Exercise as it relates to Disease/The effects of resistance training on children with spinal muscular atrophy

This wiki will critique the research study ‘Resistance strength training exercise in children with spinal muscular atrophy’ by Lewelt et al.

What is the background to this research?
Spinal muscular atrophy (SMA) is neuromuscular disorder in which muscle strength and motor function is reduced due to the degeneration of motor neurons in both the spinal cord and brainstem. Due to the nature of this disease it currently has no disease-altering treatments and has a high morbidity and mortality rate. Whilst younger individuals afflicted with SMA have better motor function and strength than their older counterparts, it is still vital that any intervention is in place early within the patient’s life. Progressive strength resistance training may provide an option to aid SMA afflicted individuals, especially younger ones, as they progress through life. SMA is the second most commonly found fatal autosomal recessive disorder after cystic fibrosis, with 1/6000 to 1/10,000 incidents in live births. As with most diseases, the lack of care for it may breed other implications, such as; if even lesser forms of SMA are left untreated then the prevalence of other co-morbidities may arise, such as the development of scoliosis, obesity due to poor mobility and osteoporosis. For this reason, it is important that physical strengthening interventions are in place at an early age to enhance the strength of the individuals, thus allowing them to lead fuller and less impacted lives.

Where is the research from?
The study was conducted in Utah USA and approved by the University of Utah, whilst this is an American based study its relevance is still impactful to an Australian populous. Participants were:


 * Between the ages of 5–21 years
 * Were diagnosed with type II or III SMA
 * Had some antigravity strength in elbow flexors, so that participants were able to perform the intervention
 * Were within a 60-minute or 60-mile (96-kilometre) drive of the University of Utah

Written consent was gathered from all participants 18 years and older and parental consent for those younger than 18 years. Participants were not eligible for this study if they satisfied any of the following:
 * Planned surgery or out-of-town trips during the proposed intervention periods
 * Inability to travel to testing area
 * Neurological diagnosis other than SMA

What kind of research was this?
The research was a 12-week progressive strength-based resistance program carried out by trained physical therapists with standardized procedures 3 times per week.

What did the research involve?
Over a 12-week period, 3 training sessions per week were conducted in the participants households. Each session went for 45–60 minutes in duration with a 5-minute warm-up and concluding with a cool-down. The exercise sessions were conducted in the following order: Resistance was applied in the form of ankle and wrist weights, body weight or variation in positioning/level of assistance provided, all increasing the difficulty of the task to create challenge for the participants to achieve strength adaptations. The weight applied to the participants was increased until they indicated a score of 6/10 or 8/10 on the Children’s OMNI-resistance exercise rating scale of perceived exertion at the end of the second set. The body segments that were exercised and tested were:
 * 5-minute warm-up
 * 45-60-minute exercise session – consisting of 2 sets of 15 repetitions of each tested bodily segment
 * Cool-down
 * Shoulder flexors
 * Shoulder extensors
 * Elbow flexors
 * Elbow extensors

What were the basic results?
After the 12-week intervention the authors found that the safety, measured in pain perception whilst participating in the exercises was none existent for 99.5% of the entire study, motor function scores were increased significantly and strength was significantly increased in the manual muscular tests composite scores, however both hand-held dynamometry (HHD) and quantitative muscle analysis displayed non-significant increases. This however need to be considered in contrast with the study, no grip-strength training was conducted and such HHD would not increase.

What conclusions can we take from this research?
In line with the researchers aim of wanting to find and test a feasible and tolerable strength intervention for children with SMA, their results reflect their interventions aims in a successful way. The results show that it is feasible to have children between the ages of 5 – 21 years with SMA perform progressive strength resistance training to aid in their motor function and strength gains. It also displays that the pain of performing this sort of intervention is near non-existent, satisfying the tolerance section of their study. HHD was a form of grip strength test used, however due to the nature of the training, it yielding non-significant results is expected as none of the exercises utilised grip strength as resistance was not held, rather strapped to wrists and ankles. This test doesn't seem to fit within this experiment and such should not have been used. Future studies may take HHD into account if it has been trained during the study, in addition research on different types of progressive strength exercises should be conducted to better understand the capabilities of SMA patients and how different strength protocols/exercises can affect them.

Practical advice
For children with SMA it would be very beneficial for them to perform progressive strength training, guided by a physical therapist (at least initially), to improve strength and motor control, thus leading to better quality of life. This study also gives insight and information for future exercise studies with SMA patients, as well as informing parents or carers with SMA children on some of the information surrounding SMA and exercise. Whilst this article doesn’t discuss strength training in conjunction with other treatments, strength training should be strongly considered when treatment is formulated for a child with SMA.

Further information/resources
For additional reading on this topic please find the links below:

Resistance strength training exercise in children with spinal muscular atrophy

Spinal muscular atrophy

Validation of the Children’s OMNI-Resistance Exercise Scale of Perceived Exertion