If the effect of a load placed at the end of an extremity is greater than the effect produced by the contracting musculature, what type of muscular contraction occurs?

The scenario described involves a situation where the load applied exceeds the force generated by the contracting muscles. In this context, the type of muscular contraction that occurs is eccentric contraction.

Eccentric contractions occur when the muscle lengthens while under tension, typically when the muscle is trying to control or slow down a load. This happens when the force generated by the muscle is less than the external load, causing the muscle to elongate in the process. For example, when a person lowers a weight, the biceps undergo an eccentric contraction as they control the descent, allowing the load to extend the muscle against gravity.

In contrast, isokinetic contractions occur at a constant speed throughout the range of motion, which is not applicable to this scenario. Isometric contractions entail maintaining a constant muscle length despite tension, where no movement occurs, and concentric contractions involve muscle shortening while generating force, typically when lifting a load against gravity. Given the condition presented, the emphasis on muscle elongation under load directly aligns with the definition of eccentric contraction.