Kev – I agree, it is tough. Sample sizes need to be big enough to get meaningful results, and that requires money. Unfortunately a lot of the money for shoe studies likely comes from the industry, which always makes you worry about bias. And don’t even get me started on the media part of the problem! I’ll keep doing what I can to put out good info :)

Thanks for the comments Scott, interesting stuff. I’ll need to dig up that Nigg paper for a future post.

Despite small sample size in the Nat’l ACSM study, the question regarding soft midsoles vs. stiffer ones is slowly being answered. See: Jennifer Baltich*, Christian Maurer, Benno M. Nigg. (2015). Increased Vertical Impact Forces and Altered Running Mechanics with Softer Midsole Shoes. PLOS ONE, DOI:10.1371/journal.pone.0125196) – Human Performance Laboratory (HPL), Faculty of Kinesiology, University of Calgary, Calgary, Alberta,
* jbaltich@ucalgary.ca (contact person)

In brief, they had a large sample size and found significantly higher vertical impact forces with softer midsole shoes (I’m guessing Hoka would claim they have the “softest” midsoles; on their website they say: “excellent shock absorption and an inherently stable ride”). Not sure they can say “excellent” shock absorption when highly cushioned shoes transmit greater vertical impact forces and create greater ankle and knee stiffness = recipe for cumulative overloading and possible injury.

Although injury rates were not tracked, it’s prudent to at least speculate injury rate “could” be greater in softer midsole shoes from what the evidence is starting to say.

A final case in point is a case study: 44 yr old male runner; 34 yrs of hard training and competition interspersed with cross training and consistent strength training with legs and upper body; never a knee problem; started wearing Hoka Stinsons 3-4 x week for 4-months; ended up with a completely torn posterior medial meniscus root (only 10% of meniscus injuries are root tears and usually root tears occur in people older than 50 yrs, who are obese and sedentary); surgery revealed normal knees with no degeneration of articular cartilages, ACL, etc; at least 51% of the smoking gun is the use of Hokas over time with increased vertical forces/loading and knee stiffness; and, physics will tell you because of the greater distance from the subtalar joint at ground contact point = increased torque about the ankle and thus knee; lengthening the moment arm = increased torque despite body weight impact force remaining the same; to confirm, Hokas increase your distance from the the ground reaction force = greater torque about the subtalar jt and knee = simple physics). Hokas: good for the road and flat, non-technical trails; otherwise, I’d caution their use.

Stay tuned…Vibram = lawsuit and debunked; Sketchers Shape Ups = found to be false claims and upheld despite Sketchers’ suing Dr. John Porcari, a well known Exercise Physiology researcher from UW-LaCrosse. If it’s too good to be true…it is. As always, no one shoe or gimmick fits all…despite what the company wants you to think…

My opinion on “I suspect less knee flexion in a shoe like a Hoka due to the soft, thick, cushy sole. This could have benefits for the knee.”

I think bigger shoes will (for most cases… according of the kinematic, kinetics and muscle contraction timing that are associate with this type of shoe)
– decrease knee flexion position at the landing (more extended knee)
– increase range of motion of flexion during the contact phase (more excursion)
– decrease pre-contration of muscle around the knee and leg (tension of the muscle-tendon unit to absorb the landing… that bring )
– increase compression force of the PF (according to timing of contraction and associated kinematics)
– increase anterior shirring stress of the tibia and tension of the ITB

– increase (?) compression force of the TiFe (according to the kinematic)

So I will say that I’m absolutely not convince that bigger shoe will help knee problems/pathologies… to the opposite of helping/protecting the foot.

All best
blaise

However, I will say this: Measuring impact force is interesting, but can be deeply misleading. 160 pounds forced on 5 square inches of platform is the same, regardless of the shape of the platform. How that force is distributed around that platform could have absolutely nothing to do with the stack height. The lacing, cushion, density, shape of the upper, heel counter, etc. etc. etc. are all working to make things happen, and an impact study can’t give much insight into that. Now add physiology, form, etc. etc. etc. and you’re back to Pete’s ultimate advice: Feels good? keep going. Start hurting? Try something else.

Did you see this recent controversy over the eating chocolate study? That whole episode made me think about how shoe science is presented in the media as well…and I agree with you that much more caution is needed in interpretation. To be honest I feel that researchers are caught in a trap in that most grant money probably comes from a particular brand who might desire certain outcomes (remember vibram had several of the less than 10 sample size studies touting its wears). The irony is that if the researcher goes it alone they are likely to be limited by small sample size as well.
Science works but it has to be done properly, that is studies must have enough participants to control for age, weight, gender, years running etc. In addition it must have clear enough boundaries in defining various shoe groups participating. This kind of study would likely require thousands of runners and quite a bit of money to undertake. Perhaps someone could design some self-reporting study with a social media app that tracks data and relies on participant reporting, obviously that would not be scientific but at least it could overcome the perpetual sample size issue. Otherwise it seems to me runners today are left with personal anecdote based off lots of choices. That’s why we need those shoe reviews! No runner can possibly even hope to try a tenth of the shoes available.

And Craig–couldn’t agree more with your Pegasus comments, might not have been the best control shoe.

Reply to Fran:

Prior to working on my FORM, I sucked. I always wore some bulky ASICS trainer. I was slow, my right knee usually started hurting after a while, and running 2-3 miles seemed really far. I never entered races and just assumed I was hopeless and that marathons were for special people. Experimentation and research helped me figure out how to become more skilled and avoid injuries.

Indeed there are many injury related claims in the video, but Hoka was smart to make they subtle enough (so that they don’t make Vibram’s mistake).

Thanks for the link.