When should you be lifting heavy and when should you be using lighter weights, and which is most beneficial?
Here’s a breakdown of the science and real life strategies that will help you know how to incorporate and structure both into your routine.
The short answer is – you should be training in all of these different rep ranges.
Define Your Weight Training Goals
Let’s start by defining heavy, light, and moderate weights.
Actually, let’s go with defining goals first. Because heavy is a relative term. So instead of defining light, moderate, and heavy loads, repetition ranges and relative load need to be determined first.
Traditionally, a low repetition program with heavy loads would use 1 to 5 repetitions per set working in the 80 to 100% of 1 repetition maximum (RM) to increase strength. A moderate rep scheme would use 8 to 12 reps per set with 60% to 80% of your 1RM. This was traditionally thought to maximize hypertrophy. This is why you see a lot of sets of ten when you start training. A high repetition scheme uses light loads and consists of 15+ reps per set with loads below 60% of 1RM. This is traditionally thought to improve muscular endurance.
But research (and working with clients) has shown that hypertrophy or muscle growth – we’re talking whole muscle growth here – can happen in a wide spectrum of loading ranges or percentages of your 1RM.
Usually with strength or hypertrophy training, the beneficial rep range is anywhere from 1 rep up to around 30 reps. We start to see some instances where it’s no longer beneficial to go over a certain rep point, and the literature points to somewhere around 25 – 30 reps for this. It can also be not so beneficial to always train in the super low rep ranges for a lot of reasons, but again, it all depends on your fitness goals.
What Is Heavy Weight Training?
Heavy weight training is a relative term. Let’s instead focus on heavy weight training as a low repetition program with heavy loads with 1 to 5 repetitions per set working in the 80 to 100% of 1 repetition maximum (RM) to increase strength.
Training with heavier loads is important. Even if you’re not a powerlifter, you should still be phasing in and out of heavier loading mesocycles. Generally, it’s good to utilize mostly compound movements for that 1-5 rep range. It’s hard to use more of those isolation movements in the 1-4 rep range just because it’s hard to maintain form as you’re doing really low reps and high weights. Compound foundational movements like squats and deadlifts definitely lend themselves well to the heavier loads.
With this type of training, you’re not going to “feel” the burn as much. This is a different type of feeling as far as fatigue goes. Your whole body is going to just feel tired over feeling the burn as you’re doing the movement.
Why Train With Heavy Weight?
Loading compound movements like squats, deadlifts, bench press, etc. super heavy is going to build raw strength. This type of training is also what’s going to build that dense muscle look. You can isolate muscles all day and get a sort of bubbly look, but deadlifting heavy is just going to make you a dense and almost indestructible human.
Several studies have found that training with low-loads (30−60% 1RM) results in similar hypertrophy to training with moderate and high-loads (>60% 1RM), and reaching failure or even close to failure at all times is not necessary to make significant gains in hypertrophy. Research also indicates that significant muscle growth occurs when the majority of your training sets are performed with ~3–4 reps in reserve which is around a 7 RPE.
What Is Moderate Weight Training?
Moderate weights are typically used in the 6-12 rep range. This is generally the rep range associated with maximal hypertrophy, but studies have shown that all of these rep ranges can build muscle if programmed properly.
What Is Light Weight Training?
With lighter weights, you’re going to most likely be doing a lot more reps. Light weight/high reps will be training muscular endurance, which has been defined as “the ability of a muscle to continue to produce submaximal force”. This is why definitions of rep ranges call anything above 12 or so “muscular endurance” training. So, lighter weights are in the 13-25 ish rep range. Obviously, with these rep ranges you’re going to be using lighter weights.
When to Train With Light Weight
Compound movements lend themselves to heavier loads, but you should also be doing them in these higher rep ranges as well. There is definitely some mental strength needed to get through a set of 20 reps of squats. With the lighter weights, you are going to be feeling more of that burn or “pump”.
However, the way to actually train muscular endurance is more nuanced than just utilizing higher rep ranges in your program.
A recent meta-analysis actually determined that if you want to be able to perform more reps with a particular percentage of your 1RM, even if your 1RM changes, it does work best to train with higher reps. However, if you want to improve your muscular endurance with a particular absolute load (unrelated to your 1RM and just with a specific number) you don’t necessarily need to do higher-rep endurance training to do so, because you are also getting stronger.
If, for example, 225 lbs is 70% of your 1RM and you can squat it for 8 reps, but you want to squat it for 10.
You can train sets of 10 until you get the capacity to get up to 225 in weight, but your 1RM might not change as quickly. So maybe 225 is still 70% but now you can hit it for 10. Great. You have definitely improved your muscular endurance.
But, you could also train lower rep ranges and increase your absolute strength (and by that I mean increase your 1RM) and then 225 would no longer be 70% of your 1RM because your 1RM is quite higher now that you’re stronger.
So, you can get 225 for 10 either way. The question is – what’s your overarching goal here? Do you want to also increase your 1RM and get stronger? Or do you really just want to train muscular endurance?
How To Weight Train Properly
In a balanced fitness routine, you should train some low reps and train some moderate/high reps to get stronger and improve your work capacity as well.
Some exercises lend themselves to heavier loads over lighter loads and vice versa. Some movements you can do all rep ranges and these are usually your compound movements. Bench press, for example, will provide a huge benefit if you’re doing 1-5 reps as well as 15-20 reps.
Here’s a template for phasing in and out of heavy rep range phases and lighter rep range phases.
Generally, a linear periodization protocol is especially great for people just starting out. This looks like starting off in the higher rep range of 10-12 reps for 4 weeks. Progressing to more moderate loads of that 6-8 rep range for 4 weeks. And then jumping to that heavier loading phase of 1-5 reps. Generally, we program phases for clients for about 4 weeks; this is because you need some specific adaptation to imposed demand. Meaning you gotta do the same sh*t to get stronger at it. So, 4 weeks tends to be a pretty good amount of time for many people.
There are so many nuances that go into how you program, though, like adding in tempo, pauses, and addressing weaknesses. But, the first question you want to ask yourself right now is what rep range do you normally train in? If you’re sticking in the more moderate rep range of 8-12 (the hypertrophy rep range) then you might want to think about jumping to a phase of heavier loads where you’re dropping the reps down to that 1-5 rep range and increasing load. This will be so good for you mentally and physically, because you’re providing your body a new stimulus you’re not used to; it’s a completely different mindset when jumping down to the lower reps and higher weights.
After that heavy loading phase, you can decide where you need to go next, as long as you’re progressively overloading. You can jump back to that more moderate rep range of 6-10 reps and add in more time under tension when doing so. Or you can jump to a higher rep phase and focus on work capacity if you need to. The main point is to not switch out of these rep ranges too quickly, so you’re giving your body enough time to adapt to the stimulus before switching it up. On the other hand, you want to make sure you don’t stay in a specific rep range/loading phase for a prolonged period of time, or else you’ll start to experience diminishing returns.
The Bottom Line On Weight Training
The most important thing to take into account, however, is frequency. How often can you actually work out? Start there. Then figure out the volume you need to see results (or your coach can) – then you can work backwards to figure out sets and rep ranges to hit the needed volume for the week.
Want to learn more about how and when to lift heavy vs moderately vs light? Check out our Stronger Than Your Boyfriend Podcast, Episode 57: Heavy Weight Light Weight.
Krzysztofik M, Wilk M, Wojdała G, Gołaś A. Maximizing Muscle Hypertrophy: A Systematic Review of Advanced Resistance Training Techniques and Methods. Int J Environ Res Public Health. Dec 4, 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950543/
Nuckols, Greg. Does high-rep training actually improve strength endurance more than heavier training? Stronger By Science. https://www.strongerbyscience.com/research-spotlight-high-rep-training/
Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Feb 22, 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7927075/