One trend I see in aerobic training is a greater focus on interval training. This is fine because interval training does increase fitness, but it is a bit too narrow-minded for my tastes. There is a good case to be made that aerobic training should encompass both interval training and continuous training.
For example, here are a couple of studies (one and two) that compare interval training versus continuous training. If you want to look only at one variable, aerobic capacity (VO2max), than interval training will be the winner every time. But what's missed is that continuous training has different benefits than interval training, benefits that interval training may not be able to reproduce. This is shown in the second study I cited, where interval training increased capillary density by 21% but continuous training increased it by 40%.
Interval training and continuous training can be performed separately or within the same session. For my own training, I find it easier to just combine the two into a single workout. Usually, I do some easy running for a few minutes, then a half-minute or so of faster running, and then directly repeat the cycle. This way I perform a volume of easy running, while also interspering the high-intensity spikes to increase fitness.









