Let’s try a thought experiment.
You purchase a pair of “super shoes”—the high-stack, next-gen midsole, plated racing shoes that are the running story of the last few years—and soon boast a new personal best or two. You start to wear the shoes not just in races and special workouts, but also on more of your regular runs. You notice that you’re covering your standard loops faster without more effort. Plus, your legs don’t feel as beat up as they usually do. So you ask yourself, Why not run in super shoes every day?
Not so fast, say some experts, and not just because of the shoes’ relatively high price and lower durability. Doing so could increase your chances of some injuries and, paradoxically, leave you less able to race at your best.
Variety is the spice of running
Shalaya Kipp is an Olympic steeplechaser and one of the researchers who investigated Nike’s first super shoe. That University of Colorado research team found that running economy (the oxygen cost of running a given pace) improved by an average of 4 percent in the Nike prototype compared to conventional Nike and Adidas racing flats. Hence, the shoe’s name when it eventually hit the market, the Vaporfly 4%.
Kipp, who is now pursuing her Ph.D. in exercise physiology at the University of British Columbia, says, “Compared to traditional racing flats, the shoes seem to reduce the amount of power required by the calf and metatarsal-phalangeal joints.” (These are the joints at the ball of your foot.) “Theoretically, wearing the shoes might help with calf injuries. The stiff carbon plate plus the foam seem to help reduce the amount of involvement of calves and Achilles tendon. This could potentially alleviate some discomfort or pain in the rehabilitation of injuries in calves or Achilles.”
Sounds great! But bear in mind that the impact forces of running have to go somewhere. Reduce the load on some body parts, and it will be transmitted elsewhere.
“I think some of the stress from the new shoes ends up in the midfoot,” says Brian Fullem, a sports podiatrist in Clearwater, Florida, and author of The Runner’s Guide to Healthy Feet and Ankles. “The shoes function with a whip-like return that may stress some tendons and ligaments beyond their elastic ability, leading to tears and strains.” In addition to midfoot injuries, Fullem has seen patients with new cases of plantar fasciitis after running a lot in super shoes.
Other clinicians point out that super shoes have a lot of toe spring—a large upward curve in the forefoot—to help the foot transition over the thick midsoles and stiff forefoot plates that characterize this type of shoe. It’s believed that toe spring can reduce forces in the foot and ankle while increasing them in the knees and hips.
Jared Ward, who placed sixth in the 2016 Olympic marathon and helped Saucony develop its Endorphin line of shoes, says, “If I do too much in the Endorphin Pros, my feet are affected. I don’t know if it’s because the plate is harder than what I’m used to, but the ball of my foot and sometimes my arches feel the strain. That said, as I adjust to differences in foot strike and mechanics promoted by my new shoes, I find myself doing more workouts in them.”
Most running injuries stem from repetitive strain—too much of the same forces applied to vulnerable body parts. Experts agree that subtly varying those forces can lower your risk of injury. Rotating among different shoes, whether they’re super or not, is one way to achieve that variety. Research published in 2013 found that runners who split their mileage among two or more different models had 39 percent fewer injuries during the 22-week study than those who did almost all of their running in the same shoes. Although this study was conducted before super shoes arrived, there’s no reason to think its overall point about variety isn’t valid.
“I rotate shoes and terrain to make sure I’m creating slight variations in my gait pattern–foot strike and stride length and frequency,” Kipp says. “When I have a monotonous, repetitive gait pattern, my body experiences stresses in very localized places.”
Is faster always better?
But what if you’re willing to increase your injury risk to run faster? After all, training is inherently risky; only runners get running injuries. If wearing super shoes daily means a better marathon PR, isn’t that worth the gamble?
It is appealing, after all, to feel faster and less achy on every run. “Being able to train at higher speeds for the same level of effort might have some neuromechanical benefits,” Kipp says. The thought here is similar to why some runners do downhill strides—to make quicker paces and turnover feel more like your norm.
There’s also the matter of less muscular fatigue in super shoes, thereby enabling harder training (and, eventually, faster races). “I ran a mile repeat in my old-school minimal flats the other day, and immediately traded back into my Endorphin Pros because my calves were already feeling shot—after one,” Ward says.
But even Ward, whose Saucony sponsorship removes the financial concern of daily super shoe use, advises against the practice. He says that being, say, 10 seconds per mile faster on all of your runs at the same effort level doesn’t necessarily mean you’re getting fitter. He likens the phenomenon to training on weight-reducing treadmills such as the AlterG.
“You can run 20 seconds faster per mile at 80 percent body weight on an AlterG treadmill and some aspects of you will be fitter—hamstrings, etc. But your heart maybe didn’t have to work as hard,” Ward says. “I feel like this phenomenon translates to super shoes. Some people are running the same times in training and it just feels easier—they aren’t stressing their body harder (or the same) by running faster.”
Fullem agrees, speculating, “If the shoes make running faster easier and you’re expending less energy to run faster, you’re not gaining as much of a training effect. I view them similarly to a pair of spikes, in that they’re designed for racing.”
“I’m not sure that 100 percent training in [super shoes] is going to get you ready for the pounding unless you’re running a ton of KILOMETRES.”
Ward also thinks that a beloved benefit of super shoes—you don’t feel as beat up after long, hard runs in them—could be a drawback on marathon day.
“The marathon is a race of attrition. Your body needs to be ready for it,” he says. “I’m not sure that 100 percent training in [super shoes] is going to get you ready for the pounding unless you’re running a ton of kilometres.” Given that Ward regularly runs more than 160 kilometres a week during marathon training, his definition of “tons of kilometres” is much higher than most recreational runners’ peak mileage.
As always, individual runners should experiment to find what works for them. But even if you can afford to wear $250 shoes daily, the consensus to date is that you’re probably better off saving super shoes for super important runs.