The problem
Serious athletes don’t want a summary number, they want to read their data: heart rate against elevation against breathing rate at minute 02:23 of last Tuesday’s run; muscle mass by week across six months.
The brief was one line, “build the analytics,” for a young team with no roadmap or sprint cadence yet. The pipe in: Garmin and other wearables, sleep, RHR, HRV, body composition, GPS-traced runs. The surface to build: dashboard, body-composition statistics, the activity detail (route map, summary, multi-axis charts), and the calendar that ties planned training to recorded sessions.
The call
Layered depth over a dumbed-down summary: one number at a glance, three numbers with effort, the full multi-axis correlation on click. And one design vocabulary across all four surfaces, so a click down reads as a depth change, not a navigation change. The open mandate was scoped into a roadmap and sprint cadence rather than an open-ended build.
Progressive disclosure, one screen
Three layers, one screen. Headline state, contributing metrics, full annotated series, surfaced on demand, not by default.
Four surfaces, one drill-down
The athlete moves through four surfaces depending on what they're asking. Dashboard for the daily check-in, Health Index, three vital signs, an AI-generated read on the trend. Statistik for the long view, a single body metric (muscle mass, body water, RHR) plotted by week with min / max / average framing. Aktivität for a single session, route map, summary card, the option to tag, review and break down. Charts for the post-mortem, heart rate against elevation against breathing rate, primary and secondary Y-axes configurable, combined mode on by default. The same components, spacing and metric definitions follow the user down through every level.
One drill-down, one design vocabulary across all four
Four levels of depth, from the daily check-in to a per-minute read of a single run. A click between levels is a depth change, not a navigation change.
Outcome
The analytics surface shipped, and the team now runs on the roadmap, backlog and release rhythm the mandate introduced, the structural layer that doesn't show up in screens but decides whether the visible work ships.
The bet: serious users reward depth on demand over simplification. Drill-down, not dumb-down.