The water at the top of a waterfall has energy.
potential
kinetic
heat
metabolic

I believe the answer is POTENTIAL ENERGY. The water at the top of the waterfall has Potential Energy. Potential Energy is defined as the energy that is stored when an object is at rest. At the top of the waterfall, water will have maximum potential energy. When the water falls down, it is will already have kinetic energy which is energy that is produced through continuous motion. When it is finally in the bottom, water will have maximum kinetic energy.  

All are great precautions but you can still lift lighter and different muscles in between hard workdays. this keeps other muscles not usually used in shape.