How fast does my heart rate recover after exercise?

AA SLAI SLAA HLAI HL Accessible Also in: Modelling, Sport

Research question

Does my heart rate after a standard exercise test decay exponentially towards my resting rate, and does the fitted recovery constant improve over six weeks of training?

Adapt it: change the place, the data or the comparison until the question is yours.

Why it makes a good exploration

Heart-rate recovery is used as a fitness indicator. Logging your own recovery with a watch or chest strap and fitting an exponential model gives personal, repeatable data and a real question about your training.

The mathematics you'll need

Exponential decay to an asymptote
Linearising with logarithms
Comparing fitted constants over time
Residuals and the early fast phase

Course labels show where a technique sits; using maths from outside your course is fine if you explain it clearly and say it is new to you.

Where the data comes from

Record heart rate every 10 s for 5 minutes after a fixed exercise test, weekly for six weeks.

phyphox (RWTH Aachen) — Free app that turns your phone's accelerometer, microphone, barometer and gyroscope into data loggers with CSV export.

Cite every source in a footnote where you use it and in your bibliography. Check the licence of any dataset you download.

A possible outline

Describe the test protocol precisely.
Fit the exponential model each week.
Compare the recovery constant over time.
Check whether a two-phase model fits better.
Reflect on sleep, caffeine and device accuracy.

Pitfalls that cost marks

Changing the test protocol between weeks.
Wrist sensors lag behind real heart rate — mention it.
Only one test per week without repeats.

Showing personal engagement

It is your own data — describe how the training felt.
Compare with a friend who does not train.
Predict your week-six constant before measuring.

See Criterion C: personal engagement for what examiners look for.

Taking it further

Fit a two-exponential model (fast and slow recovery) and compare with the single exponential.

Turn this idea into your IA

Plan this IAOpens the planner with this question, the maths and data sources filled in. Desmos workspacePlot your data, fit models and keep your graphs with your plan. AI feedback on a draftCriterion-by-criterion feedback with evidence from your own text. Coaching, not rewriting. Examiner reviewPete, a practising IA examiner, reads your draft and talks it through with you (€100).