- Pre-load/Free load: The load acting on the muscle before it begins to contract.
- Afterload: The load acting on the muscle after the muscle starts to contract.
Q.1 What is Frank Starling’s law?
- The Frank-Starling law states that “the force (or energy) of contraction, however measured, is a function of the initial length of the muscle fibers”. Up to a physiological limit, greater the initial length, greater is the force of contraction. Though originally described for the heart, it is also applicable to the skeletal muscle. [In the case of heart, the diastolic filling determines the initial length (preload) of muscle].
Q.2 Give examples of freeloading and afterloading in human body.
Afterload:
- The lifting of weight from the ground under normal condition.
Freeload:
- The continuous contraction of the antigravity muscle to maintain body posture
- Throwing a stone to a far distance with force.