Biomechanics
Question 1: Stretch- shortening cycle, plasticity, and electrochemical delay
In biomechanics, the stretch-shortening cycle refers to the active extension of the muscle, which is then followed by an instant contraction of the same muscles. During the stretch-shortening, the muscle-tendon complex quickly alters its length, which makes the tendon to act as a catapult. Plasticity is the capability exhibited by the Muscle Tendon Complex (MTC) to adjust to persistent alterations in filling up and declining. Electromechanical delay refers to the time taken before a muscle can generate power, which is between 30 and 100 milliseconds. This is the period taken from the first instances when the muscle exhibits electrical activity to the generation of measurable tension.
Question 2: Four functions of Muscle-Tendon Complex
The functions of the muscle-tendon complex include; regulation of movement through the transmission of force via the passive components to the body’s skeleton. The cardinal principle underlying how the MTC works is that it can only pull by bringing the two points attached to the muscle closer together. The MTC acts as the source of energy required for the body to move vertically, thus achieve liftoff by increasing the potential and kinetic energy of the body’s center of mass. The MTC creates force and displacement that are in the same direction. Shortening for the MTC is only achieved when the energy generated by the MTC is higher than the outward power applied to it, which is known as the concentric action. The MTC acts as a motor or source of energy during the concentric action.
The other function of the MTC is that it acts as a brake during the braking phase, which occurs when the body loses the kinetic and potential energy. This energy is absorbed by the MTC, which continues to generate power as well as extending in a process known as the eccentric action. Here the MTC acts as a brake or a sink for the energy when it absorbs the power. Through the isometric actions of MTCs at other joints with less muscle activity, energy is transferred from active muscle joints to other body parts. These MTCs at the other less active joints act as struts to transfer energy to the different sections of the body. The last function of the MTC is that during the lengthening and contraction of the muscles, it acts as a spring.
Question3: The components of the muscle-tendon complex
The two components of the muscle-tendon complex are the muscle and the tendon. Within the muscle, the functional unit is known as the sarcomere, which consists of two filaments set longitudinally with the ability to contract. The two threads are the thin and thick filaments which interact to produce a muscle action. The tendon is the other component of the MTC and is a viscoelastic structure in nature.
Question 4: How tendon produces force and its properties
Tendons offer force only in one direction when stretched, and before the power created by the muscle is transmitted to the bone, the slack must be taken up. The two main properties of the tendon that contribute to force are elasticity, viscosity, and stiffness. Tendons can stretch when a force is exerted on them. Tendons are stiff hence offer resistance to stretching, thus more power results from the stretching.
Question 5: The difference between a pennate and a parallel muscle
The parallel muscle has more elongated fiber strands arranged in series, but with fewer fiber strands arranged in parallel. On the other hand, pennate muscles have more muscle fiber strands arranged in parallel that are shorter in length. In other words, the lateral muscles have more sarcomeres in series that are long, whereas pennate muscles have fewer sarcomeres in sets, but more sarcomeres in parallel.
Question 6: The difference between fatigue and task failure
Fatigue refers to the decline in the capability of the neuromuscular system to generate force irrespective of the amount of energy need in any given circumstance. On the other hand, task failure is the failure or inability to proceed or finish a required task.
Question 7: How to increase the force-producing capability of the MTC
The force in a muscle that is in a lengthening action can be improved by following it with the contraction muscle action. The MTC force-producing capabilities are enhanced by increasing the size of the muscle fibers through heavy and consistent exercise. The ability of the MTC to produce force can be increased by lengthening the MTC, which increases the tension in the tendon resulting in an increase in the energy within the MTC. The force-producing capabilities of MTC can also be increased by increasing the velocity of the tendon, which in; turn increases the power duet the viscosity of the tendon. The amount of force produced by an MTC can be enhanced through the recruitment of various combinations of motor units.
Question 8: How a muscle works differently when attached to a tendon
A muscle works differently when attached to the tendon compared to when isolation due to several factors. Firstly, when a muscle is attached to the tendon, the tendon transmits the power generated by the muscle to the bone, which enhances movement. Due to the elasticity and viscosity of the tendons, a muscle attached to the tendon can effectively transmit power to the skeletal segment of the body as compared to one working in isolation.
Reference
Flanagan, S.P. (2019). Biomechanics: A Case-Based Approach (2ndEd).Burlington, MA: Jones and Bartlett Learning. Retrieved from: https://www.amazon.com/Biomechanics-Case-Based-Approach-Sean-Flanagan/dp/1284102335