Chapter 1
The science of the beat
Chapter 2
The tech on your wrist
Chapter 3
Training by the numbers
Chapter 4
Beyond the watch
Ch 4 · Beyond the watch
coach High heart rate variability indicates a relaxed nervous system, while low variability warns of physical or mental stress.
coach The 1960s Swedish scale helps you calibrate wearable heart-rate zones using perceived effort.
Fun Fact
Laughter cardio: Laughing 100 times can provide a cardiovascular workout equivalent to 10 minutes on a rowing machine, raising your heart rate naturally.
Quiz
What is the physiological term for a heart rate that slowly rises during a steady-paced workout?
Glossary
chest strap (noun)
A flexible band worn around the chest that houses sensors for monitoring heart rate. Polar Electro released the first wireless chest strap in 1982 for precise heart-rate zone tracking.
A flexible band worn around the chest that houses sensors for monitoring heart rate. Polar Electro released the first wireless chest strap in 1982 for precise heart-rate zone tracking.
Quiz
What is the easiest way to verify you are training in Zone 2 without using a smartwatch?
Quiz
What does losing the ability to speak in full sentences during exercise signal about your body's energy source?