About Jelle Dekker

Jelle Dekker is the founder of Theron, an adaptive triathlon training coach for the Apple ecosystem. Theron builds and adjusts swim, bike, and run plans from Apple Health recovery signals, then exports structured workouts to Apple Watch so the same device that measured readiness can run the session.

Why Theron exists

Most age-groupers do not fail because they cannot find a PDF plan. They fail because life, sleep, and niggles break a static calendar and nobody rewrites the next week. Jelle built Theron after coaching himself through that loop: log the data, then still decide by hand what to do tomorrow. The product applies established load ideas — including Banister’s fitness–fatigue impulse-response work (Banister et al., 1975) and HRV-informed session timing (Vesterinen et al., 2016; Plews et al., 2013) — so readiness can gate intensity automatically.

Athletic and product background

Jelle trains as a triathlete and ships Theron from that first-person constraint: busy weeks, Apple Watch as the training surface, and a need for the plan to move when recovery data moves. The app is not a coach marketplace. It is a closed loop for self-coached athletes who want planning automated rather than logged.

Contact

Press, partnerships, and product questions: hello@theron.app. Company page: Theron on LinkedIn.