The first proof that the muscle 'architecture' of specific groups of athletes is related to their performance has emerged from a study comparing the muscular system of sprinters with distance runners.

We have known for some time that sprinters have a higher relative proportion of fast twitch muscle fibres, capable of contracting faster and producing higher forces, so giving a performance advantage in sprint events. But until now no study has established whether sprinters' muscles have a different architecture from those of distance runners, particularly in relation to the length of muscle fibres and the muscles' angle of attachment to connective tissue (the 'pennation angle'). In this study, 23 sprinters with 100m personal bests of 10.0-10.9 seconds were compared with 24 distance runners with 5km PBs of 13.5-14.5 minutes, and 24 non-athletic controls. Muscle size, distribution and architecture were determined by ultrasound imaging.

The key findings were as follows:

* Sprinters' muscles were thicker than those of distance runners and controls in all groups except the forearm and lower front of thigh;
* Sprinters had longer fibres in their vastus lateralis and gastrocnemius muscles than distance runners, with a smaller pennation angle in both muscles;
* Sprinters had longer muscle fibres than distance runners in relation to limb length. Both the longer fibres and smaller pennation angle give the sprinters a physiological advantage for high speed muscle contractions over the distance runners.

Abe et al (2000) Med Sci Sp and Ex, 32(6) 1125-1129
 

Raphael Brandon