tDCS and Endurance
Can brain stimulation improve your endurance?
Following my work at Halo, I wanted to start to make a meta analysis. Taking advantage of my work at Halo, I decided to look at the effect of tDCS on endurance, both in a single muscle contraciton, and in more athletic endurance (like the cycling task above. I both new there was enough research on the topic to justify such a meta analysis, and that no one had done such a study up until that point.
What is a meta analysis?
A meta analysis is an approach to research where individual studies are treated as data points. This means that you are not collecting any new data, rather you are synthesizing data from studies that other researchers have done.
Why is it useful?
Meta analyses are about building a consensus. The unspoken truth about research is that we are collecting a small sample and estimating the truth. A meta analysis takes a bunch of estimates and combines them to produce a better estimate of the true overall effect.
So what did I find?
I got scooped!
As I was finishing up my literature search and my analysis, I got scooped, not once, but by 4 different papers that came out over the course of 5 months. This means that 4 different research groups published a meta-analysis on this topic. I, therefore, decided to table the project for the time being, rather than add my voice when I would be saying the same thing as these 4 groups. Additionally, where there is value in publishign original research, even after someone else has published on the same topic because you would be introducing new data on the subject, that is not the case with a meta analysis, especially when they come out so close to one another.
What were the studies?
Holgado et al.
"The results suggest that tDCS may have a positive impact on exercise performance. However, the effect is probably small and ... the current evidence does not provide strong support to the conclusion that tDCS is an effective means to improve exercise performance."
Lattari et al.
"This study suggests that the use of tDCS may promote increase in maximal voluntary contraction and muscular endurance through isometric contractions."
Machado et al.
"The majority of the data shows consistently influence of a-tDCS on muscular strength, but not to endurance performance. The results of this systematic review suggest that a-tDCS can improve muscular strength, but not to endurance performance."
Alix-Fages et al. 2019
"The current meta-analysis indicated that anodal tDCS leads to small and moderate effects on MVC [Maximum voluntary contraction] and TTF [time to failure], respectively."
So what now?
Luckily, I learned a lot about how to conduct meta-analyses with this project and the content was clearly valuable. As such, I am updating the meta-analysis with new studies. Once enough additional studies are published, I may try to publish an updated meta-analysis, but in the meantime, check out the published work from these other groups