I think what I have a difficult time 'wrapping my head around' is your generalized statements of being stronger is better / most important. I think being 'strong enough' is what is needed. Being able to squat 700 lbs does not give you an advantage in the mountains, in my opinion. I will wager most guys that can really get after it in the mountains probably can't squat 450, but they have stamina and can 'go' for hours without getting gassed. I think being strong enough, without sacrificing stamina and endurance, is the formula.One reason that I am not a fan of the use of the term “cardio” is because it is so non Specific. In the sense that you use the cardiovascular system to literally do anything, be it taking a dump, deadlifting or shoveling snow, everything is literally “cardio.”
The term “conditioning” is much more accurate because sport specific conditioning is in fact a specific adaptation. What people seem to confuse is that any and all cardio is general and this is not the case. Again, triathletes have to train all 3 sports. Why is that? Because running does not effectively condition the body for the adaptations of riding a bike.
Sense rucking is under the added stress of weight and mountain sports involve a considerable amount of time going uphill, it is a different adaptation than general running. Muscular endurance for the purposes of rucking is a specific adaptation where the capillary density of the muscles are able to continuously perform a sub maximal movement Over and over again. Strength plays a considerable role in this as the stronger the muscles, the less stressful the task, however, that capillary density adaptation is a separate (or additional) adaptation from pure strength and is specific to the sport.
Strength itself, however, is a general adaptation. Strong quads are strong quads, but there are sport specific adaptations that need to be made to perform specific sports: a cyclist may be concerned with lactic threshold as it relates to their quads, for example. As a person who puts on a backpack and hikes uphill for hours at a time, muscular endurance is where it’s at. Does it rely on the cardiovascular system? Absolutely. But, your muscles are the primary pathway to performance in this case.
Not a high quality, fancy influencers video, but it’s as simple and stupid as this video demonstrates. The semantics of this is largely where people get confused because it’s seems to be the case that few people actually understand the difference between “cardio”, which is a very non specific term, “conditioning”, which is more specific and “muscular endurance.” As it stands, people seem to lump these term all generically under the umbrella of “cardio” and express the idea that all “cardio” is therefore productive as it relates to “cardio” and that is simply false.
In the end, I will stand by this advice as the end all be all for rucking performance: get strong (general adaptation most effectively achieved by doing the basic barbell movements with heavy loads and low reps) and build your sport specific muscular endurance. If you lack the necessary strength to perform the necessary force production over and over again, you’ll have to build that along the way while conditioning and that is a very slow and arduous process. That portion of this simple equation is best achieved in the gym.