Answer: The above question actually came up in the comments section of Training Frequency for Mass Gains but I thought it was worth addressing in full.
Before actually addressing the question in terms of the frequency issue, let me make one comment about the above schedule. Depending on what movements are being done, especially on the lower day, doing upper body the day before lower can be very problematic. If someone is going to squat or deadlift on lower body day, fatigue in the back and shoulder girdle from the upper body day can cause real problems on the lower body day (clearly if other movements are being done on the lower day, this is far less of an issue).
There are two solutions to this. The first is to switch the days and put lower body first in the sequence and upper body second (this raises a second issue which is that fatigue from heavy lower body work often makes upper body go poorly but training is nothing if not a series of compromises). The second is to use a slightly different split. Doing chest/shoulders/triceps on Monday and legs/back/biceps on Tuesday and keeping that sequence avoids some of the problems although day 1 ends up being a lot easier (and usually shorter) than day 2 (which can be murderous).
Ignoring that, let me get back to the original question about training 2 on/2 off across an 8 day training cycle and the relaive optimality (or not) of that type of training. And the short-answer to the above question is that…it depends. Yeah, not very useful so let’s look at some of the things that it depends on and give the long answer.
Perhaps the biggest thing that the above depends on is life. Most people’s real-life schedules are constrained by a rather standard 7 day work week. We have Monday through Friday which are the typical work days followed by the weekend. And this tends to have massive implications for how training weeks can be set up. Note that ‘can’ and ’should’ are not synonymous here.
In fact, it’s a big part of why I tend to default to cycles that run across a standard work week, it simply reflects the reality of the majority of trainees in my experience. Anyone who has read or done the Ultimate Diet 2.0 knows that I went to lengths to fit the cycle into a standard 7 day work week. An 8 day cycle actually would have been better in a lot of ways but the reality is that most people can’t make the schedule work because their life situation is set by the standard 7 day week.
But the reality for a majority of trainees is that the above schedule tends to be a huge determinant of not only when they can train but what kinds of schedules that they can follow. Typically, and this is even more the case if they have family obligations they won’t have a lot of time during the week to train while they will generally have more time available on the weekends.
That is to say, if they get off work at 5:30pm, get to the gym at 6:30 and have some expectation of spending time with their family in the evening, a long training session during the week may simply not be realistic, even weekends may be limited due to this either because they need to spend time with the family or have chores around the house.
I addressed this in a slightly different context in the Q&A on Lifting Six Days Per Week for Mass Gains by offering the option of more frequent (but shorter) sessions during the work week with longer sessions on weekends. This lets folks get in and out of the gym quickly during the week (to ensure that they continue to have a family to go home to) while training longer on the weekends.
Even with high-level athletes, who often train full time without a ‘real’ job, training schedules still typically revolve around the 7-day work week with Sunday a day off. Why? Is it just tradition, some left-over from early religious practices (where Sunday is typically a day of rest) or work scheduling. Or is it simply because competitions typically are done on Saturday and Sunday in most sports and training needs to sequence with that to some degree. Probably a combination of those.
An additional factor that often plays a role is facility availability. Some gyms aren’t even open on Sundays (my weight room isn’t for example). That constrains training to certain days of the week which makes rotating schedules unrealistic. It’s no good to have a workout fall on a Sunday if you can’t train on that day in the first place.
The upshot of this is that training usually ends up being modified to fit the week rather than physiological needs dictating when training occurs. That is, since the work week is constraining things, coaches simply modify loading (volume and intensity) to make recovery fit into the 7 day cycle.
So, if I know you have to train upper body on Monday and Thursday, I’ll modify the loading of both days so that training progresses the way I want. With only two days rest between Monday and Thursday, I might cut things back a bit; with three days between Thursday and the following Monday, I might push it harder so that recovery takes a touch longer. Or whatever.
But all of the above has more to do with practical issues, and less physiological ones which I suspect was the genesis of the original question. The body and the adaptations that occur with training don’t care that it’s Sunday and your gym is closed, or that religion dictates that it’s a day of rest. What ‘must’ be done due to the realities of the real-world have little to do with what ’should’ be done from a physiological standpoint. It’s simply that you can’t consider the one without dealing with the other. Setting up training schedules is always an exercise in compromises and this is one of the big ones.
But let’s assume that someone has the life flexibility (and it’s worth noting that bodybuilders have rarely been constrained by the ’standard’ approaches of other training systems) to train any day they want for as long as needed, the gyms are open, and nothing is limiting them from doing what the person asking the question proposed.
That is to train 2 days in a row and then take 2 days completely off before hitting the cycle again so that there are exactly 4 days training between every workout (with the workout days rotating through the week since we’re on an 8 week cycle) rather than having 2 days of rest and then 3 days of rest or what have you. Is that better, worse, or no different?
And the answer is still…it depends.
But now it depends more on the individual trainee since we’ve eliminated the real-world type obstacles that so often get in the way. Some trainees have no problem going hard and heavy on back to back training days. For whatever reason, fatigue from a hard Monday workout doesn’t limit them in any fashion on Tuesday. They will have no problems with the proposed sequencing. They can train hard Monday, train hard Tuesday, take Wednesday and Thursday off, train hard Friday/Saturday, take Sunday/Monday off, repeat until huge or whatever.
But that’s simply not true for everyone. For some trainees, a hard Monday workout leaves them flat and fatigued on Tuesday and they can’t get jack squat done in the gym. They need a full day off between each workout and working out every other day (even across an 8 day cycle) is a better choice. Of course, that type of trainee has real problems with training 4 days per week on a 7 day schedule because at least one set of workouts has to come back to back (e.g. Monday/Wednesday/Friday/Saturday or whatever).
The type of training being performed also impacts on this. Very heavy low rep training is often more fatiguing (generally neurally more than muscularly) and the second type of athlete will often be ‘blown’ from a heavy workout (legs moreso than upper body) and need a full day off before they can go really heavy again. Trying to squat heavy on Monday and bench heavy on Tuesday just goes nowhere.
Of course, there are ways around that too. Alternating heavy and lighter workout can still allow two training days in a row before complete days off are taken. The lighter second day might be speed work of some sort or even higher repetition ‘bodybuilding’ type training (this often helps the second type of athlete recover from the heavier day). Even for pure ’strength’ athletes, lower intensities (e.g. 70-75% of max rather than 80-85% of max) is often doable on the second day even with fatigue.
I’d note that more moderate intensity bodybuilding training doesn’t tend to be quite the problem in this regards even for the second type of trainee. Unless they really grind themselves to failure and beyond with the Monday workout, they can usually come back and hit more bodybuilding type training on a Tuesday. But the intensities have to be moderate, volumes kept in check and failure pretty much steadfastly avoided.
So the answer to the original question is simply it depends. Certainly it can work for certain athletes under certain situations. In my experience, most don’t have the life flexibility to make it work and individual physiology will also impact on whether or not it’s workable.