One of the most debilitating blister areas for athletes is under the ball of the foot. You can get them:
Under the big toe knuckle (these ones)
Under the little toe knuckle
Right in the middle of the forefoot
Less commonly across the WHOLE ball of the foot!
Forefoot Anatomy & Blisters
Anatomically, this is where the metatarsal heads are. These are weightbearing bones so the skin is subjected to really high pressures. And as part of normal function, the metatarsal heads move back and forth under the skin, creating a lot of skin shear (the cause of blisters).
What Happens Under The Foot?
The metatarsal heads move back and forth a lot with every running or walking stride. It’s very normal and happens:
During propulsion (push-off)
When changing direction
On uphill and downhill terrain
When the foot plants, the metatarsal heads skid forward over the skin, and then backwards during propulsion. Imagine what's happening to everything in between the skin (stationary) and bone (moving): it's being compressed and stretched. This is shear. Shear is normal, it happens with every step we take and our tissues are able to deal with a lot of it. Watch this video to see how it happens.
You can imagine that as your activity increases in intensity and/or duration, shear may reach a point where it becomes excessive ... more than the skin can handle. At this point, damage occurs. And it occurs under the surface of the skin, a few layers deep. Blister researcher Stanley Comaish (1973) described this damage as epidermal fatigue because the connections that bind these skin layers tear under the shear load.
Why Is The Ball Of The Foot Susceptible To Blisters
The metatarsal heads are subjected to really high weightbearing forces, unlike most other parts of the foot
The skin on the sole of the foot is thicker and less mobile than other parts of the foot and this is suited to blister formation
There are more sweat glands on the sole of the foot compared to other parts of the foot
The in-shoe microclimate plus the fabric composition of the sock and shoe provide a high friction environment by default
The 5 Best Blister Prevention Strategies Worth Trying For Blisters Under The Forefoot
Preventive taping is a good place to start. It won’t always work, but it’s a good starting point. In the following video, I'll show you how. The tape I use is Fixomull Stretch (buy link below) but you can use another tape if you prefer.
2. Cushioned insoles
Cushioning has a double blister prevention effect. Firstly, it reduces peak pressure a little and therefore reduces skin shear. And secondly, cushioning materials absorb shear via their shear modulus. That is, shear goes on within the material so less of it occurs within the skin. Research has shown some cushioning does this better than others (read about Spenco, Poron and gel materials in Chapter 5). It’s important to know that blisters can still form in spite of cushioning. But if you need just a little bit of blister prevention oomph, and your current insoles are old, worn or bottomed-out, a new pair could make all the difference. Interestingly, the top surface of cushioning materials typically exhibit a high friction level! So if you're still getting blisters in spite of cushioned insoles, add the next strategy.
3. ENGO Blister Prevention Patches
This is the best way to minimise friction levels under the ball of the foot - better and longer-lasting than lubricants and powders. These patches stick onto the insole of your shoe (or orthotic) and they just stay there until they wear through about 500kms later. They make the friction side of blister prevention easy. Pictured are the large ovals. If you need broader protection, you can use the larger rectangle patches (see below).
John Vonhof, author of Fixing Your Feet likes them too.
"ENGO Blister Prevention Patches are great. I have promoted them for years. I tell runners to pin one on their bib number before a race in case a hotspot develops. They work great on the insole for ball of the feet pain." John Vonhof
4. Biomechanical Improvements
Blisters under the ball of the foot are often associated with structural and biomechanical issues. There is a lot that a podiatrist or sports medicine professional can do to alter your biomechanics to reduce the incidence of blisters under the metatarsal heads. This could involve insoles, orthotics, stretches (especially calf stretches), joint mobilisations and modifications in your gait or running style. Seriously consider seeing a podiatrist if you have ongoing blister issues here in spite of using the above three strategies!
5. Donut pads
I like these for treatment rather than prevention. If you have a blister, you'll need to take the pressure off it. The thicker the material (I use 5mm or 7mm orthopedic felt) the better the pressure relief - but the more room they take up in your shoe. If you get prevention right, you won't need these. You can get 5mm Hapla felt (the best brand) from the link below.
Take home messages
The ball of the foot is inherently susceptible to blister development due to its important biomechanical functions in gait.
Good cushioned insoles or orthotic covers are a good start (something like Spenco)
Minimise friction best with an ENGO Patch
Consult a biomechanical expert for relevant advice and treatment