Muscular System: Structure, Function, and Strength Training

Posted on Dec 11, 2024 in Physical Education

The muscular system and the nervous system form a functional unit that results in muscle contraction in response to an electrical stimulus from the nerve. This is thanks to a perfect electromechanical coupling (excitation and contraction) mediated by complex biochemical mechanisms in which calcium plays a key role. Therefore, from a functional standpoint, it would be more correct to speak of the neuromuscular system. The mineral which plays a key role is calcium. The nervous system is the first active, and thanks to it, muscle contraction is done by sending nerve impulses to muscles.

The best example of this functional unit is the motor unit, consisting of a motor neuron together with a variable number of muscle fibers. The elements that form the motor unit are a motor neuron and a variable number of muscle fibers.

Structure of Muscle

  • The characteristic anatomical element in striated muscle is the muscle fiber. This cell has the property of muscle hypertrophy significantly under the stimulus of an active motor function, which will prove crucial in training.
  • The muscle is wrapped in a sheath of connective tissue or fascia called the epimysium, which penetrates inside, forming a kind of partition that separates between muscle bundles if it is the perimysium. The muscle fibers are separated by the endomysium. The function of these bundles of connective tissue is essential to constitute an elastic component parallel to the fiber, ensuring the structural cohesion between muscle fibers and serving as support for vessels and nerves.
  • Myofibrils are the contractile element of the muscle cell and are composed of myofilaments containing two types of contractile proteins called actin and myosin, whose special provision and ultrastructure are critical in muscle contraction, and its structural unit (smaller) is the sarcomere.

Mechanism of Muscle Contraction

  • The contraction of the muscle fiber begins with the arrival of the nerve impulse and is explained by the decreased length of each sarcomere by sliding between thick and thin filaments.
  • The motor unit follows the law of all or nothing: when a neuron is stimulated, all muscle fibers dependent on it contract together or not at all. Therefore, the intensity of muscle contraction as a whole does not depend on whether the nervous stimulus is more or less intense, but rather on the number of motor units that are recruited.

Muscle Fiber Types

There are two types of fibers: type 1 and type 2. Within type 2, there are two subtypes: type 2a and type 2b.

  • Type 1: Slow-twitch, high vascularity. Contraction takes between 99-140 milliseconds.
  • Type 2a: Fast-twitch, normal vasculature. They generally contract between 44-88 milliseconds.
  • Type 2b: Fast-twitch, low vascularity.

Vascularization: Having many capillaries and plenty of blood circulation.

Muscle Function

  1. Agonist Function: The agonist or prime mover is responsible for the main motion being made. Thus, we have the main and accessory muscles that act to help the main (prime) mover.
  2. Antagonist Function: This is the muscle that is inhibited so that the agonist can do its share. Its main function is the conduct of braking and controlling movement. For example, the action it performs when the triceps contracts is the biceps brachii.
  3. Fixing Function: This is the muscle that fixes the bone in which the principal muscle is acting.
  4. Synergist Function: When several muscles work together to perform the same action. This synergy can be concurrent (where two muscles have a common action and an antagonist, contracting simultaneously to eliminate the antagonistic action and the action is common, for example, oblique), or true/when a muscle contracts to accumulate one of the actions of a multijoint muscle that contracts. Example: wrist injury, accompanied by the fingers.

Strength

The development of physical qualities, and in particular force during the early ages, for basic training, is to improve the ability to move and control the child’s body. Morehouse states that force can be defined as the ability to exert tension against resistance. Physically, force is the product of mass times acceleration. Zatziorski indicates that strength is an ability to overcome external resistance or counter it by muscular effort.

Classifications:

  1. Factor Acceleration (Naglak):
    • Explosive Strength: Resistance is overcome is not restricted, with maximum acceleration.
    • Fast Force: The stress overcomes the resistance is not maximum and a maximum acceleration is not.
    • Slow Force: Resistance is overcome with constant speed. They appear in cases of maximum resistance. The acceleration is zero.
  2. Based on Your Statement:
    • Static Force: Force developed by maintaining an external resistance so there is no movement.
    • Dynamic Force: Is one that moves or ends by resistance so there is moving in muscle.
  3. Depending on the Type of Muscle Contraction:
    • Isometric: No movement (active and passive).
    • Isotonic: If there is movement (concentric: joins both segments of muscle (biceps), closing contraction, and eccentric: muscle contraction apart).
    • Combined or Auxotonic: Different muscle groups.
  4. Terms of Training:
    • Maximum Force: The ability to achieve the maximum possible force in a muscle or muscle group.
    • Strength-Resistance: Is the repetitive contraction of muscle, keeping the maximum force possible time.
    • Explosive Strength: It is overcoming a resistance, not limit, at maximum speed. Reaching the force in the shortest possible time.
    • Speed-Strength: Ability to accelerate a mass that is not maximum acceleration.
Development of Force

Using the method proposed by Badillo for force development, include the following:

A) Method of Maximum Strength Training: We can develop the maximum force from two options: muscle hypertrophy or muscle coordination. (Method in concentric contraction scheme: maximum intensity, and pure concentric pyramids)

Specific Training
  1. Strength-Resistance: Aerobic in nature, it begins to work on both sexes around 9-10 years, but its anaerobic lactic side are girls who can begin training earlier (12-14 years), and for boys, it was delayed until 14-16 years, always incident on the repetitions. Resistance force is done in high repetitions (40-60) with low weight (low training load).
  2. Force-Velocity: In girls, it begins working at 10-12 years, and in boys, two years later, still having an impact on speed. The work force would be little repetition speed, intermediate weight but very fast execution speed (maximum = 100%).
  3. Maximum Force: Can start training for girls about 12-14 years, and boys about 14-16 years, emphasizing hypertrophy and intermuscular coordination. Working mode with few repetitions (2-4) and maximum possible weight to bear (from 90 to 100%).
Other Aspects
  • In the early ages of development, the possibility of force is weak.
  • Children are not good at supporting static body positions and prolonged muscle tension.
  • Maximum strength gain should not be a basic objective with young people.
  • A good dosage can promote growth.
  • Must make a multifaceted and multilateral training.
  • Use first car load overhead.
  • The work overload must be progressive and in accordance with the physical and biological age of the subject.