Final answer:
An attempt to lift an object too heavy to move results in an isometric contraction, where the muscle generates tension without changing in length.
Step-by-step explanation:
Attempting to pick up an object that is too heavy to be moved will result in an isometric contraction. This type of muscle contraction occurs when muscle tension changes but muscle length remains the same. This is in contrast to isotonic contractions, where muscle length changes as it moves a load but tension remains constant. In an isometric contraction, the muscle does not shorten because the load exceeds the tension that the muscle can generate. Considering the two main types of muscle contractions, isometric and isotonic with its subtypes concentric and eccentric, the latter involves either shortening or lengthening of the muscle to move a load. When the biceps contract and shorten the forearm towards the body, this is a concentric isotonic contraction. If the triceps were to contract after that, they would extend the arm by lengthening, which could also be part of an isotonic contraction.