In any case, combining aerobic exercise and resistance training is more sustainable. Lots of people, myself included, would find that doing 90 minutes of just one type of exercise three times a week to be monotonous -- unless it is hiking in the mountains, which gives me limitless exercise and pleasure.
All of us, however, get complementary benefits from aerobic and resistance exercise. Aerobic exercise increases our cardiorespiratory fitness, and resistance training increases our muscle strength and endurance. Together that's the best exercise.
