I have previously had a dig at the nature of the titles of a number of scientific papers, for example, this paper I previously reviewed was titled: “Forefoot strikers exhibit lower running-induced knee loading than rearfoot strikers“; when it could have just as easy been titled “Forefoot strikers exhibit higher Achilles tendon loading than rearfoot strikers“ as that is also what they found. In that context, the title of this new paper had me wondering:
Barefoot Running and Hip Kinematics: Good News for the Knee?
McCarthy, Colm; Fleming, Neil; Donne, Bernard; More
Medicine & Science in Sports & Exercise. September 8, 2014
Purpose: Patellofemoral Pain and Iliotibial Band Syndromes are common running injuries. Excessive hip adduction (HADD), hip internal rotation (HIR) and contralateral pelvic drop (CLPD) during running have been suggested as causes of injury in female runners. This study compared these kinematic variables during barefoot and shod running.
Methods: 3-D gait analyses of 23 habitually shod, uninjured female recreational athletes running at 3.33m.s-1 while shod and barefoot were studied. Spatiotemporal and kinematic data at initial contact (IC), 10% of stance (corresponding to the vertical impact peak) and peak angles were collected from each participant for HADD, HIR and CLPD; and differences compared across footwear conditions.
Results: Step rates when running barefoot were 178+/-13 steps.min-1 vs. 172+/-11 steps.min-1 when shod (P <0.001). Foot-strike patterns changed from a group mean heel-toe latency indicating a rear-foot strike (20.8ms) when shod, to one indicating a forefoot strike (- 1.1ms) when barefoot (P <0.001). HADD was lower at IC and at 10% of stance when running barefoot (2.3+/-3.6 vs. 3.9+/-4.0[degrees], P Conclusions: Barefoot running resulted in lower HADD, HIR and CLPD when compared to being shod at both IC and 10% of stance; where the body’s kinetic energy is absorbed by the lower limb. As excessive HADD, HIR and CLPD have been associated with knee injuries in female runners; barefoot running could have potential for injury prevention or treatment in this cohort.
This study did show changes in parameters at the hip that are correlated with knee injuries, so there are some good findings in this study.
The methods and analysis seem fine, but there are a couple of issues
- it was on a treadmill, so may or may not equate with overground running.
- this was an acute intervention, so the results may or may not be the same if they were habituated to the barefoot condition
- the participants were asymptomatic, so the results may or may not be the same in those with patellofemoral pain or iliotibial band syndrome
- they did not investigate, let alone report where loads went up to allow those changes to happen
Probably the biggest issue I do have is that last point above (and hence the title of the post and the introductory comments above) is that they did not investigate the costs to achieve those changes. You can not decrease the load in one set of tissues without increasing it in another. To get the changes that the authors found, there has to be changes elsewhere to achieve it. Most likely there would have been an increase in ankle loads (hence the title of the post) as was reported in yesterdays post and many other previous studies (eg) that actually reported on the entire kinetic chain. This lack of looking at what else changed is a shortcoming of the study and does somewhat negate the conclusion: “barefoot running could have potential for injury prevention or treatment in this cohort“. Yes, it does have the potential to help those with knee issues, but as the load would have had to increase somewhere else, its going to potentially increase the risk for injury in those tissues, so the blanket recommendation that it will have the potential to prevent injury is not supported by the data. Like a lot of studies I reported on recently, this was a lab based study on healthy people and not a clinical trial on those with an injury.
Which leads on to another issue that the authors did raise in their discussion: was it really the barefoot running that lead to the changes or the was it the change in foot strike pattern that they found (which you can do without going barefoot) or the increase in cadence which that they found (which you can do without going barefoot)? Without controlling for those factors, we do not know which one it was that was responsible for the kinematic changes that they reported. Having said that, barefoot or minimalist drills are a helpful tool to help teach different foot strike patterns and cadence manipulation when clinically indicated.
Back to where I started, the title: Even though there was a question mark at the end of the title, it is misleading as it ignores what the study did not investigate; ie the cost in other tissues to achieve those changes.
As always, I go where the evidence takes me until convinced otherwise…and there is always a cost to achieve a change. That cost in a particular individual may or may not be worth it.
McCarthy C, Fleming N, Donne B, & Blanksby B (2014). Barefoot Running and Hip Kinematics: Good News for the Knee? Medicine and science in sports and exercise PMID: 25207927