Boot Stability Versus Foot Mobility

Written on 06/11/2024
John Zombro

Giving advice on footwear selection is a tricky topic. This is particularly true when it comes to backcountry hunters and mountain athletes. Across the footwear industry, from manufacturers to retailers, there are inconsistencies in the recommendations provided to consumers. Unfortunately, much of this is driven by aggressive marketing and the goal of convincing, more than educating, the customer.

It gets worse when one person attempts to guide another based solely (pun intended) on his/her own personal experience. There are two extremes, or camps, fueling this problem…the minimalists and the maximalists. The minimalists will suggest that you need little more than a ballet slipper with some traction to function well in the backcountry. Their position is that the foot needs all the natural freedom to move that it can get, and we never want to inhibit this feature. The maximalists purport that anything less than a heavy mountaineering, rock and ice climbing type boot is insufficient for the performance demands of the backcountry athlete. 

Despite the good intentions of many of these advice-givers, they lack the biomechanical knowledge and comprehensive understanding of anatomy, gait, and human performance to properly advise others. There is a lot of context here. Of course, the footwear needs of an ultralight, trail-based thru-hiker will be less substantial than those of a backcountry sheep hunter, and seasons of the year (heat versus snow, etc.) play into these considerations. But the big (really big) issue is individual differences and this has everything to do with the inherent level of mobility in a person’s foot.

I can explain this fairly succinctly. You need the optimal or ideal amount of mobility and stability in your foot-ground interface, and that’s what appropriate footwear provides. There has to be enough mobility in that entire system to allow the foot and lower extremity joints to move adequately. Again, this is a Goldilocks range. If we restrict too much motion, force has to go somewhere, and it usually travels up the chain, wreaking havoc at knees, hips, IT bands, SI joints, and lower backs. Conversely, a foot-shoe-ground system with too much freedom of movement has the potential to excessively load joints at end range and to overstress connective tissues. 

Intelligent training can do a lot for you. It can condition muscles, tissue integrity, and gait patterns. It can make weaknesses stronger. It can make a stiff person more mobile. All of this is an important aspect of conditioning, but ultimately, a backcountry athlete is gonna take to the field with a given level of mobility in the foot. Genetics are a greater factor in this instance. 

You’ll hear all sorts of terms characterizing this intrinsic mobility issue. Pronation, supination, rearfoot valgus, forefoot varus, plantar-flexed first ray, compress-expansion relationships, absorptive and propulsive capacities…and so on. I’ve spent 40 years working with these principles. Advanced education. Extensive work experience. Thousands of clients. I’m required to have this stuff memorized, but unless you are a biomechanics pro, you may not need to. You can trust me. 

Proper on and off-trail function in the foot-shoe system is always going to be mission-specific, and it definitely exists in an identifiable range…but it must be customized for each individual. Within these situational requirements, a very mobile foot needs to be given additional stability to get it into that middle, most functional (and safe regarding injury risk) range. And a rigid (stiff) foot and ankle requires less stabilizing (stiffening) input from the footwear. It’s that simple.

The aforementioned points depict why one person will do very well with a high, stiff boot while another backcountry user will flourish, in the exact same conditions, using a much lighter and more flexible option. Most of us fall into the broad middle, in which about 68% (+/- 1 standard deviation with regard to foot mobility) of the population can use boots/shoes that are in that same middle range with flex or stiffness ratings. 

That’s a general statement. We can also make some distinctions regarding the footwear’s lateral ankle stability versus forefoot flex, protective qualities and weather resistance of the upper, traction, durability, height, and so on. Those are features to build into the selection process, but the overall concept of a boot being either more substantial (stable and stiff) or less so, is really the key. This is absolutely why so many of us learn through trial and error. Over time, you find the level of stability in the shoe that mates best with your foot mobility to provide the best function on your preferred terrain. It’s the reason that many people are convinced they’ve found the one best shoe option on the planet. In all probability they have – for them and only them – until the shoe gets discontinued or changed by marketing. And appreciating human nature, you almost can’t fault said person for encouraging others to follow in their footsteps (another pun intended) with regard to shoe selection.

That’s the trap. Beware. I can’t tell you how many people I’ve known and worked with who’ve wound up injured and miserable because they were using the wrong boot style for their foot type. Stiff dudes with high arches and bow legs don’t do so well with heavy boots most of the time. And those with really flat, flexible feet and pretzel-yoga abilities often get hurt in skimpy shoes. El Capitano Obvioso will say that you want to give a stiff hombre a little freedom of movement and a hypermobile one a little support and stability. Or a LOT in both cases, respectively.

Let’s also give consideration to bodyweight. The heavier the athlete, the more force that individual can put into the outsole, midsole, shank, and upper of a shoe or boot. They can make the footwear “flex” so this may affect their choice of flex ratings. Consequently, heavier (you can define) people often prefer or benefit from slightly more stable shoes than lightweight cats.

Enter the orthotic. You can call it a replacement insole or a beefed up sockliner. We don’t need to argue definitions here. Replacing the stock insole (which is usually one place where shoe companies save a little money – because they know you are going to do it anyway) will usually result in making the shoe more substantial. Yes, some orthotics are designed more for support or correction (a controversial topic best saved for later) while others focus more on total foot contact and cushioning. Basically, almost any orthotic (whether custom or off the shelf) will add stability to a shoe. In this manner, you can make almost any shoe slightly more stable. This is both good and bad because putting an orthotic in a shoe that’s a little too flexible for your foot can bring it into the desirable functional range. But, on the other hand (foot), you may end up pushing that boot into an overly stiff condition for your needs. I’ll give an example of inappropriate shoe and orthotic selections, and these are true stories which have happened multiple times.

Let’s say we’ve got a backcountry athlete who is into holistic health, biohacking, and just being a more natural, aware animal on this planet. Tries to wear mostly natural fibers next to skin, eats sustainably. Goes barefoot whenever possible. But also has a hypermobile foot and a history of plantar fasciitis and bunions. This hiker buys into some of the popular rhetoric and purchases a minimalist trail running shoe, pulls out and throws away the insole to get more toe room (not always a bad idea). Then she throws on a 22.4 pound pack, and heads out for a multi-week trek. Unfortunately after day 3, this cat is crippled up with debilitating foot soreness and has to abandon the trip. Not enough shoe for the person and the situation. 

Or how about this one? We’ve got a hunter getting ready for a mountain expedition. This might be sheep, goat, elk, deer. There can be differences in terrain or boot needs depending on the species and time of year, but there are often similarities. The well-meaning outfitter strongly recommends a specific brand in a stiff and stable model. Our hunter isn’t an old rodeo cowboy, but he looks and moves like one. AKA “stiff.” No amount of glucosamine supplements or Pilates is going to change this much. He gets the boots the outfitter recommended and also puts in a pair of popular orthotics marketed to this population. He gets after a rucking program, and winds up with agonizing knee and hip pain after a couple weeks. Those boots restricted (eliminated) his already highly reduced mobility. Force went up the system and caused problems.

Both those examples are seemingly extreme, but I assure you they are very common. They are just cases of the wrong shoe for the feet in question. My message in this missive was not to bash anyone, but to bring to light this very real problem of foot/shoe mismatches. Most advice-givers really do mean well. And shoe companies have a primary goal of selling products. We do well to sort through all the information with which we are inundated and make informed, personal footwear choices. Sometimes this is best accomplished by working with your friendly neighborhood physical therapist or foot/gait professional. I actually do a lot of those analyses online these days, and with very good outcomes versus cost and time. Regardless, I encourage you to experiment and find the shoe or boot that works best for your personal level of foot mobility.

Thank you for joining me today and feel free to reach out to me if you have any questions, comments, or need for service.