Most runners are familiar with the scourge of black toenails. For those who fly the trails or log epic miles the condition is an almost constant companion. After losing five toenails during one Boston Marathon, I was determined to solve this painful problem. The condition, known medically as subungual hematoma, results from repetitive trauma during downhill running. As runners descend, their feet slide forward within their shoes, causing the toes – especially the longest ones – to repeatedly strike the front or top of the shoe. This constant impact leads to bleeding under the toenail, resulting in discoloration, potential nail loss, and a whole lot of pain.

We all know that runners are amateur podiatrists, eager to impart wisdom gained through both age and experience. Who among us hasn’t been offered enthusiastic advice – whether in a shoe store, on a group run, or in the sports drink aisle at the grocery store – about all matters running-related? I’m here to tell you, in the case of subungual hematoma, traditional advice is nonsense – and doesn’t work. Don’t misunderstand me, that does not mean those offering the advice are not sincere, lack intelligence, or don’t speak from personal experience. But, in most cases, the advice – and their remedy – ignores the fundamental root cause. Traditional advice, like ensuring proper shoe fit, wearing thicker or thinner socks, or trying lacing techniques to “lock” the heel, doesn’t truly solve the issue. If relief was as simple as “shoe fit” or “sock choice,” the industry would have outrun this problem shortly after the invention of the EVA midsole. But despite advances in shoe technology, the latest foot scanners available at most running stores, and endless sock options, black toenails persist. The reality is that none of these so-called solutions effectively stop the foot from sliding within the shoe, especially during high-impact, fast, or downhill runs.

OK, so that’s a lot of blog space describing the problem and the flawed punditry of the practitioners. So, what’s the solution? It’s simple: prevent the foot from sliding inside the shoe. Blumaka’s NonSlip Insoles with Konnect Technology do precisely that, using a unique (patented?) top surface with a friction coefficient that prevents the sock from slipping. This ensures that the foot remains securely anchored, eliminating the forward slide that causes toes to jam against the front or top of the shoe. By keeping the foot stable, Blumaka NonSlip Insoles not only prevent black toenails, but also improve lower leg stability, which is crucial during the high-torque movements of running. Especially if your runs tend to be on trails, on undulating roads, or involve big miles. But wait, you might say, “why not just get a pair of grip socks?” You could. And you could see similar results. But have you priced grip socks lately? Most of us have a drawer full of running socks. Why not make every single pair of those socks a “grip sock?”

The advantages of Blumaka’s NonSlip Insoles go beyond “slogan” to actual science. Blumaka insoles enhance trail performance by working in harmony with the shoe’s outsole. When the shoe stops, the foot stops, too, creating a cohesive, responsive connection that maximizes power on uphill climbs and ensures precise control on descents. This synergy provides trail runners with greater grip, faster stopping power, and increased control on rugged terrain. With Blumaka, you can confidently tackle any trail, leaving black toenails and unnecessary foot pain behind. The same advantages can be realized on roads, tracks, and treadmills.

“Every once in a while, a new technology, an old problem, and a big idea turn into an innovation.” (Dean Kamen, American engineer and inventor).

Blumaka saw the problem, came up with a big idea, and has created an innovative product line that addresses an issue that the running community has struggled with since, well, men first laced up shoes and stood together on a chalk line.

Since perfecting the Blumaka NonSlip Insole, I’ve run hundreds of miles on all kinds of terrain – from mountains and trails, to roads and beaches – and have never had another black toenail. This isn’t an insole you just slide into your shoe; it is equipment designed to keep you locked in for high-performance running. Place it in your shoe with purpose, make sure your foot is firmly positioned, and lace up. You’re now ready to run hard and fast without the inefficiency and risk of sliding around inside your shoe. Both your sock drawer and your toenails will thank you.

Stuart Jenkins
Founder + Chief Innovation Officer
Blumaka