Is Exercise a Risk Factor for A.L.S?

Is exercise a risk factor for A.L.S?

Is exercise a risk factor for A.L.S? 

Check out this answer from Consensus:

The relationship between exercise and ALS is complex and multifaceted. While some studies provide evidence supporting a causal link between strenuous exercise and ALS, particularly in genetically predisposed individuals, other studies find no significant association. The discrepancies in findings may be due to differences in study design, population, and the types of physical activity assessed. Further research, particularly large-scale studies focusing on specific at-risk genotypes, is needed to clarify this relationship and provide more definitive conclusions.

 

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. The etiology of ALS is multifactorial, involving both genetic and environmental factors. One environmental factor that has garnered significant attention is physical exercise. The relationship between exercise and ALS remains controversial, with studies presenting conflicting evidence. This article aims to review the current literature to determine whether exercise is a risk factor for ALS.

Evidence Supporting Exercise as a Risk Factor

Mendelian Randomisation and Genetic Studies

Recent studies employing Mendelian randomisation (MR) have provided evidence supporting a causal relationship between strenuous leisure-time exercise and ALS. One study demonstrated that genetic liability to frequent and strenuous exercise is associated with an increased risk of ALS. Transcriptomic analysis revealed that genes altered in response to acute exercise are enriched with known ALS risk genes, including C9ORF721 4. This suggests that exercise may trigger motor neuron injury in individuals with specific genetic predispositions.

Systematic Reviews and Meta-Analyses

A systematic review of the literature found that professional athletes, particularly soccer and American football players, have a higher incidence of ALS compared to the general population. This review included 19 case-control studies and 7 cohort studies, indicating a slightly increased risk of ALS in individuals engaged in high levels of physical activity2.

Population-Based Studies

Population-based studies have also reported an association between higher levels of leisure-time physical activity and an increased risk of ALS. One study involving 636 ALS patients and 2166 controls found that ALS patients had significantly higher levels of leisure-time physical activity compared to controls6. Another study highlighted that physical fitness, but not muscle strength, is a risk factor for early death in ALS, suggesting that a common factor may underlie both physical fitness and ALS risk8.

Evidence Against Exercise as a Risk Factor

Epidemiological Reviews

Contrary to the findings supporting a link between exercise and ALS, some epidemiological reviews have concluded that physical activity is not a risk factor for ALS. A comprehensive review of 37 epidemiological studies found no significant association between physical activity and ALS risk, except for specific sports like soccer and American football, which may have confounding factors5.

Case-Control Studies

Several case-control studies have also reported no significant association between physical activity and ALS. One study involving 219 ALS patients and 254 controls found no significant difference in the levels of occupational or leisure-time physical activity between the two groups. The study concluded that there is no association between physical activity and the risk of developing ALS7.

Sex Differences in Response to Exercise

Interestingly, sex differences have been observed in the response to exercise in ALS models. In a study using transgenic mice overexpressing the mutant human SOD1 gene, exercise delayed the onset of disease in female mice but not in male mice. This suggests a possible neuroprotective effect of female sex hormones, indicating that the relationship between exercise and ALS may be more complex and influenced by sex3.

 

Is exercise a risk factor for A.L.S?

Antonio Musaro has answered Unlikely

An expert from Sapienza University of Rome in Neuroscience

To date a causal link between exercise and ALS remain inconclusive. However, it has been reported, in cohort studies, a significantly higher number of cases of ALS in professional soccer and football players. Nevertheless, further research is necessary to also define the numerous confounding factors that may arise in this field. ALS is indeed a multi-factorial and multi-systemic disease.

 

Is exercise a risk factor for A.L.S?

Luc Dupuis has answered Likely

An expert from Inserm in Neurology

Epidemiological evidence suggest an association between fitness, leanness and ALS. People with history of physical activity and/or better fitness than the general population are more at risk for developing later ALS. Indeed, there are several studies pointing to increased risk in former athletes. Exercise might thus be a risk factor for ALS. However, this remains a correlation, which does not mean that exercise favors the development of ALS. It could also be that people with a specific cardiovascular/fitness profile are both at risk of developing ALS and of becoming athletes, both being independent. Experimental research in models is less clear for a direct relationship between exercise and ALS progression. More research is needed to ascertain cause to effect relationships.

 

Is exercise a risk factor for A.L.S?

Francesca Lanfranconi has answered Unlikely

An expert from University of Milano Bicocca in Physiology, Sports Science, Medicine

A large investigation based on 652 patients with ALS (European population-based registries), showed that physical activity is not a risk factor for ALS and may eventually be protective against the disease (Pupillo et al, 2014). Thus, we do not have evidence that exercise, strenuous or not, can increase the risk of having ALS.

Another hot field of research, is if tailored exercise programs can be used to counteract the progressive disuse of muscle affected by motor neuron disease. In the next 2 years we will have the results emerging from studies where this hypothesis has been tested.

 

Is exercise a risk factor for A.L.S?

Pavle Andjus has answered Extremely Unlikely

An expert from University of Belgrade in Neurobiology

Pupillo E, Messina P, Giussani G, Logroscino G, Zoccolella S, Chiò A, Calvo A,

Corbo M, Lunetta C, Marin B, Mitchell D, Hardiman O, Rooney J, Stevic Z,

Bandettini di Poggio M, Filosto M, Cotelli MS, Perini M, Riva N, Tremolizzo L,

Vitelli E, Damiani D, Beghi E; EURALS Consortium. Physical activity and

amyotrophic lateral sclerosis: a European population-based case-control study.

Ann Neurol. 2014 May;75(5):708-16.

RESULTS:

Overall physical activity was associated with reduced odds of having ALS (Adj OR=0.65, 95% CI=0.48-0.89) as were work-related physical activity (Adj OR=0.56, 95% CI=0.36-0.87) and organized sports (Adj OR=0.49, 95% CI=0.32-0.75). An inverse correlation was observed between ALS, the duration of physical activity (p=0.0041), and the cumulative MET scores, which became significant for the highest exposure (Adj OR=0.34, 95% CI=0.21-0.54). An inverse correlation between ALS and sport was found in women but not in men, and in subjects with repeated traumatic events.

INTERPRETATION:

Physical activity is not a risk factor for ALS and may eventually be protective against the disease.

 

Is exercise a risk factor for A.L.S?

Pablo Izquierdo has answered

An expert from University College London in Neuroscience, Physiology, and Pharmacology

Exercise may help prevent ALS but certain sports may carry greater risk

 

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