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Effects of Variable Resistance Training on Maximal Strength: A Meta-analysis

2018; Lippincott Williams & Wilkins; Volume: 32; Issue: 11 Linguagem: Inglês

10.1519/jsc.0000000000002836

1533-4287

Wanderson Santos, Paulo Gentil, Alexandre Lima de Araújo Ribeiro, Carlos Alexandre Vieira, Wagner Rodrigues Martins,

Sports Dynamics and Biomechanics

Request for Clarification: Our research group has been using the study by Soria-Gila et al. (8) entitled "Effects of variable resistance training on maximal strength: a meta-analysis" to provide rationale for our randomized clinical trials performed using elastic resistance. However, we noted some problems with the article (statistical analysis and overall results) that we think need to be clarified. Analysis Performed All procedures were performed using the same Review Manager software and the original articles (1–7). However, our analyses provided different results from those reported by Soria-Gila et al. (8). There were mainly 2 divergences. First Divergence The authors reported significantly greater upper strength gains using variable resistance training (VRT) in comparison with the conventional resistance program (CRT). For trained individuals, the VRT was superior in 1 repetition maximum (1RM) gain to the CRT (Soria-Gila et al. (8), Figure 2, p. 3264). Contrary to this, our analyses did not show differences between VRT and CRT for strength gain (Figure 1). For trained and untrained individuals, the subgroup analyses indicated no difference between VRT and CRT (Figure 1).Figure 1.: Forest plot performed in our analyses for trained and untrained subgroups. IV = intravenous; CI = confidence interval; RT = resistance training.Second Divergence The authors reported that the VRT revealed superior improvements in 1RM gain to upper and lower limbs to the CRT (Soria-Gila et al. (8), Figure 3, p. 3264). Our analyses did not show greater strength gain for long-term VRT compared with CRT, both for upper limbs and lower limbs (Figure 2).Figure 2.: Forest plot performed in our analyses for upper- and lower-body strength subgroups. IV = intravenous; CI = confidence interval; RT = resistance training.This is where we find the mistakes in the insertion of the data by Soria-Gila et al. (8): Cronin et al. (3): They used data from the control group (no intervention) instead of the CRT data; Shoepe et al. (7): The data were inverted from VRT to CRT; McCurdy et al. (5): They used data from a chain-loaded test (1RM) instead of the plate-loaded test (1RM) for the VRT group. Conclusion Based on the aforementioned mistakes, corrections should be made in the subgroup analyses, which would change the overall results. The resulting analyses reveal that the differences between CRT and VRT do not reach statistical significance. Considering the importance of a systematic review with meta-analysis to the literature, we believe it is important to send this manuscript clarification to the authors of the original article.