Anyone who has ever gone into a gym has either heard or said the word “gains”. While most people say this as a joke, almost everyone that goes to a gym wants to gain or develop muscle. Any untrained individual will see improvements regardless of how or what they are training. Once you’ve experienced training for a long time and you wish to increase your muscular size, more specific training methods are required. The primary training method for achieving this is known as ‘hypertrophy training’. Hypertrophy is a technical term for the increase and growth of muscle cells, and can be broken down into two different types:

Myofibrillar Hypertrophy: 

This is the growth of the muscle fibers. Myofibril is the contractile protein of muscle fiber and is composed of actin, myosin, and other proteins. Without this, our muscles would be unable to contract. When myofibrillar hypertrophy occurs the number of myofibrils in the muscle fiber increases and thus leads to an increase in muscle fiber density and strength. This is seen primarily in powerlifters or other types of athletes, while this does not lead to the huge changes in size/muscle mass, it does help develop strength and muscle mass simultaneously. 

• This is typically performed at rep ranges from 3-5 reps (with rest times of 2-5 minutes) and greater amounts of sets from 4-6 sets. 

• Typically achieved by performing compound movements (ie. squats, deadlifts, bench press, etc.). This form of training leads to performance and size improvements. 

Sarcoplasmic Hypertrophy: 

The way most bodybuilders develop muscle mass (without as many gains in strength) is through Sarcoplasmic Hypertrophy. This refers to the increase in the volume of sarcoplasmic fluid within the muscle cell. This, unfortunately, leads to no actual increase in muscular strength and is typically defined as “the pump”. This is not long term and only lasts for a short period of time. Bodybuilders use this in combination with myofibrillar hypertrophy prior to getting on stage to maximize the size of their muscles and leads to a more “ripped” look. 

• This form of training typically occurs at greater rep ranges (10-15), slightly less sets (3-4), shorter rest periods (60 seconds), and fewer weights. 

• For most athletes, this form of training is not beneficial as it does not elicit significant improvements in strength, endurance, and/or power. However, this form of training for individuals looking to develop a more ‘chiseled’ physique is perfect for them.

Now that we’ve explained hypertrophy (developing bigger muscles, toning, and/or muscle definition), and the different types of hypertrophy, and what the benefits of it are there’s one important thing to mention. Hypertrophy training specifically works towards increasing muscle size, toning and/or definition but typically doesn’t affect strength and endurance training. While hypertrophy training still leads to some adaptations in strength and endurance it is not proportionate to the increase in size or muscle fibers. Certain adaptations require more specific training to elicit the desired results. Depending on the desired fitness goal, training always needs to be specific!

Okay, that is cool to know but how does one get ‘jacked’, how do we train to improve our size? The most recent studies suggest that training at a 10-rep max (RM), meaning once you complete your tenth repetition you cannot do an eleventh in order to maximize your training for hypertrophy. This leads to the most amount of motor units being recruited (discussed further below) thus promoting the greatest potential for size increases. Hypertrophy is mainly achieved via mechanical tension (muscular force produced) typically as a result of lifting heavy with compound lifts, and metabolic stress (going for higher reps aka chasing ‘the pump’ or ‘the burn’). This is achieved through movements that focus on isolating muscles. Examples of these types of movements are bicep curls, leg extensions, lateral raises, etc. 

In addition to this, a technique often used which can further help to improve and increase size, regardless of whether you are focusing on myofibrillar or sarcoplasmic hypertrophy is to ‘focus on the negative movement’. In essence, the lowering of the weight or in more technical terms emphasizing the eccentric portion of the lift. Maintaining tension throughout the lift as you are stretching the muscle (going down in your lift) can elicit much higher force onto the muscles leading to greater muscle damage. Muscle damage promotes muscle growth. This needs to be carefully executed because if you put too much stress onto the muscle you may risk injury even though increased stress onto the muscle is very beneficial. Stress on a muscle is very beneficial because it leads to much greater increases in muscle mass. It is advised to carefully use this technique or seek the guidance of a fitness professional.

Neurological Component:

Furthermore, scientifically speaking, there is also a huge neurological component to this type of training. The recruitment of motor units! Motor units function as the connection between your brain and muscles. Basically, your muscles take the order from the brain to contract and then make the muscle do so. The more motor units recruited the better. Studies have shown that hypertrophy training leads to the most recruitment of motor units which leads to the increase in muscular size and development. Greater amounts of motor units lead to even greater improvements in size as well as strength. With studies showing the greatest amount of recruitment in those performing a 10RM, and shorter rest periods, a caveat to this is that neurological fatigue (which leads to less motor unit recruitment) thus no longer providing the same benefits. This neurological fatigue begins to occur following the third set at the previously mentioned intensity for any given exercise. 

More motor units = more/bigger muscle fibers = larger muscles

While this is an oversimplification of the process and the science involved helps outline overall the picture. In conclusion, hypertrophy training is specific to training for size and muscle growth but it is not indicative of proportionate increases in strength and/or endurance. There are still improvements in this area, but it mainly impacts an increase in size. The main ways to achieve hypertrophy are through mechanical tension and metabolic stress, eccentric contractions, and this is best achieved and maximized through training at a 10-RM intensity. Lastly, if you want to work towards developing greater size/muscle mass be sure to follow either the myofibrillar hypertrophy; low reps (3-5), high load/weight, long rest periods (2-5 minutes), and 4-6 sets, with the focus on compound movements and improvements in both performance/strength and muscle mass, or sarcoplasmic hypertrophy; high reps (10-15), low load/weight, short rest periods (60 seconds), and 3-4 sets, with more focus on isolating movements and improvements strictly in muscle mass.

While this is an oversimplification of the process and the science involved helps outline overall the picture. In conclusion, hypertrophy training is specific to training for size and muscle growth but it is not indicative of proportionate increases in strength and/or endurance. There are still improvements in this area, but it mainly impacts an increase in size. The main ways to achieve hypertrophy are through mechanical tension and metabolic stress, eccentric contractions, and this is best achieved and maximized through training at a 10-RM intensity. Lastly, if you want to work towards developing greater size/muscle mass be sure to follow either the myofibrillar hypertrophy; low reps (3-5), high load/weight, long rest periods (2-5 minutes), and 4-6 sets, with the focus on compound movements and improvements in both performance/strength and muscle mass, or sarcoplasmic hypertrophy; high reps (10-15), low load/weight, short rest periods (60 seconds), and 3-4 sets, with more focus on isolating movements and improvements strictly in muscle mass.

References

Chertoff, J. (2019, February 26). Muscular Hypertrophy and Your Workout. Retrieved December 04, 2020, from https://www.healthline.com/health/muscular-hypertrophy 

Heywood, M. (2019, October 24). Sarcoplasmic vs Myofibrillar Muscle Growth: What's the Difference? Retrieved December 04, 2020, from https://myfitnessgear.co.uk/muscle-growth/sarcoplasmic-vs-myofibrillar-muscle-growth-whats-the-difference/ 

Roberts, M. D., Haun, C. T., Vann, C. G., Osburn, S. C., & Young, K. C. (2020). Sarcoplasmic 

Hypertrophy in Skeletal Muscle: A Scientific "Unicorn" or Resistance Training Adaptation?. Frontiers in physiology, 11, 816. https://doi.org/10.3389/fphys.2020.00816

Sprague, R. (2015, February 14). The Science of Building Muscle: 2 Ways to Maximize Hypertrophy. Retrieved December 04, 2020, from https://www.stack.com/a/sarcoplasmic-myofibrillar-hypertrophy 

Travis Pollen, T. (2015). The 3 Essential Workout Methods for Muscle. Retrieved December 04, 2020, from https://www.t-nation.com/training/3-essential-workout-methods-for-muscle 

Walker, S., Davis, L., Avela, J., & Häkkinen, K. (2012). Neuromuscular fatigue during dynamic 

maximal strength and hypertrophic resistance loadings. Journal of Electromyography and Kinesiology, 22(3), 356-362