You don't need to keep volume high. In fact you can cut volume by 2/3rd's you just need to lift the same weight.
"Both research and practical experience over the years has pointed out one very important thing with regards to training: the amount of training that it takes to maintain a given adaptation is much much less than it took to develop it in the first place. That is to say, while it may take a significant amount of work to develop something (strength, size, aerobic capacity), you can generally maintain that level of adaptation with much less work.
This is actually a tenet of some types of periodization schemes: acknowledging that it becomes progressively more difficult to develop everything at once as folks get more advanced, many approaches to periodiziation of training will alternate periods where something is being focused (being trained at full volume) with periods of it simply being maintained (while something else is developed).
I’ve actually written about this on the site in the article series
Periodization for Bodybuilders and I’ll be repeating some of those ideas here. When I use specialization routines with folks (something I’ll write about eventually), I will move non-specialized bodyparts to maintenance using the recommendations that I outlined in that article series and will repeat below.
The basic conclusion, again from both research and practical experience is that both volume and frequency of training can usually be cut by up to 2/3rds (that is, to 1/3rd of what you did to improve it) but with one massively important caveat:
the intensity of that training must be maintained.
Put another way, you could maintain volume and frequency at the same level but if you cut intensity, you will lose the adaptation. Basically any combination that’s ever been looked at only works if intensity is maintained.
That last one is the key and goes to a lot of what I mentioned in
Weight Training for Fat Loss Part 1, if you reduce the intensity of your weight training (and here I’m using intensity to indicate weight on the bar), you will lose the adaptations that you worked so hard to develop (strength or size).
Let me put this into more practical terms. Let’s say you’ve just finished a hypertrophy phase where you were training to gain muscle. On average let’s say that you were performing 6 heavy sets of 6-8 repetitions per muscle group twice per week (say an upper/lower split as discussed in my article on
Training Frequency for Mass Gains).
Based on the 2/3rds rule, you could conceivably cut back to 2 heavy sets of 6-8 reps (maintaining the same weights you finished the cycle with to the best of your ability) once per week and maintain your strength and size. That is, both volume (6 sets becomes 2 sets) and frequency (2 workouts becomes 1 workout) can be reduce by 2/3rds but ONLY if intensity (weight on the bar) is maintained."