Exercise as it relates to Disease/The effect of implementing a resistance training program to improve strength and mobility in children with Cerebral Palsy

This Wiki Page is an article critique of; Scholtes VA; Effectiveness of functional progressive resistance exercise strength training on muscle strength and mobility in children with cerebral palsy; a randomised controlled trial. Developmental Medicine and Child Neurology. 2010;52(6):e107-e13

The critique forms part of The University of Canberra unit; Health Disease and Exercise Unit assessment item. Written September 2019.

For the purpose of this page, Cerebral Palsy will be abbreviated to CP.

What is the background to this research?
Recent studies suggest the true definition of Cerebral palsy is still unknown. In 2006, Peter Rosenbaum et al, defined as a “permanent disorder of the development of movement and posture, causing activity limitations, that are attributed to non-progressive disturbances that occur in developing foetal or infant brain”. In 2010, Scholtes VA et al, suggested CP as a “group of disorders in the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occur in the developing brain”.

Scholtes et al furthered their definition in 2010, stating that CP is the most common cause of movement disability in children. For both clinical and research purposes, CP is generally classified based on the degree of neural impairment it causes as well as the anatomical distribution of motor abnormalities. Either categorised as spasticity, ataxia, dystonia and athetosis. The main issue that children with CP face is Spasticity. Which can be defined as the sequelae of neuromuscular disability and causes constant muscular contraction. Until recently, many researchers were hesitant behind introducing strength-based training programs for children with CP due to the belief that doing such would increase spasticity. This paper reports conflicting results from recent uncontrolled studies and suggests such results can be attributed to their low methodological quality and high variability in training methods.

Along with interruptions to what can be classified as normal muscular functioning there are a range of associative conditions attached to CP. As CP is a neuromuscular condition it affects the muscle tone, gross and fine motor skills as well as balance and coordination. In developing children this poses an increased injury risk as loss of balance and coordination leads to an increased falls incidence rate. Although still inconclusive in regard to CP, previous strength and conditioning programs have been seen to improve mobility via the development of strength to improve balance skills. Hence reducing the risk of falls and injury.

So not only will implementing a strength and conditioning based program in this population have beneficial effect on way of life its results will fill the gap and lack of valid and reliable evidence in this field.

Where is the research from?
Vanessa A Scholtes is a well renowned author in this field, who has written and published over 70 journal articles. She achieved her PHD at the Amsterdam University Medical Centre between the years of 2000-07 where she then worked Post Doctrine position from 2008-11. She currently works as a Senior Researcher in the Department of Orthopaedics at OLVG.

Associated authors on this paper are all are well respected, highly acknowledged authors that have both individually and collectively contributed to the rehabilitation and orthopaedic field in their respected institutions.

This paper has included a large collaboration from academics from a range of different areas within one collective field. Due to the diverse background of each author and the education and field they have personally excelled in; this article’s reliability is therefore enhanced. With the results it achieved therefore becoming more valid and hopefully contributing to the ever-advancing subject area.

What kind of research was this?
This research is a randomised control trial, meaning the selection of participants from a range of schools was conducted randomly via sealed envelopes It was undertaken to evaluate the successfulness of intervening a Progressive Resistance Training Program to improve muscle strength and mobility in Children with CP.

This study was approved by the medical ethics committee of the UV University Medical Centre in Amsterdam, and full written consent from parents and each child was obtained before enrolment. Two independent research assistants performed all assessments and data entry and during the treatment allocation process they were blindfolded.

A control group was used for comparison of results.

In comparison to other study designs the method of a Randomised Control Trial is considered to be the most reliable evidence on the effectiveness of interventions because the processes used minimise the risk of cofounding factors influencing the results.

What did the research involve?
Children with Spastic unilateral or bilateral CP, were selected with the extensive inclusion criteria. Children were excluded if they had unstable seizures or were taking any medication for spasticity within 3–6 months before the study.

The training group followed a 12-week progressive strength training program for lower limbs, which replaced their conventional physical therapy sessions. Each session involved one child adapted leg press exercise and three functional exercises with a weighted vest.

The primary measure was mobility, measured via the 66- item version of the Gross Motor Function Measure (GMFM- 66), the Sit-To-Stand (STS) test, and the Lateral Step-Up (LSU) test. The GMFM- 66 test is an internationally validated test that evaluate the changes in gross motor capabilities in children with CP. The STS assess the amount of repetitions a child can sit to stand in a time period and the LTU gauges the amount of times a child can step up 11 cm in 30 seconds.

The secondary measure muscle strength was assessed via a 6RM leg press test and isometric strength tests of the hip flexor/ abductor, knee flexor/extensor, ankle dorsi/plantar flexion and using a handheld dynamometer, hand strength.

The control measure was spasticity. Evaluated on a scale of 0-5. Calculated as the sum of catch in response to a fast muscle stretch in 5 leg muscles. Muscle soreness was also assessed on a weekly basis via a Likert scale.

For the population group, this methodology was likely the most applicable and achievable in the time frame. However, limitations do exist. Of a total of 36 sessions, 3 were cancelled due school related activities, compliance measures sat around 93%. Although, compliance and attendance were quite high, the study itself only had 49 participants. In the larger picture this is a small study. Also, the intervention group performed better at baseline on all outcome measures and therefore outcome measures were controlled for baseline differences.

What were the basic results?
This 12-week program resulted in 8% improvements in handheld isometric strength in the training group compared to the control. 11% improvements in hip-abductors and 12% in knee extensors were also seen. Scholtes suggested these results supported the idea of specified strength training as the circuit training specifically targeted these areas.

However unexpectedly improvements in mobility did not align with strength increases. The suggested reason for this was that the increase in strength was not in individual muscles making gains in mobility difficult.

There was no change in spasticity, during, directly after or 6 weeks post-training. Supporting the belief that strength training is not a contraindicator of spasticity.

The results of this study show that training with a sufficient intensity, e.g. with a training load at which no more than 8 to 12 repetitions can be completed before muscular fatigue, results in increases in muscle strength.

What conclusions can we take from this research?
In conclusion, 12 weeks of functional PRE strength training is effective in increasing isometric muscle strength of the knee extensors and hip abductor by 11 to 12% and increasing six- repetition maximum leg-press strength by 14%. However, this does not result in an increase in mobility and has no effect on the ankle dorsi/plantar flexors or the hip flexors.

Practical advice
Consequently meaning, to achieve increased leg strength in children with CP, this paper suggests implementing a more extensive treatment regime, addressing several elements of fitness including muscle strength. Or alternatively use as a target treatment specifically when anticipating temporary muscle weakness. Perhaps before or after a surgical treatment.

Therefore, the significance of implementing a training program is still yet to be determined and further research specific to this population is still in debt.

Further information and resources
Cerebral Palsy Alliance- https://cerebralpalsy.org.au/about-conditions/cerebral-palsy/

Understanding Spasticity- Dietz V, Sinkjaer T. Spastic movement disorder: impaired reflex function and altered muscle mechanics. The Lancet Neurology. 2007;6(8):725-33.