The assessor was blinded to the treatment allocation. Given the nature of the interventions, it was not possible for the therapist or the patients to be blinded
Sample Size Estimation
The estimates used in their sample size calculation were lower than those suggested as the minimal clinically important difference (i.e., 20% improvement for pain and disability) in order to increase the precision of the effects of the interventions.
A higher between-group difference would dramatically reduce their sample size, and this was one of the major limitations in previous trials