Gear
Boots, socks and the blister problem
Load changes how your foot moves inside the shoe. What to do about it before 20 km, not after.
8 min read · updated 16 August 2026
Blisters end more rucks than fitness does. They are also almost entirely preventable, and the prevention is unglamorous: the right socks, shoes with room in them, and stopping the moment something feels hot.
Why load makes it worse
A blister forms from shear — layers of skin sliding against each other repeatedly — accelerated by heat and moisture. Load makes all three worse. It presses your foot down, spreading it wider and pushing it forward in the shoe; it increases the force of every step; and it makes you sweat more.
This is why shoes that are perfectly comfortable for an unloaded 10 km can produce blisters at 6 km with a pack. The shoes did not change. Your foot did.
Footwear
| Choice | Good for | Watch out for |
|---|---|---|
| Trail runners | Road and firm trail, most rucking | Less ankle support; thin soles under heavy loads |
| Approach shoes | Mixed terrain, moderate loads | Often stiff out of the box |
| Boots | Rough ground, heavy loads, ankle history | Heavier; need genuine breaking in |
- Half a size up from your normal shoe is common among ruckers — feet spread under load and swell over distance.
- A thumb's width between your longest toe and the shoe's end, measured while standing with the pack on.
- Never a brand-new pair on a long ruck. Twenty to thirty kilometres of ordinary walking first.
- Boots are not automatically better. Most rucking happens on surfaces where trail runners are the better tool.
Socks matter more than shoes
No cotton
Cotton holds moisture against your skin and loses its shape when wet. Merino wool or a synthetic blend, every time. This one change fixes most blister problems on its own.
Beyond material, two approaches work. A single well-fitted merino sock suits most people. A liner sock under a thicker outer sock moves the shear between the two sock layers instead of between sock and skin, which is worth trying if you blister persistently.
Carry a spare pair on anything over about 15 km. Changing into dry socks halfway is startlingly effective, and it costs 90 seconds.
Lacing
Heel lift is the main cause of heel blisters, and it is a lacing problem more often than a shoe problem. A heel-lock lacing — using the top eyelets to form a loop on each side, then threading the opposite lace through — pins your heel in place without over-tightening the whole shoe.
For descents, tighten the laces before you start down. Your foot slides forward on downhills, and that is where black toenails come from.
Hot spots: stop immediately
A hot spot is a blister that has not happened yet. It is a localised warm, rubbing sensation, and it is the single most useful signal your feet produce.
Stop. Take the shoe off. Put tape over the area — zinc oxide tape, kinesiology tape or a purpose-made blister patch, applied smoothly with no wrinkles. Two minutes at that point prevents an injury that will otherwise dictate the rest of your week.
Pushing on through a hot spot to avoid a short stop is the most reliably regretted decision in the sport.
If you already have one
- Small and not painful: leave it intact and cover it. Intact skin is the best dressing there is.
- Large or under pressure: drain it with a sterilised needle at the edge, press the fluid out, and leave the roof of the skin in place.
- Never remove the skin over a fresh blister.
- Cover with a hydrocolloid dressing and tape over that so the dressing does not migrate.
- Red streaks, spreading warmth or pus mean infection. That is a doctor, not a dressing.
The pre-ruck checklist
- Toenails cut short and square before a long one.
- Non-cotton socks, no seams over pressure points.
- Tape any area that has blistered before, prophylactically.
- Spare socks in the pack for anything over 15 km.
- Tape and a hydrocolloid dressing in the first-aid kit, in a pocket you can reach.