Muscle Building: Hypertrophy And Physiology - How To Lift Weights To Maximize Mass!

Mountains of Rippling Muscle! What does it take to get there? Learn about the different types of muscle fibers, the physiology of muscle growth, training parameters that work best for hypertrophy, and sample training programs below!

So you want to gain muscle. There are many different programs and methods of training out there that are going to accomplish muscle growth. Add to that the fact that each individual is unique and that what may work for someone in acquiring muscle mass may not work for another person.

There are, however, general standards and principles that most 'mass gaining' training programs are based upon; and while many use traditional methods of training for hypertrophy, there are other ways to achieve the same, if not better, results. This article will discuss the different types of muscle fibers, the physiology of muscle growth, training parameters that work best for hypertrophy, and provide a sample program for muscle building.

Muscle Fibers and Types

Slow Oxidative Fibers

Slow oxidative fibers are commonly referred to as Type I muscle fibers. These muscle fibers are recruited first during activity, contracting slowly due to slow Myosin ATPase activity. Although Type I fibers have a high Myoglobin content, they contain low glycogen levels, using aerobic glycolysis for Adenosine Triphosphate (ATP) (i.e. energy) synthesis.

A high oxidative capacity, due to the many capillaries and mitochondria that they contain, allows them to have a slow rate of fatigue, therefore making them best suited for endurance activities such as distance running (Marieb, 2004).

Fast Oxidative Fibers

Fast oxidative fibers, also called Type IIa muscle fibers, are recruited second during exercise. Like Type I fibers Type IIa fibers have high Myoglobin content and many capillaries and mitochondria. However, instead of low glycogen stores, their glycogen content is moderate, causing them to be moderately fatigue resistant.

Alongside this, they have fast contractile speeds and Myosin ATPase activity, therefore making them best suited for activities that use both the anaerobic Glycolysis and aerobic Glycolysis energy systems, such as sprinting (Marieb, 2004).

Fast Glycolytic Fibers

Fast glycolytic fibers, the Type IIb muscle fibers, do not use oxygen for fuel, and are recruited third during activity. Type IIb fibers have few capillaries and mitochondria and low Myoglobin content. Although Type IIb fibers depend entirely on glycogen for fuel, despite having high glycogen stores, they fatigue quickly. This coupled with their powerful contractile ability and fast Myosin ATPase activity make them best suited for short-term intense or powerful movements, such as used in resistance training (Marieb, 2004).

Physiology of Muscle Growth

When muscles are used they adapt and change. Changes are dependent on the type of activity and muscle fiber types used, the load exerted on the muscle, and the velocity and duration of the contraction (Marieb, 2004).

Muscle growth, also referred to as muscle hypertrophy, is an example of muscular adaptations and changes.

Muscle hypertrophy occurs primarily through chronic anaerobic, high-intensity resistance activity, like that which happens during resistance training lifting weights (Brown, McCartney & Sale, 1990; Cureton, Collins, Hill, & McElhannon, 1988; Marieb, 2004; McCall, Byrnes, Dickenson, Pattany, & Fleck, 1996).

Resistance training causes neural adaptations, which result in changes in muscular endurance and muscular strength, and eventually, the size of the muscles (Fleck & Kraemer, 2004).

Resistance training causes an increase in the cross-sectional area (CSA) of all muscle fiber types (Brown, et al., 1990; Cureton, et al., 1988; Holm, et al., 1991; McCall, et al., 1996; Widrick, Stelzer, Shoepe & Garner, 2002), without an increase in muscle fiber numbers (McCall, et al., 1996).

Age and sex have been shown to influence the degree to which hypertrophy occurs in an individual (Martel, et al., 2005).

Training Parameters

Type Of Exercise

Anaerobic, high-intensity resistance training (Brown, et al., 1990; Cureton, et al., 1988; Marieb, 2004; McCall, et al., 1996) is the best exercise stimulus for muscle growth.

Training Splits

Current training status (beginner, intermediate, advanced) will determine what type of training split you should use. For example, a beginner or novice to resistance training would be best served with 2-3 resistance training sessions a week, working the FULL body each session, as working the full body produces more anabolic hormone than just doing the upper or lower body alone (Heyward, 2006).

Although the more muscle fibers activated during a session the better hypertrophy occurs, for the experienced or veteran trainee 3-6 day body-part splits would be recommended, as they need something more than 2-3 sessions a week or just full-body to stimulate further muscle growth, and can better adapt their training sessions for higher muscle recruitment and focus on a specific muscle or muscle groups.

Resistance Training Exercises

Exercises that build muscle the best are compound, multijoint exercises, as they recruit more of the body to perform the exercise (Heyward, 2006) and thus recruit and activate more muscle fibers (Charlebois, 2007).

The best compound exercises for hypertrophy are the squat and the deadlift, as they use pretty much every muscle in your body (Baechle, Earle & Wathen, 2000). Other compound exercises that are good to include are the power clean, bench press, shoulder press, pull-ups, and dips.

Mode Of Weights

Those wanting to gain muscle mass may want to use a variety of both free weights and machines to achieve hypertrophy. Although it does not matter how the load is placed on the muscle for muscle growth, research has shown that free weights such as barbells and dumbbells are superior to machine weights in muscle recruitment and activation, as they require more muscles to be used for any given exercise (McCaw & Friday, 1994).

Intensity And Volume

For those wanting to improve their muscular endurance alongside muscle gains, it is traditionally recommended to use low to moderate intensity (50-75% 1RM - standing for 50 to 75 percent of your 1 rep max) with a very moderate volume (3-6 sets of 10-20 reps, with 8-12 reps being the hypertrophy range) (Charlebois, 2007; Wathen, Baechle & Earle, 2000).

However, muscle growth is best achieved using heavy load resistance training of at least 70% 1RM (Holm, et al., 2008); and for those wanting to gain muscular strength as well as muscle mass, then high intensity (at least 70% 1RM), high volume (whether they be low or high rep, as long as they are high volume) training programs work extremely effectively to achieve this (Charlebois, 2007; Holm, et al., 2008).

Exercise Velocity

Although both fast and low velocity resistance training increases muscle CSA of all muscle fiber types, fast velocity training induces greater development of the muscle, especially in Type IIa and Type IIb muscle fibers (Shepstone, et al., 2005).

Progressive Overload

Progressive overload must continually occur in order to induce adaptations and changes resulting in muscular hypertrophy. Progressive overload can be achieved through several methods, including increasing the intensity of exercise or resistance/weight used while staying with the same set and rep range, increasing the volume by increasing the number of sets and/or reps at the same or higher weight, changing tempo and training velocity, rest periods, etc. (Fleck & Kraemer, 2004).

Training Program

Training programs such as the 5x5 or 6x6 work well for muscle growth, all of which are high intensity, high volume regimens. The 10x3 training program, created by Derek "The Beast" Charlebois (2007), is of a similar nature, with mass AND strength results achieved. For more information on the principles behind the 10x3 Training Program, read The Power to Be Pretty: Training for Strength and Lean Mass (Charlebois, 2007).

The following 10x3 training program is an adaptation of the original program. Recommended only for experienced and more advanced lifters, it is a 6-day a week program, and completed for 12 weeks requires dedication and sacrifice, but is well worth it in the end.

Monday: Squats

Tuesday: Squat Assist

Wednesday: Bench Press

Thursday: Bench Assist

Friday: Deadlift

Saturday: Back Assist

Sunday: Off


There are three different muscle fiber types in the body: Type I, Type IIa and Type IIb. The best type of activity for inducing muscular hypertrophy is resistance training. Factors such as age, sex and training status all affect and influence the degree to which hypertrophy occurs in an individual.

However, training parameters can be manipulated in the pursuit of muscle growth, including training splits, exercises, weight mode, intensity and volume of exercise, and training velocity, with the best hypertrophy regimes being high intensity, high volume, using compound exercises at a fast velocity that employ progressive overload over the program period. Through this, resistance training increases the CSA of all muscle fiber types.

Be aware that training is not ALL one must do to gain muscle. Nutrition is also highly important, and without the correct manipulation of diet toward hypertrophy, one can train as hard and as long as they want and still not get results.