ratebeer

Using the formulae at Training Peaks, and listening to your VO2 needs, I'd suggest Tabata Intervals. Workout for 4 minutes a day with a day of rest per week. You keep your intensity high and mileage low and you'll be able to both recover and dramatically increase your VO2max while maintaining or improving your LT. The great thing about Tabata is that your legs feel great the next day, despite your heart and lungs getting a tremendous workout.

To answer your question, I think recovery is largely for rebuilding after training breaks you down. Sleep, get active rest (moving around slowly is better than being sedentary) and relax your mind. Those are key components to letting your hormones rebuild you into a stronger athlete.

To summarize, heart and lungs quickly recover from very high intensity workouts. Legs aren't as resilient, so focus on a massive VO2max improvement. The best way to do this is through Tabata HIT. Tabata et al were able to improve VO2max 15% with a two-week interval training program. Any other program that comes close would involve a syringe.