A "strenuous hike" refers to a challenging and physically demanding walk or climb in nature. It usually involves steep slopes, long distances, or difficult terrain that requires a lot of effort and stamina to complete. Full definition
I wear them for lighter hiking and trail running - I had a gore tex pair for more strenuous hiking too. (corporette.com)
Mark Adams decides to trace the journey of the man who claimed to «discover» Machu Picchu, Hiram Bingham, and takes a very strenuous hike through Peru (goodreads.com)
Hiking is something I usually enjoy so I was up for it, even though I was a little nervous since it was a 3.1 mile moderate to strenuous hike with +1,323 ′ net elevation gain. (crunchydomesticgoddess.com)