Hot off the press is my new course “Shaping and Shifting Muscle”, which looks at muscle hypertrophy, architecture and fibre type.

Here is a snippet from the hypertrophy module around active and passive tension.

Muscular tension is produced by both force generation (active tension) and stretch (passive tension), and when these two are combined there may be an additive effect. When muscles are actively contracting, they can produce force either while shortening, lengthening, or remaining at a constant length (isometric). In all cases, greater mechanical loading can increase cross-sectional area (CSA) irrespective of contraction type, thereby confirming the key role of muscular tension.

Hypertrophy has also been reported after passive stretching of inactive muscle. Interestingly, when muscle contractile activity is reduced by means of  immobilisation, such as in space flight or due to injury, rapid muscle loss or atrophy occurs. This loss is accentuated when immobilisation occurs at short muscle lengths and attenuated when immobilisation occurs at long muscle lengths, as in a stretched position.

It seems that muscle fibres can detect the difference between mechanical tension provided by active contractions and passive stretching, and there is evidence that combining both active and passive loading can provide an additive effect to muscle growth. This has some interesting implications for programming. Find out more HERE.