High-tops or trail shoes? What actually protects your ankles on the trail

There’s a reasonable-sounding mechanism behind the boot recommendation, some genuine biomechanical evidence supporting part of it, and then a fairly large gap between that evidence and what actually happens to injury rates in the field. Pulling that apart properly matters, because neither “boots are essential” nor “boots are a myth” holds up — both get stated far more confidently online than the evidence supports.

Where the “ankle support” claim comes from

The logic is intuitive: a high-cut boot wraps above the ankle joint, so it should physically limit the joint rolling into the position that causes a lateral sprain — forced inversion, where the sole of the foot turns inward. And at the level of pure biomechanics, that part checks out. Laboratory studies going back to the 1990s — using rigs that mechanically force the ankle into inversion while measuring the angle and speed of movement — have consistently found that high-top shoes reduce both the amount and the rate of inversion compared to low-top shoes. One frequently cited study found high-tops cut peak inversion angle by around 4–5 degrees and slowed the rate of inversion by roughly 70–100 degrees per second compared to low-tops under the same loading conditions. A 2020 systematic review and meta-analysis pooling six such biomechanical studies reached the same conclusion: shoe collar height measurably restricts the ankle’s range of motion in the coronal plane.

So the mechanism is real, but the problem is that “restricts ankle motion in a bench test” and “prevents ankle sprains in the field” are two different claims, and only the first one has strong support.

What happens when you test it in the field

The most directly relevant evidence comes from an actual thru-hiker cohort. A 2009 cross-sectional study in Wilderness & Environmental Medicine surveyed 128 long-distance hikers (all over 500 miles in) on the Appalachian and Pacific Crest Trails, comparing sandals, running shoes, hiking shoes, and boots against reported injury and illness. There was a trend — paresthesias (numbness/tingling) rose with footwear rigidity, from 29% in sandals up to 68% in boots — but once the researchers adjusted for pack weight, footwear dropped out as an independent predictor; pack weight was doing most of the work. And critically, footwear showed no significant association with joint sprains, chronic pain, or muscle injury — the outcomes boots are sold on preventing. It’s one study, and a survey rather than a trial, so it doesn’t settle anything on its own — but it’s the closest thing to on-trail data that exists, and it points the same direction as everything else here.

The larger, more rigorous body of evidence comes from adjacent populations where injury tracking is easier to control. A 1993 prospective, randomised trial in the American Journal of Sports Medicine put 622 college intramural basketball players into high-top, high-top-with-air-chamber, or low-top shoes for a full season and tracked every ankle injury against player-minutes on court: no statistically significant difference in sprain rate between groups. That result was substantially reinforced in 2015, when a Military Medicine meta-analysis pooled 16 studies (12 with comparable injury definitions) comparing US Army recruits training in combat boots versus running shoes across decades of Basic Combat Training cycles — again, essentially no difference in overall injury (risk ratio 1.04 in men, 0.94 in women) or lower-extremity injury specifically. That’s a much larger cumulative sample than any single trial, landing on the same conclusion.

None of this is a hiking-specific randomised trial — that study doesn’t exist yet, which is a genuine gap. Basketball’s repetitive lateral cutting and military drill aren’t identical to a hiker’s occasional misplaced footfall on a rock or root, and that limitation deserves stating plainly rather than glossing over. But between the thru-hiker survey, the basketball RCT, and the military meta-analysis, three different populations using three different methods land in the same place: no clear evidence that boot height reduces sprain or injury risk in practice, despite a real, measurable effect on ankle biomechanics in the lab.

The cost nobody puts on the box: what heavier footwear does to your legs

If ankle protection isn’t the clear win boots are marketed as, the trade-off you’re accepting for that extra ankle coverage matters more. And this side of the equation has been tested repeatedly, by different research groups, over four decades, with remarkably consistent results.

The foundational work came out of the US Army Research Institute of Environmental Medicine in the 1980s. In one study, fourteen subjects walked and ran on a treadmill in their own athletic shoes (average 616g per pair) and in leather military boots (1,776g per pair) — a swing of just over a kilogram across both feet. Oxygen uptake was 5.9–8.4% higher in the boots across walking and running speeds. A companion study in women the following year found essentially the same pattern.

The obvious objection is that this is 1980s military leather-boot technology, and modern hiking boots are lighter and better engineered. That’s a fair point, and this exact question was re-tested in 2023 using contemporary US Army combat boots (1.2kg per pair) against standard running shoes (0.6kg per pair) in 34 active soldiers on a treadmill. The result: oxygen cost of walking was 6–9% higher in the boots, essentially unchanged from the 40-year-old data despite genuine improvements in boot design over that period, with heart rate and respiration rate rising in step. The mechanism is straightforward physiology: mass added at the extremity of a limb costs disproportionately more energy to accelerate and decelerate with every stride than the same mass carried closer to your centre of mass — which is also the physiological logic behind why a heavy pack on your back is more efficient than the same weight distributed onto your feet or ankles.

You’ll sometimes see this summarised online as a fixed rule — “a kilogram on your feet costs as much as five or six kilograms on your back.” That figure gets repeated with a level of precision the underlying research doesn’t support. Load-carriage studies that have tried to quantify the multiplier directly have found it varies with speed and sex, landing anywhere from roughly 2 to nearly 5 times the equivalent torso load, not a single fixed number. The direction of the effect is well established and consistent; the specific multiplier isn’t — treat any single-number version of this rule as a rough order-of-magnitude, not a precise conversion.

Where boots earn their weight

None of the above means trail shoes are the correct answer for every hike — the evidence gap is specifically around ankle-sprain prevention and energy cost, not about boots being pointless. There are contexts where the case for a stiffer, higher boot is stronger, on different grounds entirely:

Where trail shoes make sense

Conversely, for day hikes and well-maintained multi-day trails, in reasonable weather, without a heavy pack: the evidence doesn’t support boots as the safer or more protective option, and the metabolic and fatigue cost is real and cumulative over long days. Lighter footwear also tends to run cooler, dry faster after stream crossings, and reduce the friction and pressure points that drive blistering — a far more common trail-ending problem on any given trip than an ankle sprain.

Bringing it together

The biomechanics are real: high-top boots measurably restrict ankle inversion range and speed in controlled testing, and this part of the marketing claim holds up.

The injury-prevention claim is not well supported: a thru-hiker cohort study, a basketball RCT, and a military meta-analysis pooling 16 studies all land on the same conclusion — no meaningful difference in sprain or overall injury rate by footwear height. Genuine hiking-specific trial data doesn’t exist yet, but three independent lines of evidence now point the same direction.

The energy cost is real, consistent, and has held up across 40 years of re-testing: heavier footwear increases the oxygen cost of walking by roughly 6–9%, from 1980s military boots through to modern combat boots. The oft-quoted “5x multiplier” rule of thumb is directionally right but overstates the precision of the underlying research.

Context still matters more than a blanket answer: heavy loads on rough ground, technical or snowy terrain, harsh weather, genuine ankle instability, and inexperience with a loaded pack on unmarked terrain are all legitimate reasons to choose a boot — just not primarily for the ankle-support mechanism the marketing leads with.

The most useful shift isn’t “always wear boots” or “always wear trail shoes” — it’s separating the reasons people give for choosing boots (ankle protection) from the reasons that hold up once tested (weather, terrain, load, personal history), and picking footwear based on the ones that are true for your specific trip.

Planning footwear and kit for a specific trip?

Generic gear advice doesn’t account for your itinerary, terrain, pack weight, or personal injury history. If you’d like your kit list — footwear included — reviewed against the actual conditions you’re heading into, it’s worth talking through properly before you go.