Shivering uses the energy produced by hydrolysis of ATP to generate heat.
In other words, we shiver to keep warm.
Shivering is the involuntary contraction and relaxation of skeletal muscles in small movements.
The enzyme myosin-ATPase is the enzyme that catalyzes the hydrolysis of ATP to produce the energy for muscle shortening.
During shivering, the ATP hydrolysis is uncoupled from muscle shortening, so that as much as 80 % of the energy is released in the form of heat.