You can get attached to your favourite trainers, whether it’s because they look great with your gym kit, they’re super comfy, or they helped you get a new PB. But if you want to avoid hurting yourself and continue performing at your best, it’s important to make sure you replace them regularly. The question is, though: how are you supposed to know when they need to go? 

Knowing when to change your trainers is particularly important if you’re into high-impact cardio like running, during which your shoes strike the pavement, trail or treadmill repeatedly. The shoes you wear can have a big impact on your form, and can make the difference between a successful run, and one where you do yourself an injury.

The good news is, there are some rules of thumb you can keep in mind, so that you know when it’s time to start shopping around for a new pair. We asked fitness experts for their insights into why, when, and how often you need to replace your trainers. 

As time goes on, your trainers “lose their shape, support and their bounce”, says Tashi Skervin, a runner, trainer, and founder of fitness bootcamp TSC Method. This means that they stop absorbing impact effectively, which “could lead to injuries due to an increase of stress and impact on your joints”. When your shoes lose their ability to effectively support your feet, this also “alters your running gait”, says Kerry Dixon, a personal trainer and founder of The Athlete Method. “This puts a lot of strain on the joints, tendons and ligaments”. 

According to Tashi, it can be difficult to pinpoint when your trainers need replacing, because “old trainers that are worn in often feel really comfortable”. She says that, as a result, it is a good idea to keep an eye on how they look: “does the heel look squished? Has the rubber worn away on the soles? When you put your shoes on, are they flat or do they still have some shape?” 

Sports doctor Sarah Davies from Panacea Health says to also look out for whether “the sole has worn through to the under layer, the midsole buckles easily under pressure, the heel has become bendy, or your toes have worn through the upper”.

Beyond just how they look and feel on your feet, Kerry says that how your body feels when you wear them during exercise is a good indicator, too. Once your shoes stop providing adequate support, your feet could start to feel sore after your workout. Blisters and aches “in your lower back, knees and shins” are also a sign that it is time to switch the shoes. 

Sarah says that “there is no absolute timescale”, because how long your trainers last “depends on both you and your overall mileage”. For runners though, a good guideline for replacing trainers is after you’ve done “about 500 miles in them”. However, depending on how you run and on what surface, “for some people the wear can be significant at 200 miles”.

For example, Tashi says that foot strike can be a big factor in how often you need to change your trainers. “If you heel strike when you run (meaning your heel makes contact with the ground first), you’re more likely to wear the heel of your trainers down than forefoot or midfoot runners”. 

This may sound difficult to keep track of, so Kerry recommends getting a smart watch or keeping a training diary, to help you stay on top of how much ground you have covered. Then, when you’re coming up to the benchmark, “you can be aware of the signs”. 

Follow @StrongWomenUK on Instagram for the latest workouts, delicious recipes and motivation from your favourite fitness experts. 

Images: Getty