It increases strength
According to one study, strength can increase up to 10% percent when a person yells or screams. This happens because the fight or flight response gets activated as the body believes it’s in danger.
It empowers them
When a man screams he feels stronger. This kind of psychological feeling can help him lift the heavy weights he is carrying easier.
Distraction from pain
The act of screaming can shift the person’s attention from the pain he is feeling, and as a result can help him lift heavier weights easily.
Activating the nervous system
According to a study, screaming while lifting can help activate the nervous system, and as a result help the body recruit more muscle fibers that assist in weight lifting. (See How to strengthen your core muscles?)
Forced to exhale
Sometimes the grunting or the screaming sound happens when a person finds himself forced to exhale as a result of lifting a heavy weight.
To show off
Some men scream and make certain sounds while training to show off their strength and power.
To catch attention
Some men scream while lifting to catch the attention of someone they are interested in. (See Why are some people are attention seekers?)
To intimidate other men
Some men scream while lifting weights to intimidate others in order to reach one or more of their personal objectives.
Why do some men scream while lifting weights?
Why do people scream when working out? Why do You feel the Need to Grunt When You Lift Weights?