2 ObjectivesIdentify and classify motor skills under the heading of moving the body on the ground or other resistant surface.Describe the anatomical and mechanical nature of the major locomotor patterns.Name and state anatomical and mechanical principles that apply to locomotor patterns.Evaluate the performance of major locomotor patterns.Analyze the performance of a locomotor skill.
3 LOCOMOTIONThe act or power of moving from place to place by means of one’s own mechanisms or power.In the human being, it is the result of the action of body levers propelling the body.Ordinarily by lower extremities.Occasionally by all four extremities.Sometimes by upper extremities alone.
4 WALKING Description Alternating action of the two lower extremities. Translatory motion of the body brought about by angular motion of some of its parts.Two phases:SwingSupportFig 18.1
5 WALKING DescriptionKinematics are often described in terms of strides and steps.Stride: from heel strike to the next heel strike of the same leg.Stride length: distance covered in one stride.Step: from heel strike of one leg to heel strike of opposite leg.
6 WALKING DescriptionChief sources of motion in the swing phase are gravity & momentum; ballistic movementSources of motion for support phase:1st Half: momentum of forward moving trunk.2nd Half: contraction of extensor muscles of supporting leg.
7 WALKING Anatomical Analysis Major Components of WalkingPelvic rotationPelvic tiltKnee flexionHip flexionKnee and ankle interactionLateral pelvic displacement
9 WALKING Anatomical Analysis:Swing Phase Spine and Pelvis:Movements: Rotation of pelvis toward the support leg and of spine in the opposite direction; slight lateral tilt of pelvis toward swing leg.Muscles: Semispinalis, rotatores, multifidus, and external oblique abdominals on side toward which pelvis rotates.Erector spinae and internal oblique abdominals on opposite side.Psoas & quadratus lumborum support pelvis of swinging limb.
10 WALKING Anatomical Analysis:Swing Phase Hip:Movements: Flexion; outward rotation; adduction at beginning and abduction at the end of phase.Muscles: Iliopsoas is prime mover of hip.Assisted by rectus femoris, sartorius, gracilis, adductor longus and pectineus.
11 WALKING Anatomical Analysis:Swing Phase Knee:Movements: Flexion during 1st half; extension during 2nd half.Muscles: Quadriceps extensors contract slightly at end of phase.Sartorius & short head of biceps femoris chiefly following toe off.Largest contributor is gravity when the knee extensors relax at toe-off.
12 WALKING Anatomical Analysis:Swing Phase Ankle and Foot:Movements: Dorsiflexion; prevention of plantar flexion.Muscles: Tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius (slight to moderate intensity at beginning of swing phase, taper off during middle portion of phase).Contract again to prepare for heel strike.
13 WALKING Anatomical Analysis:Support Phase Spine and Pelvis:Rotation of pelvis toward same side and spine to opposite side; lateral tilt away from support leg.Lumbar portion of erector spinae contracts at heel strike to stiffen spine for support.
14 WALKING Anatomical Analysis: Support Phase Hip:Movements: Extension through foot flat to toe off.Reduction of outward rotation.Followed by slight inward rotation.Prevention of adduction of the thigh and dropping of pelvis to opposite side.Muscles: During heel strike gluteals and hamstrings contract statically (moderate intensity), taper off during foot flat and disappear at midstance.Only muscles active during last part of phase - adductor magnus, longus, and brevis.
15 WALKING Anatomical Analysis:Support Phase Knee:Movements: Slight flexion from heel strike to foot flat, extension from midstance until heel lift.Muscles: Quadriceps contract moderately in early part of phase, then gradually relax.Vastii contract throughout the 1st half of this phase.Hamstrings at the end of phase.
16 WALKING Anatomical Analysis:Support Phase Ankle and Foot:Movements: Slight plantar flexion followed by slight dorsiflexion.Prevention of further dorsiflexion.Plantar flexion of ankle and hyperextension of metatarsophalangeals at end of propulsive phase.
17 WALKING Anatomical Analysis: Support Phase Ankle and Foot:Muscles:Tibialis anterior, extensor digitorum longus and hallucis longus early in phase.Gastrocnemius and soleus active from midstance to heel off.Tibialis posterior middle part of phase.Flexor digitorum longus (slight) in middle portion of phase, moderate in the last portion.Toe and intrinsic muscles respond to pressure of ground against toes.
18 Action of Upper Extremities in Walking Arms tend to swing in opposition to the legs.This reflex action is usually without obvious muscular action and serves to balance rotation of the pelvis.Maximum flexion of shoulder and elbow occurs at heel strike of opposite foot.Maximum extension of shoulder and elbow occurs at heel strike of same foot.
19 Neuromuscular Considerations Walking relies heavily on reflex.Reflexes also control movements of supporting limb and trunk in resisting the downward pull of gravity.Stretch reflex: at extremes of motion.Extensor thrust reflex: may facilitate the extensor muscles of lower extremity as weight rides over the foot on the support leg.
20 Anatomical Principles in Walking AlignmentReduces friction and decreases the likelihood of strain and injury.Stability of weight bearing limb and balance of trunk over this limb are factors in smoothness of gait.Unnecessary lateral movements decrease gait economy.Excessive trunk rotation with excessive arm motion.Pelvis may drop on one side without support.Pelvic rotation should be just enough to enable the leg to move straight forward.
21 Anatomical Principles in Walking Normal flexibility of the joints reduces resistance.Tendons of two joint muscles of lower extremity contribute to economy of muscular action in walking.Properly functioning reflexes contribute to a well coordinated, efficient gait.Injury, disease, or substance abuse can interfere with the walking reflexes.
22 Mechanical AnalysisTranslation of the body’s center of gravity forward as a result of the alternating pattern of lower extremity joint movements during the stance and swing phases.Forces that control walking are;External forces of weight, normal reaction, friction, air resistance.Internal muscular forces.Direction & interaction of these forces determine the nature of the gait.
23 Mechanical Principles in Walking Inertia of the body must be overcome with every step.A brief restraining action of the forward limb serves as a brake on the momentum of the trunk so as not to move the center of gravity beyond the new base of support.Translatory movement is achieved by alternating the lower extremity angular motion between the foot (support) and hip (swing) (inverted pendulum).
24 Mechanical Principles in Walking The vertical component of ground reaction force serves to counteract the pull of gravity.The horizontal component serves to:check forward motion during heel strike.produce forward motion during toe off.Speed is increased by increasing stride length, stride rate, or both.Speed is directly related to magnitude of force and direction of application.
25 Mechanical Principles in Walking Efficiency of locomotion partially depends on friction and ground reaction force.Most efficient gait is one that is timed to permit pendular motion of the lower extremities.Alternating loss and recovery of balance.Lateral distance between feet is a factor in lateral stability, with average step width at ~ 10% of leg length.
26 Walking Variations: Individual Variations in Gait Variations may be structural or functional.Structural: body proportions & limb differences.Functional: personality characteristics.Pathological : disease, injury, or deformity may produce deviations.Age: decreases in strength and flexibility.Balance becomes a concern.Obesity: increased impact but smaller propulsive forces.Medial and lateral forces increase.
27 Walking Variations: Stairs & Ramps Up stairs or a ramp: Forward lean of body to direct the push of legs through the body’s center of gravity.Swing phase has exaggerated knee lift and dorsiflexion of the ankle.Down stairs or a ramp: Eccentric contraction of muscles to lower body at a controlled rate and maintain line of gravity toward back of the base of support.Swing phase has a slight lifting of rear foot to clear the step.
28 Walking Variations: Race Walking Adaptations to produce maximum speed.Must show a period of double support.Minimizes double support period;Increasing stride rate.Decreasing stride length.