Resistance training systems: Matrix 21s

pump those guns with 21s

This training method is one of the first training systems that most gym users are exposed to, generally in the form of “21s” for bicep curls.

The matrix system can be utilised when performing most resistance exercises and involves breaking a set into three distinct phases: outer range, inner range, and full range. Each phase is performed for 7 reps, 21 reps in total, hence the name “21s”.

A set of “21s” for bicep curls would be performed as follows:

  • 7 reps from extension to 90 degrees of elbow flexion
  • 7 reps from 90 degrees of elbow flexion to full flexion
  • 7 reps full range of movement

The premise of the matrix method is it increases time under tension per set and thus promotes an increase in hypertrophy.

Check out the example in the video below:


If you would like to learn more advanced training systems like these then check out our level 3 personal training course.

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