Damian Farrow (2018) in ‘All the Racquet: What science tells us about the pros and cons of grunting in tennis’, put the advantages of a grunt in simple terms.
Ball velocity increases with a grunt.
In fact if you check out “The effects of grunting on serve and forehand velocities in collegiate tennis players”. You’ll see two impressive figures.
If you grunt, you get: a 3.8% increase in groundstroke-hitting velocity and a 4.9% enhancement in velocity.
According to that report “The velocity, force, and peak muscle activity during tennis serves and forehand strokes are significantly enhanced when athletes are allowed to grunt.”
“Grunt history, gender, perceived advantages, and disadvantages of grunting, years of experience, highest level of competition, and order of testing did not significantly alter any of these results”
I must confess that the exact science behind this phenomenon slightly eludes me, but allegedly, increased force on impact lies within the concept of kinetic energy. KE is the energy of motion which is transferred on impact. KE is calculated as one half of the product of mass and velocity squared.
Grunting, so brainy people say, tightens the body core which increases the mass behind the tennis strike, thereby increasing the force on impact resulting in the increased velocity of the tennis ball.
The carry over to Olympic weightlifting at CrossFit London is obvious. If you lift quietly, the chances are you are missing out on some free energy that could move the bar to where you want it.
Try grunting when you snatch.
by Andrew Stemler