Definition
Myofibrillar hypertrophy refers to muscle growth that occurs from increasing the number and density of myofibrils, the long protein chains that make up muscle fibers.
Explanation
- Myofibrils are thickened and multiplied with progressive overload training, especially higher weight and lower rep ranges.
- This expands the cells’ capability for contractile force and power output. It makes up ‘quality muscle.’
- Myofibrillar hypertrophy leads to gains in strength that accompany size gains with heavy, compound lifting.
- Sets of 1-8 reps recruit the highest threshold motor units in Type II fast twitch fibers to stimulate myofibrillar growth.
Examples
- The sustainable muscle built using heavy weights with enough time under tension.
- Powerlifters’ predominantly myofibrillar hypertrophy increasing contractile strength.
Related Terms
- Sarcomeres, Type II muscle fibers, contractile elements, 1RM strength
Common Questions
- Does myofibrillar hypertrophy make you appear bigger? Less than sarcoplasmic growth, but provides dense muscle cell strength.
- Is it better than sarcoplasmic hypertrophy? They complement each other. Myofibrillar provides strength and function.
Do Not Confuse With
- Sarcoplasmic hypertrophy – Increased volume of sarcoplasm fluid around fibers.
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