Explosivelyfit Strength Training

Physiological effects of resistance training with different load intensities

Variations in the levels of resistance elicit different metabolic reactions that involve the breakdown and synthesis of proteins.

One of the goals of a lifter interested in gaining more strength is increased myofibrillar hypertrophy of the muscle fibers as opposed to sarcoplasmic hypertrophy. Myofibrillar is an enlargement of the muscle fiber whereas sarcoplasmic hypertrophy is characterized by an increase in the sarcoplasm (the semi fluid interfibrillar substance).

Loading intensities determine which is being developed and to what extent it progresses. Elite lifters develop the myofibrillar while the bodybuilders develop the sarcoplasmic side. The main difference in the two is the amount of volume and the percentage of the one repetition maximum to the load lifted during the training time. Myofibrillar hypertrophy training must be adjusted to “stimulate the synthesis of contractile proteins and to increase filament muscle density”.

According to the current energetic muscle cell hypertrophy theory the critical factor that determines the balance between protein catabolism and anabolism is the amount of energy available to provide for protein synthesis. If the resistance is small, then energy is available for both growth and muscle action.

However if the resistance is great then more energy is used for doing the muscular work, leaving little for anabolism thus protein is degraded within the cell. Striking the correct balance between intensity and volume to increase myofibrillar hypertrophy is the key to successful strength gain.

Review the following chart and see how it works:

As can be seen here the higher the resistance (percentage of 1RM) the greater the protein degradation, but also notice the amount of mechanical work is small which means the total amount of protein degradation is also small. Now compare the high load to the small load percentage and notice the protein degradation is also small. But for a different reason. That reason is the protein used for the heavy load is used in the contractile muscular elements of the muscles whereas in the small load it is lost in the mechanical work of the muscles.

The moral of the story is find a load and intensity that will balance out the rate and mechanical protein degradation nearly equally. This is the key to successful muscle myofibrillar hypertrophy, aka powerful and useful muscles that can be applied in your sport and not just in front of the mirror,

Science and Practice of Strength Training Zatsiorsky, V. M. Human Kinetics publishing 1995

Science and Practice of Strength Training Zatsiorsky, V. M. Human Kinetics publishing 1995

Danny M. O’Dell, MA. CSCS*D