By Paul Freary
In recent years we’ve seen the amount of cushioning or stack height of running shoes increase more and more. It began increasing at such a rate that World Athletics, the sport’s global governing body introduced a limit on the amount of cushioning in a shoe, or at least in competition shoes for elites.
HOKA Rocket X2
‘Maximal’ or ‘Max-Cushioned’ Running Shoes
Such has been the shift to highly cushioned shoes that they’ve even coined their own category with ‘maximal’ shoes or ‘max-cushioned’ models becoming a specific type of shoe in their own right.
The barefoot or minimalist era of footwear was relatively short-lived but maximal cushioned models look like they are here to stay.
Most brands now have specific max cushioned models or have increased the amount of cushioning in existing shoes in a shift towards the maximal trend. After the World Athletics 40mm limit was introduced, this figure seems to have become somewhat of a benchmark with brands for their most cushioned models.
While many brands ‘max-out’ their shoes now around 40mm in height, a few go beyond this figure in an attempt to maximise the attention seen by such models.
High Stack Running Shoes
Adidas
Adidas launched the Prime X model with a stack of 50mm and saw great attention in what was deemed to be a ‘banned’ shoe. This model was an ultra-high stack version of their road racing model, intended for use by elite athletes to allow them to make the most of the benefits brought about by the additional cushioning in their daily training.
Brooks
Brooks recently introduced the Ghost MAX, an increased stack height version of their most popular model, the Ghost. The MAX model upped the stack height by an extra 5mm over the best-selling Ghost model.
On
On running released the Cloudeclipse, an everyday training shoe that was the brand’s most cushioned to date, stretching the tape measure to 37mm of Cloudtec cushioning in the rearfoot.
HOKA
HOKA, already the brand that would claim starting the maximal cushioning trend released their latest racing model, the Cielo X 1 with a 39mm stack, much higher than their previous road racing model, the Rocket X 2 that featured a 36mm stack of foam.
What are the Stack Height Limit Rules?
It’s also prudent to point out that while many brands quote the stack height of these new models at 39 or 40mm to satisfy the World Athletics rules for the technical specification of competition shoes to be a maximum of 40mm, brands are seemingly bending or stretching the rules to hit regulation height.
The measurement point of cushioning in a shoe is taken at 12% of the overall length of the shoe (USA size 8) from the rear. Working within this rule, Mizuno has their racing model, the Rebellion Pro 2 with a drastically cut-away heel. While the midsole measures well in excess of 40mm at the deepest point, at the point of measurement for World Athletics rules it comes in within the 40mm limit!
The Science
Some studies show that the benefit from an increase in cushioning is better for recovery. Recovering from your hard training session quickly allows you to go again the next day. Many runners found themselves wanting to wear the Nike Vaporfly Next% shoes for every run such was the manner in which they felt their legs felt ‘less beat-up’.
Of course, not all science and studies agree. Some suggest that there’s no direct link to higher cushioned shoes reducing the level of impact.
A study in the Orthopaedic Journal of Sports Medicine recently caught the attention of max-shoe wearers as it showed runners exhibited increased impact forces and loading rates, just two variables that have been associated with a higher risk of running-related injuries in max-cushioned shoes compared to their more ‘regular’ counterparts.
Injury Risk
With a deeper stack of cushioning under the foot, the proprioception of protection is naturally increased and can lead to some, particularly inexperienced runners over-striding and heel striking. This is naturally going to increase loads throughout the feet, ankles, knees, hips and lower back.
The perceived protection afforded by additional cushioning can also give inexperienced runners a false sense of security and lead to overuse injuries. This is before the potential risks associated with instability that can go hand in hand with a higher-stacked shoe.
Running Shoe Responsiveness
A term now more commonly used when describing shoes is responsiveness. With the introduction of softer and springier foams, we often read about how responsive a shoe feels. Of course, like many metrics that can be so personal the responsiveness is more of a personal measure rather than something that can be specifically measured.
But is a Softer Foam Better?
There will be a ‘happy medium’ in terms of the softness or firmness of a shoe’s midsole and factors such as running speed and runner weight will affect this. This is perhaps why some ‘running influencers’ don’t find the latest elite-level racing shoes as comfortable as their daily trainers. They have perhaps become a little desensitised to the firmer and more responsive nature of a competition-level shoe because they are used to soft, cushioned shoes for their much slower-paced running than that of the elite athletes such shoes have been designed for.
Generally speaking, a slightly firmer foam is going to be a little more responsive as the feet and legs need something to react with. With a soft shoe, the foam compresses and means the legs and muscles need to work a little harder as they search for something to respond to. It’s a tricky concept but imagine running on the beach. Your feet sink a little into the soft sand and it’s harder to run. It’s a soft, comfortable experience but a little harder than running on the firmer sand. Again, it’s about finding the sweet spot.
Speaking of a sweet spot, we have recently seen brands introduce carbon plates into training shoes. One of my favourite shoes of 2023 was the Saucony Kinvara Pro. This high-stack model offers soft foam cushioning combined with a carbon plate in a shoe able to cope with more regular use. The plate helps stabilise the shoe and get the most out of the foam.
Are Max-Cushioned Runing Shoes OK for Me?
Above all, when changing running shoes one should gradually adapt to a new model. Be that a lighter-weight racing shoe or a more cushioned model it’s always best to slowly introduce a new model into your weekly running routine.
Some models as mentioned above help make this transition a little easier, so perhaps moving from a Brooks Ghost 15 to a Brooks Ghost Max would be a more straightforward progression. But again, introduce the Max over several weeks and build the miles gradually.
Writing this, I realise how fortunate I am to have a rather large collection of models at my disposal to try and looking back at the last week I’ve probably worn a different shoe every day. A few of these have been max-style, with the New Balance SC Trainer used on my long Sunday run, the HOKA Cielo x1 taking on a mid-week 10 miles and the Brooks Ghost Max seeing a few other shorter outings. Throw in the new ASICS Metaspeed Paris for a 5k and I really did mix things up!
When wearing new, high-stack models I always consider stability as much as cushioning as I’ve previously worn support-type shoes in the past. Fortunately, many of the new high-tech foams are more stable and with the added stability of plates it’s not as much of an issue for someone such as myself, a ‘mild’ over-pronator, but do take care in this respect.
Like carbon-plated racing shoes, don’t consider max-cushioned models to give you ‘free miles’, you still need to put the work in. Your muscles and cardio system still need to experience the time on your feet and miles covered, but perhaps they can make those miles just a little more comfortable and enjoyable.
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