep upper body press tends to go wide and well outside the shoulder on the early pull through. At the beginning of the late pull-through, the arms are bent and the hands are underneath the hips. A swimmer should not overemphasize the end of late pull-through and lift the hands out of the water too high; instead, he or she should keep his or her hands as close to the surface of the water as possible in the early recovery phase. With the undulating body motion in the butterfly, the swimmer takes a breath by lifting the upper body upward throughout the underwater pull-through. The swimmer should use the forces generated by the pull-through to lift the upper body just enough for the shoulders and head to clear the surface, but it is common for swimmers to forcefully arch the back and throw the head upward to do this. The butterfly stroke requires the legs to move as one. This requires special strength in the gluteus maximus. The hamstring muscles, situated on the backs of the legs, also are extremely important because the legs must kick in a backward motion instead of the scissoring motion used in most other swimming strokes.