Strength and pure endurance. For my part, given some of the situations I have found myself in, both were critical to my getting out alive. While you can most assuredly get results with sets with rest, the point is, for me at least, sustained effort- because I have at times had to call on my body for precisely that. Such as: I hung from the neck of a horse after being flung forward without warning while my horse and a guide horse got into a nasty kicking contest. I had to hold myself there long enough, with my body out of the way of the flying hooves, until the horses were through with their hissy fits. After that I pulled myself right back up without my feet ever touching the ground. I was 67 at the time, that was during a horse riding trip in not far from Moshe, Tanzania last March. Also, I was crossing a croc- and hippo-infested river in Central Kenya on that same trip. The river was swollen due to the previous night’s heavy rains. As the horse lost touch with the river bed, the water nearly swept me downstream where the hippos waited. If I didn’t have the strength and endurance not only to hang onto my saddle against a powerful current but also to haul myself back on as we approached the shore, I’d have ended up as lunch. This is what I do for a living. If I am not very strong and fit, I can die. That simple. It’s one of the reasons I have multiple pullup bars in the house; that’s a weak point for me and I have to work not only on those but also a ton of rear delt and lat work.
So the answer to your question, Kurt, is what do you want out of that work? If it’s only bragging rights, or if it’s to show off, or win a bet (that was handy) or if it’s the muscularity, those are some outcomes. For me, as an adventure athlete, I damned well better have access to sustained strength. The other piece is this: research has shown that the number of pushups you can do in a row is an excellent predictor of real health. Your numbers are only part of the picture (BP, VO2 max, BPM, etc.) Researchers found with a longitudinal study of firemen that a better predictor of overall fitness AND of cardiovascular health was how many pushups they could do. For those fireman who could do at least ten, the incidences of cardiovascular incidents dropped. For those who could do more, the incidences dropped even more. As in, a lot more. So that’s an additional motivation. BP and heartrate are indicative, but not always, because a low heartrate or BP could be from an underlying condition rather than actual health. Pushups, apparently, can do a lot more than win us a bet. To that please see this:
I’m a great advocate of functional fitness as opposed to who has the bigger biceps. If the biceps are for show and not for strength, I can’t use ’em. I have wood to haul, I have horses to ride, mountains to climb. And every so often I have to use strength and endurance to survive a situation. What’s impressive in a pose on stage may not be useful at all to me if my ass is hanging halfway off a horse in a pitched fight between two 1500-lb animals. I’m not a fitnses expert. I am only informed about how said fitness works for this body and how I use it. Hope that answers your question.