This is an interesting one…
A number of previous studies have looked at the mechanical and economy parameters with minimal running shoes compared to traditional running shoes. Some of these studies were cross-sectional and some were prospective and followed a period of adaptation or transition. One of the concerns expressed about some of these studies, especially from those who did not like the results, are about the adequacy of the instruction or education in proper running form that apparently should accompany the transition to the minimal running shoes. For example, a sizeable % of runners still heel strike after transitioning to minimalist running shoes or barefoot running. I have no idea what is meant by proper changes in the running form or technique as we do not know what the proper running technique is and no study has yet demonstrated that there is actually anything wrong with heel striking. There are certainly many clichés such as ‘its not about the shoes, it about the form‘ doing the rounds, but they tend to be used to justify the results of research that someone does not like rather than contribution anything useful to the discourse.
Given that, I came across this recently available PhD thesis from the Dublin City University:
Transitioning to minimal running footwear; implications for performance and running related injury when compared to conventional running shoes.
Warne, Joe P.
PhD thesis, Dublin City University. 2014
AIM: To investigate any changes in running economy or factors related to injury before and after a minimalist footwear (MFW) transition with gait-retraining when compared with conventional running shoes (CRS).
INTRODUCTION: Recent interest in barefoot running has resulted in the development of a new footwear type which incorporates minimal cushioning and structural properties, in contrast with CRS. These MFW have been suggested to influence running kinetics and kinematics and may have a positive impact on performance and injury risk. However there is currently a dearth of scientific evidence available to support this theory. Of the limited research available the vast majority has only used acute comparisons between CRS and MFW, and has not considered the effect of “transitioning” into MFW over a period of time, with or without “barefoot” gait-retraining.
METHODS: In all studies, effects for time (pre to post intervention), and condition (MFW vs. CRS) were evaluated, where participants were required to familiarise with MFW during the intervention. Study one examined changes in running economy (RE) with no feedback or gait-retraining, in contrast study two examined RE with deliberate gait-retraining included to the MFW transition. Study three investigated changes to plantar pressures and forces. Finally, study four evaluated kinetics and kinematics associated with injury.
RESULTS: Following a MFW intervention, RE was found to improve 8.09% in MFW but not in CRS. However, when gait-retraining was included, no significant change in RE was observed over time. RE was significantly better in MFW compared to CRS irrespective of time (approx. 2.9% better in MFW). A MFW transition with gait-retraining was found to reduce plantar forces by 17.6%, loading rate by 33%, and the impact peak by 9%, which was not observed to the same degree in CRS. However, significantly higher plantar pressures and loading rates were observed in MFW when directly compared to CRS throughout testing.
CONCLUSION: A MFW transition was found to significantly improve RE when gait-retraining was not included. However, gait-retraining may have a negative influence on RE. MFW and gait-retraining reduced impact variables over time. In addition, there was a reduction in plantar pressures under the heel, and no significant increase in pressures in the forefoot as a result of the intervention. With respect to condition, RE was better in MFW, but higher plantar pressures and loading rates were noted in MFW vs. CRS that may increase injury risk during this transition period.
The thesis consisted a several studies and I won’t comment on them all in this post.
One of the studies aimed to determine changes in RE as a result of a familiarisation period in MFW with no feedback on the running gait. This will be compared to the same participants wearing CRS and found:
Fifteen male trained runners (age: 24 ± 4yrs; stature: 177.2 ± 6.21cm; mass: 67.9 ± 7. kg and O2max 70.2 ± 5.2 ml. kg.min-1 ·) were recruited. Participants completed two RE tests; hours apart, in a random order, in both the SBR and shod condition (pre-test) at 11 and 13km h. Oxygen uptake ( O2), heart-rate, stride frequency, and foot strike patterns were measured in both conditions. Participants then completed a 4-week familiarisation period of SBR, before repeating the 2 RE tests (post-test). At pre-test, there was no significant difference in RE between SBR and shod running (p=0.463), but following the 4 week familiarisation period RE was significantly better by 6.9% in the SBR condition compared to shod (46.4 ± 0.9 v 43.2 ± 1.2 ml.kg.min-1; p=0.011). A significant improvement in RE was observed in the SBR condition (8.09%) between the pre-test and post-test (47.0 ± 1.2 v 43.2 ± 1.2 ml. kg.min-1 ; p=0.002). RE improved in the SBR condition as a result of familiarisation, and became significantly lower in SBR compared with shod running
No issues there. The results were consistent with the recently published systematic review and meta-analysis that concluded the same thing.
The second study is where it gets interesting. This one aimed to: “Does a familiarisation to MFW and gait-retraining influence RE in trained male athletes when compared to running in CRS?” and found:
Twenty-three trained male runners (Age 3 10 years, stature 177. 9. cm, body mass 7 .8 10. kg, 02max: 56.5±7.0 mL·min-1 ·kg-1 ) were recruited. Participants were assigned to either an intervention group (n=13) who gradually increased exposure to MFW and also implemented gaitretraining over an 8 week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and 8 weeks, in a random order. In contrast the control group (n=10) had no MFW exposure or gait-retraining and were only tested in CRS. The intervention had no effect on RE when using either MFW or CRS (p ≤ 0.00). However, RE was significantly better in MFW (mean difference 2.72%; p=0.002) at both pre and post-tests compared to CRS. Stride frequency increased as a result of the intervention (+3. 6%; p ≤ 0.00), and was also significantly higher in MFW vs. CRS (3.79%; p ≤ 0.00). Whilst a better RE in MFW was observed when compared to CRS, familiarisation to MFW with gait-retraining was not found to influence RE.
This second study incorporated a transition to minimalist shoes and included ‘gait retraining’ to achieve “changes to stride frequency (+10% steps per minute), a mid/forefoot strike pattern, more upright posture and a softer landing were adopted by the participants“. This showed that there was not an improvement in running economy when the runners changed their form or technique to what is widely promoted as components of Pose and Chi type running. This means that the gains in running economy with the use of the minimalist running shoes was ‘undone’ by the use of instruction and practice in Pose/Chi type running. This is consistent with the two other studies that have now shown that Pose and Chi type running are a less economical way to run.
As always, I go where the evidence takes me until convinced otherwise and we have to be slaves to the data and the results of this thesis speak for themselves. Transitioning to minimalist running shoes improves running economy. Transitioning to minimalist running shoes combined with adopting a Pose/Chi type technique does not improve running economy. I look forward to see this thesis and all the studies in it published in full.