First off, the title might be misleading. Progressive overload on the one hand is a seemingly simple concept; do more than you did last time. The “more” however, is where most people’s understanding needs clarity. Does progressive overload just mean more weight on the bar? Or more reps and sets? Before we get into the "simple" tenets to ensure progressive overload and how to ensure that you’re meeting the requirements, let’s look at what we mean by the term.
Progressive overload is the continued adaptation to a progressively larger stressor that is big enough to disrupt homeostasis to induce higher levels of strength or hypertrophy (or any other fitness attribute).
So in a very simple sense, it CAN mean adding more weight to the bar each session, but in reality, what we’re after is novel physiological stress (or stimulus) over time that results in positive adaptation.
Physiologically, when we train and are required to produce force we recruit muscle fibers to meet those force demands. When heavier loads are introduced or we fatigue, we need to recruit additional muscle fibers to continue to be able to move the weight. The magnitude of the load as well as the number of muscle fibers called on to meet the force demands dictates the amount of tension that is placed on the muscle. Over time, and if the tension is sufficient we see an increase in protein filaments that contract, which, when they grow the produce more force upon contracting. More force ability means more tension handling ability, which means a greater threshold for tolerance, and this requires more stimulus to continue the positive adaptation process.
Why is load important for progression and hypertrophy?
When lifting heavy loads for fewer repetitions, a large % of muscle fibers are recruited from the very beginning of the set. This is just a natural requirement to be able to move the weight from A to B, which at heavy loads requires greater force production from the get-go. This would come under the umbrella of mechanical tension, which it’s pretty much accepted sits in the driver’s seat when it comes to driving hypertrophy. But, lighter loads lifted for higher reps can also recruit a large % of fibers, albeit at a slower rate. Muscle fibers that are known as “low recruitment” (think of these like the first few people that get picked for sports teams) get fatigued first, and “high recruitment” need to step in to pick up the slack (these are our last picks to round out the team). These high recruitment fibers will also eventually get fatigued as we get closer to failure and force production drops, which will place them under mechanical tension also.
This means that both the low rep and high rep training is useful for hypertrophy, but in both cases, the goal should be to get stronger in whatever rep range. Practically though, it can make more sense to stick to low to moderate rep ranges depending on the exercise, due to the recoverability factor. 20 rep squats are no joke, and if these are done at the beginning of a session, good luck trying to complete the rest of the session with any appreciable load and effort. That’s not to say it can’t be done, but from a cost to benefit perspective, might there be a more “optimal” approach. Following this line of thought, higher rep sets might make more sense to include for exercises where there is less neural and global fatigue as the likelihood of completing these exercises with quality is higher.
Where does volume factor into progressive overload?
Volume can be described as the total workload of a given exercise or session, often expressed as reps x sets x kg. While higher volume does not necessarily equal greater levels of hypertrophy, it often matches up with the requisite stress that initiates the process by which we get bigger and stronger. Below is an example of where volume would not equate to hypertrophy:
Week 1:
Leg extension 3 x 15 @ 40kg
Week 2:
Leg extension 3 x 20 @ 40kg
There has been an increase in volume from week 1 to week 2, an additional 200kg lifted, but how much of this has been “effective” volume. If we keep in mind that load and how close the muscle fibers are to failure dictate how much muscular recruitment and tension is taking place, simply doing 5 additional reps with the same weight the following week doesn’t mean anything. If neither of these sets was close to failure, then all we’ve done is increase repetitions at a moderate effort not enough to induce the positive adaptations that we’re after. Add into this that it can be hard to gauge failure the higher reps the sets become because what we perceive as actual muscular failure can be muddied with cardiovascular fatigue and localised pain. There have been many times when training individuals with a relatively short training age, who have told me that they can't do any more reps, and then incredibly manage another 8 to 10.
If on the other hand we’ve only been able to lift a weight for a true 7 reps, which is easier to determine as the heavier load will result in earlier fatigue of muscle fibers, and the following week we can lift the same weight for 8 reps (more volume), then we know that progressive overload has taken place.
The other danger with relying on volume too much can mean that trainees can often reach a point of diminishing returns when it comes to the total work done. Many general population trainees could usually do with something being taken away from their programme rather than having anything extra put in. 25 sets per muscle group per week is a fairly significant amount of volume, but if only half of these sets involve reps that are taken close to failure to produce the homeostatic disruption necessary to signal hypertrophy, then are we just throwing more sprinkles on the cake after it’s already covered? This is where the term junk volume is often applicable. This is additional volume beyond what is required for growth, which can also be a limiting influence on the intensity of work we’re putting into the minimal effective volume that is needed.
Navigating a path forward?
Both volume and load are tools to use at appropriate times to induce progressive overload in training. However, understanding what progressive overload is and what it isn’t, is crucial to know when to implement those tools and when they are actually effective. Remember, it’s not just adding weight to the bar that does the trick. Nor is it a case of adding a set each week of low effort work and thinking this is the magic bullet. The underlying mechanism taking place here is that the heavier weight and additional volume provide a potent enough disruption to our body’s homeostasis that results in physiological adaptations over time that raises our threshold.
From a practical perspective for programme design, it can make more sense to stick to moderate load and moderate-heavy weight for the bigger compound lifts to manage performance and recovery and implementing some higher rep work for isolation and machine exercises. Either way, you’ll want to focus on getting stronger in that rep range, and managing the volume of work you’re doing with the efficiency and intensity of that workload.
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