Centre of Gravity and Base of Support

The centre of gravity (COG) is an imaginary point through which gravity acts on an object, it is the point where the entire weight of the body is concentrated (point of balance). A shift of the segments or limbs of the body results in movement of COG.

The base of support (BOS) is the area beneath and between the points of ground contact of an object (i.e. foot contact). The BOS is necessary in creating balance, a wider stance and or staggered/split stance enhances stability whilst a narrow BOS attributes to instability (see COG and BOS).

The distance between the COG and BOS is of high importance in retaining stability, the closer they are, the more balanced an object becomes with instability being exacerbated with larger distances (Video Description).

Wherever the COG is concentrated also aids in trajectory of an object, the body will follow the direction of the COG when a force is applied. The link to the right features a prime example of Usain Bolt and his sprinting stance upon starting a race. Note his COG out in front of him, this leaning aids in propulsion of his body.

The above points explain why when observing a professional sporting activity; the players usually adopt a lower COG in a widened or staggered stance (e.g. low driving movement for a tackle in Rugby Union). These movements are important to create stability during activity to (i.e. lessen chances of being knocked down) and improve the efficiency of movement (i.e. efficiency in weight transfer and kinetic chain) (see link to the left). Innovate specialises in creating exercise programming to help develop these strength and stability attributes for athletes of all levels in preparation for competition and enhanced performance.




References:

• McGuiness P.M. Biomechanics of Sport and Exercise, Second Edition, 2005. Centre of Gravity Pages 129-130, Centre of Gravity and Performance Page 135 and Centre of Gravity and Stability Pages 137-140.

Thanks,

Mitch