- Load: the force exerted by the weight of an object, such as a dumbbell, on a muscle;
- Muscle tension: the force exerted on the object in question by the contracting muscle.
Muscle tension and load, therefore, are opposing forces which, as such, oppose each other.
To overcome a load, the muscle tension must be greater than the force (weight) it exerts.
Muscle Contraction and Types of Contraction
Muscle contraction is the active process by which a force is generated within the muscle.
There are two types of contractions: dynamic contractions and static contractions.
).Plyometric contraction
The plyometric contraction is an explosive concentric contraction, immediately preceded by an eccentric contraction; in this way the energy accumulated in the elastic structures of the muscle in the previous eccentric phase is exploited.
To learn more: Plyometry: What is it and How does it work? Applied, the muscle does not change its length and the distance between the muscle insertions remains unchanged.
The muscle develops tension and changes its length by producing work.
The distance between the insertions varies during the contraction.
The voltage developed is such as to allow the applied resistance to be overcome. The muscle shortens causing the insertions to approach.
The developed tension is less than the applied resistance and the muscle stretches, leading to the removal of the insertions.
The muscle shortens by developing a tension that remains constant for the entire duration of the shortening period. In reality, there are no isotonic contractions in vivo, as the tension developed varies with the variation of the lever. The isotonic contraction is approached by performing the exercises with the use of equipment equipped with cams.
The muscle develops maximum tension for the entire range of motion, shortening at a constant speed (special isokinetic equipment is used).
The developed tension increases progressively with the muscle shortening (eg elastic bands).
These are explosive concentric contractions immediately preceded by eccentric contractions; in this way the energy accumulated in the elastic structures of the muscle in the previous eccentric phase is exploited.
.jpg)
