ESPECIALLY IF YOU’RE training for a half marathon or marathon, running more miles per week, and running a combination of different types of workouts (easy long runs, speedwork, track sessions, maybe even trails), you should own and run in more than just one pair of shoes. Think of it as having the right shoe for each workout – not to mention that shoe rotation is a key ingredient in preventing overuse injuries. Many runners beat the same pair of shoes into the ground every workout. In 4 – 5 months of relatively high mileage training (i.e. a typical half marathon or marathon training cycle), you will usually cover enough miles to wear out a single pair of shoes – which means that if it’s your only pair, the cushioning is pretty dead by race day, and at the last minute you’ll realize that your options are either to run the race in practically new shoes, or in ones that will need to be thrown away after the race. Needless to say, neither scenario is ideal!
Don’t rely on checking the wear on the outsole or the condition of the upper. What really matters is the condition of the midsole cushioning, which you can’t see from the outside. It is most often made of EVA foam, though there are various different foam compounds these days. Some of the newer technology has made certain types of foam (e.g. Adidas Boost or Saucony Everun) more durable than EVA, but they all break down eventually. Rotating your shoes won’t make them last longer in terms of the mileage you get out of the shoe, but of course if you only wear each pair of shoes for some of your workouts rather than all of them, you’ll have that shoe in your rotation for many more months, and a better chance of having a race day shoe that still has a decent amount of cushioning left.
From an injury prevention perspective, you’ll want to vary the loads on your body and challenge your feet, legs and the whole chain upwards to adjust to slight variations in heel drop, shoe weight, amount of cushioning and the ways in which a shoe supports your foot. A study conducted in Luxembourg in 2013 found that having two (or more!) pairs of shoes that are slightly different from one another helps keep you healthier – runners in the study who rotated at least two pairs of shoes reduced their injury risk by 39% within just a 22-week period. It’s obviously a good idea to stick to a shoe type that suits your biomechanics (neutral or support), and all/both shoes need to be comfortable for you to run in, but you can happily play around with heel to toe drop, level of cushioning and weight of the shoe. Running is a very repetitive motion; if your feet have to keep adjusting to slightly different shoes, you will significantly reduce your risk of developing an overload or overuse injury!
The other thing to consider is that running shoes are designed for different purposes. A racing flat will be much too flexible and flimsy for rocky trails, and a generously cushioned daily trainer will start to feel pretty heavy on the track right around your second 400-meter repeat. If you were to run primarily in two pairs of shoes, a good combination would be a well-cushioned and comfortable shoe for longer runs, and a more streamlined option (with less weight, less cushioning and often also a lower heel to toe drop) for tempo and speed sessions. If you’re a fairly efficient runner, that lightweight shoe will be a great option for race day too, for 5K, 10K, even up to the half marathon. For the marathon (and possibly half marathon too), you’ll have to pick a race shoe based on your running efficiency, how much you weigh (heavier runners tend to need more cushioning), your experience over that distance as well as your target for the race and any previous or existing injury concerns. Though of course if you have done this shoe rotation thing right, there should be far fewer injuries to worry about!