Running in old or worn out running shoes is one of the most common causes of running injuries. Over time and through normal use your running shoes will lose their ability to cushion, support and stabilise. Continuing to run in worn-out running shoes increases the stress and impact on your legs and joints, which can lead to overuse injuries in much the same way that running in the wrong shoes can. The easiest way to help prevent those types of injuries is to replace your running shoes when they’re worn-out. Which begs the question, how do you know when your running shoes need to be retired?
Don’t use the treads of your running shoes to determine whether you should replace your shoes as this is the most durable part of a running shoe, whereas the life of your shoes is dictated by the softest part ñ the midsole. The midsole is the (usually) white piece of foam which provides the cushioning and stability in your shoe, often supplemented by additional technology such as gel or air. The foam is usually the first part of the shoe to break down as it is the hardest working component in the shoe, and it will usually do so before the bottom shows major signs of wear. If you’ve been feeling muscle fatigue, sore shins, or some pain in your joints – especially your knees – you may be wearing running shoes that no longer have adequate cushioning and/or stability.
Most manufacturers will suggest that an average runner should replace their running shoes every 400 to 600 miles, depending on their running style, body weight, and the surface on which they run. Smaller, lighter, and more mechanically efficient runners can get new running shoes at the upper end of the recommendation, while heavier and less mechanically efficient runners should consider replacing their shoes closer to the 400 mile mark. Also, if you run primarily on rough terrain, you’ll probably need to replace your running shoes sooner than if you primarily run on a treadmill, as the wear and tear on the shoe will be greater.
A handy guideline for consideration comes from adidas customer service office, who point out that assuming a runner weighs 75kg and runs 45 miles per week, with an approximate stride length of 1.4m, the total load in a 6 month period amounts to over 100 tons (100,000kg) per foot. This is obviously a heavy load to bear for both feet and shoes, especially given that most running shoes weigh somewhere in the region of only 350g.
Here are a few tips on gauging the life of your shoes and when to start thinking about replacing them…
Use a speed and distance system such as the Nike+ system or the adidas miCoach (coming soon!), which will log your mileage and keep a record for you, making it easier to keep track of how much work they’ve actually done.
Mark your calendar when you buy a new pair of running shoes so you remember when to replace them. If you use a training log, be sure to record when you bought new shoes – it will help you track how many miles you’ve run in them.
Writing the purchase date on the inside of each shoe’s tongue is another good way to help remember when you first started running in them.
If you’ve been feeling muscle fatigue, soreness in the shins, or some pain in your joints you may well be wearing shoes that have lost their cushioning.
See if your shoes fail the twist test: if you hold your running shoes at both ends and twist the shoe, it should feel firm. A worn shoe will twist easily as the supporting structure of the shoe becomes weaker through use.
A clear tell-tale sign that your running shoes are past their best is if you can see excessive wear on the outsole. The outsole should last longer than the shoe’s cushioning so if the soles are worn down, it is definitely time for new ones.
Look for creasing of the midsole material in areas of high load (under the heel or the ball of the foot). A worn out midsole will have wrinkles and creases there as the cushioning material becomes compressed and unable to regain its former springiness.
Take them into your local Run 4 It and ask the staff. At Run 4 It your running experience is our number one concern, we want you to get the most out of your shoes and your running. We will never tell you your shoes need replacing if they still have plenty of life in them, and our staff will be happy to check your shoes are still giving you the correct degree of support and stability.