brisk up vs brisk

brisk up is not an adjective while brisk is an adjective.

Word	Noun	Adjective	Verb	Adverb
brisk up	No	No	Yes	No
brisk	No	Yes	Yes	No

As verbs, brisk up and brisk are synonyms defined as:

Other synonyms of brisk up include brisken.

brisk up (adjective)	brisk (adjective)
	very active
	quick and energetic
	imparting vitality and energy

brisk up (verb)	brisk (verb)
become brisk	become brisk