Training Loads: the “Sweet Spot” for Muscle Hypertrophy


You know you have to challenge your muscles to make them grow. Muscles increase in size in response to overload, a condition where they’re forced to deal with resistance greater than what they’re accustomed too. Makes sense, doesn’t it? If a muscle or group of muscles has to push against more weight than it routinely does, it grows larger and stronger to make the job easier. Your body has an amazing ability to adapt to the stress placed on it.

While the concept of overload is simple enough to understand, there are different degrees of overload. In other words, you can overload your muscles a little more than they’re used to or a lot. If you train with a resistance that’s only slighter heavier than what your muscles can easily handle, you can do a greater number of reps, or a higher volume, before the muscles fatigue. If you use a very heavy resistance, the number of repetitions, and, therefore, the volume you can do, will be less since your muscles will tire more quickly.

So, if you’re trying to build muscle size, or hypertrophy the muscles, what is the best approach? Is there a “sweet spot” in terms of load and volume and which your muscles can best grow? Research shows you should fall somewhere in the middle of the high intensity – low rep and low intensity – high rep continuum if your main goal is to build muscle size.

The One-Rep Max Test

To select an appropriate load to use for training, fitness trainers sometimes use the one-rep max test, the purpose of which is to find the heaviest weight you can lift a single time using good form. In practice, it’s easier to measure one-rep max using a sub-maximal strength measurement since it’s safer than working with a heavy weight you can only handle for one rep. Instead, some fitness trainers use a 10-rep max test.

With the 10-rep max test, you find a weight you can lift only 10 times before experiencing muscle failure. Once you’ve identified that weight, you plug it and the number of reps you did into a one-rep max calculator to determine your one-rep max. These calculators are available online and in our free workout Manager. For example, if you lifted 100 pounds for 10 reps, plugging the values into the calculator shows you have a one-rep max of 133 pounds.

Once you know your one-rep max, you can use it to select the appropriate training load based on the goal you’re trying to achieve. If your goal is to build maximal strength, you’ll maximize your results by working at a high percentage of your one-rep max – between 85 and 95%. Because you’re using such a heavy load, you’ll only be able to complete between 5 and 1 reps.

Building Size versus Strength

What about maximizing hypertrophy? Working at a high percentage of your one-rep max is ideal for building strength, but not as much for hypertrophy. To build muscle size you need more training VOLUME than working with a very heavy resistance allows. Unlike strength training where you maximize the benefits using a heavy load and volume is less important, volume IS important for hypertrophy gains. Studies show that to hypertrophy muscles to a significant degree, you need a load that’s at least 75% of your one-rep max. This is a resistance that usually allows you to complete 8 to 10 reps before muscle failure.

You can push the load a little higher and still generate enough volume to build muscle size, but should avoid doing most of your training at 90 to 100% of your one-rep max because you can’t do enough volume to maximize growth. Yes, you’ll get stronger and build some size but you won’t maximize your hypertrophy gains. In general, work with a resistance that’s between 75 and 80% of your one-rep max when you’re hypertrophy training.

Periodization for Greater Gains

Of course, if you consistently work at 60% to 80% of your one-rep max, even with progressive overload, your muscles will eventually adapt to that routine and stop growing. One way to get around that and to build strength, hypertrophy, AND endurance over a period of time is to periodize your workouts. Periodizing means rotating through different training cycles also referred to as mesocycles as you will find in my STS workout series, where you focus on one goal or type of training for a period of time. The training cycles can vary in length, but a two to four weeks per mesocycle is common.

For example, during the first mesocycle, you could focus on lifting lighter weights (around 60% of one-rep max) and high volume to build muscle endurance. During the second one, the focus might shift to hypertrophy training where you train at 75% to 80% of your one-rep max. During the third mesocycle, you might increase the resistance to 85% to 95% of your one-rep max and lower the volume still further to concentrate on strength. With this type of periodization, you’re moving from low intensity and high volume to high resistance and low volume in a cyclic fashion.

Some people also incorporate power training into the cycle. It depends on your goals and objectives. All the mesocycles taken as a whole is called a macrocycle. A macrocycle may be several months or more than a year long, depending on how long each mesocycle is.

There are a variety of periodization schemes, including linear and non-linear periodization, which we won’t go into here, but the principle is to vary the modality you’re working cyclically. The benefits? By periodizing your workouts, you reduce the risk of overtraining and avoid plateaus by exposing your muscles to different volumes and intensities. Plus, you’re continuously challenging your body in a different way. Some studies also show that periodized programs yield better results than non-periodized ones.

The Bottom Line

To maximize muscle strength, lifting a heavy load is your biggest priority, using good form, of course. For maximal muscle growth, strike a balance between using a heavy load and achieving enough volume. The “sweet spot” is between 75% and 80% of your one-rep max. Try to take it to failure on at least one set. To avoid plateaus and overtraining, consider periodizing your training using one of the many periodization schemes available.



Essentials of Strength Training and Conditioning, 2: 395-425. (2000)

ACE Fitness. “Periodized Training and Why It Is Important”

Medicine & Science in Sports & Exercise, 33, 635-643.


Related Articles By Cathe:

Strength Training: To Get Stronger, Rest Longer

One-Rep Max: Are You Lifting Heavy Enough?

4 Reasons We Lose Strength as a Result of Loss of Muscle as We Age

Is There a Threshold Intensity at Which You Need to Train for Muscle Growth?

Can You Build Strength Lifting Lighter Weights?

New Study Sheds Light on Best Way to Build Strength


Related Cathe Workout DVDs:

STS Strength 90 Day System





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