Lesson
Exercise using all Lower Body Joints
Squat Exercise:
Benefits calf muscles, quadriceps femoris, glueteal muscles and back extensors
The following motion is described for a person rising on their toes at the start. During the squat, there is forward trunk flexion over knees.
1.START Standing position. Ankles slightly dorsiflexed. Knees fully extended, quadriceps femoris relaxed.Hips neutral and slightly laterally rotated, with upright posture maintained by gluteus maximus and hamstrings. Vertebral column is erect.
2.HEEL RAISE Ankles in plantarflexion with concentric contraction of gastrocnemius, soleus and plantaris. Foot arches raised by foot extrinsic and intrinsic muscles. Weight of the body then transferred to all metatarsal heads and all toes. Knees remain close packed, quadriceps femoris contracting strongly to maintain close packed position. Hips become slightly extended and glutei act statically to maintain balance. Flexor, Extensor and Lateral flexor muscles of the trunk contract statically to maintain position of trunk and balance of body
3.KNEES BEND PHASE Knees unlocked from close packed position by popliteus, pulling lateral side of lateral condyle, thus rotating femur laterally. This slides medial condyle slightly forward, and knees are then able to flex under body weight, controlled by eccentric quadriceps femoris.More power needed for more control as knees flex more. Movement arrested when buttocks and posterior thigh contact the heels and calf. Ankles dorsiflex because of gravity and change in position of tibia, but posterior calf muscles act eccentrically to control the movement. Feet maintain high arches as weight still borne on metatarsals and toe pads. Hips are flexed as trunk bends forward for equilibrium, controlled by eccentric hamstrings and gluteus maximus. Adductors and abductors combine to maintain balance.
- RISING PHASE Knees are extended by powerful, concentric action of quadriceps femoris, maximum force applies when knees fully flexed. At full extension, knees move into close packed position, femur rotates medially with respect to tibia and medial femoral condyle slides back wards on tibial plateau.Simultaneously, ankles plantarflexed by concentric posterior calf muscles hips extended by concentric Glute Max. and Hamstrings and trunk extended by concentric postvertebral muscles