Something that requires a lot of physical or mental strength, energy, or concentration and is therefore tiring.
example
Nach acht Stunden Arbeit war der Tag wirklich anstrengend.
After eight hours of work, the day was really exhausting.
Usage tips
Word structure
'Anstrengend' (strenuous/exhausting) is the present participle of the reflexive verb 'sich anstrengen' (to make an effort). So something that is 'anstrengend' forces you to exert yourself.
EXAMPLE
Man muss sich wirklich anstrengen, um diese Prüfung zu bestehen.
You really have to make an effort to pass this exam.
Typical collocations
The adjective describes not only activities such as 'eine anstrengende Wanderung' (a strenuous hike) or 'ein anstrengender Job' (a demanding job), but also people or things that are tiring, such as 'ein anstrengendes Kind' (a difficult/exhausting child) or 'ein anstrengendes Gespräch' (an exhausting conversation).
EXAMPLE
Die Diskussion mit dem Kunden war sehr anstrengend.
The discussion with the customer was very exhausting.
Sentence structure with 'für'
To express for whom something is strenuous or exhausting, use the preposition 'für' followed by the accusative.
EXAMPLE
Das Training war für mich heute besonders anstrengend.
The training was especially strenuous for me today.
Compare with
antonym
anstrengend vs leicht
light / easy
'leicht' and 'anstrengend' are opposites when it comes to effort and energy. Use 'leicht' when something requires little work, little concentration, or little strength. Use 'anstrengend' when something takes a lot of energy and makes you tired, physically or mentally. A task can be easy because you understand it quickly. A long workday can be exhausting even if you know the tasks.
anstrengend
Der Weg nach Hause ist wegen des starken Schnees sehr anstrengend.
The way home is very exhausting because of the heavy snow.
leicht
Morgen macht mein Bruder eine leichte Aufgabe in der Küche.
Tomorrow my brother is doing an easy task in the kitchen.