Final answer:
The assertion about muscle activation is false; muscles generally can handle more load during eccentric contraction than concentric, with less effort.
Step-by-step explanation:
The statement that a load that activates 75% of a muscle during concentric action will only need 50% activation eccentrically is false. Generally, muscles can handle more weight during eccentric contractions compared to concentric ones. This is because the muscle is lengthening and thereby can handle greater loads with less perceptible effort.
Different muscles and different exercises might activate varying percentages of muscle fibers during concentric versus eccentric actions. However, the exact ratio of activation is not a fixed 75% to 50%. Muscle activation during eccentric contraction typically requires less effort because the muscle is resisting the lengthening process rather than actively shortening as it does during concentric contraction.