Skeletal muscles contract when strength or force is applied. Contractions come in different varieties: concentric, isometric and eccentric. The components of force distinguish which type of muscle contraction is experienced. Line of force, application of force, direction and magnitude make up the controlling factors; any variances alter the contraction. Additionally, muscle size affects muscular force development.
Components of Force
Pushing and pulling movements exhibit muscular force. The amount of force applied equates to magnitude. The force used must be greater than the weight you are lifting. Force requires direction, such as horizontal, vertical or both. The point of application is determined by which area of the body or the implement the force application takes place. The last element taken into account is the line of force or line of action. Make a line through the direction of force from the point of application to show the line of force. For maximum force, increase the amount applied in the exact direction of the desired motion. All components play a role during muscle contractions.
Muscular Contractions
Shortening of the muscles to create motion is a concentric contraction. To measure concentric strength, find the one repetition maximum of an exercise. Eccentric contractions are the opposite of concentric and generate significantly more tension as the muscles lengthen or stretch. Slower motion increases generated force for concentric contractions, whereas faster moves raise eccentric force levels. During isometric contractions, skeletal muscles try to shorten, but there is no motion.
Force During Muscular Contractions
Resistance with eccentric contractions dominates force. Guiding skeletal muscles back to the starting position after a bicep curl exemplifies eccentric contracting. Gravity provides the force, and the muscles bring the resistance. Contrarily, concentric contractions force defeats resistance. As the arm lifts the weight to complete a bicep curl, it overcomes resistance. An isometric contraction entails two equal opposing forces, resulting in tension without movement. Exercises that call for holding a specific position and stabilizing the body comprise isometric contractions.
Muscle Size and Force
Skeletal muscle contractions produce force contingent on the recruitment of muscle fibers. More fibers recruited equates to greater force output during contractions. Larger muscles contain more fibers; they turn out added force. Muscle length before contraction matters because stretching a muscle improperly ends with sub-par force levels. The effects of force on contracting muscles vary with each muscle and movement difference.
References
- "Fitness: The Complete Guide"; Frederick C Hatfield, PhD; 2008
- "Oxford Dictionary of Sports Science and Medicine"; Michael Kent; 2006
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