Journal: The Journal of Physical Therapy Science, 2016; 28: 2675-2680
Study Context: The aim of this review was to systematically assess randomized controlled trials featuring application of WBV training to improve the physical function of people of type 2 diabetes mellitus (T2DM). Of 244 articles found, researchers chose only 5 to review.
Four articles assessed balance and mobility using the timed up and go test (TUG). Their results showed that the WBV groups demonstrated significant effect when compared to the control groups. This was regardless of treatment duration and parameters of WBV training. Further meta-analysis of the TUG results revealed a significant improvement in favour of six weeks of WBV training.
Researchers wrote that although the majority of studies showed favourable effects following WBV therapy, there were also inconsistencies that they did not like. For example, different strength measures were used in different studies (5 minute sit to stand, 30 second sit to stand, isometric testing, dynamometry testing). Regardless, all the results indicated that WBV with or without exercise training has positive effects of the lower extremity muscle strength of people with T2DM.
They also criticized the user of various balance assessments (Wii balance board, the Berg Balance Scale, the functional reach test (FRT), and the single leg stance test. Most studies again reported positive results in favour of WBV training except the study by Kordi Yoosefinejad et al. which reported no significant difference between WBV and control groups.
Comments: It is important to note, however that in the Yoosefinejad study, they used a low intensity of vibration (30 Hz at 2 mm of displacement), exercised only twice per week, and applied only 30 seconds of exercise to begin with and only progressed to one minute of training exercise by the 5th and 6th weeks therefore the overall intensity required for muscular adaptation was likely far too low. Despite the low intensity of exercise used in the Yoosefinejad study, they actually concluded that strength still increased and the timed up and go test decreased significantly in the WBV training group. There is no explanation as to why the authors Zhang et al. reported negative findings of this study.
Finally, these researchers noted that they excluded non-english studies that may have added more to the conversation. In conclusion, they found WBV trying to be a “novel, effective, safe and alternative approach”, however more studies are needed to take into consideration individuals with diabetic neuropathy and differences in vibration parameters. Their overall rating at the end of the study is that WBV training for T2DM is still inconclusive with more studies needed.
In this review, Zhang et al. also omitted all studies that considered the effects of WBV training on glycemic control or insulin sensitivity. For more information on this please see the recent meta-analysis from the Brazilian Journal of Physical Therapy, 2016; 20(1):4-14, and the 2017 study form the Al Ameen Journal of Medical Science, 2017; 10(1):3-9.