This chapter focuses on standing control and interventions that can be used to improve standing and standing balance skills. Careful examination of the patient's overall status in terms of impairments and activity limitations that affect standing control is necessary and should include musculoskeletal alignment, range of motion (ROM), and muscle performance (strength, power, endurance). Examination of motor function (motor control and motor learning) focuses on determining the patient's weightbearing status, postural control, and intactness of neuromuscular synergies required for static and dynamic control. Examination of sensory function includes utilization of sensory (somatosensory, visual, and vestibular) cues for standing balance control and central nervous system (CNS) sensory integration mechanisms. Finally, the patient must be able to safely perform functional movements (activities of daily living [ADL]) in standing in various environments (clinic, home, work [job/school/play], and community).
Standing is a relatively stable posture with a high center of mass (COM) and a small base of support (BOS) that includes contact of the feet with the support surface. During normal symmetrical standing, weight is equally distributed over both feet (Fig. 9.1). From a lateral view, the line of gravity (LoG) falls close to most joint axes: slightly anterior to the ankle and knee joints, slightly posterior to the hip joint and posterior to the cervical and lumbar vertebrae, and anterior to the thoracic vertebrae and atlanto-occipital joint (Fig. 9.2). Natural spinal curves (i.e., normal lumbar and cervical lordosis and normal thoracic kyphosis) are present but flattened in upright stance depending on the level of postural tone. The pelvis is in neutral position, with no anterior or posterior tilt. Normal alignment minimizes the need for muscle activity during erect stance.
Normal postural alignment—frontal plane In optimal alignment, the LoG passes through the identified anatomical structures, dividing the body into two symmetrical parts.
Normal postural alignment—sagittal plane In optimal alignment, the LoG passes through the identified anatomical structures.
Postural stability in standing is maintained by muscle activity that includes (1) postural tone in the antigravity muscles throughout the trunk and lower extremities (LEs) and (2) contraction of antigravity muscles. The gluteus maximus and hamstrings contract to maintain pelvic alignment, the abdominals contract to flatten the lumbar curve, the paravertebral muscles contract to extend the spine, the quadriceps muscles contract to maintain knee extension, and the hip abductors contract to maintain pelvic alignment during midstance and during lateral displacements.
Limit of stability (LOS) is the amount of maximum excursion possible in any one direction without losing balance; it is determined by the distance between the feet and the length of the feet as well as the person's height and weight. ...