Synonyms of the word 
STRENUOUS → ARDUOUS - EFFORTFUL - ENERGETIC - STRAINING
strenuous
- adj. vigorous, energetic, ardent, zealous.
- adj. Requiring great exertion.
arduous
- adj. Needing or using up much energy; testing powers of endurance.
- adj. (obsolete) burning; ardent.
- adj. Difficult or exhausting to traverse.
effortful
- adj. Requiring or showing effort.
energetic
- adj. Possessing, exerting, or displaying energy.
- adj. Of or relating to energy.
straining
- v. present participle of strain.
- n. The act by which one strains.
If you are interested in words, visit the following sites :
- wiktionary.org/strenuous For complete definition of a word
- 1word.ws/strenuous to play with words, suffixs, prefixs, etc.