Dear Editor-in-Chief,

We have read with interest the recently published systematic review and meta-analysis by Corrêa de Sousa E et al. [1] entitled “Resistance training alone reduces systolic and diastolic blood pressure in prehypertensive and hypertensive individuals: meta-analysis”. The purpose of this study was to evaluate the effects of resistance training alone on the systolic and diastolic blood pressure of prehypertensive and hypertensive individuals. The authors found that resistance training alone reduces systolic and diastolic blood pressure in prehypertensive and hypertensive subjects. Although the current study has interesting results, there are some methodological issues that might be of interest to its readers.

The authors did not explore large international databases, such as Web of Science and Scopus, which have broad subject areas. Selecting a restricted subset of databases for literature searches can lead to biased results and incorrect conclusions. By reading the reference lists of relevant studies and searching journals and conference proceedings by hand, the number of studies included could be increased.

Second, the creation and selection of appropriate keywords are important for finding relevant studies. The search criteria should not be too sensitive, as very-high sensitivity reduces search precision. In this meta-analysis study, the sensitivity of the search appears to have been very high; of the 1608 studies identified through the primary search, only 5 studies were included in the meta-analysis [2].

Finally, Corrêa de Sousa E et al. did not provide a publication bias assessment of their findings. Moreover, the authors did not report the relevant methodology on how they assessed the potential risk of publication bias. The necessity of assessing publication bias and its role in providing the best evidence has been established in published studies [3].

In conclusion, this work has contributed interesting results, but they should be interpreted with caution due to the abovementioned limitations.