A Silly Split

About the Author: Eric Cressey

The more I write, the more weird emails I receive. I’m always very accommodating in answering people’s questions even if they’re rude and critical of my work; in fact, I enjoy defending my assertions. I’m a firm believer that there must be a rhyme and a reason for everything a coach or writer recommends; what better way to prove it than to defend those recommendations in the face of criticism. Just recently, I had one such opportunity when I received an email criticizing me for writing a four-days-per-week training program that didn’t “adhere” to the Mo-Tu-Th-Fr training split. Apparently, my actions constituted a serious program design faux pas, so I felt it necessary to justify my recommendation with an entire article on the very topic.

In short, I’m not a big fan. It’s a split designed for convenience. Unfortunately, there isn’t much about the iron game that is inherently “convenient.” Loading hundreds of pounds onto barbells and then lifting them isn’t convenient, nor is sprinting, or preparing healthy meals, for that matter. Yeah, so you want the weekends off; who doesn’t? Speaking anecdotally, I don’t think that most trainees inflict enough damage to warrant two days of complete rest (and, for many, complete gluttony in front of a TV screen for college and NFL football games). And, to those who insist that the two days is enough for supercompensation to occur, I don’t think you really even understand what supercompensation is; it take a lot longer than two days. I don’t necessarily include MWF splits in this category, however, as they tend to be full-body training sessions that complement other training (e.g. sport-specific conditioning, cardiovascular activity, team practices, extra assistance sessions).

First, let’s consider why I don’t like it from a logical perspective. You should know to prioritize work for your specific weaknesses by placing it on a “fresh” day (immediately after a rest day). Now, the Mo-Tu-Th-Fr training split allows for two fresh days, whereas a Mo-Tu-Th-Sa split, for example, allows for three. This might not seem like a big difference, but consider that it means trading roughly 50 pseudo-depleted sessions for 50 fresh sessions over the course of the year. In my mind, this corresponds to significant gains over the course of a training career; take a look at the template advocated by the lifters at Westside Barbell Club, which follows such a structural template, and you’ll see that the proof is just as much in the numbers as it is in the logic.

Next up, let’s look at this from a pragmatic perspective. Are the gyms busier on weeknights or weekends? If you answered “weekends,” you ought to just give up and take aerobics classes. Some of the best sessions of my training career have been on weekends simply because my mind was more clear of the all the nuisances of the “weekday world.”

Now, let’s consider the Mo-Tu-Th-Fr split from a scientific perspective. Research has shown that following a resistance training session, skeletal muscle protein synthesis can be elevated for up to 48 hours (1). However, these researchers studied untrained subjects (2). MacDougall et al. (1995), on the other hand, found that in resistance trained subjects, protein synthesis had returned to baseline at 36 hours post-exercise (3). Keep in mind that I’m assuming that you’re reading this site because you actually train, so we’ll classify you with the latter group. If you don’t train, why not head over to the Good Housekeeping forums? I’m sure that everyone will appreciate you sharing a few recipes while Martha Stewart is making license plates instead of quiches.

To apply this protein synthesis data to you, we’re going to calculate a thing I like to call “downtime.” This is the time between training sessions minus 36 hours; basically, it gives you the amount of time in between sessions that you aren’t above baseline in protein synthesis. We want to minimize this!

Let’s say that you’re a Mo-Tu-Th-Fr evening lifter. Skeletal muscle protein synthesis is elevated rapidly, so we’ll say that you stimulate it by 8PM on all days. From the time that you get the marked elevations on Friday to the time that protein synthesis is kickstarted on Monday, you’re looking at 72 hours, the last two of which are essentially spent in a catabolic state during training (keep in mind that you’ll be in a catabolic state all weekend if you’re hopelessly intoxicated the entire time!). That leaves a full 36 hours of downtime (72 minus 36). Moreover, you get another 12 hours of downtime from 8AM to 8PM on Thursday; this is pretty much unavoidable, given your schedule. In all, theoretically speaking, that gives you two days per week (48 hours) that you aren’t above baseline.

Now let’s consider what happens with the Mo-Tu-Th-Sa split and the same lifting times; assume once again that you’re firing up protein synthesis around 8PM on all days. Because you took two rest days during the week and only one on the weekend instead of one during the week and two on the weekend, you have three 12-hour periods of downtime during the week (8AM-8PM on Monday, Thursday, and Saturday). Therefore, with the Mo-Tu-Th-Sa split, we have only 36 hours at baseline. A difference of twelve hours might not seem like much to you now, but over the course of a year, that works out to be an additional 26 days with protein synthesis elevated!

If you don’t buy into my scientific perspective, consider it from an anecdotal perspective by observing the outstanding results numerous trainees have experienced from programs that emphasize more frequent training (even if it means shorter sessions). While Bulgarian weightlifters have taken it to an extreme (albeit successfully) with several sessions per day, you can also read about the benefits of frequent training sessions in Joel Marion’s Center Your Training; Ripped, Rugged, and Dense 2.0; and Sequential Development for Size.


The next time you write up your training program, ask yourself if it’s based on logical, pragmatic, and scientific principles. Or, is it designed to make things convenient for you? If you find yourself answering yes to the latter question, chances are that you’re sacrificing gains in both size and strength. Be sure to get your priorities straight before you determine how to break things up. With that said, let the angry email barrage commence!


1. Phillips SM, Tipton KD, Aarsland A, Wolf SE, Wolfe RR. Mixed muscle protein synthesis and breakdown after resistance exercise in humans. Am J Physiol. 1997 Jul;273(1 Pt 1):E99-107.

2. Rasmussen BB, Phillips SM. Contractile and nutritional regulation of human muscle growth. Exerc Sport Sci Rev. 2003 Jul;31(3):127-31.

3. MacDougall JD, Gibala MJ, Tarnopolsky MA, MacDonald JR, Interisano SA, Yarasheski KE. The time course for elevated muscle protein synthesis following heavy resistance exercise. Can J Appl Physiol. 1995 Dec;20(4):480-6.