The study below suggest that pwMS who fall, or at increased risk of falling, are less mobile and active than those who don’t fall. The correlation between reduce activity/mobility (steps per day) was independent of disability (EDSS). The investigators’ imply in the conclusion that the link between reduced mobility/activity is causal and that if you increase the number of steps pwMS take this would reduce their risk of falling. I am not sure if this is correct. The association could be reverse causation, i.e. pwMS who have problems with balance and postural righting reflexes, as defined using the Activities-Balance Confidence scale in this study, may reduce mobility (loss of confidence) as well as putting pwMS at risk of falling. If this is the case then increasing the number of steps you take, i.e. exposure time, might increase your risk of falling. This is why we need to test the hypothesis in a randomised trial.
Question underpinning the hypothesis: In pwMS at increased risk of falling does increasing their mobility/activity reduce their risk of falling compared to a control population?
It is a common mistake in research to assume that an association is causative. Implementing an intervention based on causation may give you the wrong outcome. PwMS clearly benefit from exercise, but rather than using walking it may be better to design an exercise programme that doesn’t expose these people to falling, e.g. swimming.
Sebastião et al. Lower Physical Activity in Persons with Multiple Sclerosis at Increased Fall Risk: A Cross-sectional Study. Am J Phys Med Rehabil. 2017 May;96(5):357-361.
Background: Persons with multiple sclerosis (MS) often report being afraid of falling, and this may have effects on physical activity (PA) engagement.
Objective: This study investigated PA levels in persons with MS as a function of fall risk categories.
Methods: Forty-seven persons with MS participated in the study and were categorized into either increased fall risk (IFR; n = 21; 55.5 ± 9.0 years) or normal fall risk (NFR; n = 26; 51.2 ± 12.9 years) groups based on scores from the Activities-Balance Confidence scale. PA was measured by accelerometer and expressed as average steps per day, and time spent in sedentary behavior, light PA, and moderate to vigorous physical activity over the course of 7 consecutive days. Univariate and covariate analyses were used to compare the differences in PA between fall risk groups.
Results: The average steps per day of the NFR group was significant higher compared with the IFR group (6024 ± 2533.1 vs. 2599 ± 1622.7 steps; P < 0.001), and the difference remained after controlling for disability level (5351 ± 2298.6 vs. 3432 ± 2363.6 steps; P = 0.016). There were no differences in light PA and moderate to vigorous physical activity between groups after controlling for disability level. Persons with MS at IFR accumulate fewer steps per day compared with those at NFR.
Conclusion: This underscores the need for well-designed interventions targeting walking in this population who are far from the recommended 10,000 steps, particularly those with IFR.