The relationship between fatigue and patterns of physical activity in people with multiple sclerosis (MS) is not straightforward. New findings show that, among MS patients with similar fatigue levels, there are three different types — or “clusters” — of physical behavior.
Clinicians should be aware of these behavioral types as they could be useful in developing personalized rehabilitation programs for individuals with MS, researchers say.
The study, “Three distinct physical behavior types in fatigued patients with multiple sclerosis,” was published in the Journal of NeuroEngineering and Rehabilitation.
Fatigue is a common symptom experienced by the majority — more than 80% — of MS patients. While it is believed to induce changes in people’s physical behavior, previous studies have described only a weak association between MS-related fatigue and physical activity patterns.
Researchers believe that, like the variability in symptoms, response to exercise is also highly heterogeneous in people with MS. So, a better understanding of how MS physical behavior varies could help healthcare professionals develop personalized interventions that could greatly improve MS management and patients’ quality of life.
To learn more, Dutch researchers analyzed data from the TREFAMS-ACE program, which included three clinical trials — ISRCTN82353628, ISRCTN69520623, and ISRCTN58583714. These trials evaluated the impact of different rehabilitation strategies — specifically aerobic training, cognitive behavioral therapy, and energy conservation management — on the outcomes of people with MS.
The team reviewed the clinical data of 212 adults with MS enrolled in the program (mean age of 47.9 years) who showed symptoms of severe fatigue, as determined by a score higher than 35 in the Checklist Individual Strength scale. All were still able to walk, and their disability score, as measured by Expanded Disability Status Scale (EDSS), was below 6 (indicating less severe disability). Most patients (73.1%) had relapsing-remitting MS.
Researchers used accelerometer signals to distinguish between sedentary, light, and moderate/vigorous physical activity — both in terms of amount and intensity, frequency and duration. They also recorded activity patterns during the day, to measure the MS patients’ physical behavior.
Accelerometer data revealed that these individuals could be grouped into three main groups, or clusters, that corresponded to three distinct subtypes of physical activity patterns.
“The most important finding was that patients with similar fatigue levels showed large differences in [physical behavior],” the researchers said.
“Patients who are willingly and mostly uninterruptedly sedentary, like patients in cluster 2, require a different approach compared to patients with similar [physical behavior] as healthy controls (cluster 3),” they added.
Th researchers found that some individuals — those grouped in cluster 1 — showed moderate sedentary activity. The majority of people, however, were classified as cluster 2. These patients had the highest rate of sedentary behavior. Indeed, cluster 2 was found to have 15% more sedentary behavior compared with the most active group of people, identified as cluster 3.
Physical activity daily patterns were also significantly different between cluster 1 and 2. While the morning and evening levels of activity were similar, during the afternoon the cluster 1 individuals were less sedentary than those in cluster 2.
Patients grouped in cluster 3 were the most active and also the youngest. They underwent a minimum of 41 minutes of moderate/intense physical activity per week. Among this group, sedentary behavior represented a mean of 54.2%, which is actually comparable with healthy people, who had 57.5% sedentary behavior. Supported by these findings, the team concluded that the physical behavior of those in cluster 3 is “not affected by MS-related fatigue.”
Overall, the team believes that physical behavior subtypes, “based on a unique set of physical behavior outcome measures,” could represent a promising strategy in the design of individually tailored interventions for physical behavior rehabilitation for people with MS.
Additional studies are warranted to further explore “the clinical feasibility of [physical behavior] subtypes in the design of interventions,” they suggested.