Function Muscle coactivation allows muscle groups surrounding a joint to become more stable. This is due to both muscles (or sets of muscles) contracting at the same time, which produces compression on the joint. The joint is able to become stiffer and more stable due to this action. For example, when the bicep and the triceps coactivate, the elbow becomes more stable. This stabilization mechanism is also important for unexpected loads impeded on the joint, allowing the muscles to  coactivate and provide stability to the joint in a quick fashion . This mechanism is controlled neuromuscularly, which allows the muscle(s) to contract. This occurs through a motor neuron sending a signal (through creating action potentials) to the muscle fiber to contract by releasing Acetylcholine . When signals are sent to all muscle fibers in a muscle group, the muscle group will contract as a whole.
Function Muscle coactivation allows muscle groups surrounding a joint to become more stable. This is due to both muscles (or sets of muscles) contracting at the same time, which produces compression on the joint. The joint is able to become stiffer and more stable due to this action. For example, when the biceps and the triceps coactivate, the elbow becomes more stable. This stabilization mechanism is also important for unexpected loads impeded on the joint, allowing the muscles to quickly coactivate and provide stability to the joint . This mechanism is controlled neuromuscularly, which allows the muscle(s) to contract. This occurs through a motor neuron sending a signal (through creating action potentials) to the muscle fiber to contract by releasing acetylcholine . When signals are sent to all muscle fibers in a muscle group, the muscle group will contract as a whole.
R
bicep
biceps
A
quickly
D
in a quick fashion
R
Acetylcholine
acetylcholine