Muscle contraction ability refers to

The ability of muscles to contract is relatively important for human health. It mainly refers to the phenomenon of the muscle's ability to contract in response to stimulation. For example, there are isotonic contraction, isokinetic contraction and so on. Good muscle contraction can make a person's muscle coordination very good. For example, some football players have particularly good muscle contraction ability in a certain part of the body, so they can kick a better-looking football.

Muscle contraction ability

Muscle contraction is the phenomenon of muscle contraction in response to stimulation. In a narrow sense, it refers to the contraction of vertebrate skeletal muscles by propagating action potentials. A single action potential produces a monotonic contraction, and repeated action potentials produce a tonic contraction. In most cases, muscle contraction without action potential is caused by non-propagating depolarization. If the depolarization is limited to local muscles and is transient, it is called local contraction.

If the depolarization is complete and sustained in the muscle, it is called a contraction. The sustained contraction seen in smooth muscle is generally called spasm, but many are still accompanied by repeated action potentials or sustained depolarization. However, the sustained contraction seen in the adductor muscle of bivalve molluscs does not involve a change in electrical potential; this contraction is due to a gate-like structure.

(1) Isotonic contraction

The applied resistance is constant, and when the tension develops to a level sufficient to overcome the applied resistance, the tension no longer changes. However, at different joint angles, the tension generated by muscle contraction is different. The point in the entire range of joint motion where the muscles exert the greatest force is called the "apex". At this joint angle, the bone lever is least efficient.

For example, when pressing a barbell, the biceps contraction tension is greatest when the joint angle is 120°, and the biceps contraction tension is least when the joint angle is 30°.

During maximum isotonic contraction, the muscle can only achieve maximum contraction at the "apex", that is, the joint angle where the bone lever is least efficient. At other joint angles, muscle contraction is less than its maximum force. Within the entire range of joint motion, the tension generated by isotonic contraction of the muscle is often not the maximum tension of the muscle.

(2) Isokinetic contraction

A muscle contracts with maximum force at a constant speed throughout the joint's range of motion. But the resistance of the device is not constant.

Isokinetic trainer:

A nylon rope is connected to the centrifugal brake. Due to the centrifugal braking effect, the faster the rope is pulled, the greater the resistance generated by the device.

Features: The resistance generated by the equipment is adapted to the strength of the muscles.

Advantages of isokinetic contractions:

The applied resistance can be precisely adjusted as the joint moves, allowing the muscles to produce maximum muscle tension throughout the entire range of joint motion. .