Strength training increases the cross-sectional area of the muscle.  What exactly occurs during adaptation to resistance training within the fibers metabolically and structurally is a continuum of scientific research.

The term Sarcoplasmic Hypertrophy has become a descriptive term and a point of study.  Sarcoplasmic hypertrophy refers to an increase in the volume of sarcoplasmic fluid in the muscle cell.  The fluid and its components are an energy resource surrounding the myofibrils in muscle.  It has been purported in the scientific literature that, “.... higher volume resistance training may facilitate fiber growth through a disproportionate increase in the volume of sarcoplasm relative to myofibril protein accretion.”

Until recent years it has been assumed and accepted by the scientific community that when a muscle significantly increases its cross-section the percentage of intracellular space consumed by myofibrils, myofibrillar protein and sarcoplasm volume is predictable.

What is becoming mainstream thinking is that, by increasing the volume of  sarcoplasmic fluid in the muscle cells you can maximize the size of the muscle, not necessarily the actual muscular strength. This gives credence to the term in bodybuilding - ‘pumped’.

Currently, sarcoplasmic hypertrophy of skeletal muscle is in its infancy and much of the researchers' conclusions are from a theoretical and mechanistic perspective. A great read on the subject is found in the journal, Frontiers in Physiology,Sarcoplasmic Hypertrophy in Skeletal Muscle: A Scientific “Unicorn” or Resistance Training Adaptation?”

The following is an example of Sarcoplasma Stimulating Training and one of the many methods being used. 

  1. Choose a weight at 70–80% of 1RM and train until volitional fatigue

  2. Rest 20 seconds and repeat

  3. Rest 20 seconds and repeat

  4. Remove 20% of the load and this set lower each rep in 4 seconds, pause 1 second and repeat additional reps in the same manner until failure

  5. After 20 seconds of rest lower each rep in 4 seconds, pause 1 second and repeat additional reps in the same manner until failure

  6. Rest 20 seconds and do an isometric hold at right angle of joint flexion

Pendulum Shoulder/Incline