One of the criticisms of some studies comparing the mechanics of minimalist vs traditionally shod footwear is that the intervention is acute and the effects were not measured after a period of appropriate acclimation to the different conditions. The results may or may not be the same after that acclimation or transition – we simply do not know if they would have been the same or not. Of course, those who don’t like the results of the study will point that out, but will ignore it if they like the results of the study. In reality, we have no idea if the results are going to be the same or not. For example, some of my previous reviews on acute interventions: Vertical Ground Reaction Forces Produced in Shod Running vs. Barefoot Running; Tibial strain and barefoot running; Continuing to heel strike after transition to minimalist running shoes; Increased Lower Limb Loading with use of Minimalist Running Shoes; and Running with a minimalist shoe increases plantar pressures. In that context, this study was recently published which measured the mechanical parameters before and after a transition to minimalist running:
Effects of a seven-week minimalist footwear transition programme on footstrike modality, pressure variables and loading rates
Isabel Sarah Moore, William Pitt, Michael Nunns & Sharon Dixon
Footwear Science; 20 Nov 2014
Purpose: The aim was to compare footstrike modality and kinetics pre and post a seven week minimalist footwear transition programme.
Methods: Ten recreational athletes (mass: 78.6 (8.7) kg, height: 179.4 (7.6) cm, age: 21.0 (0.7) years) performed overground running trials (3.8 m·s−1) whilst barefoot (BFT), minimal shod (MS) and shod (SH) both pre and post the programme. Ground reaction force and pressure data were simultaneously recorded for all footwear conditions. Footstrike modality was determined via visual inspection of the pressure distribution. Peak impact force, loading rate and peak regional pressures and impulses were compared pre and post, and between footwear conditions. The transition programme comprised of a two-week foot strengthening period followed by a five-week running transition.
Results: Post transition there was a general trend for runners to adopt a more anterior footstrike in all three conditions. Additionally, loading rates and several peak pressures and impulses were found to decrease after the transition programme, with region specific changes evident for the effect of footwear. Furthermore, loading rates were higher whilst BFT and MS (instantaneous loading rates pre transition of 446.0 and 379.3 BW·s−1, respectively) compared to SH (105.8 BW·s−1).
Conclusion: Whilst a seven-week MS transition programme was shown to decrease several kinetic variables, it was evident that both BFT and MS led to greater loading rates and peak pressures than SH running.
This study basically took 10 runners with a >1 year history of running in traditional running shoes; measured a range of mechanical parameters in them and then did the measures again after a 7 weeks transition to minimalist running shoes. The transition program followed the advice given by Vibram FiveFingers. The test conditions were the Asics Gel 1500, Vibram FiveFingers and barefoot.
Nothing in the methods and the data analysis jumps out at me as being a problem. Some (especially those who don’t like the results of the study) might have a problem with the sample of size of 10. I don’t have a problem with it. Incidentally, I never cease to be amazed at the rejection of studies by fan boys because of what they perceive as too small a sample size! I rarely would reject a study based on that and generally those that do are just displaying and ignorance of sample size calculations, power calculations, p values and effect sizes. I look at that before conisdering a study has such a small sample size that it is an issue.
What did they find:
- after the transition to minimalist footwear, the runners had lower loading rates, peak pressures
- when comparing footwear conditions, the loading rates and peak pressures were lowest in the shod condition. Impact loads and peak pressures were higher in the barefoot and minimalist condition.
- following the transition a trend towards a more anterior footstrike, however:
Interestingly though, only during the BFT condition did some individuals adopt a more posterior footstrike post transition compared to pre transition.
Another interesting observation by the authors was:
However, it was also apparent that seven runners exhibited two different footstrike modalities during the ﬁve trials post intervention when SH, compared to only one runner pre intervention. This suggests that transitioning back to SH running after MS running produces a more variable running gait in the previous habitual running condition, conceivably due to reacting to reduced somatosensory feedback and greater external cushioning when SH compared to MS.
The results were similar to an acute intervention that did not involve a transition or acclimation period: Tibial Accelerations in Heel and Forefoot Strikers
As always, I go where the evidence takes me until convinced otherwise, and this study shows that a transition to minimalist footwear does not reduce load rates when running in minimalist shoes compared to traditional running shoes.
Moore, I., Pitt, W., Nunns, M., & Dixon, S. (2014). Effects of a seven-week minimalist footwear transition programme on footstrike modality, pressure variables and loading rates Footwear Science, 1-13 DOI: 10.1080/19424280.2014.971352