Honda TRX420FPA Owner's Manual page 86

Braking
Your ability to brake in a turn and to brake hard in an emergency
situation are important riding skills.
When descending a long, steep grade, use engine compression braking
by downshifting (in the ESP mode), with intermittent use of both brakes.
Continuous brake application can overheat the brakes and reduce their
effectiveness.
Riding with your foot resting on the brake pedal or your hands on the
brake levers may overheat the brakes, reducing effectiveness.
For information on how to apply the brakes in various riding situations,
see the following section, Riding Your ATV .
Basic Operation & Riding 77