A good indicator is how worn out the tread is, over time this will show signs of wear and if it becomes too smooth, you won't get the traction that you need. Alternatively, when they start to 'feel' different.

It was truly innovative creating a one-piece breathable upper, engineered for precision fit and a second-skin feel for runners. From blistering 5Ks to marathons, or simply for daily jogs or lifestyle use, you can't go wrong with a pair of Nike Flyknit running shoes.

When Will Unworn Running Shoes Begin to Deteriorate? While shoes won't start to deteriorate immediately after buying them, you should begin using them six to 12 months after your purchase. According to Stump, this is when they start to break down little by little.