A Japanese chiropractor thinks he knows why Freiza lost to Gokku in Dragon Ball Z. And what is said reason? Bad posture.
In an interview with Netarika, chiropractor Yuji Ogawa discussed exactly this, pointing out Frieza's poor positioning in his hover pod.
Ogawa notes that it's hard to tell how first-form Frieza sits in the pod from the manga, so he used a collectible to explain what he meant.
Frieza sits slightly forward in his hover pod, making a strong impression when viewed head on. But from the side, he's hunched over.
Which makes it easier to see said posture in these images from the anime.
"In the pod, he's relaxing in a stooped over position. He also has his arms in the worst position." Because of that, Ogawa says that he will get stiff shoulders, which aren't good if you are planning on kicking Goku arse.
Ogawa images that Frieza is in this position for long stretches of time, saying this not only puts a burden on his nervous system, but also his internal organs.
All this means he is not operating in optimal condition. And because this, he was not going to perform well and was bound to lose.
His third form, no doubt, was a direct result of slouching, so please, sit up straight regardless or not if you're going to fight Goku.
But in his final form he had perfect posture and form.
I was expecting him to say "He lost because he cut in half between these to vertebrae here."
Yep, that's what I was thinking too.