Strenuous is a related term of confusing.
As adjectives the difference between strenuous and confusing
is that strenuous
is urgent, ardent, zealous while confusing
is difficult to understand; not clear as lacking order, chaotic etc.
As a verb confusing is
Urgent, ardent, zealous.
Requiring great exertion.
* 1961 : J. A. Philip. Mimesis in the ''Sophistês'' of Plato . In: Proceedings and Transactions of the American Philological Association 92. p. 467.
- We can achieve this god?likeness only by unremitting and strenuous effort of the intellect.
difficult to understand; not clear as lacking order, chaotic etc
- Several sections in that book are really confusing .