These images are with the kind permission and full consent of my male patient for this case study.

Apart from the feeling of generalised stress in his lower limbs while running. My 25-year old patient had no particular over-use injury. He wanted an assessment to gain knowledge and information to improve his running ability and efficiency as he transitions from rugby to triathlon. With some modifications to training habits this would normally be a steady but achievable transition if executed carefully, including the appropriate footwear choice.

The opening image 1, shows my patient running in the Vaporfly Next% 2 that has completely collapsed at midstance. This is because the narrow longitudinal profile of the midsole (EVA shore value <30) is too unstable to support his body weight. While the client’s heel bone will be everted during pronation, the shoe has collapsed to such an extent that its heel support collapses into even great eversion rendering the shoe completely ineffective. This tells us that the motion of the shoe’s heel counter (heel support) and midsole has little resistance to the direction of force and buckles beyond effective support under pressure. Note: I see this collapse behaviour in some lighter runners too that use the Vaporfly.

Looking behind the knee of the supporting leg we can see that the insertion of one of the hamstrings medially (inside) is particularly tensioned while the lateral (outer) hamstring tendon of Biceps femoris has no tension at all, as the hip extends the leg during contact. This is because the shoe is so collapsed around the foot that the whole legs is internally rotated creating asymmetry in hamstring function. The motion of the shoe will also increase ground contact time and unwanted forces up through the legs to the pelvis. This is far from ideal in an athlete looking to improve performance. Image 2, is my client standing on the pressure plate demonstrating increase upward pressure under the left heel on the longer left leg side (structural asymmetry). It also shows the clients good foot posture, highlighting the point that the Vaporfly has completely collapsed even under a good foot.

1. The first video is of my patient running in the Vaporfly Next% 2. This is a shocking video and is every sports injury specialist’s worst nightmare. This is an overuse injury waiting to happen.

2. The second video is the patient’s second and more recent shoe purchase (New Balance FuelCell v3) which is a neural cushioned shoe and still not ideal. It is however a vast improvement on the Vaporfly but I’m still not happy with the shoe performance for this patient.

3. The third video is my own Brooks Adrenaline GTS which is two-years old but we were the same shoe size and I advised the patient to run in my shoes as a trial. Look at the complete contrast to the Vaporfly and New Balance. The Brooks kept the heel vertical maintaining foot posture in its correct orientation, and creating a marked improvement in running style and efficiency, thus reducing tissue stress and risk of over-use injury. The Brooks is often my go-to shoe for my patients. Qualitatively, the

2 first shoe caused my patients good foot posture to take on an abnormal position due to shoe midsole collapse, and the Brooks shoe (my personal running shoe) worked well holding both the foot and heel counter in a favourable vertical posture under load.

So why can elite athletes wear this genre of Nike runner shoe while many others can’t, including me as an ex-international athlete? On October 12 th 2019 Kenya’s Eliud Kipchoge ran 1.59.4 to become the first personal to run a sub-2-hour marathon, and the very next day his team mate Bridget Kosgei smashed the women’s World marathon record running 2.14.04, both wearing Nike Vaporfly Next%. There is no doubt that these shoes are present when records are broken, but was it the shoes; great coaching; the elite gene pool that these runners are born from; nutrition and sports science or something else, including the power of perception born from great marketing? It is fact that two opposing truths can be present at once i.e. that these shoes can enhance performance in some elites, while creating reduced performance and increased injury risk in some non-elites. Is it the individual or the shoes? Eliud Kipchoge was wearing the Nike Air Zoom Alphafly Next% 2 to break his own World record to run 2.01.09 in the Berlin marathon on Sunday 25 th Sept.

What I also don’t understand is the almost universal praise that the Vaporfly et al gets from the running influencers. In fact, many of them are calling for some kind of ‘mechanical doping’ laws to be introduced because they claim that they universally and unfairly enhance athletic performance. This certainly isn’t my experience, but put this over exuberance down to lack of true expertise and the ‘Dunning-Kruger effect’.
There are such vast differences in running demographics yet a comparatively narrow band of purchasing choice, made even narrower in our minds by the vast marketing budgets of the large running shoe giants. I observe that the most popular shoes tend to be the ones most influenced by marketing, and in elites the brands that pay the most in sponsorship. As we all know money talks in sport.

Elite performance shoe are designed with elite athletes in mind, by highly motivated shoe experts in the research labs of the larger brands. If I was a shoe technologist I’d want to make elite running shoes to break world records too, in the knowledge that they would then be sold to the populous who don’t stand a chance in hell of achieving the same times. This raises the question: is it ethical to sell elite running shoes to none elite athletes if there is a greater risk of injury? You wouldn’t find an F1 racing car available for sale in a domestic car show room, nor encourage the public to jump from Tom Daley’s highest driving board. Why? Because they will get injured.

Elite athletes have a combination of physiological, musculoskeletal, and behavioural features that are so rare in combination that they are completely unique and therefore only present in a tiny cohort of individuals. Parents often bring in their child to me claiming that they will be the next great footballer or athlete, but I can tell just by looking at them that they simply don’t have this rare collections of special features. When I do come across these

World beating feature in young athletes there is something different about them. A posture, presence and mental attitude that is different – special.
I actually don’t think that shoes make a huge difference to performance. I believe that one good running shoe and brand is as good as another good running shoe and brand. They use similar design software and many of them use similar production facilities in Asia.

Hype from marketing is a powerful elixir to performance.

We have had mind blowing athletic performances for decades that have steadily improved with advances in sports science, biomechanics, coaching and sports shoe technology etc, arguably available to all. In my opinion based on my own personal experience , the shoe form a tiny part in this equation. What makes the difference between elites and the rest is those rare special features I mention previously. In particular a specific foot type that predisposes the individual to a natural inherent forefoot strike, that has the mechanics and axes of motion to hold form (stability) under great load, and therefore has a limited ground contact – what we call the time:pressure integral. This limits drag and friction on the ground and when coupled with specific musculoskeletal features in the ankle and legs that convert the stored potential energy into fully utilised kinetic energy during what has been described as the ‘Spring Mass theory’, the athlete is launched into the air. This highly efficient and specialised utilisation of gravity meets Newton’s 3 rd Law at the very highest level of efficiency is what makes an elite athlete faster, especially when it is repeated over 26.2 miles without interference from excessive tissue stress. In my opinion, not a structured piece of moulded rubber and plastic we call running shoes. Ethiopian running Abebe Bikila proved this when winning the 1960 Olympic marathon bare footed.

In conclusion, I would just remind runners that shoes that might help an elite athlete to break World records may not have the same effect on you; that a higher price tag doesn’t necessarily mean increased performance; and that although shoe design software and innovative manufacturing techniques have all improved exponentially – it doesn’t mean that running shoes today are any better than they were in previous decades.

This case study was based on my clinical experience over 35-years and 25 thousand active patients, and as a runner for the last 50-years. Nor is this meant to be a dig at any particular brand. I was sponsored by Nike as an athlete, and have worked for Nike as an expert, for which I will be eternally grateful.