This article explores the importance of frequency in an evidence-based program & the role it plays in building more strength, muscle & skill.
Training frequency refers to how often you train. We can look at it both from the point of view of how many times you train a particular body part or movement, or from a total training session standpoint.
Many different schools of thought exist over training frequency. At one end of the spectrum, you have advocates of HIT-style training, as popularised by the likes of Mike Mentzer and Dorian Yates, where you only train each body part once every 7-14 days, but at an extremely high-intensity, and go beyond the point of concentric failure. (i.e. you incorporate techniques such as negative reps, forced reps and static holds once you can no longer complete full repetitions on your own.)
Then right at the other end, we have DUP-style training, which initially emerged from Soviet Bloc countries, and uses a much higher frequency. Many Olympic lifters still train in this style, and will often do the same lifts 5-7 times per week, or even twice a day if they're doing multiple sessions.
As with so much in training and nutrition, there is no 'best' frequency. This article aims to uncover the reasoning behind various training frequencies, so you fully understand what you're doing and why.
Understanding The Studies
Before launching into looking at what the data says, it's important to understand potential limitations.
Most studies are done on untrained populations, or those who are relatively new to lifting. The reason for this is because trained lifters are very unlikely to want to volunteer to train at a different frequency to normal, for fear they might impair their strength or size improvements.
Therefore, we get a good idea of what may be best for different people in different situations from the studies, but the results may not extrapolate perfectly to more trained subjects.
What the Studies Say
Some studies seem to show that a low to medium frequency is beneficial (or at least not detrimental) to strength and size gains.
A 2018 study from The Journal of Strength & Conditioning Research for example, split subjects into two groups - subjects training with a body part split, training a different muscle group(s) each session, so they hit each muscle group just once every 7 days, and subjects hitting their whole body each time. So frequency of 5 times per week.
Both groups trained 5 times per week, and by the end, no significant differences were found in their 1 rep max improvements. (1)
A second study, this one from the Applied Physiology, Nutrition, and Metabolism journal put a high-volume, low-frequency program (twice a week,) against a low-volume, higher-frequency program (4 times per week,) and found while both strategies improved performance and lower-body muscle mass, only the high-volume, low-frequency program increased upper-body hypertrophy and body composition. (2)
It seems this is where most of the more recent research supporting lower-frequency programs ends, though.
Most suggest that when total weekly volume is matched (i.e. you do the same number of sets, reps and weight across the week,) you're better off spreading your training over more days. (3)
A 2016 study from Schoenfeld, Krieger and Ogborn found splitting volume over 2 sessions rather than 1 was beneficial, and hypothesized that splitting the same volume over 3 sessions would be even better, though they didn't test this. (4)
A 2018 study did test this however, and found it to be true. (5)
It appears that, when volume is matched, a higher frequency is like to produce greater results, simply because you go into each session less fatigued.
So Should We All Train Every Day?
In short, no. There's no need for that.
It's safe to say that only hitting a muscle group once per week is likely to impact on your strength and size gaining potential.
This is because when you train, your levels of Muscle Protein Synthesis (MPS) are raised. MPS is essential for recovery, adaptation, and getting bigger and stronger.
Following a training session, MPS increases rapidly, and reaches roughly double its baseline level at around 24 hours. It then declines rapidly, returning to baseline at around 36 hours. (6) This doesn't mean we all need to train every body part every 36 hours to maintain progress, but it does mean if you're only training your back once a week, or your legs once a week, or whatever body part once a week, you're not taking advantage of the extra MPS spikes you'd get from training more frequently.
Additionally, practicing a movement more frequency can aid skill development.
On the flip side, you can overdo it.
Recovery is a crucial, often overlooked aspect of building and maintaining muscle and strength.
It's very likely tougher sessions will give you DOMS (Delayed Onset Muscle Soreness,) which can last for 72 hours-plus, in some cases. While training with DOMS isn't necessarily detrimental, it does put you at higher risk of injury, and means performance may be compromised.
Similarly, your central nervous system needs recovery time, especially after more draining lifts, like squats or deadlifts, and so training these too regularly could certainly have a counterproductive effect.
So What Is Best?
That's going to depend on a lot.
We can fairly safely say that hitting a muscle group two to three times a week is the best best for increasing strength and muscle in a caloric surplus, or maintaining them in a deficit, which is why no matter which program you're following inside the platform, you'll be hitting major muscle groups and even most main lifts multiple times per week.
The bottom line is, the 'right' frequency is one where you're training often enough that you're getting bigger and stronger (or at least maintaining size and strength while losing fat,) and not training so frequently that you're feeling too beaten up or getting rundown and sick from overdoing the frequency.