step-up

Short definition from Wiktionary

Adjective

1. 1
   That increases in stages.
2. 2
   That increases a voltage.

Noun

1. 1
   A workout movement wherein one leg stands on an elevated surface and lifts in the concentric part the rest of the body up onto it to target – depending on angle and starting distance of the other leg and weights applied by the arms – the femoral and gluteal muscles variously.
2. 2
   An increase.

Verb

1. 1
   To increase, augment, or advance, especially by one or more steps.
2. 2
   To assume or take responsibility.