Dynamic Stories
Clinician Interview: Ginny Paleg
What does the Research say about Lack of Movement?

Michelle L. Lange, OTR/L, ABDA, ATP/SMS

Ginny Paleg, PT, DScPT is a pediatric physiotherapist from Silver Spring, Maryland, USA.  For the past 17 years, she has worked with children aged 0-3 years in homes and childcare. She specializes in posture and mobility assessment and interventions for children at GMFCS Levels IV and V. Ginny is involved in research and is always ‘in the know’ on the latest evidence. She was kind enough to spend some time with me on the phone and share her thoughts.

What are your thoughts on why providing movement within a seating system is so important?

Lack of movement and Muscle

We know from research that the stem cells (a.k.a. satellite cells) in muscles begin to go away which leads to muscle atrophy (disuse atrophy) at just 9 months of age in children who are not moving. Lack of movement also leads to increase of lipids and collagen in muscle tissue and decreased diversity in the muscle fibers themselves. When we try to strengthen this “altered” muscle, it doesn’t respond the way we expect.

Muscles include sarcomeres, the contractile unit of a skeletal muscle fiber. Research has shown that these units are lengthened (longer) in hypertonia and shortened in hypotonia.  This is yet another reason why stretching or passive range of motion is not effective at increasing muscle length, since the sarcomeres are already over-lengthened.

Lack of movement and Bone

Premature babies in the NICU (neonatal intensive care unit) have low bone density once they reach term age, with less trabeculae present in the bone. Babies born at term have had more movement by this age which has supported typical bone density. Bone density is increased when the body responds to gravity, weightbearing, and muscle pull.  When children are lying down most of the day (14-16 hours for children who are non-ambulatory), weightbearing for less than two hours a day, and not ambulatory for at least two hours a day, the bone responds by giving up calcium and decreasing its density. The result can be pain from low bone mineral density and/or pathological fractures.  Once the child has had one fracture, they are at high risk for more.

Lack of Movement and Overall Health

Mark Peterson, PhD, Associate Professor in Physical Medicine & Rehabilitation at the University of Michigan has found that when people are more sedentary, metabolic disease, morbidity and mortality increases. Other researchers have found that people who lie or sit more than 8 hours a day are at increased risk of pain, lowered metabolism, contracture, orthopedic changes, morbidity, and mortality.

Dynamic Seating is beneficial in a number of clinical scenarios, however, use with people who have increased tone is undoubtedly the most common application.

“We need evidence that moving is good. We have evidence of what happens when we don’t move.”

While we need more, newer, and stronger research, the literature does support use of Dynamic Seating for many people using wheelchairs. You can read the most up to date version of our Literature Review here.

Lack of Movement and Sensory Function

We cannot separate motor and sensory. This all works together. When motor movement is impacted, the sensory system is not getting input. 

Indications and contraindications:

“Dyskinesia is the best indication to trial dynamic seating.  These children usually have a combination of spasticity of the extremities, hypotonia of the trunk, and extraneous or ballistic movements of the extremities.  Many children posture in extreme ranges of motion and are in motion all the time.  When we “block” them, they bruise, or get agitated.  When we allow them to move, they calm.  A contraindication is when the child uses the movement to self-soothe or “stim” and is then unable for participate.”

What about walking?

“There are a few supported stepping devices on the market which have dynamic components.  I recommend the one that is dynamic in all three planes (up and down, side to side, and the seat swivels) yet provides excellent support at the pelvis and trunk (two separate systems), as well as accommodates many different head supports, including dynamic ones.”

What do you think is missing in the world of Dynamic Seating?

Ginny has several thoughts on what is needed or can be improved in this area:

1. Folding back for ease of transportation. Many of the families she works with need to fold the mobility base for transport – and without adding a lot of weight.

2. More Dynamic Seating options on adaptive strollers for very young children. And any Dynamic Back would need to fold with the stroller.

3. Dynamic Seating design to keep the client from losing position upon return to a starting position, particularly at the hips.
   This is a very important design consideration. Click here to read a past blog, “Allowing Movement of the Pelvis Without Loss of Position.”

4. Dynamic Seating which responds to client rotation, not just extension.
   This is also an important design consideration. Some Dynamic Seating components will ‘activate’ with extension or rotation. Other components may ‘jam’ if rotational forces are present. Seating Dynamics has designed components to respond to client force with movement, even if rotation is present.

Thanks, Ginny for your valuable time and expertise, as always! Keep up the wonderful work that you do!