It really cracks me up when I walk into a training facility and I see someone performing a compound movement such as; power clean, deadlift, squat, bench press, etc…
And they are performing 8-12 reps thinking they are focusing on strength & power development. There is nothing wrong with performing 8-12 reps on those given lifts, except for the “power clean”. Now if your main focus is strength & power development 8-12 reps is dead wrong!
This is why understanding rep ranges and how they relate to the two types of hypertrophy is so important. So let’s break it down! Rep ranges 1-6 = Strength & Power, Rep ranges 7-12 = Hypertrophy and Rep ranges 13 – above = Endurance.
When weights are lifted micro-traumas occur to the muscle fibers. The three phases of dynamic movement: Eccentric / Isometric/ Concentric muscle actions cause damage. Especially if the lifter is using progressive overload and forcing the muscle to adapt to a new stimulus. When the muscle fibers are damaged, the body repairs itself by various means. It does not want damaged muscle fibers, so it will rebuild them. The body will also recognize that it needs more muscle to meet the demand imposed on it, so it adds muscle. It breaks down proteins in the damaged muscle and adds more protein on top to create the additional muscle. This added effect is made in small amounts so it does take quite some time. Adding muscle is called hypertrophy.
There are two types of hypertrophy. One is “functional”, or myofibrillar hypertrophy. The other is “nonfunctional”, or cytoplasmic hypertrophy. Myofibrillar hypertrophy develops from the use of heavyweights. This is typically a much slower means of gaining muscle size, but the increase in the size of the muscle fiber increases the strength of the muscle fiber. This hypertrophy occurs in actin & myosin heads within the muscle, which increases the strength of contraction. Cytoplasmic hypertrophy develops from using lighter weight and higher volume. It taxes the muscle, but not in how much it is able to move. The damage to the muscle is different. Myofibrils do not increase, but the space in between the sarcomeres does. This type of hypertrophy does not feature consistency between the size of the muscle and the force it can produce, which is why it is called nonfunctional.