Similar to many of you who are reading this, I'm not a big fan of aerobic exercise. Compared to lifting weights, it can be downright boring and repetitious. Of course, you can make aerobics more interesting and challenging by applying some sort of overload effect. Indeed, doing this is necessary to ensure continued gains in muscle endurance and cardiovascular benefits from aerobics. Just as lifting the same weights over and over with no attempt to increase resistance in the form of added reps or weight will not produce any muscle gains, doing the same level of intensity constantly in aerobics will not lead to any improvements in cardiovascular capacity or endurance. It will simply burn calories and maintain any endurance that you have previously developed. Some wacky websites take it a bit further. They make outlandish claims, such as that after a while aerobics works in reverse in that it slows the resting metabolic rate. Some internet morons even say that aerobics can promote body fat gains, which makes no scientific sense at all. But whoever said that typical 'Bro science was based on any existing scientific principles?
I would wager to say that most people engage in aerobics for at least two reasons. One is that aerobics is still the best way to train your cardiovascular system. Some think that you can get the same cardiovascular benefits as aerobics by simply reducing the rest time between sets. But there are problems with that assertion. For one, reducing rest time, while raising the pulse rate considerably, also greatly decreases strength gains. Although there is no direct cause and effect relationship between strength gains and muscle gains (as in you can get stronger without necessarily making any muscle gains) the ability to lift gradually heavier weights is the basis for the entire progressive resistance training system that has been the standard of suggested effective training for over 100 years. More recently, studies have shown that you can still gain muscle mass by lifting weights as light as 30% of one-repetition maximum if you also do higher reps, up to 30 per set, and train to complete muscular failure. On the other hand, the gains made with this lighter style of training involve mainly the type-1 muscle fibers also known as slow-twitch muscle fibers. In the past, these muscle fibers were thought to not be subject to muscular hypertrophy, but rather provided the basis of muscular endurance because they were slow to fatigue. But it is now known that type-1 fibers can hypertrophy or grow in a manner similar to the type-2 muscle fibers, which were considered the primary muscle growth and strength fibers. Still, if you are interested in gaining both muscular size and strength, you have no choice other than to lift heavier weights, since only the type-2 muscle fibers will promote strength gains.
You can simulate many of the cardiovascular benefits produced by aerobics . . .