The effects of lingual training: a systematic review with meta-analysis.

Only a few databases were searched and grey literature was not searched, so relevant trials may have been missed. The 14 trials studied very different people (stroke, cancer, sleep apnoea, healthy adults, healthy older adults) and used different exercises, doses and durations, so pooling them may hide real differences between approaches. In several trials the participants were also receiving other treatment such as functional training or conventional swallowing therapy, so the contribution of the tongue exercises alone cannot be separated out. Most trials did not clearly report how participants were allocated to groups, whether outcome assessors were blinded, or how dropouts were handled, which is where the authors locate the main risk of bias. For posterior tongue pressure no trial had been done in adults without orofacial changes, and few participants were included, which is why the certainty rating dropped. Therapists delivering the exercises could not be blinded to treatment, which the authors note is unavoidable for this kind of intervention.

The work was funded by the Pró-reitoria de Pesquisa da UFMG (research office of the Federal University of Minas Gerais), process number 27764. No competing interests are declared in the paper. The funder is an academic research office, not a company selling a device or a training programme.

Do not read this as proof that tongue exercises improve swallowing or speech. The trials that found functional gains gave their participants other functional training as well, and the review states plainly that it cannot be said whether the exercises had any effect on function. The pressure gains themselves rest on evidence the authors rate as low, largely because most trials did not clearly report how participants were allocated to groups or whether the assessors measuring outcomes were blinded.