How to prevent blisters while running

Blisters are something every runner will have encountered at one time or another. And while for the most part they’re a minor – but painful – inconvenience. For ultra runners putting in the big miles or taking on multi-day trail races. Blisters can quite quickly become a race-ruining disaster. We take a look at how to prevent blisters while running – and share some tips on how to deal with blisters on the move if you’re suffering mid-race.

What causes blisters?

In runners, blisters are typically caused by friction which damages the upper layer of skin and causes a small ‘bubble’ of fluid to form between the top layer of your skin and the deeper layers. And while the blister actually forms to prevent further damage being done – they’re also pretty painful. Ill-fitting running shoes, socks that rub or conditions that leave you with wet feet for a sustained period of your run are usually the culprit for blisters.

How to prevent blisters

While posting photos of your crater-sized blisters on Strava post-event can be seen as a bit of a badge of honour in the world of ultras and trail running. Coming home from a race with the soles of your feet resembling a lively sourdough starter or the surface of the moon doesn’t have to be the rule of thumb. And there are plenty of measures you can take to avoid getting blisters while running – or at the very least, reduce the severity of your blisters.

Get running shoes that really fit – and factor in the conditions you’ll be racing in

It doesn’t matter how great the energy return feels or how beautifully grippy they are. If your trail running shoes don’t quite suit the shape of your feet or your gait, they’re going to cause your trouble.

If your shoes are too tight, they’ll create pressure points and hot spots. Making it more likely that your socks will rub or your toes will be crammed together. Which is an issue not only on the blister front, but can also lead to painful bruising. But if you size up a touch too far, then shoes which are too loose will cause your foot to shift around inside your shoe. That’ll create friction as your foot moves, particularly on the downhills, which can lead to blisters. And you’re going to feel pretty unstable negotiating technical terrain.

So you’re looking for the goldilocks effect when it comes to how your running shoes fit. Your foot should feel securely locked down in the shoe, without pressure around the ankle or top of the foot. There should be enough wiggle room in the toe box for you to slightly spread your toes. And a small amount of space between the ends of your toes and the front of the shoe to allow for a little movement, without slipping back and forth or feeling like you’re running in clown shoes.

It’s important to know that your feet can swell up in hot conditions. So if you’re racing in the height of summer you may need to size up. If you’re shopping for new running shoes it’s worth trying them on later in the day, when our feet tend to have swelled a little from our daily activities.

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How to tie your running shoes to avoid blisters

Once you’ve found a pair of trail shoes that work for the shape of your feet (and for the terrain/weather conditions you’ll be tackling) it’s also worth considering how you tie your laces. Getting your lacing right can really help to lock your foot down into your shoe, without causing pressure points or hot spots. Below we’ll outline two of the most effective shoe lacing techniques for runners: the heel lock (aka runner’s loop) and window lacing. Plus an alternative that does away with the hassle of laces entirely.

Heel lock / runner’s loop lacing

Heel slippage can cause painful chafing and blisters on the backs of your heels, and it might mean your foot is slipping forwards in your running shoe, causing your toes to bump up against the toe box. If your shoes fit well otherwise, then the solution might come in the form of runner’s loop lacing.

1. Start by lacing your shoes as normal until you reach the second to last eyelet.
2. Pull the lace through the second to last eyelet, and then instead of crossing it over to the opposite side of the shoe, insert it back into the top eyelet on the same side of the shoe – creating a loop.
3. Repeat the step on the other side, so you have two small loops on either side of the shoe.
4. Take the lace end on the right side of the shoe, and pull it across to feed through the loop on the left side of the shoe. Repeat with the left lace, pulling it through the right loop.

Window lacing

If your shoes fit too tightly across the top of your foot, this can put pressure on the tendons and nerves in front of your ankle. Creating uncomfortable numbness and tingling, as well as hot spots and blisters. Window lacing can help to alleviate this pressure, without compromising on how locked down your foot feels in your shoe.

1. Start by lacing your shoes as normal until you get to the area where you’re experiencing pressure on top of your foot.
2. Instead of crossing over as usual at the pressure point, instead feed the lace through the next eyelet on the same side. Repeat on the other side.
3. Then resume crossing over as usual – you should have a ‘window’ where the laces don’t cross over in the middle of the shoe.

BOA lacing system

If all that tying and untying of laces sounds like far too much hassle, the other option is to go for one of the growing number of trail shoes that use the innovative BOA laces. Trail brands such as Speedland, La Sportiva and Scarpa have all added BOA fastening trail shoes to their ranges in recent years. BOA is a fastening system which uses super-strong yet lightweight wire ‘laces’, which you can adjust tighter or looser simply by twisting a low-profile dial on the side of the shoe.

This dial allows for fine-tuned micro adjustments, without having to completely re-lace your shoes every time to get it right. Not only does this mean you can quite literally dial in the perfect fit. It also makes adjusting the fit of your shoes mid-run incredibly easy and time efficient. You can adapt the fit of your shoes to match the terrain, without losing time. For example if you’re running a long downhill section and you find your feet slipping forward in your shoe, you can easily twist the dial to tighten up the fit. And then loosen off again once you hit the flat to avoid any pressure points.  

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Choose your socks wisely – and carry spares for ultra marathons

Getting the right shoes and dialling in the fit is just one part of the blister-avoidance equation. Your socks can also have a big impact on your comfort levels. Experiment with different socks in training. Some trail runners prefer to use toe socks, while others prefer to tape their toes and opt for regular socks instead. It comes down to personal preference, and what works best for your unique biomechanics. So it’s important to try out a range of options in training so you know what your best option is way before race day.

Wet feet – due to sweat or puddles – can be a major contributor to getting blisters. For summer racing, you’ll want to go for socks that are breathable, quick-wicking and fast-drying so you’re minimising how sweaty your feet get. Meanwhile for winter racing, waterproof options may be your best bet where cooling is less of a priority but keeping the elements at bay is vital.

If you’re doing a lot of miles on sandy or gravelly terrain, you might also want to avoid double layer socks as these can trap debris and create extra abrasion. It’s also well worth carrying at least one spare pair of socks in your pack so that if your feet get wet, sandy or sweaty you can change your socks before it becomes an issue.

Use lubricants/barrier creams and tape to reduce the likelihood of blisters forming while running

Even with the best shoes and socks in the world, if you’re putting in the big miles you’re likely to experience at least some level of chafing and friction. Using lubricants or barrier creams can be a great way to pre-empt this to prevent maceration and blisters during long trail runs and ultra marathons.

Again, you’ll need to try out a few different options to find out what works best for you. But products such as Trench Foot Cream, petroleum jelly or even Sudocreme (which top level ultra-runner Kim Cavill recently told us she used to avoid blisters during a 100-mile race, to great effect) are good places to start. During training, regularly inspect your feet and take note of any areas where you tend to get hot spots or chafe. You can use products such as K-tape or Mole Skin (which comes in ergonomically pre-cut shapes) to tape up any areas where you know you’re likely to experience blisters.

Stop and take action to deal with any chafing or hotspots before they turn into blisters

When you’re in the zone and ticking off the miles, particularly during a race, it can be tempting to ignore any discomfort and power through. But taking a minute or two to stop and sort out any hot spots or rubbing before a blister forms is likely to save you time overall because you’ll be able to maintain better form in the later stages of the race if you’re not dealing with unnecessary blister-related pain.

If you can feel a hot spot, try changing your socks, applying more of your barrier cream/lubricant of choice, taping up if necessary – and adjust your shoe laces to ensure your foot is dialled into your shoe.

Take care of your feet at check points during ultra marathon events

Foot care needs to be a priority throughout your run training to ensure you get to the start line with your feet in good shape. But during an ultra it becomes even more important to stay on top of your foot care during the race. You’re counting on your feet to get you to the finish line and it’s not like you can pack a spare pair in your drop bag!

At the check points, take the opportunity to clean and dry your feet. Reapply your lubricant/barrier cream. Put fresh socks on and dry your shoes out as much as possible if they’re wet. If you have picked up any blisters, tape them up or get help from a medic before they become a real problem.

Winter-specific tips to prevent blisters

Winter ultra marathon events bring with them an additional challenge. Keeping your feet as clean and as dry as possible while contending with rain, snow, ice, mud – or all of the above, all at once.

Ahead of last year’s Winter Spine Race, we spoke with experienced ultra-runner and coach Jayson Cavill to get his tips and hacks for winter running gear. Alongside using gaitors (or trail shoes with built-in gaitors) for winter ultras. Jayson also suggested trying knee-length waterproof socks to keep your feet dry. He also notes that it’s worth wearing a sock liner with your waterproof socks so that if you do get some water ingress, you can swap them for a spare pair.

Breathability is far less of a concern for winter events, so it’s worth getting some waterproof trail shoes. A top tip from Jayson is to use a simple wax coating (such as clear wax boot polish) to waterproof the uppers of your preferred trail shoes if you don’t have a waterproof option.

What to do if you get blisters during an ultra marathon

Sometimes you can do everything right, and things still go wrong. So what should you do if you start getting blisters during your ultra marathon event?

Plenty of the big, multi-day Ultra events such as Cape Wrath, Dragon’s Back and the Spine race have a blister kit on the mandatory kit list. This typically consists of sterile hypodermic needles, anti-septic/alcohol wipes and a form of dressing. It’s worth carrying these things in your pack, even if they’re not on the mandatory list, so that if you get a bad blister – you can do something to relieve it. Keep the blister clean, carefully drain any fluid and then use the dressing to prevent further damage. Consult a medic at a checkpoint if you need help. And if there are any signs of your blisters becoming infected (such as filling with pus, and/or red, hot skin around the affected area) then definitely get them checked out.

Aside from treating the blisters, it comes back to pressing on with all the preventative measures we’ve outlined above. Clean your feet to get rid of any abrasive debris, and dry them off as often as possible. Change your socks, tape up where you need to and keep reapplying your lubricant/barrier cream at regular intervals.

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