WHY STRENGTH ISNT THE ONLY FACTOR OF MUSCLE SIZE Strength is dependent on plenty of factors, but tendon insertions play a huge role in the ability to exert maximal force. Lets use a biceps curl as an example. Say youre curling a 60-pound dumbbell and youre halfway up at 90 degrees and moving very slowly. To figure out a general estimate of muscle force requirements of the biceps, you divide the moment of the resistance arm by the length of the muscle arm. This means that you multiply the resistance (60 pounds) by the resistance arm (say 15 inches from the elbow to the dumbbell) and then divide it by the muscle arm (say 1 inch from the elbow to the biceps insertion). This would give us 900 inch-pounds, a measure of torque. In this example, the biceps must produce 900 inch-pounds of force. What happens if the individuals biceps tendon inserts 2 inches away from the fulcrum? Now you divide by 2 instead of 1, which means that the biceps now only has to produce 450 inch-pounds of force to hold a 60-pound dumbbell at a 90-degree elbow angle. This demonstrates just how advantageous tendon insertions are to external force production - two guys could have equal strength in their biceps but one can lift twice the amount of weight due to his leverages. Torso, arm, femur, and tibia lengths and proportions all play a large role in the display of strength as well.
Posted on: Tue, 06 Jan 2015 23:18:03 +0000
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