A reflex.
The body regulates the strength of muscle contractions primarily through two mechanisms: motor unit recruitment and frequency of stimulation. Motor unit recruitment involves activating additional motor units to increase the force of contraction, allowing more muscle fibers to participate in the action. Additionally, the frequency of stimulation refers to the rate at which nerve impulses are sent to the muscle fibers; higher frequencies can lead to greater tension through a process called summation, where successive contractions build on each other.
Electrical stimulation of the brain. DBS.
Electrical nerve stimulation
Peristalsis is the term for the rhythmic contractions of the esophagus. These wavelike contractions move food toward the stomach.
The tendon that connects the hamstring to the knee is called the patellar tendon.
WHAT IS THE ANSWER ISN'T IT CALLED "ANSWERS" GIMME THE ANSWER
only in the last trimester when they prepare the uterus for labor and are called Braxton Hicks contractions.
Tapping on the patellar tendon stretches receptors called the muscle spindles in the quadriceps muscle group of the anterior thigh. This stimulus evokes a rapid motor reflex to contract the quadriceps and shorten the muscles. This process is called the patellar reflex.
I think you may be referring to what are called "Braxton-Hicks" contractions.
a spasm
the heart
peristalsis