Strengthening in children with cerebral palsy and other neuromuscular disorders can be beneficial for long-term functional gains, improved movement patterns, and optimal posture. Children with cerebral palsy and other neuromotor impairments have decreased muscle strength, work capacity, peak muscle power, and muscle endurance; and an increased energy cost of movement. Strength- and endurance-training programs have become more common in children with neuromotor dysfunction, and their goals are to lessen the deterioration of functional capacity as the child ages; and to improve range of motion, strength, and functional endurance.

BENEFITS OF STRENGTH TRAINING

Strength training has cardiovascular- and neuromuscular-system benefits as well as psychological, fitness, and functional benefits. Strength-training programs have shown that an increase in overall strength relates to improved functional changes. These improvements have been noted with the Gross Motor Function Measure, increased physical activity, and increased self-selected walking velocities.1,2

Strength training has been proven to improve self-image, encourage socialization, and promote a more active lifestyle. McBurney had 11 children with spastic diplegia perform a lower-extremity-strengthening home program. He found the children had increased strength, decreased activity limitation, improved mobility, and increased perceived societal participation.3

CAN CHILDREN WITH CEREBRAL PALSY BENEFIT?

Physical educators have been using resistive exercises to develop strength and skill in children with cerebral palsy for more than 50 years. Until recently, the physical therapy field seems to have dismissed strength training for other treatment options. Part of this dismissal of strength training may have come because when therapists began strength training children with cerebral palsy, as they had done with children with polio, they did not see the same significant functional gains.

There was also the mind-set that strengthening clients with spasticity would not yield functional gains. Many feared that strengthening may increase spasticity and tightness. It was believed that because of poor selective control and use of synergies to move, strength-training performance would be limited. Also, many believed that weakness was not a primary impairment in cerebral palsy, and focus was shifted to other impairments.

In general, cerebral palsy is defined as weakness originating from the brain. Damiano found that children with cerebral palsy were significantly weaker than their peers, but strength training children with cerebral palsy can increase strength to near normal values.4,5 Anderson found that strength training did not decrease, and possibly increased, range of motion. Fowler found no changes in spasticity when comparing an exercised leg with a nonexercised leg.3

During typical development, a child begins to build core strength through continuous practice of active movements and movements against gravity. A child will practice small components of a movement pattern before using the pattern functionally. Children with atypical motor development have a limited repertoire of movement patterns. Compensatory movement strategies learned in early development lead to decreased strength and endurance of key muscle groups later in life.

Due to atypical motor development in infancy, children with neuromotor dysfunction often have common muscle weaknesses. The typical weaknesses are described below with some basic exercises and progressions to work each area, as well as fun exercise ideas. Many functional movements and activities are wonderful because they can be used to strengthen more than one area.6

SPINAL EXTENSORS

Weakness: Spinal extensors, especially thoracic extensors, are generally weak. This weakness presents as difficulty moving against gravity and maintaining optimal posture and alignment. There is often an overuse of flexors, such as pectorals, that limit activation of the antagonist extensors.

Exercise: To work the spinal extensors, active prone extension is key. The child will lie prone and then will lift his or her upper body and legs off the surface (flying like Superman), and hold for up to 30 seconds. This exercise can be progressed by extending the arms overhead or leaning over the edge of the table and extending beyond the height of the table. Thoracic extensors (middle and lower trapezius and rhomboids) can also be exercised seated for children who cannot tolerate prone by elevating arms above head and extending back.

Fun ways to exercise:

  • Doing prone activities on a scooter, sling swing, or platform swing to push off a wall, reach, and knock down objects;
  • Wheelbarrow walking; or
  • Swimming with support under the belly in a pool.

ABDOMINALS

Weakness: Abdominal weakness presents with shallow breathing, a flared rib cage, and difficulty maintaining optimal posture and alignment with movement. Children often have a poor connection between their upper and lower body, and have difficulty flexing against gravity.

Exercise: Abdominals are composed of the rectus and transverse abdominis, and the internal and external obliques. Core exercises that engage all the abdominal muscles are key. Sit-ups are the most-often-thought-about abdominal exercise. To engage the rectus abdominis, the child needs to lift his or her head and shoulder off the surface; the obliques can be added with rotational movements.

Challenging a child’s trunk control can be done with numerous exercises besides the typical sit-up or curl-up. Rotation exercises in sitting, in which the child rotates his or her trunk while holding a ball or bar with both hands, can be done. Progress by adding weight through a medicine ball or cuff weight attached to the bar, or by adding varying angles of flexion and extension with rotation. In supine, lifting and lowering the legs off the surface works the lower abdominals.

Fun ways to exercise:

  • Playing catch with a medicine ball, and moving the location of where to throw and the level from which the ball is thrown;
  • Hanging from a swinging bar and lifting legs to knock over objects; or
  • Rolling or crawling up and down inclines.

HIP EXTENSORS

Weakness: Hip extensors are usually weak in all positions in children with neuromotor dysfunction. Gluteals are elongated during infancy through physiological flexion and do not become effectively activated for functional use and strengthening.

Exercise: Many children have a difficult time activating their hip extensors through a full range of motion. Often, the exercise begins with active assistance and looking for improving muscle contraction. Bridges, in which the child is hooklying and pushes through his or her feet to lift his or her buttocks off the surface, are a simple exercise to engage the hip extensors. This exercise can be progressed to being performed single legged. Hip extension can also be performed in quadruped or prone, lying with the hip extended through the available range of motion. Partial squats are great for overall lower-extremity strengthening. A squat motion while the back is leaning against the wall (wall slides) is easier to perform than a squat. Or, a child can perform a stand-to-sit movement but rise just prior to sitting. Backward walking is also a wonderful functional strengthening exercise, and it can be progressed by adding resistance with elastic tubing around the trunk or on inclines.

Gait training on a treadmill can also offer strength training for children with weakness against gravity. The treadmill’s movement facilitates hip extension and can offer movement through greater ranges of motion.

Fun ways to exercise:

  • Backward kicking to knock over objects;
  • Climbing activities on stairs and obstacles;
  • Kicking and splashing water in prone in a pool or tub; or
  • Backward walking through an obstacle course.

HIP FLEXORS/QUADRICEPS

Weakness: The quadriceps are two joint muscles that extend the knee and also flex the hip. The quadriceps are generally very weak against gravity and in weight-bearing. Many children have hamstring spasticity that limits their available range of motion for quadriceps training. The quadriceps are often very weak in terminal knee extension. Hip flexors (iliopsoas and quadriceps) are generally shortened and work with other flexors, and they are often not considered weak muscles. But they are very weak when isolated; and this can greatly affect their function, including during step length and stair climbing.

Exercise: Movements to work the quadriceps in weight-bearing (closed-chain exercises) can include step-ups, partial squats, sit to stand, and leg presses. Open-chain exercises include seated knee extensions (long-arc quads), supine straight-leg raises, or end-range knee extensions with a small ball or roll under knee (short arc quad).

Fun ways to exercise:

  • Kicking a ball or balloon while sitting;
  • Seated pushing a scooter or rolling chair backward;
  • Using a bicycling or stepping machine; or
  • Pumping legs on a swing.

DORSIFLEXORS

Weakness: Dorsiflexors are often elongated and weak due to increased plantarflexor activity. Usually, the anterior tibilias is inactive or too weak to counteract plantarflexor tone, which limits heel contact during gait.

Exercise: Dorsiflexion can be worked in sitting or supine easily with resistance added manually or with elastic tubing. A subtle way to work dorsiflexion is weight shifting with feet flat in all directions and progressing to performing on a balance board. Heel walking is also a challenging way to work dorsiflexion.

Fun ways to exercise:

  • Tapping the foot to play music on a mat piano or shaking bells;
  • Drawing in shaving cream with the feet; or
  • Hitting switches with the feet.

PLANTARFLEXORS

Weakness: Plantarflexors are usually shortened but weak when attempts are made to use them through their full range. It is often surprising to see that children who do not get heel contact during gait cannot plantarflex actively. Strengthening plantarflexors during gait can help with push-off, balance, and control during gait and stance.

Exercise: Plantarflexors should be worked through their entire available range of motion. In standing, this can be done with heel raises. This can be progressed to heel raises with the heel off a step or holding weights. Plantarflexion can also be performed in sitting and supine with manual resistance to elastic tubing to progress.

Fun ways to exercise:

  • Similar activities to dorsiflexion but focusing on the opposite direction.

HIP ABDUCTORS AND ADDUCTORS

Weakness: Proximal hip control and weakness are often seen in children with cerebral palsy. The hip adductors are often spastic and tight, limiting the active control the abductors can attain. Strengthening the hip abductors can improve stability and gait patterns.

Exercise: To work the hip abductors, sidelying hip-abduction exercises are simple and can be begun with active assistance. Also, in hooklying, a child can abduct and adduct his or her legs (butterfly motion). To progress this motion, resistance can be added manually or by having a child squeeze a ball or balloon to more work adduction. In weight-bearing, hip abduction and adduction can be worked with sidestepping exercises or lateral step-ups.

Fun ways to exercise:

  • Karate kicks at a bolster;
  • Relay races while holding a balloon or small ball between the legs; or
  • Sidestepping on a balance beam.

SCAPULAR STABILIZERS

Weakness: In many children with neuromotor dysfunction the scapular stabilizers are generally weak and present with significant scapular winging during arm movements. The scapular stabilizers are weak because of tightness and overactivity in the pectorals and the latissimus dorsi. This weakness limits weight-bearing on extended arms and efficient upper-extremity tasks.

Exercises: The best exercises to work scapular stabilization are in weight-bearing on upper extremities. When the child is exercising, it is important to encourage or look for improvements in how the scapula moves smoothly along the thoracic wall. Often, the scapula will follow arm movements with a poor stable connection to the trunk.

Wheelbarrow walking, in which the therapist holds the child’s feet and the child walks on their arms, is a great exercise. This can be made less challenging by decreasing the arm level and holding the child higher on the legs or trunk as needed. The child also can perform scapular-protraction exercises in supine with his or her arms straight or while punching the straight arm up toward the ceiling. Resistance can be added by holding weights, a medicine ball, or a wand with a cuff weight.

Fun ways to exercise:

  • Rolling over a bolster on extended arms to pick up objects;
  • Having a big ball war: Two children, or a child and a therapist, on either side of a ball pushes into the ball to see who can move the other past a line (similar to tug of war);
  • Pushing with arms on a scooter or swinging in prone; or
  • Playing and reaching activities in a side-sit position, in which the child is weight-bearing on one arm and weight shifting over that arm at the same time.

Strengthening can be a very rewarding and beneficial aspect to most children’s physical therapy plans. Simple strengthening exercises can make very effective home programs. And when strengthening activities are incorporated into play and functional activities, strengthening can offer benefits to all age ranges.

Joanne Bundonis, PT, PCS, ATP, is a senior PT at 1st Cerebral Palsy of New Jersey in Belleville. She offers pediatric physical therapy home study courses through www.ptcourses.com. She is a trainer with Mobility Research, Tempe, Ariz, and she can be reached at .

References

  1. Blundell SW, Shepherd RB, Dean CM, Adams RD, Cahill BM. Functional strength training in cerebral palsy: a pilot study of group circuit training classes for children aged 4–8 years. Clin Rehabil. 2003;17:48-57.
  2. Dodd KJ, Taylor NF, Graham HK. A randomized clinical trial of strength training in young people with cerebral palsy. Dev Med Child Neurol. 2003;45:652-657.
  3. McBurney H, Taylor NF, Dodd KJ, Graham HK. A qualitative analysis of the benefits of strength training for young people with cerebral palsy. Dev Med Child Neurol. 2003;45:658-663.
  4. Damiano DL, Dodd K, Taylor NF. Should we be testing and training muscle strength in cerebral palsy? Dev Med Child Neurol. 2002;44:68-72.
  5. Damiano DL, Abel MF, Pannunzio M, Romano JP. Interrelationships of strength and gait before and after hamstrings lengthening. J Pediatr Orthop. 1999;19:352-358.
  6. Grimenstein J, Diienno M. Functional exercise and strengthening in the neurologically impaired child [course notes]. Toms River, NJ: Princeton University; November 2004.