There’s a good chance that if you’ve trained in the same circles that i have and hung around the right people you have heard the topic of muscular hypertrophy being discussed amongst coaches, athletes and clients. If you are new to this terminology let me first give you a definition of the word.
Hypertrophy- the increase in the volume of an organ or tissue due to the enlargement of its component cells.
Now, to simplify this discussion, We are talking basically about muscle tissue here and the “increase in size” of said tissue. This often tends to send some people who are unfamiliar with the concepts of fitness, running in fear screaming “I don’t want to be bulky!!!” The simple facts are the if you don’t understand what the definition of and the different types of hypertrophy you are kind of sabotaging you efforts to get healthy and this knowledge put into your toolbox can help you get and stay in the shape that both safe and sustainable in the long run.
First we need to understand that all muscle tissue is not the same. It is generally accepted that muscle fiber types can be broken down into two main types: slow twitch (Type I) muscle fibers and fast twitch (Type II) muscle fibers. Fast twitch fibers can be further categorized into Type IIa and Type IIb fibers.
Slow Twitch (Type I)
The slow muscles are more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time. They fire more slowly than fast twitch fibers and can go for a long time before they fatigue. Therefore, slow twitch fibers are great at helping athletes run marathons and bicycle for hours.
Fast Twitch (Type II)
Because fast twitch fibers use anaerobic metabolism to create fuel, they are much better at generating short bursts of strength or speed than slow muscles. However, they fatigue more quickly. Fast twitch fibers generally produce the same amount of force per contraction as slow muscles, but they get their name because they are able to fire more rapidly. Having more fast twitch fibers can be an asset to a sprinter since she needs to quickly generate a lot of force.
Type IIa Fibers
These fast twitch muscle fibers are also known as intermediate fast-twitch fibers. They can use both aerobic and anaerobic metabolism almost equally to create energy. In this way, they are a combination of Type I and Type II muscle fibers.
Type IIb Fibers
These fast twitch fibers use anaerobic metabolism to create energy and are the “classic” fast twitch muscle fibers that excel at producing quick, powerful bursts of speed. This muscle fiber has the highest rate of contraction (rapid firing) of all the muscle fiber types, but it also has a much faster rate of fatigue and can’t last as long before it needs rest.
Keeping this in mind you can see that the different types of fiber serve us in different functions. For long range endurance athletes such as triathletes and marathon runners there would be a considerable amount of type 1 muscle fiber recruitment wherefore when looking at a power athlete such as a sprinter, olympic weightlifter, or a throwing athlete (shot-put, javelin, dwarf) you would see considerably more type 2 use. Then we get into other sports such as tennis, combats, soccer, lacrosse where you will see utilization of both. But I must digress at this point to bring it back around to the main topic of hypertrophy in the muscle cells and its different types.
Myofibrillar ~VS~ Sarcoplasmic
In the bodybuilding and fitness community and even in some academic books skeletal muscle hypertrophy is described as being in one of two types: Sarcoplasmic or myofibrillar. According to this hypothesis, during sarcoplasmic hypertrophy, the volume of sarcoplasmic fluid in the muscle cell increases with no accompanying increase in muscular strength, whereas during myofibrillar hypertrophy, actin and myosin contractile proteins increase in number and add to muscular strength as well as a small increase in the size of the muscle. Sarcoplasmic hypertrophy is greater in the muscles of bodybuilders while myofibrillar hypertrophy is more dominant in power athletes These two forms of adaptations rarely occur completely independently of one another; one can experience a large increase in fluid with a slight increase in proteins, a large increase in proteins with a small increase in fluid, or a relatively balanced combination of the two.
Sarcoplasmic hypertrophy is an increase in the volume of the non-contractile muscle cell fluid, sarcoplasm. This fluid accounts for 25-30% of the muscle’s size. Although the cross sectional area of the muscle increases, the density of muscle fibers per unit area decreases, and there is no increase in muscular strength . This type of hypertrophy is mainly a result of high rep, “bodybuilder-type” training .
One of the biggest problems I see with the training of power athletes (football players, baseball players, basketball players, wrestlers and even powerlifters) is too much emphasis on training in the 10 – 15 rep range. This type of training has its place, yet should not be the focal point for these athletes. For example, most football lineman benefit from added bulk to prevent from getting pushed around on the field. “Bodybuilding” methods, using these rep ranges, can be beneficial if incorporated during the season to prevent muscle mass loss, as well as after the season to add bulk, which may have been lost during the season. Also, there is some scientific evidence that states a bigger muscle may have a better chance of becoming a stronger muscle once maximal strength training methods are employed. The key to remember is that this type of hypertrophy has little to do with such explosive movements as hitting, running, throwing, jumping or performing a one-rep max. This is why professional bodybuilders, whose training mainly hypertrophies the Type IIA fibers and causes an increase in the non-contractile components of the muscle (sarcoplasmic volume, capillary density, and mitochondria proliferation) are not the fastest or even the strongest of all athletes. This is despite the fact that they generally have more muscle than any other class of athlete! I consider this type of hypertrophy to be form over function.
Myofibrillar hypertrophy, on the other hand, is an enlargement of the muscle fiber as it gains more myofibrils, which contract and generate tension in the muscle. With this type of hypertrophy, the area density of myofibrils increases and there is a significantly greater ability to exert muscular strength (2). This type of hypertrophy is best accomplished by training with heavy weights for low reps (3).
One must remember that the average football play lasts 4.5 seconds, it takes about 3 seconds to complete a 1 RM, it takes less than a second to swing a bat, less than a second to throw a punch and less than a second to jump for a rebound. As you can see, most athletic activities are explosive in nature. This is why it is imperative for athletes to incorporate maximal strength training methods (1-5 reps), which train the part of the muscle responsible for these explosive contractions, into their routines. Repetitions in the 1-5 rep range, using 85 – 100% of a 1RM, also have the added benefit of training the nervous system – which I feel is the most overlooked component of training the athlete. Some of the many benefits of training the nervous system are: increased neural drive to the muscle, increased synchronization of motor units, increased activation of the contractile apparatus, and decreased inhibition by the protective mechanisms of the muscle (golgi tendon organ) (1). These training methods also hypertrophy the pure fast twitch fibers – the high-threshold, Type IIB fibers. Incorporating these training methods into your routine at the right time will undoubtedly improve your muscles ability to generate more force and contract maximally during any sporting activity. In essence, myofibrillar hypertrophy is what I would term functional hypertrophy.
This also brings up the theme of what i describe as “educated muscle” or muscle that saves a purpose and function. Developing a higher rate of contractile power with myofibril hypertrophy will give you exactly that, the ability to perform tasks better by being able to generate more power. Many times we see an “athlete” who although they may be carrying muscle mass that muscle only seems to get in the way when they are given an athletic task to carry out. In combat sports you’ve heard it said “Buff aint enough.” When a ripped and jacked monster gets beaten around the ring or mat by a seemingly less athletic opponent. Dick Butkis , legendary Chicago football coach made the statement “Looks like Tarzan, plays like Jane.” although I know in this day and age “Jane” is fully capable of keeping up with with Tarzan or even surpassing his performance if she is put on the proper path of training.
Seeing this will also lead us to see that the “light-medium weight/ high reps” methodology that many people utilize might not be the most optimal way to actually get yourself down to a smaller size. I have many clients who have put on muscle mass and decreased size. In all actuality myself and my team have found great results for our athletes and clients by keeping them working in a 2-5 reps range using 80-90% of a modified 1 rep max. This is not saying that higher rep ranges are not at all useful but the point i am getting at here is the overall theme of getting strong, fast and explosive while decreasing overall body fat in the process.