Final answer:
During the "sticking point" of an exercise, muscle force is equal to the resistance, leading to a temporary halt. This involves the power stroke of the cross-bridge cycle where actin and myosin form attachments, pulling the filaments together and shortening the sarcomere to facilitate muscular contraction.
Step-by-step explanation:
During the "sticking point" of an exercise, the force produced by the muscle equals the resistance of the weight being lifted. At this critical juncture, cross-bridge formation between the actin and myosin molecules is paramount. The release of inorganic phosphate (Pi) facilitates a conformational change in the myosin head, known as the power stroke, where the head moves toward the M line, pulling the actin filament with it and shortening the sarcomere.
This is the mechanism through which muscle tension and contraction are generated. However, during the sticking point, there is an equilibrium, meaning the muscular force is equal to the external resistance, resulting in a momentary halt in movement until the muscle can generate additional force to continue the lift.
The concept of the 'sticking point' is critical to understand in resistance training as it implicates the level of tension produced by a muscle and the amount of cross-bridges formed. The number of muscle fibers contracting and the force of their contractions determine the overall strength of the muscle's contraction. The optimal length-tension relationship is achieved when there is the greatest zone of overlap between actin and myosin, and muscles that are overly stretched or compressed do not produce maximal power.