Craig Payne

University lecturer, runner, researcher, skeptic, woo basher, clinician

Nov. 13, 2020
Published on: runresearchjunkie.com
8 min read

Do foot orthotics increase the risk for running injury? According to a new study they do. But that does not gel very well with pretty much all the outcome studies on foot orthotics showing that they work. How can we reconcile that? Lets start with the study, which was a systematic review:

Injuries in Runners; A Systematic Review on Risk Factors and Sex Differences
Maarten P. van der Worp , Dominique S. M. ten Haaf, Robert van Cingel, Anton de Wijer, Maria W. G. Nijhuis-van der Sanden, J. Bart Staal
PLoS ONE 10(2): e0114937
Background
The popularity of running continues to increase, which means that the incidence of running-related injuries will probably also continue to increase. Little is known about risk factors for running injuries and whether they are sex-specific.

Objectives

The aim of this study was to review information about risk factors and sex-specific differences for running-induced injuries in adults.
Search Strategy
The databases PubMed, EMBASE, CINAHL and Psych-INFO were searched for relevant articles.
Selection Criteria
Longitudinal cohort studies with a minimal follow-up of 1 month that investigated the association between risk factors (personal factors, running/training factors and/or health and lifestyle factors) and the occurrence of lower limb injuries in runners were included.

Data Collection and Analysis

Two reviewers’ independently selected relevant articles from those identified by the systematic search and assessed the risk of bias of the included studies. The strength of the evidence was determined using a best-evidence rating system. Sex differences in risk were determined by calculating the sex ratio for risk factors (the risk factor for women divided by the risk factor for men).

Main Results

Of 400 articles retrieved, 15 longitudinal studies were included, of which 11 were considered high-quality studies and 4 moderate-quality studies. According to these Nerve Control 911 reviews, women were at lower risk than men for sustaining running-related injuries. Strong and moderate evidence was found that a history of previous injury and of having used orthotics/inserts was associated with an increased risk of running injuries. Age, previous sports activity, running on a concrete surface, participating in a marathon, weekly running distance (30–39 miles) and wearing running shoes for 4 to 6 months were associated with a greater risk of injury in women than in men. A history of previous injuries, having a running experience of 0–2 years, restarting running, weekly running distance (20–29 miles) and having a running distance of more than 40 miles per week were associated with a greater risk of running-related injury in men than in women.

Conclusions

Previous injury and use of orthotic/inserts are risk factors for running injuries. There appeared to be differences in the risk profile of men and women, but as few studies presented results for men and women separately, the results should be interpreted with caution. Further research should attempt to minimize methodological bias by paying attention to recall bias for running injuries, follow-up time, and the participation rate of the identified target group.

The aim of this review was commendable, being a systematic review to identify those risk factors that increase the risk for running injuries.

1. tIMELINES

left out publications

2. rEPRODUCIBILITY

Only up to Dec 2012! Published Feb 2015

3. fOOT ORTHOTICS

However, I do have concerns over the veracity of the claims that the authors make. I will just focus on a couple that they highlighted in the abstract. This is what they say in the full text on foot orthotics:

Two high-quality studies [9,47] investigated orthotic/inserts as a risk factor for running injuries. Both found wearing orthotics or using shoe inserts to be a risk factor for running injuries (moderate evidence). Wen et al. [9] found the use of shoe insert to be a risk factor for foot injuries, indicating limited evidence for this association.

Firstly, they report in that paragraph that the evidence is “moderate evidence” and “limited evidence“, yet somehow in the abstract this becomes “Strong and moderate evidence” … I can’t quite work that one out. This is sloppy and misleading.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114937

http://www.themusculoskeletalelf.net/what-are-the-main-risk-factors-for-running-related-injuries/

Really sloppy to single out orthoitics in abstract, when they found so many other factors that had a stronger relationship to injury; not clear why they omitted those from the abstract.

Was the evidence they used good – the only two weaker retrospective studies were the two on orthotics (all the other studies included were the more stringer prospective design.

Confounding by indication

http://www.ncbi.nlm.nih.gov/pubmed/11941379

4. Running shoes

Additionally, they reported this second conclusion in the abstract:

How would you interpret that? Again, this is sloppy and misleading writing, as this is what they actually reported they found:

Two high-quality studies [9,17] analyzed the relationship between shoe use and running injuries. There was limited evidence that changing shoes more frequently was a risk factor for overall injuries [9] and limited evidence for using one pair of running shoes or alternating between two pairs versus alternating between more than two pairs of shoes as a risk factor for knee injuries [9]. Furthermore, limited evidence was found for a higher number of shoes as a risk factor for shin injuries [17].

Can you see anything there about “wearing running shoes for 4 to 6 months were associated with a greater risk of injury“? Misleading. And, yet another potential study missing from their review: Why did they not include the Malisoux et al (2013) study in the review?

They conclude the paper by claiming that based on what they allegedly found that “The use of orthotics/inserts should be discouraged“. There may or may not be reasons for discouraging that, but their data does not come remotely close to supporting that. Again, sloppy and misleading reporting of research. The overwhelming preponderance of evidence shows the exact opposite!

I have only dug into two of the conclusions made by the authors and found them wanting, not reflective of what they actually found and not put into the context of what other studies have found. I do not know (nor care) about the veracity of their other findings based on what I have written above.

As always, I go where the evidence takes me until convinced otherwise, and no, the data does not support the conclusion made by the authors that wearing foot orthotics are a risk factor for running injury.

van der Worp MP, Ten Haaf DS, van Cingel R, de Wijer A, Nijhuis-van der Sanden MW, & Staal JB (2015). Injuries in runners; a systematic review on risk factors and sex differences. PloS one, 10 (2) PMID: 25706955