Movi Body™
Strenuus

The Strenuus photochromic lens transitions in approximately 20–45 seconds when moving from low light into direct UV exposure. The return to clear — when moving into shade or indoors — takes slightly longer, around 60–90 seconds. For running purposes, the transition is seamless — you don't notice it happening, which is exactly the intended experience. The lens tracks the run, not the other way around.

No — photochromic lenses activate via UV light, which is blocked by most automotive glass and tinted surfaces. The Strenuus is designed for outdoor running, where UV is direct and unfiltered. If you're driving to the start line, the lens will appear clear until you step outside. Within the first minute of running under open sky, it begins activating.

At full activation under strong UV, the Strenuus lens reaches Category 3 protection — the same standard as dedicated sun lenses used for bright outdoor conditions. For road running, trail running, and open-sky training, this is full sun-day coverage. At partial activation (overcast, shade, mixed light), the lens sits in the Category 1–2 range — ideal contrast enhancement without over-darkening.

Marginally, yes — any shade reduces the UV reaching the lens, which slows full activation. In practice, runners with caps report that the lens still activates fully within 60–90 seconds of entering open sun, since the brim only shields the top of the lens partially. On mixed-terrain runs alternating between shade and sun, the lens tracks well regardless of cap use.

Same standard as everything we make. If the Strenuus doesn't fit, doesn't perform as described, or simply isn't right for your run — we handle it directly. No automated returns process. No forms designed to discourage you. A person picks up the conversation and resolves it. That's the only way we know how to do it.

Shipping usually takes 5–15 business days, depending on your location.