The Fuss about Zero Drop

Author: Altra Red team Robert Henning (Pacer Coaching)

A few weeks ago I opened my brand new pair of Altra Escalante’s with the same excitement my son had when he first discovered that bunnies laid chocolate eggs in the garden at Easter. Slipping those shoes on felt like coming home; just the right amount of comfort and cushioning for my oddly-dimensioned feet. I often get asked what the hype around these shoes are all about, and then I progress to a soliloquy about the natural movement of the feet during running, and how we are not meant to be running in high heels etcetera. But donning my first pair of Altra’s, a ‘Zero-Drop’ shoe, was the culmination of a 6-month progression.

First, the transition from normal workday shoes to a pair of severely minimalist Vivobarefoot shoes, as well as walking around barefoot as much as possible to doing short runs on grass barefoot. After about 6 months I plunged into my first pair of Altra Paradigm’s, running 25km in my first run, and never looking back. Now wearing my old pair of Nike’s feels like I’m undergoing the old practice of foot binding.

What sparked this transition needs a bit of background. About 3 years ago, in the winter of 2017, I was training for a series of races here in the Cape called the Cape Winter Trail Series. Most trail runners this side will be familiar with it; it is a series of four races scattered on various locations throughout the Western Cape, with short and long distances of 6-8 and 12-16km respectively of which I had entered the long. I had only been taking running seriously for about a year then and decided to give all four races a go. If you entered all four you got logged on an overall leaderboard. Along with this, I decided to enter my first Ultra - the Bastille Day 50km Trail Run. A gruelling trail run on the mountains of Franschoek on one of the coldest winter periods in the cape. Snow on the mountain tops is usually the order of the day.

Any runner with two brain cells would say that training for both short and ultra distances, especially as a beginner, is possibly a recipe for disaster. I was trying to do 2-3 speed and interval sessions a week, combined with hill training and a long run. Needless to say, after my second summer trail series race I was hit with the dreaded ‘I’ word - Injury; A bad case of Proximal Hamstring Tendinopathy, or basically high hamstring pain. It was so bad that I was limping for three days, and couldn’t run for almost three months.

Luckily for me, I can’t simply do nothing, and I began researching like crazy on the root causes of this syndrome. Above from the straightforward answer of doing too much speed and hill work, one thing that kept creeping up was running style and the effects of that on hamstring stress. What I uncovered was that there is a difference between rearfoot and forefoot or midfoot running. In layman’s terms, running with your heel hitting the ground first compared to the front of the foot or the middle hitting the ground first. And - dare I say it - I was a rearfoot striker. But what was this difference, and was there a link between my injury and something as simple as foot strike? For this, I took a dig into the literature.

The Science
I discovered that running by striking your heel first (rearfoot - RF for short) showed a larger shock impact on your lower body than forefoot (FF) or midfoot (MF) striking. [1] A lightbulb switched on; could this influence for high hamstring injury risk? Surely it should? A 2014 study showed exactly this. [2]

The researchers took 70 runners, 35 who had hamstring injuries, and 35 who were considered ‘healthy’. The results from this study showed that 75% of runners with hamstring injuries generally showed a greater overstride, that is, the placement of the foot in front of the vertical line from the hip, and a subsequent more RF strike pattern compared to 43% of healthy runners. Also, a further 35% of healthy runners showed a FF striking pattern compared to only 6% of the RF runners. Another study showed something very similar in those runners whose RF strike showed almost twice the stress injury risk than their FF striking counterparts. [3]

The reason for this is two-part. Firstly, the hamstrings are under a lot of stress during running, particularly during the late swing phase, i.e. the point just before the foot hits the ground. [4]. Therefore, with a larger extension of the hamstring as shown during forefoot running, the stress on the hamstring is more. Secondly, the impact load on the lower body is higher in RF striking than FF. a The same study above showed that when running RF, a rapid, high-impact peak in the ground reaction force (GRF) is shown during the first phase of the running stance, compared to barely any GRF in FF runners. [3] This difference in GRF can clearly be seen in Figure 1 and 2 below.

FIGURE 1: Top, GRF and kinematics (traced from a high-speed video) for the same runner at 3.5 mIsj1 wearing standard running shoes during a RFS (A) and a FFS (B). Circles on the force trace indicate the instant of the kinematic trace.[3]

FIGURE 2. Runners receiving visual biofeedback during gait retraining. They were asked to reduce the vertical impact peak by softening their footfalls.
 
Research also shows that RF runners are 2.6 times more likely to have mild injuries, and 2.4 times more likely to have moderate injuries than FF strikers. They are also at a higher risk of lower limb stress fractures, plantar fasciitis, and other injuries such as hip pain, knee pain, lower back pain, medial tibial stress syndrome (‘shin splints’), and patellofemoral pain. [3] This could be directly linked to the sheer force of RF running on the body, as well as the possible overstriding often seen in RF running. What this tells us is that landing on your fore-or mid-foot while running can reduce running-related injuries, and has some scientific evidence to back this up.
There are studies showing which types of shoes almost forces one to run on their forefoot, and these shoes can be classified as minimalist. In a study involving four conditioned runners, all who are trained, minimalist-forefoot runners, each runner was assigned either minimalist or traditionalist shoes, trained for weeks in them, and then ran 50km outdoors in those shoes. The runners then swapped to the opposite shoe type, trained in those shoes for another 4 weeks, and repeated the same 50km. The researchers found that the majority of runners started running more RF using traditional shoes than when in the minimalist shoes. [7] Basically, if you are conditioned to running more FF, then changing to a traditional shoe with a high heel to toe ratio and lots of cushioning will almost force you to start running striking your heel first.

While this is interesting, I am not for one second suggesting we should go out and buy a pair of minimalist shoes. What I am saying that there seems to be some link between FF running, minimalist, zero-drop shoes, and reduced injury risk. If you have been struggling with injuries and would like to try something which could possibly benefit you, then this may be something to give a bash. However, I should emphasize that the research shows that the benefits are shown in MINIMALIST shoes with zero drop, and that maximally cushioned running shoes actually amplify impact loading. [8]

FIGURE 3: Examples of various shoe paradigms. Clockwise from top left: traditional (Brooks Epinephrine 18), minimalist (New Balance Minimus Trail 10), zero-drop (Altra Torin 2.5) and maximalist (Hoka Bondi 6).[5]

Should you transition?

In short? Maybe. If, like me, you struggled with a few injuries that you can directly pinpoint to your running style and stride, then yes. If you have been struggling with recurring injuries year after year, then maybe. If you have absolutely no injuries besides from a few basic niggles caused by maybe a twisted ankle or a bad fall, then probably not. If you have no injuries but would like to get faster, then maybe. In my honest and professional experience, I have seen runners transition from RF to FF who have become better runners, and all of my athletes whom I coach that are FF runners are faster, more efficient, and do better in longer races.

But let’s say for argument’s sake that you would like to transition. How do you go about it? There is no one size fits all approach, but there are methods that can help you which I will try outline below:

1. Buy yourself a pair of zero drop every day shoes. Altra has a few shoes that you can pull off at the office (Escalante, Cayd, or Wahweep), plus the whole Vivobarefoot range is great, and they have options for every occasion (link to purchase below).

2. Wear these shoes every day for at least a month.

3. In the meantime, begin a strengthening program outlined in Figure 4 below, a minimum of three days per week.

4. Buy yourself a pair of zero drop or minimalist running shoes.

5. Start running in your shoes. Partially, at first, at least 10% for the first week with the remainder of your runs in your usual shoes. Slowly increase this incrementally over a 12-week period. After this, you can almost safely run all your runs in your new shoes. (See figure 5 below) If, however, you begin to feel slight niggles, particularly in your calf and achilles region, then back of to around 75% of your runs being in your new shoes and gauge it from there. If the problem persists, back off to 50%, and so on. (for detailed information, see reference 6)

FIGURE 4 Simple injury prevention exercises suggested for a minimal footwear transition. Note that these exercises require systematic evidence for their role in reducing injury risk. Exercises should be included several times a week, and the dynamic exercises should only be included after a minimum of 2 weeks due to the increased load and plyometric nature of these exercises. Sets/reps should be decided upon by a trained professional in line with the FITT-VP principles (frequency, intensity, time, type, volume, progression). [6]

FIGURE 5: A simple example of how one might structure the initial stages of a MFW transition. Note that it is not intended that a MFW transition takes. [6]

There You Have It

You are now officially transitioned! Please keep in mind that running more FF will not counteract poor training load and poor running biomechanics. This should form part of a well-designed training program, and should ideally take place during your off season where no important races are coming up.

With that, I hope you have a great 2020.

Happy Running!

Coach Robert

References

[1] Gruber A et al. Impact shock frequency components and attenuation in rearfoot and forefoot running. Journal of Sport ad health Science 3 (2014). 113-121

[2] Sugimoto D et al. Running Propensities of Athletes with Hamstring Injuries. Sports (2019). 7. 210. doi:10.3390/sports7090210

[3] Daoud A et al. Foot Strike and Injury Rates in Endurance Runners: A Retrospective Study. Medicine and Science in Sports and Exercise (2011). doi: 10.1249/MSS.0b013e3182465115

[4] Heiderscheit, B.C et al. Identifying the time of occurrence of a hamstring strain injury during treadmill running: a case study. Clin. Biomech. (2005), 20, 1072–1078.

[5]Napier C & Willy RW. Logical fallacies in the running shoe debate: let the evidence guide prescription. British Journal of Sport Medicine (208) 0

[6] Warne J & GruberA. Transitioning to Minimal Footwear: a Systematic Review of Methods and Future Clinical Recommendations. Sports Medicine - Open. (2017) (3) 1

[7] Kasmer M, Ketchum N, & Lio X. The effect of shoe type on gait in forefoot strike runners during a 50-km run. Journal of Sport and Health Science. (2014) (3)2. 122-130

[8] Kulmala JP et al. Running in highly cushioned shoes increases leg stiffness and amplifies impact loading. Scientific Reports. Nature. (2018) 8. doi:10.1038/s41598-018-35980-6

Useful Links:

Bastille Day Trail Run: http://bastilledaytrailrun.co.za/

Cape Trail Series: https://www.trailseries.co.za/

Buy Altra Shoes: https://thesavage.biz/collections/

Buy Vivobarefoot Shoes: https://www.nativesport.co.za/