Ive done a 100 reps with a little less weight and I have also run a marathon wich is 26.2 miles. the marathon was much harder. not even in the same league. you work alot of muscles running 26.2 miles. took me 3 and a half hours to run 26.2 miles.. I was in perfect condition for a show. It was marathon or show and I chose the marathon that year just to be able to list it to my credentials. man after I ran that marathon I have alot of respect for top runners much harder than bodybuilding. 3.5 hrs is a great time but the top runners hit around 2 hrs 18 minutes that was the best time that day. I still placed very high for my age group I was 21 when I did the marathon. training for a show is something to be proud of but running a marathon is on a wholoe diffrent level.
ANY sports is harder than bodybuilding.
Bodybuilding is basically a sports for lazy people, especially if you go by "one muscle group per day". 45mins to one hour workouts, you can't even compare that to playing soccer, basketball, handball, skiing, martial arts, dancing, track and field and so on.