When it comes to discussing laborious tasks that require a lot of effort and can be physically exhausting, "backbreaking work" is a commonly-used phrase. However, there are a variety of synonyms that can be used to describe this type of work, including grueling, arduous, taxing, heavy, strenuous, and demanding. These words all convey a sense of work that is difficult and challenging, requiring a lot of concentration and effort to complete. Other words that could be used to describe backbreaking work include strenuous, exacting, burdensome, and onerous. Regardless of the specific word used, these synonyms all capture the challenging nature of physically demanding, time-intensive work.