Question: Are my shoes (or boots) causing blisters?

A common cause of blisters is shoes or boots that are too tight or too loose. One of our clients is a “seasonal” runner who routinely starts training for his annual running/physical fitness test about two months out. This year, he began noticing blisters on his pinky toes. 

Though he ramped up his miles abruptly (going from 0 to 15 miles per week…in 2 weeks),  he denied experiencing foot blisters since way back in boot camp. He had, however, bought a new pair of shoes for his upcoming physical fitness test.

Answer: Check the shoe’s liner

1. Remove the liner insert from the shoe and stand on it.

The size and shape of the liner should match your foot all the way around. Any spillage of your foot or toes over an edge of the liner means that the shoe will have to stretch to accommodate the difference. The resulting foot “overhang” is likely to cause blisters and pain down the road. There’s no way to work around spillage – trade up a size or width of the shoe and recheck.

2. For the right amount of toe wiggle room, you’ll want some space between the end of your longest toe and the front edge of the shoe.

To get it right, use the “Rule of Thumb.” While standing on the liner, be sure your heel is centered in the area made for the heel. Then, place your thumb down on the liner material between the end of your toe and the front edge of the liner. If the gap is more or less than a thumbnail’s width, switch to a different shoe size.

Spillage solved

Our runner discovered that he had spillage of the outer fourth and fifth toes in both shoes. He tried sizing up but then found that the larger shoe’s liner was too long, with nearly double the “Rule of Thumb.” This extra length could cause his foot to slide forward and back when running, leading to blisters on the bottom of the foot! Ultimately, he was able to find a different brand of shoe that offered wide widths, and that didn’t cause any more blisters. 

If you are noticing blisters and can’t find an immediate cause (e.g., ramping up a new activity too quickly), check the liner in your shoes or boots, and change the size or width if needed.

Questions or comments about foot pain or injuries? Send us a message

If you have a friend or teammate who could use this information, please share it with them. Thanks!

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