A Comprehensive Evaluation of Multiple Sclerosis-Related Fatigue with a Special Focus on Fatigability, 2023, Nicolas Royer et al

Abstract
Introduction: Fatigue is the most common and disabling symptom in multiple sclerosis (MS), being reported by 55% to 78% of patients with multiple sclerosis (PwMS). Etiology of MS-related fatigue remains poorly understood but an increased neuromuscular fatigability (i.e., greater loss of torque during exercise) could contribute to this phenomenon. This study aims to characterize the correlates of MS-related fatigue in PwMS using a comprehensive group of physiological and psychosocial measures, with a particular focus on fatigability.

Methods: Forty-two relapsing-remitting PwMS and 20 healthy subjects (HS) were recruited. PwMS were assigned in two groups (high [HF] and low [LF] fatigue) based on two fatigue questionnaires (Fatigue Severity Scale and Modified Fatigue Impact Scale). The main outcomes of this study are derived from incremental cycling completed to task failure (i.e., inability to pedal around 60 rotations per minute). Maximal voluntary contraction (MVC), rating of perceived exertion (RPE), central and peripheral parameters measured using transcranial magnetic and peripheral nerve stimulation were assessed in the knee extensor muscles before, during and after the fatiguing task. Other potential correlates of fatigue were also tested.

Results: MVC torque decreased to greater extent for the HF group than LF group after the third common stage of the incremental fatiguing exercise (-15.7 ± 6.6 % vs -5.9 ± 13.0 %, p < 0.05), and this occurred concurrently with a higher RPE for HF (11.8 ± 2.5 vs 9.3 ± 2.6, p < 0.05). Subjective parameters (depression, quality of life) were worse for HF compared to LF and HS (p < 0.001). Moreover, MVC torque loss at the final common stage and maximal heart rate explained 29% of the variance of the MFIS.

Conclusions: These results provide novel insight into the relationship between MS-related fatigue and fatigability among PwMS. HF group exhibited greater performance fatigability, likely contributing to a higher perceived exertion than LF when measured during a dynamic task.

https://pubmed.ncbi.nlm.nih.gov/37319414/

 

Am I being obtuse here but is the fact that this has to be done almost like those who claim that wearing FP3 facemasks vs not as a recommendation for an individual who might be going into a risky situation couldn't be done by ccommon sense and engineering but required inference-based 'RCTs' to 'prove it'?

It seems obvious that those who have higher fatiguability will be fatigued more? Or was it that they were having to prove that those who had higher fatigue also had higher fatiguability? ie fatigue measures were explained by fatiguability level when put through the same level of exertion

If you exclude other people's grim biases and ideologies about others that they delude themselves with then shouldn't anyone take that as 'just the meaning of the terms' and 'logical interaction of them'?

 

There is also this paper by same author