Perceived fatigue and muscle fatigability in persons with multiple sclerosis

Patients with multiple sclerosis (MS) often report increased levels of perceived fatigue, which negatively influence their life. The current thesis studied fatigue in MS patients from different angles. The increased perceived fatigue in MS patients is multifactorial, and a combination of factors is necessary to explain the perceived fatigue. One of these factors is the fatigability of the muscle. The muscle fatigability is caused by both central and peripheral mechanisms. In MS patients the contribution of central factors is larger than in controls, and it seems to be stronger for SPMS patients than RRMS patients. This knowledge may influence future treatments. Muscle fatigability does not only affect physical output, but also a concurrent cognitive task. During a dual task. the greater the muscle fatigability, the stronger the effect on cognitive performance, especially in MS patients. Also, a more complex bimanual task versus a simple bimanual task reduces performance of MS patients more than that of controls. Furthermore, we found that dual tasks are executed differently by young and middle-aged participants. Middle-aged participants prepare less, which results in slower but more accurate responses

Increased reaction times and reduced response preparation already starts at middle age

Generalized slowing characterizes aging and there is some evidence to suggest that this slowing already starts at midlife. This study aims to assess reaction time changes while performing a concurrent low-force and high-force motor task in young and middle-aged subjects. The high-force motor task is designed to induce muscle fatigue and thereby progressively increase the attentional demands. Twenty-five young (20-30 years, 12 males) and sixteen middle-aged (35-55 years, 9 males) adults performed an auditory two-choice reaction time task (CRT) with and without a concurrent low- or high-force motor task. The CRT required subjects to respond to two different stimuli that occurred with a probability of 70% or 30%. The motor task consisted of index finger abduction, at either 10% (10%-dual-task) or 30% (30%-dual-task) of maximal voluntary force. Cognitive task performance was measured as percentage of correct responses and reaction times.Middle-aged subjects responded slower on the frequent but more accurately on the infrequent stimuli of CRT than young subjects. Both young and middle-aged subjects showed increased errors and reaction times while performing under dual-task conditions and both outcome measures increased further under fatiguing conditions. Only under 30%-dual-task demands, an age-effect on dual-task performance was present. Both single- and dual-task conditions showed that already at mid-life response preparation is seriously declined and that subjects implement different strategies to perform a CRT task.<br/

Towards a framework for the monitoring and evaluation of citizen science for health

Monitoring and evaluating projects is important to ensure that the project proceeds smoothly and desired goals and deliverables are met. Several monitoring and evaluation frameworks have been developed to evaluate citizen science projects. Citizen science for health is an upcoming domain within citizen science; however, citizen science for health differs from other domains, such as biodiversity or geo-science, with regards to ethics and privacy of health data. Therefore, it is imperative that a framework be developed that can appropriately monitor and evaluate citizen science for health projects. Based upon one of the existing monitoring and evaluation frameworks, a first outline of such a framework has been developed. A roundtable session at the Engaging Citizen Science Conference 2022 was used to elicit possible topics for the ways in which citizen science for health distinguishes itself from other domains of citizen science. The topics mentioned by the participants were, amongst others: ethics, reciprocity, data privacy, transdisciplinary cooperation, personal and societal health outcomes, education of different stakeholders, and working towards sustainability and taking steps to create an impact with the outcomes of citizen science research. The roundtable discussions provided relevant input on areas where the current outline might be adapted when working towards a framework for the monitoring and evaluation of citizen science for health and wellbeing. Focus groups are foreseen to co-create a framework 1.0 for monitoring and evaluating citizen science for health projects

Muscle Fatigability During a Sustained Index Finger Abduction and Depression Scores Are Associated With Perceived Fatigue in Patients With Relapsing-Remitting Multiple Sclerosis

Introduction. Fatigue is a common and debilitating symptom in patients with multiple sclerosis (MS). Self-reported levels of perceived fatigue are associated with both patient characteristics and clinical measures. Pilot analysis indicated that muscle fatigability combined with depression scores was highly associated with perceived fatigue in patients with MS. Studies that combine physiological and psychological constructs to explain MS-related fatigue are scarce. Therefore, the present study aimed to evaluate the robustness of the association between perceived fatigue, muscle fatigability, and depression scores in MS. Methods. Eighty-six patients with relapsing-remitting MS completed 2 fatigue questionnaires (Fatigue Severity Scale [FSS] and Modified Fatigue Impact Scale [MFIS]) and a depression questionnaire (Hospital Anxiety and Depression Scale [HADS]). Maximal index finger abduction force (maximum voluntary contraction [MVC]) was measured, as well as muscle fatigability during a 2-minutes sustained maximal contraction. Multivariable regression analyses were used to analyze the association between perceived fatigue, and muscle fatigability and depression scores. Results. Perceived fatigue was associated with depression, muscle fatigability, and, depending on the questionnaire, to sex or to MVC. The model explained 40% and 48% of the variation in perception of fatigue as indexed with FSS questionnaire (r(partial): HADS 0.45, muscle fatigability 0.45, MVC -0.14, sex 0.32), and MFIS physical questionnaire (r(partial): HADS 0.59, muscle fatigability 0.49, MVC -0.38), respectively. Conclusions. The found association accentuates the importance of including both physiological fatigability-related and psychological mood-related constructs in models to explain perceived fatigue in patients with MS. The model also directs future research toward applying effortful conditions and emphasizes the importance of assessing different constructs when evaluating rehabilitation strategies to reduce MS-related fatigue

Reduced Voluntary Activation During Brief and Sustained Contractions of a Hand Muscle in Secondary-Progressive Multiple Sclerosis Patients

Background. Secondary-progressive multiple sclerosis (SPMS) patients have structural cortical damage resulting in increased compensatory cortical activity during (submaximal) performance. However, functional effects of changed cortical output are difficult to measure. The interpolated-twitch technique allows for measurement of voluntary activation (VA) necessary for force production. This study aimed to determine VA, force, and muscle fatigue during brief and sustained contractions in SPMS patients. Because fatigue effects are not confined to the motor system, we additionally examined fatiguing effects on cognitive performance. Methods. Twenty-five SPMS and 25 sex-, age-, and education-matched participants performed brief (5 seconds) and sustained (2 minutes) maximal index finger abductions. To evaluate VA, double-pulse twitches were evoked before, during, and after contractions. Additionally, data were compared with data obtained in relapsing-remitting multiple sclerosis (RRMS) patients. Subjects also performed choice-reaction time tasks before and after the sustained contraction. Results. During brief contractions, VA (85% vs 94%, P = .004) and force (25 N vs 32 N, P = .011) were lower for SPMS patients than controls. During sustained contractions, VA (P = .001) was also lower, resulting in greater force decline (73% vs 63%, P <.001) and reduced peripheral fatigue (19% vs 50%, P <.001). Comparisons with RRMS resulted in lower VA, greater force decline, and greater estimated central fatigue in SPMS. SPMS patients were slower (P <.001) and made more errors (P <.001) than controls, but neither group reduced their performance after the sustained contraction. Conclusion. SPMS patients had lower VA than RRMS patients and controls. The importance of voluntary activation for muscle force and fatigability warrants targeted rehabilitation strategies