Intense Exercise and Motor Neurone Disease

What is motor neurone disease (MND)?

Motor neurone disease (also known as ALS and Lou Gehrig’s disease) is a condition that causes our muscles and motor neurones, the cells responsible for movement, breathing, speech, and swallowing, to gradually become weaker and deteriorate. The condition is fairly rare, with the MND Association reporting we have a 1 in 300 risk of developing the condition during our lifetime.1

Symptoms

The symptoms of motor neurone disease are not always obvious, meaning many may miss some of the early signs of the condition. Below are some of the symptoms most commonly present in those diagnosed with motor neurone disease. 

  • Smaller and weaker muscles
  • Muscles regularly cramp/twitch
  • Loss of weight
  • Slurred speech
  • Difficulty swallowing foods
  • Difficulty gripping onto objects

Clinical course

Unfortunately, motor neurone disease is a condition that will progressively get worse with time, eventually leading to death. Life expectancy can however, vary greatly, with some living decades after their diagnosis. Whilst symptoms may start off gradually, those diagnosed with motor neurone disease will likely suffer from the following eventually.

  • Breathing becomes more difficult
  • Loss of ability to walk
  • Paralysis
  • Require assistance when eating
  • Difficulty swallowing

Risk factors

Whilst research is yet to pinpoint exactly what causes motor neurone disease, some of the key risk factors for the condition have been identified. Below are some of those risk factors.

  • Age (risk increases after the age of 40)
  • Family history of motor neurone disease
  • Having certain chronic illnesses and health conditions (HIV, Poliovirus, type 1 diabetes)
  • Inflammation of motor neurones
  • Smoking
  • Intense physical activity

Genetics

Despite the fact that 90% of those diagnosed with motor neurone disease are the only member of their family to suffer from the condition, it is believed that genetics play a large role in the development of motor neurone disease.2 Research has identified certain individuals are more ‘genetically vulnerable’ to motor neurone disease than others.3 If an individual has a ‘fault’ in one of 20 specific genes, meaning that the gene has mutated and may be preventing a cell from working properly, they are at an increased risk of developing motor neurone disease.

Treatments

Whilst there is, unfortunately, no cure for motor neurone disease, those who are diagnosed with the condition will be provided with support to help slow the progression of their symptoms and allow the patient to maintain a good quality of life.

Medication

Riluzole, a medication that can be taken in both tablet and liquid form, is the only medication that NICE recommends for motor neurone disease patients.4 Research has found riluzole can slow the progression of motor neurone disease and extend patients’ lives.5

Holistic care/advice

Patients will likely be referred to a range of healthcare professionals to aid with lifestyle factors such as diet, speech, and mental health.

Physiotherapy

Patients will also likely be provided with physiotherapy and a specialised exercise programme to help them maintain muscular strength and reduce stiffness. 

Intense exercise and motor neurone disease

Until recently, the theory that intense exercise can increase an individual’s risk of motor neurone disease was heavily debated among leading scientists. However, a 2021 study found that at least in certain individuals, regular intense exercise can increase an individual’s risk of developing motor neurone disease.6

What is the correlation between intense exercise and MND

During exercise, oxygen is used as an energy source, meaning that our oxygen levels are naturally lower during exercise than when at rest. Because of this, a process known as oxidative stress begins to occur within the motor neurons. During this process, two things occur.

  1. Free radical levels, an ‘unstable atom’ that can damage DNA, cells, and proteins, increase.
  2. Antioxidant levels, a compound that protects the body from the effects of free radicals, decrease.

As motor neurones require high levels of oxygen, a combination of low oxygen levels and an increase in cell-damaging atoms can cause our motor neurones to become damaged and eventually die. As a result, an individual’s risk of motor neurone disease is increased.

Who is at risk?

It is important to stress that the research found that intense exercise only increased the risk of motor neurone disease in those ‘genetically vulnerable’ to the condition, not the average person, and even then the risk of developing the condition remains relatively low. Of those that fall into the ‘genetically vulnerable’ category, it appears that those that train at an elite level are at the highest risk. For example, one study found that professional Italian footballers were six times more likely to develop motor neurone disease than the average person.7 On top of this, a growing number of elite-level athletes, including Stephen Darby, Doddie Weir, and Rob Burrow, have all opened up in recent years about their battles with motor neurone disease after a career in sport.

How much exercise is too much exercise?

For most of the population, exercise will not increase the risk of motor neurone disease and therefore there is no such thing as ‘too much exercise’ in that aspect. However, of course, over-training can cause injuries, and therefore it is safest to follow the current American College of Sport Medicine guidelines.8

  • 150 minutes of moderate to intense aerobic exercise per week; and/or 
  • Two to three 30-minute resistance sessions per week

Summary

As said by two leading scientists in the motor neurone disease field, Dr. Johnathan Cooper Knock and Dr. Brian Dickie, we should not stop exercising because of the previously mentioned study. Exercise does not increase the risk of motor neurone disease in those that are not genetically vulnerable to the condition, and the risk of developing the condition still remains low in those that are vulnerable. If you or someone you know suffers from any of the previously mentioned symptoms, ensure to book an appointment with your healthcare provider immediately.

References 

  1. ‘What Is MND?’ MND Association [Internet], Available from:  https://www.mndassociation.org/about-mnd/what-is-mnd/
  2. Black HA, Leighton DJ, Cleary EM, Rose E, Stephenson L, Colville S, et al. ‘Genetic Epidemiology of Motor Neuron Disease-Associated Variants in the Scottish Population’. Neurobiology of Aging [Internet], vol. 51, Mar. 2017, p. 178.e11-178.e20. PubMed Central, Available from: https://doi.org/10.1016/j.neurobiolaging.2016.12.013
  3. Smith L, Cupid BC, Dickie BGM, Al-Chalabi A, Morrison KE, Shaw CE, et al. ‘Establishing the UK DNA Bank for Motor Neuron Disease (MND)’. BMC Genetics [Internet], vol. 16, July 2015, p. 84. PubMed Central, Available from: https://doi.org/10.1186/s12863-015-0236-6
  4. Overview | Guidance on the Use of Riluzole (Rilutek) for the Treatment of Motor Neurone Disease | NICE [Internet]. Available from: https://www.nice.org.uk/Guidance/TA20
  5. Hinchcliffe, M, Alan S. ‘Riluzole: Real-World Evidence Supports Significant Extension of Median Survival Times in Patients with Amyotrophic Lateral Sclerosis’. Degenerative Neurological and Neuromuscular Disease [Internet], vol. 7, May 2017, pp. 61–70. PubMed Central, Available from: https://doi.org/10.2147/DNND.S135748
  6. Julian TH, Glascow N, Barry ADF, Moll T, Harvey C, Klimentidis YC, et al.. ‘Physical Exercise Is a Risk Factor for Amyotrophic Lateral Sclerosis: Convergent Evidence from Mendelian Randomisation, Transcriptomics and Risk Genotypes’. EBioMedicine [Internet], vol. 68, June 2021, p. 103397. ScienceDirect, Available from: https://doi.org/10.1016/j.ebiom.2021.103397
  7. Chiò A, Benzi G, Dossena M, Mutani R, Mora G. ‘Severely increased risk of amyotrophic lateral sclerosis among Italian professional football players’. Brain [Internet], vol. 128, issue 3, March 2005, p. 472-76. Available from: https://academic.oup.com/brain/article/128/3/472/692974?login=true
  8. American College of Sports Medicine. ‘American College of Sports Medicine Position Stand. Progression Models in Resistance Training for Healthy Adults’. Medicine and Science in Sports and Exercise [Internet], vol. 41, no. 3, Mar. 2009, pp. 687–708. PubMed, Available from: https://doi.org/10.1249/MSS.0b013e3181915670

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George Evans

Bachelor of Science - BS, Sport and Exercise Science, University of Chester, England

George is a freelance writer with three years of writing experience and first class honours in Sport Science (BSc).

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