Which of the following describes twitch summation?
Alpha motor neurons are the motor neurons that innervate skeletal muscle fibers. The alpha motor neuron divides into many branches as it reaches a muscle, each innervating a muscle fiber (note this in the image above). A motor unit is made up of one alpha motor neuron and all of the muscle fibers it innervates. The size of the motor unit is related to the muscle’s function. The motor units in muscles that need precise, organized control are very small, with only 3-5 muscle fibers per motor neuron. The motor units in muscles that regulate eye movement and muscles in our hands are relatively small. The motor units in muscles that perform more powerful but less organized acts, such as those in the legs and back, are huge, with 1000s of muscle fibers per motor neuron.
Author: OpenStax College; URL: https://commons.wikimedia.org/wiki/File:1012 Muscle Twitch Myogram.jpg; Copyright: This file is available under the Creative Commons Attribution 3.0 Unported license.
Twitch, summation and tetanus of skeletal muscle – easy and
), ten were fast-fatigue resistant (FR), and ten were fatigable quickly (FF). For these MUs, the relationship between maximal force and contraction time followed an inverse power function (Figure 1(a)), which was consistent with the one proposed by Fuglevand et al. . (1) (a) (b) If you want to be more formal (a) Figure 1: Twitches in the medial gastrocnemius muscle of the rat. (a) Models of the experimentally determined twitch forces of the selected 30 MUs (red: all MUs are shown) (the same colors are used for the three MU types). (b) Comparison of one experimental twitch and its two variants using the Raikova et al.  6-parameter function and the Fuglevand et al.  2-parameter function. The experimental twitch shape was modeled for each MU using the Raikova et al.  6 parameter analytical function, which was checked and confirmed on a large group of twitches reported experimentally. After applying the same firing pattern, these 6 parameters were, one FR, and one FF MU, respectively. The force scales for the four plots are all different. To measure MUs and muscle forces as a result of different stimulation patterns, custom software written in MATLAB was created. The inputs were taken from a text file (datatw.txt) with the following information:
Muscle twitch and muscle tension – motor unit size and force
Do you want to improve your endurance? What about the issue of power? Is it appropriate to give up hopes of being an all-star hitter or marathon runner because twitch ratios aren’t ideal? Certainly not. The muscle fibers targeted in various training programs may have an effect on athletic performance goals.
Specific muscle fibers make up skeletal muscles. Muscle fibers, like muscles themselves, are not exactly the same. Fast-twitch and slow-twitch skeletal muscle fibers have distinct roles that must be understood when it comes to movement and exercise programming.
Slow-twitch muscle fibers are immune to fatigue and are based on smaller, more prolonged movements and postural control. As compared to fast-twitch fibers, they have more mitochondria and myoglobin and are more aerobic. Because of their blood flow, slow-twitch fibers are also known as type I or red fibers. Fast-twitch muscle fibers produce larger and more intense forces for shorter periods of time before being fatigued. They are often referred to as white fibers or type II because they are more anaerobic and have less blood supply. Both types of fibers exist in skeletal muscles, but their proportions vary depending on a number of factors such as muscle function, age, and training.
Types of skeletal muscle
A muscle contracts and then relaxes when it is activated by a single action potential. The latent cycle occurs between the stimulus and the start of contraction, and is followed by the contraction period. The muscle relaxes and returns to its resting place after a peak contraction. These three cycles are referred to as a twitch when taken together.
Muscle Twitch Contraction: The latent phase is the interval between stimulation and contraction. Following a contraction, the muscle relaxes to its resting stress. These three cycles combine to create a single muscle twitch. If an additional action potential triggered a muscle contraction before a previous muscle twitch had fully relaxed, it would contribute to the overall amount of stress generated in the muscle. Summation is the name for this addition. Summation may occur within a muscle both through motor units to recruit more muscle fibers and within motor units to increase the frequency of contraction.