Muscle hypertrophy, or the increase in muscle size, is one of the key goals of many fitness enthusiasts. Whether you're looking to add mass or build strength, muscle hypertrophy is the foundation of any successful training program. But how does muscle hypertrophy actually occur? What are the mechanisms that contribute to this process?

Well, buckle up, because we're about to dive deep into the nitty-gritty of muscle hypertrophy. To fully understand this process, we need to break it down into two main factors: mechanical tension and muscle damage.

Muscle Hypertrophy Mechanisms

Mechanical tension refers to the force that muscles generate when they contract. This tension is essential for muscle hypertrophy as it stimulates the mechanotransduction pathway. This pathway is activated when mechanical tension is applied to muscles, which initiates a cascade of chemical reactions that lead to protein synthesis, and ultimately, muscle growth.

Muscle damage, on the other hand, occurs when muscle fibers are broken down and damaged during exercise. While this might sound counterintuitive, muscle damage is a necessary component of muscle hypertrophy. When muscle fibers are damaged, the body responds by initiating a repair process that ultimately leads to muscle growth. This repair process involves the activation of satellite cells, which are specialized cells that fuse to existing muscle fibers and help repair and grow new muscle tissue.

But wait, there's more. Another crucial factor in muscle hypertrophy is metabolic stress. This occurs when muscles are subjected to high levels of metabolic stress, such as during high volume training, where multiple sets and repetitions are performed. The accumulation of lactate, hydrogen ions, and other metabolites during exercise creates a challenging environment for muscles, which leads to further activation of the mechanotransduction pathway. This, in turn, leads to an increase in protein synthesis and ultimately muscle growth.

So, to sum it all up, muscle hypertrophy occurs through a complex interplay of mechanical tension, muscle damage, and metabolic stress. To maximize muscle growth, it's essential to incorporate a variety of training stimuli that target each of these factors. This might include heavy resistance training to induce mechanical tension, high volume training to create metabolic stress, and exercises that challenge muscles in new ways to create muscle damage.

Types of Muscle Hypertrophy

There are two different “types” of muscle hypertrophy that are often considered. In other words your muscles can increase in size in two different ways: Sarcoplasmic and myofibrillar hypertrophy.

Sarcoplasmic hypertrophy is where there’s an increase in size of the non-contractile components within the muscle, and essentially the “fluid” within the muscle. For that reason it’s sometimes referred to as “non-functional” hypertrophy as it doesn’t result in a muscles ability to produce more force. If you’ve ever wondered why an individual can look much stronger than they actually are, it’s likely a product of their training resulting in greater sarcoplasmic hypertrophy and less neurological adaptations, among other factors.

It’s worth noting that “non-functional” isn’t an accurate way to describe this type type of muscle building. Sarcoplasmic hypertrophy brings about increases in your ability to store energy and glycogen within the muscle, which of course has a function to play in things like fuel availability. Sarcoplasmic hypertrophy usually occurs more as a result of higher repetition training methods.

“Functional” hypertrophy is also known as “myofibrillar” hypertrophy. The last time you heard about actin and myosin might have been in a high school biology class. But, it’s these myofibrillar proteins that make up around 20% of your muscles. Myosin being the most abundant of these. An increase in size and number of these creates a larger muscle and greater force-producing capabilities.

If you want your muscles to perform and be as strong as they look, you need to train them using progressively heavier weights and a variety of repetition ranges. Generally speaking, lower repetitions and more weight used for your sets will be better at creating more myofibrillar hypertrophy than higher repetition sets that are still within the muscle-building repetition range but encourage more sarcoplasmic hypertrophy. To grow muscle optimally then you want to encourage want both “types”.

What is Muscle Building Volume?

Volume is the total amount of work performed in an individual workout or entire week. When you say that you completed 6 sets of an exercise in your workout then you’re referring to the total volume of work for that muscle. Studies have shown a linear relationship with muscle growth up to around 10+ sets per muscle group per week. In other words doing more than 10 sets is better than doing 6 sets, which is better than 3 sets.

However, individual differences in optimal volume exist. This is due to genetic and lifestyle factors. While one person might achieve the best results at 22 sets per muscle per week, say, another may only need 8. Studies have shown this. Based on the available science, a good general recommendation for volume would be to complete around 10-20 sets per muscle group per week. You should also be willing to experiment to see what works best for you, and this is why keeping a detailed training diary is important. Outside of workout performance you should also monitor things such as your your daily energy, soreness, digestion, sleep and motivation to train. Adjust your volume accordingly.

What you’re not monitoring then you’re not managing!

What is Muscle Building Intensity?

Intensity refers to the amount of weight lifted. It’s a term often misused for someone describing how hard they’re working. Technically speaking though, it refers to the weight you’re lifting, and is usually expressed as a percentage (%1RM), or repetition maximum (RM). For example when doing 4 sets of 10 repetitions with a 12 RM, the intensity is the 12 RM or around the 70% 1RM you might be using.

Intensity directly relates to the number of sets you’ll aim to complete in a set. Since training to failure isn’t essential, for the most part you should be selecting an intensity that allows you to complete each set with one or two repetitions in reserve. This can vary based on a number of factors, but a good general rule to stick to. 

There’s an inverse relationship between the amount of resistance you use and the number of repetitions per set. The higher the weight you use (or lower RM or higher %1RM) the more sets you will also perform. That’s because a higher weight will require fewer repetitions which require more sets to get the same hypertrophy stimulus. For example both 2x20 and 4x10 will both have a muscle-building effect, but with more repetitions there should also be fewer sets per exercise.

The total number of repetitions you do each set will be based on those that maximize the development of lean muscle tissue. Hypertrophy studies have shown muscle can be built using a large variety of repetition ranges: Most of your time should be spent in the 8-15 repetition range, some of your time should be spent in the 16-30 repetition range, and few should be spent in the 5-7 repetition range. Regardless of repetitions, you should be completing these close to (1-2 reps short-of) failure. Many have a hard time growing any muscle using anything above 15 reps because it’s harder to gauge how close to failure they are, and those who don’t tolerate metabolic stress techniques well will finish their set earlier, or not use enough weight in these higher repetition ranges to build muscle.

So next time you hit the gym, remember these mechanisms, volume, sets and reps that contribute to muscle hypertrophy. With the right training program, consistent effort, and a commitment to proper nutrition, you can achieve the muscle gains you've been dreaming of. Stay focused, stay committed, and keep pushing yourself to new heights.

Ready to get bigger? Find out more about how to train for mass.

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