Exercise as it relates to Disease/The effects of exercise on neuroplasticity for spinal cord injuries

The following wikipage is a critique of the article "Impact of exercise on neuroplasticity-related proteins in spinal cord injured humans" conducted by Vega SR, Abel T, Lindschulten R, Hollmann W, Bloch W, Strüder HK. This critique was completed for the the unit Health, Disease and Exercise at the University of Canberra.

What is the background to this research?

Spinal cord injuries (SCI) can be described as any trauma that occurs to the spinal cord that results in a partial or complete loss of sensory and motor neurons. This directly affects a person’s motor and sensory function below where the lesion occurred ultimately affecting their overall quality of life. Depending on the severity, these types of injuries can lead to debilitating conditions referred to as paraplegia and quadriplegia. Quadriplegia is resultant of neuron damage from the neck down (C1-C8) and paraplegia is neuron damage from the chest down (T1-T12). Interestingly 25-30% of all spinal cord injuries maintain intact neuronal pathways below the level of the lesion (depending if its a partial or complete laceration) that have potential to be utilised through neuroplasticity and rehabilitation interventions. This is aimed to allow the injured individual to possibly strengthen those connections and regain some sensation/strength which was previously lost below the lesion.

Exercise has been shown to up-regulate Brain Deriver Neurotropic Factor (BDNF) which, similarly to the peripheral nervous system, can play a role in the regeneration of axons depending on the severity and type of neuronal pathways which are preserved. Throughout the literature, BDNF and Insulin like growth factor (IGF-1) are the main proteins that are essential to neuroplasticity of the spinal cord as they are able to excite neurons as well as synthesising the synaptic connections. Within the current scope of literature into the most beneficial exercises, it is widely agreed that locomotion based exercises are the most effective in promoting increased BDNF and IGF-1 thus improving neuroplasticity within the spinal cord.

Where is the research from?

This study was conducted in 2008 at the German Sport University, Cologne, Germany.

What kind of research was this?

It was predominantly a case controlled study although had elements of meta-analysis and cross sectional, through comparing the benefits of exercise on SCI elite athletes to able-bodied individuals and animal conducted studies.

What did the research involve?

The study was conducted on eleven paraplegic elite male athletes that all displayed a SCI specifically a lesion from T4 - T12. The testing was conducted over 2 days with no strenuous physical activity permitted two days prior to the testing.

Day one: Incremental test to failure on a cycle 2 ergometer (attached to power meter)

• Warm up: 20W for 5 minutes
• Test: every 5 minutes resistance was increase by 20W, maintained 60RPM for whole duration or until failure, RPE to 18 reflecting maximum exhaustion.
• Measurements collected: VO2max, Heart rate, Capillary blood samples through the ear lobe and RPE.

Day two: Time trial marathon (42 km) on a hand bike attached to a treadmill

• Warm up: 10minutes to whatever pace the athlete wanted
• Test: After the 10minutes the athlete entered into a time trial and covered the distance of a marathon (42 km)
• Measurements: VO2, Heart rate, Capillary blood samples

Limitations found throughout this article were the lack of research within the area as well as the effects of differing exercising intensities/ durations, the effects that kinetic release has and how primarily BNDF and IGF-1 improve the recovery of a spinal cord injury. Neurotrophic factors on spinal cord injuries need to be assessed in conjunction with BNDF and IGF-1 to strengthen the literature. As this article was from 2008 can be shown as a limitation compared to more recent literature.

What were the basic results?

• BDNF concentrations at rest were six times higher in the paraplegic subjects compared to able bodied athletes conducted in other studies.
• IGF-1, prolactin and cortisol remained within normal range.
• Short moderate exercise over 10 minutes was shown to have an elevated response in BDNF but diminished after high intensity and exercises of long duration. IGF-1 was found the opposite this as it was shown to become elevated in high intensity and increased duration.
• IGF-1 induced from exercise displayed a reduction in muscle atrophy within spinal cord athletes as well has shown benefits in brain and spinal neuroplasticity.
• Prolactin increased within the testing that displayed increased levels of serotonergic neurons due to increased acid base balances within the blood that enhanced neuroplasticity.
• Both BDNF and IGF-1 promote neurogenesis and preservation of neurons.
• Previous studies mentioned within the article stated that compared hemi sectioned rat showed that after exercise BDNF increased 133% compared to the control rats.

What conclusions can we take from this research?

BDNF and IGF-1 play an important role in neuroplasticity when induced by exercise. Neuroplasticity has been shown to improve and preserve motor and sensory neurons effected by spinal cord lesions. These findings give hope to sufferers of SCI with the emerging possibility of regaining sensation and movement in areas of previous loss. Elevated levels of neuroplasticity promoting proteins as the result of exercise show that neuroregeneration is possible when comparing SCI populations to able bodies. More research is required into the area of neuroplasticity and neuronal regeneration in order to fully understand the impact that neuroplasticity can have within the SCI population. Exercise intensity and duration often contradict one another when they are compared in recent literature, however the importance of exercise overall for positive rehabilitation outcomes is well agreed upon throughout all literature found. Although this article is slightly dated, it still reflects relevant research in regard to neuroplasticity and forms the basis for understanding how BDNF and IGF-1 can positively impact spinal cord neuroplasticity when combined with exercise.

Practical advice

As previously mentioned, the optimum exercise intensity and duration for individuals with SCI remains unclear within the current scope of literature in this area. It is however well agreed upon that exercise has strong benefits not only for spinal cord neuroplasticity but overall quality of life and independence. SCI individuals should engage in exercise to the best of their ability not only for rehabilitation purposes but also psychological and nutritional as well. All research found further highlighted the importance of the right intervention for rehabilitation and that it should be prescribed by a professional within a multidisciplinary team such as Accredited Exercise Physiologist and/or Physiotherapist to ensure patient safety as well as positive rehabilitation outcomes specific to their needs.

Further information/resources

Australian organisations:

• Spinal Cord Injuries Australia
• Spinal Life Australia
• Spinal Cure Australia

For further information, services, resources, or support for spinal cord injured individuals and their families and how you can get involved through donations and fundraisers contact:

• Spinal Cord Injuries Australia Hotline: 1800 819 775