The problem the EZ Hydro-Glide addresses is well known.
Thermoregulation in the water is notoriously difficult, as the body’s regular cooling mechanism, based on evaporative cooling, simply does not work underwater. Thermoregulation depends almost entirely on conduction and convection to the surrounding water.
Elite swimmers can produce 600–1,000+ watts of metabolic heat during high‑intensity efforts. Only a fraction of that becomes mechanical propulsion; the rest must be dissipated. To remove this heat efficiently, the water must be substantially cooler than skin temperature to maintain a strong temperature gradient.
If the gradient is insufficient — for example, in moderately warm water (≥26–28 °C) or when wearing a wetsuit, which reduces conductive heat loss — the swimmer accumulates heat faster than it can be shed. This leads to rising core temperature, which is strongly associated with reduced power output, impaired technique, and increased perceived exertion.
In these conditions, phase‑change materials (PCMs) provide an additional cooling pathway by absorbing heat through latent heat transfer, helping maintain thermal balance when environmental cooling is inadequate.
The EZ Hydro-Glide has been tested with the support of both professional and amateur swimmers. All of them reported improved performance from maintaining lower head temperatures in the water. The device also improved head hydrodynamics, with tests reporting gains of up to 2 seconds per 100 meters. Swimmers additionally reported improved head position and better leg positioning closer to the surface.
