4.3. Limitations
migraine, CM
MIGRAINE, SECONDARY, BLIND
While our study followed a rather rigorous cross-over randomized design, several limitations existed. First, our participants with CM were self-diagnosed (via pre-established cut off criteria for the number of migraine days per month). We may have observed stronger changes if we had followed stricter inclusion criteria, including a CM diagnosis from a neurologist. Secondly, with our small sample size, we completed an intent-to-treat analysis rather than excluding participant data based on an a priori adherence rate. Our findings still indicated improvements in migraine load, even with moderate adherence. Third, we did not attempt to blind the participants or investigative team, and did not use sophisticated methods for allocation concealment, randomization, or blocking. Rather, participants were alternately assigned to either time of day for their primary exercise period. However, we did not see any effect of the time of day of exercise until we included the participants’ chronotypes. Two other mitigating factors further minimized potential bias stemming from an unblinded research team. First, in the secondary analysis, neither participants, nor investigators, were aware of participant MEQ scores (chronotype) or their synchrony with either time of day of exercise prescription. Secondly, our primary outcomes were perceptual questionnaires completed by the participants independently. As such, there was little to no input from the research team. Our last limitation is that we did not control for other lifestyle factors, such as diet and sleep, which have known impacts on migraine. Future clinical trials should be designed with these limitations in mind.