Resistance training systems: Matrix 21s

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

The matrix system can be utilised when performing most resistance exercises and involves breaking a rep down into three distinct phases – normally described as outer range, inner range and full range. Each phase is performed for 7 reps, giving a total of 21 reps, hence the name “21s” being synonymous with the matrix method.

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.

Active IQ, Level 3 certificate in personal training, programming personal training with clients (2014)

Join our Members Club

FREE Subscription to our Members Club newsletter - delivering motivational tips, advice and support for anyone aspiring to succeed in the health and fitness industry.