As runners, we generate lots of different sorts of forces when we run. Let’s focus on one: the impact force when you land. The first thing to know is that impact force changes considerably as the pace changes. This makes intuitive sense. Faster running requires flying farther through the air, and that means a greater impact when you land. So the faster you run, the greater the impact.
Okay, so what’s the point? Here’s why the precise amount of impact force matters. The impact force changes so dramatically from pace to pace that midsole foam (it doesn’t matter which kind) can’t correctly react to all paces. In fact, the impact force at 6 min/mile (3:45 min/km) is different enough from the force at 8 min/mile (5:00 min/km) that no midsole can respond efficiently to both paces. This is physics! The only way to address this issue is to tune midsoles by pace zone. By tuning shoes according to pace, we’re able to optimize the cushioning you get given the forces you generate.
What’s so important about optimized cushioning in a running shoe? Your current shoe almost certainly doesn’t have the proper amount of cushioning. You’re likely running on a midsole that’s either too hard or too soft for the particular impact force you generate. If it’s too hard, you don’t get the cushioning you need to stay healthy. If your midsole is too soft, you can have stability issues. You’ll also be running in shoes that smush down on landing and wreck your efficiency. Kind of like running on marshmallows.
I think we can all agree that running on marshmallow midsoles wouldn’t be ideal. Why not run in shoes optimized to respond to the forces inherent at your pace? Hello pace-tuned shoes.