Q: Should I discard athletic shoes based on volume of use or time of purchase?
A: Reviewing the recommendations of athletic shoe manufactures and walking/running enthusiast websites, the general recommendation is to replace your athletic shoes every 500 miles.
The average U.S. adult takes about 5,900 steps daily (2.95 miles). If athletic shoes were worn for all 5,900 steps, a new pair of shoes would be needed every six months. Sedentary U.S. adults take about 2,000 to 3,000 (1 to 1.5 miles) steps a day, which would mean a new pair of shoes about every 12 months.
There are a number of factors that will increase the rate of deterioration faster than six months to a year. Here are a few:
- Amount of walking actually occurring vs. the average example listed.
- Running – Regular runners will need to replace shoes more frequently than every six months.
- Surface – Walking/running on roads vs. off-road (grass).
- Body weight – The more you weigh, the faster the shoe will breakdown.
- Gate/foot strike – An unconventional gate or foot strike pattern may lead to uneven wear and shoe breakdown.
Outside the normal wear and tear, shoes naturally age. Certain things occur as soon as a new shoe leaves the assembly line:
- Glue holding the shoe together starts breaking down.
- Air pockets or other cushioning materials start to lose their spring.
- Normal environmental elements will lead to shoe oxidation and breakdown while the shoe is in transit, storage, or sitting on the display shelf.
To summarize, most athletic shoes used on a regular basis need to be replaced about every six months. The best strategy is to purchase the current year models to minimize deterioration not related to use.
The following websites were used as references in answering the question:
http://www.asics.co.uk/sports/running/preparation/changing-your-running-shoes-knowing-when-is-the-right-time
http://msue.anr.msu.edu/news/know_when_to_replace_athletic_shoes
http://www.livescience.com/43956-walking-10000-steps-healthy.html