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 3 · Training by the numbers
coach Zone 2 training stimulates the protein PGC-1alpha to build new mitochondria, making muscles highly efficient at burning fat instead of limited sugar.
Quiz
Which cellular structures, often called the powerhouses of the cell, multiply during Zone 2 training?
coach Wearable heart-rate data helps athletes avoid the unproductive middle intensity of training.
Fun Fact
Mitochondria power: Consistent endurance training can double the volume of mitochondria in your muscle cells in just six weeks, supercharging your energy.
Quiz
What is the term for the maximum rate at which your body can consume oxygen during exercise?
Glossary
maximum heart rate (noun)
The highest number of beats per minute that a person's heart can safely reach during exercise. In 1970, researchers William Haskell and Samuel Fox developed the classic formula to estimate this physiological limit.
The highest number of beats per minute that a person's heart can safely reach during exercise. In 1970, researchers William Haskell and Samuel Fox developed the classic formula to estimate this physiological limit.