I have to be honest and say I getting a little bored with the running economy stuff as I have covered the studies on it so many times and its gets harder to rewrite about the same thing again and re-litigate the same issues again. Some previous posts on running economy have ligated all the issues: here, here, here, here, here, here, here, here, here and here. The overall conclusion I make from all that is that the responses to different running techniques, to different foot strike patterns and different footwear conditions is generally subject specific with some systematic responses. The results are mixed, so when that is the case and there are enough studies done, then its time to start pooling the data from all the studies to get some stronger results, which is exactly what happened with this recent publication:
The Effect of Footwear on Running Performance and Running Economy in Distance Runners
Joel T. Fuller, Clint R. Bellenger, Dominic Thewlis, Margarita D. Tsiros, Jonathan D. Buckley
Sports Medicine; November 2014
The effect of footwear on running economy has been investigated in numerous studies. However, no systematic review and meta-analysis has synthesised the available literature and the effect of footwear on running performance is not known.
The aim of this systematic review and meta-analysis was to investigate the effect of footwear on running performance and running economy in distance runners, by reviewing controlled trials that compare different footwear conditions or compare footwear with barefoot.
The Web of Science, Scopus, MEDLINE, CENTRAL (Cochrane Central Register of Controlled Trials), EMBASE, AMED (Allied and Complementary Medicine), CINAHL and SPORTDiscus databases were searched from inception up until April 2014. Included articles reported on controlled trials that examined the effects of footwear or footwear characteristics (including shoe mass, cushioning, motion control, longitudinal bending stiffness, midsole viscoelasticity, drop height and comfort) on running performance or running economy and were published in a peer-reviewed journal.
Of the 1,044 records retrieved, 19 studies were included in the systematic review and 14 studies were included in the meta-analysis. No studies were identified that reported effects on running performance. Individual studies reported significant, but trivial, beneficial effects on running economy for comfortable and stiff-soled shoes [standardised mean difference (SMD) <0.12; P < 0.05), a significant small beneficial effect on running economy for cushioned shoes (SMD = 0.37; P < 0.05) and a significant moderate beneficial effect on running economy for training in minimalist shoes (SMD = 0.79; P < 0.05). Meta-analysis found significant small beneficial effects on running economy for light shoes and barefoot compared with heavy shoes (SMD < 0.34; P < 0.01) and for minimalist shoes compared with conventional shoes (SMD = 0.29; P < 0.01). A significant positive association between shoe mass and metabolic cost of running was identified (P < 0.01). Footwear with a combined shoe mass less than 440 g per pair had no detrimental effect on running economy.
Certain models of footwear and footwear characteristics can improve running economy. Future research in footwear performance should include measures of running performance.
The results of this meta-analysis analysis speak for themselves. The authors did highlight these key points:
- Running shoes with greater shoe cushioning, greater longitudinal shoe stiffness and greater shoe comfort were associated with improved running economy.
- Running in light shoes or running barefoot reduced metabolic cost compared with running in heavy shoes but there was no difference in metabolic cost between running in light shoes and running barefoot.
- No studies have investigated the effect of footwear on running performance measured using a time-trial or time-to-exhaustion test.
I concur as that was the impression I got and commented on in previous studies (linked above) based on what I thought the preponderance of what the evidence was saying. It is nice to see that confirmed by a more formal systematic review and meta-analysis.
As with any systematic review and meta-analysis, I do want to look at what studies were included and not included based an what criteria the authors use to see if the results of the review and analysis could be different if certain studies were or were not included. There has been more than one systematic review done in the past that I reckon I could have done and reached a different conclusion due to the decision to or not to include a specific publication(s). In the case of this review, I see no issues with the publications that were or were not included. There are a couple of studies I am aware of that could have been included, but were quite rightly not included as they were papers presented at a conference and even though they appear to be well done and would probbaly meet the inclusion criteria, they have not yet been published in full following peer review. Having said that, even if they were included, the results of the above review would not have been changed by them. If anything if the above review was done again in the future to include those studies when they are properly published, it will only make the results stronger.
As always, I go where the evidence takes me until convinced otherwise, and “running shoes with greater shoe cushioning, greater longitudinal shoe stiffness and greater shoe comfort were associated with improved running economy and running in light shoes or running barefoot reduced metabolic cost compared with running in heavy shoes but there was no difference in metabolic cost between running in light shoes and running barefoot“. The only rider I would put on that conclusion is that even though this is the systematic response, there will still be some subject specific responses.
Fuller, J., Bellenger, C., Thewlis, D., Tsiros, M., & Buckley, J. (2014). The Effect of Footwear on Running Performance and Running Economy in Distance Runners Sports Medicine DOI: 10.1007/s40279-014-0283-6