Free endurance training resources

Know your numbers.
Train with a plan.

Free calculators and practical guides for Norwegian 4×4 training.

Set up your session.

Free. No signup needed.

Find your work and recovery zones.

Convert pace, speed or a 5K time.

Time your warm-up, intervals and recovery.

3,513 heart-rate readings from one person, with methods and limits.

Why the timer keeps counting while your heart rate catches up.

What Apple Health can tell you about your training.

From Archline Labs, makers of Ramp4x4. Our evidence & affiliate policy. Educational information, not individual coaching or medical advice.