Muscle Mania Part VI: Training Talk 02
Exploring Training Frequency/Split Selection and Repetition Tempo
Last time in the Muscle Mania Series (I, II, III, IV, V), we started picking apart how key training variables contribute to hypertrophy. Here, we’ll continue down this path, moving on from volume, proximity to failure, and intensity – what I consider to be the most pivotal factors in a resistance training program – to some other important variables to consider: frequency/split selection and tempo. Without further ado, check out the recap below for a refresher of pertinent information and concepts we’ve discussed thus far, then dive right in.
Check out my reference list for Part VI here.
Recap
Muscles are ultimately composed of contractile proteins, called myofilaments, which are organized into structural units, called sarcomeres.
Muscular hypertrophy, or muscular growth, involves building and incorporating myofilaments into sarcomeres to grow the overlying muscle.
Muscle hypertrophy and atrophy are the results of an interplay between muscle protein synthesis (MPS) and muscle protein breakdown (MPB); interestingly, both processes are essential for building muscle.
Protein synthesis involves a macro-level signal (like lifting weights or eating protein) inducing a cellular signal at the micro-level, which provokes transcription of specific parts of the cell’s DNA (i.e. specific genes) into mRNA, the translation of that mRNA by ribosomes, and the construction of the correlating proteins. During muscle protein synthesis, those genes code for specific muscle proteins that will be incorporated into sarcomeres.
Our muscle cells utilize 3 pivotal processes to initiate and propagate hypertrophy: ramping up muscle protein gene expression by activating transcription factors, increasing nuclear capacity via satellite cell addition, and expanding translational capacity through ribosome biogenesis.
Key molecules involved in hypertrophy-related cell-signaling include mTORC1, Akt/PI3K, Myostatin, MAPKs, and intracellular calcium; additionally, key hypertrophy transcription factors include MEF2, SMAD2/3, SRF, UBF, and Pax7.
Mechanical tension, the force placed on a muscle fiber during contraction, is likely the key mechanism for initiating hypertrophy-related cellular pathways; however, some suggest that metabolic stress and/or muscular damage play supportive roles in the process of instigating muscle growth.
It makes the most sense to take hypertrophy research with a grain of salt, due to small sample sizes, small effect sizes, and biological variability; furthermore, rather than blindly following the research, it is most reasonable to combine expert opinions and study results with your own experience when considering your own exercise strategies.
Progressive overload, the process of gradually switching up the stimuli in your training in order to challenge your body and produce further adaptations, underlies all exercise programming.
Volume load, the total amount of weight moved during a training session – easily calculated as (weight) x (reps) x (sets) – is likely the cardinal variable in a resistance training program. In terms of sets per week, volume and hypertrophy seem to exist in a graded-dose response relationship, meaning that greater volumes produce greater hypertrophy up until a maximum threshold of beneficial volume. In terms of volume per session, it appears that more sets produce more hypertrophy up until about 6-10 sets per muscle group per session where the benefits begin to plateau.
In general, it appears that training to absolute failure does not provide superior hypertrophy as compared to training near failure, provided that volume is equated; nonetheless, it is reasonable to imagine that there is a minimum threshold of proximity to failure for inducing hypertrophy, and some research suggests that training to failure becomes more important for more advanced lifters and when training with lighter loads.
Research shows that you can achieve significant and comparable amounts of hypertrophy with weights ranging from 30%-90% of 1-rep-max (1RM), provided the sets are taken to failure and volume load is equated.
Frequency and Split Selection
Now, all of the technique and programming in the world isn’t worth a dime if it doesn’t fit into your schedule. For this reason, frequency, or how often you train each muscle group per week, is as important as any variable from an efficacy standpoint; similarly, your ideal training split – the schedule of which muscle groups you exercise each training session – which goes hand in hand with training frequency, is dependent upon your availability and desired time commitment. But, how do these variables fair in terms of effectiveness? In other words, feasibility aside, do different training frequencies and weekly splits result in different amounts of hypertrophy?
Similar to that for intensity, research around frequency suggests that a broad range of 1-4+ sessions per muscle group per week provides comparable hypertrophy results, provided that volume load is equated for. (I, II, III, XVI) In other words, as long as you are meeting the same volume load, you can achieve similar muscle growth whether you are training a muscle once, twice, three, and even four plus times per week. With that said, as we discussed in Part V, it appears that the upper limit for the optimal volume per session is around 6-10 sets per muscle group when using 90-120 second rest intervals between sets; consequently, it may be necessary to increase frequency if you are chasing greater than 10 sets per muscle group per week. (I, IV, V, VI, VII, VIII, IX) Breaking your volume up into multiple sets per week may provide advantages from psychological and set quality stances as well, in that mental fatigue may decrease your force output and increase the likelihood of form breakdown in the latter half of a longer training session – the former of these issues ultimately leading to less volume load and less total mechanical tension.
In addition to avoiding volume overload in one session, Dr. Mike Israetel, PhD in sports physiology, recommends approaching frequency from a common sense point of view, where you take as much rest as is necessary to complete the next training session with high quality and effort at the desired intensity. In other words, if you still can’t sit on the toilet without wincing from the soreness in your glutes, you probably aren’t recovered enough to hit leg day hard again, and doing so prematurely will likely impede your muscle growth rather than propagate it. Interestingly, due to the repeated bout effect (RBE) – the attenuation of post-training soreness and decreased physical performance that occurs after recurrent training – the time it takes to reload before your next training session likely declines the more you train in a given medium or fashion. (I, II, X, XI, XII)
Check out this video from Renaissance Periodization for Dr. Mike Israetel’s full recommendation on training frequency.
All of these points on frequency, suggest that no training split – whole body, upper/lower, push/pull/legs, bro split, etc. – is better than another de novo; rather, they suggest that the split that allows you to consistently train at your desired volume load, effort, and intensity is best for you. If you are looking for the minimum effective dose (M.E.D.), this could lead you to one full-body session per week; whereas, if you are a trained lifter aiming to maximize your muscle gain, you likely should find yourself in the gym multiple times per week and hitting each muscle group multiple times to accumulate a high weekly volume. So, aside from meeting weekly and per-session volume targets, it appears that whatever training split(s) allows you to train consistently, comprehensively, and with high quality and effort is ideal.
Tempo
One of the first things you’ll notice in the resistance training world is the wide variety of speeds with which lifters perform their reps. On one hand, you have the heavy hands, accepting a torso swing in exchange for maximizing the intensity of their set of 8 bicep curls; whereas, on the other hand, you have Mr. and Mrs. fundamentals, meticulously controlling every inch of movement in their 15 incline presses. Tempo, the speed with which you perform each repetition, is one of the most commonly exploited variables in resistance training, and it can be broken into three main components: concentric, end-range (isometric), and eccentric. The concentric portion of the movement is that in which you are contracting and shortening the muscle of interest; whereas, the eccentric portion consists of lengthening that muscle. In a bicep curl, for example, the upwards movement is concentric, and the downwards movement is eccentric. The end-range portion constitutes the farthest point in the concentric movement where lifters commonly pause to maximally activate the muscle of interest – in this case, the bicep.
Although classically associated with muscle damage, more modern thought surrounding the mechanisms of hypertrophy described in Part IV connects tempo to mechanical load and metabolic stress, in that focusing on the timing of different portions of a movement can impact the total load and metabolic demand placed on target muscles. The loading aspect makes sense when you consider that the maximum amount of weight you can safely lower is greater than the total amount of weight you can safely lift. With this in mind, you can understand that tinkering with different tempo’s – for example, 2 second concentric, 0 second pause, and 1 second eccentric vs. 1 second concentric, 1 second pause, and 4 second eccentric – could allow you to use different intensities and induce different total mechanical loads on your muscles. Tempo, in theory, should also impact metabolic stress, in that longer repetitions and sets should lead to greater hypoxia and metabolite accumulation.
For a deep dive into how repetition tempo impacts strength and muscle gain, check out this review by Wilk et al.
In terms of the optimal tempo for hypertrophy, research focusing on repetition duration while controlling for other training variables suggests that such a range, if one necessarily exists, is wide. (I, XIII, XIV) In their 2015 meta-analysis on the topic, Schoenfeld and colleagues found that total set durations of 0.5-8 seconds showed similar degrees of hypertrophy; whereas, “super slow,” training with total set durations greater than 10 seconds was inferior for muscle growth. (XIV) In contrast, Wilk et al.'s 2021 review found that super slow training was effective in some instances, but that no one tempo was definitively superior; however, they did generally recommend prioritizing faster concentric movements and slower eccentric movements. (XIII) As Wilk et al. alluded to, though tempo appears to have little influence on its own, it is inherently important due to its effects on volume load, intensity, and proximity to failure. (XIII) In particular, tempo can largely impact volume load if you consider time under tension as a fourth variable in the volume load equation. In other words, instead of (weight) x (reps) x (sets), maybe the equation should look like (weight) x (reps) x (sets) x (time under tension) in order to precisely track the mechanical load placed on the given muscle. Nonetheless, for the most part, it appears, provided that weekly volume, per-session volume, a minimum of 30% 1RM intensity, and a close proximity to failure (~5-0 reps away) are all accounted for, choice of tempo within 0-10 seconds will not have a large impact on hypertrophy outcomes.
With that said, tempo’s greatest contribution could be maintaining proper form and maximizing tension on the target muscle by limiting momentum and swinging during the given movement. In this way, using a restricted tempo on the concentric or eccentric portions of a movement or using an isometric pause at the end-range of the movement could help maximize tension on the target muscle and improve the lifter’s mind-muscle connection – their ability to selectively activate the target muscle, rather than other supporting muscles. Interestingly, some research suggests that focusing on the mind-muscle connection, rather than simply moving the weight, can lead to greater hypertrophy over time (12.4% vs. 6.9% relative increases in biceps thickness over 10 weeks), likely because this creates maximal tension on the target muscle instead of dispersing the load across other muscles. (XV)
Check out this article for Dr. Peter Attia’s take on how eccentric training impacts the risk of injury with aging.
Til’ Next Time
Stand fast for Part VII of the Muscle Mania Series (I, II, III, IV, V), where we’ll break down some more training variables and continue building our hypertrophy arsenal. In the meantime, if you enjoyed this Shortcut, check out similar Shortcut U content below.