Mixed

Resistance exercise training shifts the acute protein synthesis response to be specific to myofibrillar proteins, whereas endurance exercise training shifts it to be specific to mitochondrial proteins, despite both stimulating mixed muscle protein synthesis acutely in the untrained state.

If your goal is to increase muscle size and strength, you must perform resistance training. This type of training specifically triggers the synthesis of myofibrillar proteins, which are responsible for muscle contraction and size. If you only do endurance exercise (like running or cycling), you will not stimulate myofibrillar protein synthesis, even if you are in a fed state. Conversely, if your goal is endurance performance, endurance training specifically targets mitochondrial proteins. Do not assume all exercise builds muscle equally; the type of exercise dictates the type of protein built.