Does yelling while you lift make you stronger?

Short answer

Yes, for squeezing, kicking and racket strokes. Shouting while squeezing gave 17% more grip force, and kick force and tennis ball speed also rose. Whole-body pulling was different: when 31 people pulled a fixed bar in a deadlift position, there was no difference.

Does yelling while you lift make you stronger?
'Shout → the brain's brake loosens → more force': is it true?
A common belief is that a sharp shout when lifting something heavy gives you more force. Tennis players and fighters also shout as they strike. We started with experiments where the same people alternated between shouting and staying quiet.
Squeezing while shouting?
Grip force was 17% higher
19 people squeezed a handle as hard as they could once silently and once while shouting. Grip force was 259.7 without a shout and 304.4 with a shout, about 17% higher. The order was switched between people.
Why more force?
The brain's brake got shorter
In the same experiment, the moment when the brain briefly cuts the signal to the muscle shrank from 195.3 to 179.3 milliseconds while shouting, and the pupils got larger. In another experiment, 16 people shouted while holding a hard squeeze, and grip force rose then too.
It worked in sport movements too
Kick force and tennis ball speed went up
20 people kicked harder with a shout than without, with how hard the bag was pushed going from 22 to 24.2. 10 people hit the tennis ball 3.8% faster when grunting, with no difference in oxygen use or how hard it felt. In a study of 32 people, serve and forehand speed also rose.
But not in the deadlift
Pulling with the whole body showed no difference
31 people pulled a fixed bar in a deadlift position 3 times with a shout and 3 times without, and maximal force showed no difference. In a study where 10 people did trunk exercises with shout-style breathing for 3 weeks, hockey shot speed also showed no difference.
Does it have to be a shout?
A hard exhale showed no difference in force
In a test pushing hard on a force plate in a forehand position, there was no difference in force between grunting and a hard exhale. Grunting gave more force than breathing in or holding the breath while pushing. When 42 people silently repeated a swear word in their head, grip force showed no difference from repeating a neutral word.
Summary: a shout adds force to one short, hard effort
No difference when pulling in a deadlift position
In moves that need maximal force at once, like squeezing, kicking and hitting with a racket, a shout raised force by 3.8 to 17%. In the whole-body deadlift position there was no difference. For one short burst like squeezing or hitting, making a sound or exhaling hard is enough, and no result showed bigger muscles from shouting.